adaptation to climate change

French edition of Scientific American

Special publication realized in partnership with

ADAPTATION TO CLIMATE CHANGE

www.inra.frMarch 2015

2] Pour la Science - INRA 2015

INRA, for a fine, useful, shared

and responsible ScienceThe French National Institute for Agricultural Research (inra) is a public research organisation

set up in 1946 and placed under the supervision of the ministries in charge of Research and Agriculture. It is entrusted with 7 main missions :

Producing and disseminating scientific knowledgeContributing to the definition of the national research strategyInforming public and private decision-making bodiesDeveloping innovation and know-howContributing to training in and through researchDeveloping scientific culture and participating in the science/society debate Promoting ethics and a code of conducts in research

Within its three main domains of interest, food, agriculture and environment, inra carries out research activities whose aim is to promote an agriculture that is competitive, environment- friendly, favourable to territories and natural resources and better suited to human nutritional needs as well as to the new uses of agricultural products. Those activities intend mainly to contribute to food security in a context of global climate change by 2050.

At the beginning of 2014, inra employed 8,290 full-tenure staff members, including 1,840 research scientists and 1,756 engineers. Its 186 research units and 48 experimental units are located in 13 scientific divisions and 17 regional centres.

Based on scientific publications, inra ranks 3rd in the world in agriculture and 4th in plant and animal sciences. In addition, inra ranks among the first research organisms in the world on microbiology, ecology and environmental sciences.

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[3 Pour la Science - INRA 2015

Producing and disseminating scientific knowledgeContributing to the definition of the national research strategyInforming public and private decision-making bodiesDeveloping innovation and know-howContributing to training in and through researchDeveloping scientific culture and participating in the science/society debate Promoting ethics and a code of conducts in research

FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4F . Houllier

ADAPTATION TO CLIMATE CHANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6J .-M . Guehl, J .-F . Soussana

CHALLENGES FACING AGRICULTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10F . Debaeke, S . Pellerin, J . Le Gouis, A . Bispo, T . Eglin, A . Trvisiol

ADAPTING LIVESTOCK SYSTEMS TO CLIMATE CHANGE . . . . . . . . . . . . . 14A . Mottet, D . Renaudeau, J .-F . Soussana

TOWARDS ADAPTIVE FOREST MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . 18F . Lefvre, D . Loustau, B . Marais

PRESERVING THE RICHNESS OF AQUATIC ENVIRONMENTS . . . 22M .- . Perga, . Prvost, J .-L . Baglinire

ANTICIPATING A DECREASE IN WATER RESOURCES . . . . . . . . . . . . . . . . 26F . Habets, Ph . Mrot, B .Itier, A . Thomas

MOVING TOWARDS A NEW DISCIPLINE HEALTH ECOLOGY . . . . 30O . Plantard, L . Huber, J .-F . Gugan

HOW DO WE COPE WITH MIGRATION FLOWS? . . . . . . . . . . . . . . . . . . . . . . . . . . 36F . Gemenne

THE ECONOMIC ISSUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38P .-A Jayet, S . De Cara, N . de Noblet-Ducoudr

FROM THREATS TO SOLUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42J .-F . Soussana, T . Caquet, J . Mousset

THE INRA METAPROGRAM ON ADAPTATION OF AGRICULTURE AND FORESTS TO CLIMATE CHANGE . . . . . . . . . . . . 46T . Caquet, J .-M . Guehl, N . Breda

Table of contents

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The successive assessment reports issued by the Intergovernmental Panel on Climate Change, the IPCC, showed that major climate changes are underway and their impacts have been proven. Regardless of what policies are implemented to re-duce greenhouse gas emissions, these impacts will continue to increase for several decades to come due to inertia in both the climate system and the direc-tions of our societies.

Profound changes are expected to affect not only natural continental and oceanic systems, agricul-tural, forestry and fishery production, but nume-rous other economic and human activities. Once merely the object of scientific research for a more or less precisely defined future, the issue of cli-mate change has become a major challenge facing society today. Beyond significant advances already made furthering our knowledge about different aspects of the subject, there re-mains one clear need which is for a "solutions agenda" - and while the scientific community is not solely concerned with developing this agenda, it has a clear responsibility to address the concerns of society and an important role to play.

In this context, research on the interactions between climate change and crops, grasslands, fo-rests, wetlands and natural environments are clearly essential. These more or less anthropized continen-tal surfaces cover a major percentage of our planets land masses and support essential services for so-ciety: food safety, water resources and global health all depend directly or indirectly on these areas.

These continental surfaces are deeply involved in the cycles which determine changes in atmospheric concentrations of greenhouse gases, which we know to be the origin of observed and expected climatic changes. Whether naturally occurring or directly related to human activities, the numerous processes

and factors involved have been the subject of scienti-fic research for several decades: biogeochemical and ecological mechanisms; monitoring, quantification and modeling of greenhouse gas emissions and car-bon cycle, with particular attention paid to soils and biomass and their derived products; and effects of agricultural and forestry practices. The fight against climate change rapidly became the priority and re-mains the essential issue today: emission reduction commitments were signed at the international level (at the Kyoto Protocol of 1997 and in follow up ses-sions) and European and national public policies were put in place with the view to reducing green-house gas emissions.

In the diversity of their nature and uses, these continental surfaces are affected by changes in at-mospheric composition and the climate. In France, in the 2000s, the observation by Isabelle Chuine that

grape harvest dates are gradually advancing and Nadine Brissonss analysis of the role climate plays in the stagnation of wheat yields both contributed to the recognition of the existence and the extent of the phenomenon; the drought and heat wave that occurred in the summer of 2003 also played a major role in raising awareness of the fact that projected increases in climate variability are at least as - if not more - significant than the underlying average rates of global temperature increase. Beyond these emble-matic examples, characterizing risks associated with climate change remains an important scientific issue as viewed from several angles: the frequency and magnitude of impacts caused by extreme events;

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Research on adaptation to climate change: a priority !

Adaptation obviously raises distinct scientific issues. It is clear that effective adaptation

strategies will require a combination of different disciplines, technologies and approaches.


Forewordthe evaluation of their economic and social consequences.

With the existence of global warming well established and the diversity and magnitude of its impacts progressively becoming more obvious, it is adaptation to climate changes that has emerged in recent years as the priori-tized area for research. In 2006, Nicholas Stern reported the effect of global warming on the world economy: he stressed that strong, early action through adaptation measures would outweigh the costs of not acting. At the 2010 United Nations Climate Change Conference held in Cancun, adaptation to climate change was presented as a necessary complement to mitigation policies. Depending on the nature of the systems under consideration, adaptation obviously raises distinct scientific issues. In all cases, however, it is clear that effective adap-tation strategies will require a combination of different disciplines, technologies and ap-proaches: diversification, agronomy and plant genetics related to crops; animal nutrition, ge-netics, methanization for waste treatment and building design for livestock; adaptive mana-gement for forests and numerous natural envi-ronments. Raising awareness about increasing climate variability and anticipated health risks also appear more and more frequently as major challenges to be addressed.

Understanding the role agricultural and natural continental surfaces play in the major biogeochemical cycles, conducting detailed analysis and assessments of the impacts of cli-mate change, designing and evaluating com-bined mitigation and adaptation strategies: these different areas of focus are very clearly interrelated. All call for a certain dialogue between disciplines between natural, physi-cal, life sciences, Earth and planetary sciences and economic and social sciences - and a dia-logue between observation, experimentation and modeling. They also require far more than isolated studies to further our unders-tanding of the dynamics that exist on different scales, to develop systematic approaches and to strengthen international collaboration between research institutions. Today, we are seeing a proliferation of national, European

and global scientific initiatives. Aligning and ensuring consistency of these complex pro-jects are challenges in themselves, but their diversity also stands out as an indicator of the wide spectrum of relevant issues and of an increasingly mobilized scientific community.

This publication is the result of an editorial collaboration with Pour la Science and a col-lective scientific project coordinated by Jean-Marc Guehl, Thierry Caquet and Jean-Fran-ois Soussana, an initiative I welcome. Viewed through the prism of research and expertise at the French National Institute for Agricultural Research (INRA) and its numerous collabora-tions, this publication shows just how far re-search on global warming has evolved; it des-cribes advances of knowledge and illustrates the movement committed to climate change adaptation - which I am pleased will contribute to developing the urgently needed solutions agenda. This work is all the more important given that, with regard to food safety, water re-sources, biodiversity and global health issues, climatic transition is happening today within the context of a series of multiple transitions and global changes - demographic transition, food and nutritional transition, energy transi-tion, changes in land use - the combination of which represents a true challenge.

Franois Houllier, President of INRA

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AGRICULTURE, FORESTS AND ECOSYSTEMS

Jean-Marc GuehlDirector of INRA AAFCC metaprogram.Head of the INRA-Universit de Lorraine Forest Ecology and Ecophysiology Joint Research Unit.

Jean-Franois SoussanaINRA Scientific Director Environment.

The first volume of the Fifth Assessment Report on climate change by the Intergovernmental Panel on Climate Change (IPCC) was published on September 27, 2013 . It addressed the climate system and climate changes . This report confirmed the occurrence of global warming since the 1950s with temperatures rising as much as 0 .6C . Projections for 2100, dependent on human activities and uncertainties in modeling, estimate warming to vary between 1 .1 and 4 .8C . A second volume issued on March 31, 2014 detailed the impacts of climate change, possible adaptive actions and the vulnerability of exposed systems and human populations . A third volume devoted to research aimed at mitigating the impacts of climate change was published on April 11, 2014 . In October 2014, a final synthesis was released . The 21st Conference of Parties on Climate Change, which will take place in Paris in December 2015, will address its findings .

Adaptation to climate change

This exercise in collective scientific expertise and forward reasoning involved more than 800 scientists from around the world. It is based on thorough analysis of scientific publications and methodology. Each conclusion is characterized by a confidence index and an index of uncertainty. While the first report from 1990 only involved specialists in climate science, the current report highlights the interdisciplinary character of adaptation approaches. Experts in both natural and social sciences participa-ted, indicating a common interest in informing poli-tical, economical and social choices by assessing the scientific basis of climate change and the impacts that need to be addressed, which will vary significantly depending on the region of the world.

Continental land surfaces, in all of their diverse nature and uses, whether cultivated or semi-na-tural environments (forests, grasslands, aquatic

environments, wetlands and wilderness areas), have a particularly complex role in the context of climate change. The potential risks and impacts are huge relative to plant and animal resources, rela-ted economic activities, food safety, the functioning of ecosystems, biodiversity, water resources and health. Furthermore, these surfaces emit green-house gases (carbon dioxide, methane, nitrous oxide) through natural processes, but also because of human activities (agriculture, livestock, defores-tation). But we will see that, at the same time, they can absorb and sequester large amounts of carbon and therefore can mitigate the importance of cli-mate change.

The Swedish chemist Svante Arrhenius was the first to predict, in 1896, that the accumulation of carbon dioxide in the atmosphere linked to the use of fossil fuels would lead to a warming of the

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Faced with progressive warming of the Earths surface over several decades and the increased frequency of extreme events, it is time to do more than just fight the greenhouse effect and estimate the full magnitude of climate change. It is necessary now to evaluate the consequences of these changes and anticipate adaptations that should be considered.

Within this framework, the French National Institute for Agricultural Research (INRA) has created a metaprogram called Adaptation of agriculture and forests to climate change (AAFCC).

The publication of the fifth IPCC report has provided the opportunity to present a comprehensive overview of research conducted on adaptation to climate change.


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Modeling results (CNRM-CM5 model) indicating annual average differences in rainfall (in millimeters per day, top image) and temperature (in C, bottom image) between the period 1970-2000 and the period 2071-2100 for the scenario RCP8.5 described in the 5th IPCC report. It would rain less in some tropical regions, including the Amazon, and temperatures could increase by 10C in more northern regions.

planet. But it was in 1958, as part of The International Geophysical Year, that geochemists Charles Keeling and Ro-ger Revelle of the Scripps Institution of Oceanography installed at the Mauna Loa Observatory, located at the summit of the volcanic island of Hawaii, the first monitoring station for continuous-ly measuring concentrations of atmos-pheric carbon dioxide. These measure-ments represent the longest time series available today.

Changing carbon dioxide sinks and sourcesWhat were the main findings? The atmospheric concentration of carbon dioxide has increased dramatically since 1958. Close to 315 ppmv (parts per million by volume) in 1958, it exceeded 400 ppmv for the first time in May 2013. Values recorded in air bubbles trapped in Arctic and Antarctic polar ice before the industrial era (late 18th century), are close to 280 ppmv. The rate of increase in carbon dioxide concentration is also growing: from 0.7 ppmv per year recorded in the early 1960s, it rose to 2.0 ppmv per year between 2000 and 2010. This acceleration is similar to the rise in fossil carbon dioxide emissions, due notably to the use of fossil fuels (coal, oil, gas): these emissions reached 35 gigatons (35 billion tons) in 2011. Deforestation, another source of carbon dioxide emissions, presents a contribu-tion from tropical forests of 4 gigatons of carbon dioxide per year.

But next to these disturbing figures, research shows that there in fact exist "shock absorbers" to limit the magni-tude of these increases. As such, what we find in the atmosphere represents about half of the amount of carbon dioxide actually emitted. This pheno-menon applies to assessments conduc-ted over the last decade, but also to levels recorded since the beginning of the industrial era. It is estimated that 2,000 ( 312) gigatons of carbon dioxide were emitted into the atmos-phere from 1750 to 2011 due to human activities, of which 1,340 ( 110) were attributed to the use of fossil fuels and cement production, and 660 ( 295) to deforestation and land use changes; a "mere" 800 gigatons accumulated in the atmosphere.

Progress made in evaluating car-bon fluxes and assessing ocean-atmos-pheric and land-atmospheric interface exchanges, through measurements and

stocks. In addition, the increased concentration of carbon dioxide has a "fertilizing" effect, stimulating photo-synthesis and forest productivity and therefore rendering this "trap" more efficient. In addition, atmospheric de-position of mineral nutrients from air pollution, such as nitrogen and sulfur, could strengthen this fertilizing effect. The contribution from agricultural sur-faces is more variable: in Europe, grass-lands would represent a carbon sink, whereas crop fields act as a source.

Will the terrestrial carbon sink continue to be as effective in the future? This is not certain. It could become increasingly less effective, or even stop working due to two given mechanisms: the first is that forest bio-mass and soils in the terrestrial ecosys-tems could become saturated, which

process modeling, helped to clarify this phenomenon. It originates in intensive exchanges of carbon dioxide between ocean and land surfaces on one hand, and the atmosphere on the other. These exchanges occurring in both directions are estimated to be 290 gigatons of car-bon dioxide per year for oceans and 400 for land surfaces. However, the assessment shows a slight imbalance resulting in a net accumulation of rou-ghly 9 gigatons per year in oceans and about as many in terrestrial systems. Thus, these systems mitigate the in-crease of atmospheric carbon dioxide.

The regional decomposition of the fluxes revealed that temperate and boreal forests in northern hemisphere represent significant carbon sinks. Indeed, these surfaces are globally expanding, increasing biomass carbon

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would reduce the capacity for carbon sequestration; the second is that future climate warming and higher frequency of droughts could affect these ecosys-tems turning carbon dioxide sinks into sources, as photosynthesis would be reduced and decomposition of organic matter in the soils would be stimula-ted. The reduction in productivity and carbon sequestration observed across Europe as a result of the drought and heat wave in 2003 may be considered as an example of what could happen.

Carbon dioxide is not the only green-house gas that contributes to global warming. Two additional gases, among others, are nitrous oxide (N2O) and me-thane (CH4) whose atmospheric concen-trations have been measured conti-nuously since 1976 and 1983 respectively.

Other greenhouse gasesThese gases accumulate rapidly in the atmosphere and contribute substanti-ally to global warming, despite their lower atmospheric concentrations, as their molecular capacity for trapping infrared radiation emitted from the Earth is greater than that of carbon dioxide. Methane is by nearly half (between 35 and 50 percent) natural

emissions continue to rise. Therefore, in addition to continuing trying to mitigate the impacts of climate change, it is also essential to look for ways to adapt.

How can we adapt to climate change?First, by better anticipating future cli-mate trends. Climate models have been significantly improved due to a better understanding of the whole set of greenhouse gases and of radiative forcing (or climate forcing), which is the difference between solar energy received by the Earth and the energy radiated back to space. Radiative for-cing ultimately determines global warming. The increased availability of computing power, improved modeling methods, and an unprecedented mobi-lization in the modeling community who have committed to taking a com-mon approach, allowed for the compa-rison of a set of models. Finally, spatial resolution of models has improved significantly. For example, the grid size of the Euro-CORDEX simulation sys-tem is 12 km, making representation of local phenomena and extreme events - such as heat waves and droughts - much more precise.

in origin, issued from wetlands. The rest comes from agriculture (enteric fermentation of ruminants, effluents from livestock, rice paddies), from waste fermentation, and emissions related to fossil fuel and biomass combustion. Moreover, future climate warming in northern hemisphere high latitudes would lead to the di-sappearance of a part of the perma-frost, as the thawing process would cause the release of high quantities of methane currently trapped in these permanently frozen soil surfaces. As for nitrous oxide emissions in the at-mosphere, two-thirds originate from natural processes, notably the denitri-fication of soil and oceans, with one third being anthropogenic in origin linked directly to the use of nitrogen fertilizers, biomass burning and emis-sions associated with atmospheric deposition of nitrogen.

Thus, biomass and soils today are responsible for partial mitigation of the impacts of climate change because they sequester carbon. However, not only are terrestrial carbon sinks likely to be-coming less effective, but other sources of greenhouse gases might appear at the same time agriculture-related

A miniature weather station in an Argentine vineyard. Climbing in altitude or changing latitude could be a way to adapt to climate change.

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Four new types of climate scenarios, or rather theoretical scenarios deve-loped by the IPCC, are based on dif-ferent radiative forcing values, linked to as many hypotheses for mitigating an-thropogenic greenhouse gas emissions. Simulations using these models have shown that warming since 1950 (+0.6 C) and the frequency of extreme events can be explained by external climate forcing (linked to human activities). According to these simulations, warming in the medium-term (2035) will remain fairly limited, regardless of the scenario; glo-bal warming in the long-term (2100) will be more significant and contrasted depending on the scenarios, but could exceed 4 C in Europe.

Southern Europe should suffer more rapid warming than northern Europe in the summer, and warming in the winter will be more rapid in eastern and northern Europe. Rainfall should increase in northern Europe and decrease in southern Europe (in-cluding southern France). Dry periods will be more pronounced and will hap-pen with greater frequency, and heat waves will likely occur more often.

In the short and medium-term, the increased atmospheric concentration of carbon dioxide and global warming could have positive consequences on the ecosystems and agriculture, notably for high latitude production. However, in the long term, adverse ef-fects related to high temperatures and drought could become prevalent. They are already threatening the dry tropical zones and the Mediterranean region.

Adaptation to climate change will also require thorough understanding of responses of organisms, populations and communities, and more generally of natural and anthropized ecosystems. Essential ecological and biological pro-cesses will likely be altered, starting with production and the beginning and end of active periods, which, each year, deter-mine species interactions within ecosys-tems. Furthermore, species distribution will be changed. In French latitudes, an increase by 1 C has been associated with a displacement of thermal areas as much as 150 km northward in the plains or 150 m altitude in the mountains.

This effect will trigger a migration of the most mobile organisms (microor-ganisms, animals, rapidly dispersing plants and plants with short repro-duction cycles), whereas less mobile

cropping calendars, water require-ments and plant health, without for-getting that possible crop displace-ment could present new opportunities.

The limited magnitude of changes expected to happen in the medium-term (2035) could be alleviated in large part by the inclusion of adaptive mea-sures in current management practices to promote the resilience of systems to inter-annual climate fluctuations. However, the increase of extreme events may already disrupt agricultu-ral production and have serious eco-nomic consequences. More intensive climate changes expected to occur in the second half of the 21st century will necessitate more radical adaptive mea-sures. Production areas will need to be modified, which in turn will lead to changes in economic sectors, land management techniques and to the development of socially acceptable technical innovations.

Anticipating the changesIt will be particularly important to an-ticipate these changes in systems with slower dynamics (forests, permanent grasslands, lakes). Managing these adaptations will be easier for highly anthropized systems whose conditions are more controllable (annual crops, livestock systems) than for the more natural systems (permanent grass-lands or non-cultivated forests, lakes, rivers and wilderness areas) for which we will only be able to consider accom-panying or palliative measures.

Thus, the challenges posed by cli-mate change to society and to scientists are considerable. It is urgent that we define appropriate ways of managing our existing resources, the environment and land (agriculture, forestry, natu-ral environments) while at the same time anticipating the consequences of these changes. It will be particularly important to preserve all systems that contribute to climate change mitiga-tion, which sequester carbon and limit greenhouse gas emissions.

organisms, such as trees or those living in closed environments like lacustrine species, will experience imbalances that will threaten their survival. In cer-tain cases, natural responses, such as the ability of a population or a species to acclimate without genetic variation when the environment changes, or ra-pid genetic adaptations, could reduce these impacts. But it will be necessary to assist these responses, for example

by setting corridors to promote species migration, by moving species artificially via the transfer of seeds, or by assisted regeneration or forest plantations.

Progress made in modeling how cultures function or of the dynamics of forests and other ecosystems will be use-ful for defining options for adapting to future climate changes. As such, in the CLIMATOR project, scientists cross-re-ferenced climate models with agrono-mic and forest models. Future impacts of climate change on agriculture and forestry were analyzed relative to yield, to the quality of agriculture products,

The impact of climate change on the frozen soils of Siberia is being carefully monitored.

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N. Brisson et F. Levrault (d.), Le livre vert du projet CLIMATOR (2007-2010). Changement climatique, agriculture et fort en France : Simulations dimpacts sur les principales espces, Ademe, 2010.

J.-F. Soussana (coord.), Sadapter au changement climatique, Agriculture cosystmes et territoires, Quae, 2013.

References

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Sylvain Pellerin Research Director INRA- Bordeaux Sciences Agro , Atmosphere Plant Soil Interactions Joint Research Unit.


Agriculture is being subjected to the negative effects of climate change while at the same time contributing to greenhouse gas emissions. Therefore, both adaptation and mitigation approaches are needed. Mobilization of plant genetics and agronomy may provide solutions.

Under the impacts of climate change, agri-cultural production is likely to be signi-ficantly affected. This could have serious consequences on food security as well as on agri-cultural market activity, at both local and global levels, in a context of population growth and shor-tage of natural resources - water, energy, arable land and phosphorus.

It is imperative that agriculture adapts to these changes to reduce crop vulnerability and to become not only less sensitive but more resilient to both climate trends and extreme events. This adaptation will be possible through changes in agricultural practices and plant breeding, but also through the displacement of cultivation areas.

The urgency remains, however, in addressing the reduction of greenhouse gas emissions. On a

worldwide scale, agriculture is responsible for 13.5 percent of these emissions - 31 percent if we consi-der activities linked to land use such as deforesta-tion. In France, this contribution rises to 20 percent. France has decided to reduce its greenhouse gas emissions by one quarter. For the agricultural sector, dividing these emissions by half would be more realistic, while this is still an ambitious goal.

Shorter crop cyclesTo quantify the impacts of climate change on crop production several methods may be used, whether through observation, experimentation or modeling (see illustration on the next page). These methods have been used to understand retrospectively how climate change has impacted agriculture over the past decades. Temperature being the driver of

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Jacques Le GouisMember of the Steering Committee of AAFCC metaprogram. Research Director INRA- Universit Blaise Pascal Genetics, Diversity and Ecophysiology of Cereals Joint Research Unit.

Philippe DebaekeMember of the Steering Committee of AAFCC metaprogram. Research Director INRA-INPT-ENSAT-EI Purpan Agroecologies-Innovation- Ruralities Joint Research Unit.

Antonio Bispo, Thomas Eglin & Audrey Trvisiol Research Engineers ADEME Agriculture and Forests Service.

Challenges facing agriculture


plant development, researchers have observed an acceleration of certain key phenological stages, for example, for budding, flowering or maturity for all crops in both temperate and Mediter-ranean climates. As such, wheat anthe-sis today occurs 8 to 10 days earlier than it did 20 years ago. Depending on the species, the advancement of these cycles is not without consequence on agricultural production: it causes a decrease in the number of days during which plants absorb solar radiation for photosynthesis, which in turn reduces crop yields. For twenty years, water deficits have increased during the grain filling period. Combined with an increase of days when maximum temperature exceed 25C, this leads to poorly filled grains and in turn, again, a reduction in yield.

If wheat has suffered negative impacts of recent climate change, it has not been the case for other spe-cies such as sugar beet. Grown in nor-thern Europe, this crop has benefited from warmer temperatures and the advancement of its cycle without ex-periencing yield loss associated with

a decrease in water availability. Like sugar beet, some species will bene-fit from climate change, while others (more numerous) will suffer, particu-larly those in southern countries.

This is where the complexity lies: the consequences of climate change will vary according to species and geogra-phical areas. In France, the CLIMATOR project coordinated by INRA and sup-ported by the French National Research Agency (ANR) forecasted a possible increase in wheat yields of between 0.9 and 1 ton per hectare. This increase would be the result of higher concen-trations of atmospheric carbon dioxide, which is favorable for photosynthesis.

Conversely, irrigated corn yields would drop by 1 to 1.5 tons per hec-tare due to the shortening of cycles and the fact that corn metabolism is not sensitive to atmospheric carbon dioxide increase.

Modeling has been used to simulate the possibility of displacing cultiva-tion areas in upcoming years. In some cases, new land will become available for cultivation. In other cases, soils will no longer be cultivatable. Productions

from fruit trees and grapevine will be deeply affected, as their economic va-lue is often closely related to the ter-roir in which they are grown.

Adaptation strategiesTo reduce crop vulnerability to cli-mate change, several adaptation pathways should be considered as possible options. The first, prioritized for exploration and the most likely to be accepted is the genetic pathway. It consists of breeding plants with escape, avoidance or tolerance stra-tegies. Escape strategies aim to offset the more sensitive crop stages so that they do not occur at the same time as adverse weather conditions. Thus, for winter crops, early maturing varieties would fill their grains in more tempe-rate conditions. These strategies are among the most widely studied today because they suggest that rapid posi-tive results are achievable and because the genetic mechanisms controlling the development stages are becoming increasingly better understood.

Avoidance strategies aim specifical-ly to limit plant sensitivity to adverse

How can we predict the effects of climate change?To identify the best adaptive measures for climate change, we need to be

able to measure the impact of its different components . To do this, researchers use mainly three methods .

The first consists in retracing the past development of crops in relation with previous climate changes . Using available historical records, for example, it was possible to establish the correlation between stagnation in wheat yield in Europe over the past 15 years and unfavorable thermal and water conditions during the most sensitive crop phases .

The second method is experimentation under controlled conditions . This commonly involves using phytotrons or greenhouses where environmental parameters are adjustable - temperature, humidity, and atmospheric concen-tration of carbon dioxide and light radiation levels . By manipulating these para-meters it is possible to describe and understand the responses of plant physio-logical functions . However, these systems are expensive and relatively small in size, which make it impossible to cover all possible combinations involving the climate, soils, species, varieties and agricultural practices .

The third method is based on modeling . This is used to simulate the beha-vior of a cultivated species in response to different climatic scenarios . This approach is the only one that allows a range of possible future conditions to be explored . Uncertainties in model outputs are commonly due to the reduced complexity of models as compared to real-life situation and to uncertainties inherent in modeling climatic and socio-economic scenarios .

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Using a range of controlled parameters, such as light, temperature and humidity levels, plant development under diverse conditions is studied in laboratories.


conditions. This involves, for example, promoting a deeper root system ca-pable of a greater water uptake. Water loss can also be limited by reducing leaf surface area, which consequently limits evapotranspiration. Lastly, tolerance strategies rely on physiological or bio-chemical processes facilitating plant development under adverse condi-tions: selecting, for example, enzymes whose functioning is not affected by high temperatures.

All of these approaches rely on na-tural genetic variability in cultivated species, on genetic resources conser-

ved in collections as well as on op-portunities from biotechnology. They nevertheless face two challenges: first, being able to anticipate precise future climatic conditions in order to select the best adapted varieties, notably for perennial species planted for seve-ral decades; and second, to success-fully combine within a single variety adaptation mechanisms for several constraints, whose rate of occurrence and level of intensity vary from year to year, and from one location to another.

The other adaptive route is through agronomy. To respond to advanced crop development, certain tactical adap-tations can be implemented. Spring crops, such as, for example, corn and sunflower could be sown earlier using late varieties. This adaptation, which has already been spontaneously adop-ted by farmers, has contributed to the increase in corn crop yields for a decade

in France. The rise in early seasonal tem-peratures promotes photosynthesis for this species of tropical origin.

In a more general sense, accentua-ted climatic hazards will necessitate a review of current crop cycle calendars to avoid as much as possible extreme conditions during the most susceptible growth periods. If the risk of freezing decreases again, and if the improved varieties allow it, we could also envi-sage sowing in autumn (which would require less water) for species current-ly sown in spring. This is already the case for peas.

However, advancing cycles could also have other adverse consequences, such as more attacks from pests and di-seases or damage caused by excessively low temperatures, which will further complicate the search for optimal solu-tions. It is for this reason that models, despite their imperfections, will help to identify the most promising solutions and to test a variety of scenarios. For the period 2030-2050, simulations indicate that advancing cycles will help compen-sate, at least in part, for elevated risks associated with decreasing rainfall.

After the year 2050, water shortage is expected to be noticeable and the ef-fects of higher temperatures more pro-nounced. Through genetics and agro-nomy, current research is focused on breeding for species that are tolerant to extreme temperatures and iden-tifying ways to avoid periods when thermal risks are the most elevated

(offsetting planting dates, cultivating early sowing varieties). Water demand is expected to increase to compensate for both evaporation (from leaves) and a decrease in rainfall. But with water resources already subject to severe pressure, it is not certain that irriga-tion can be increased or even maintai-ned, given an increase in demand.

Addressing the causes of global warmingIn any case, possible actions for adap-ting to climate change will depend above all on its magnitude and on our ability to act on addressing its causes by reducing greenhouse gas emissions. Responsible for one fifth of these emis-sions in France, agriculture plays an im-portant role. Nitrous oxide, for which the warming capability is 300 times greater than that of carbon dioxide, re-presents 50 percent of these emissions. Closely associated with the use of ferti-lizers, it is produced by cultivated soils through nitrogen transformation reac-tions (nitrification and denitrification). Methane contributes some 40 percent, and is largely associated with livestock. As for carbon dioxide, it accounts for only 10 percent of the total emissions and comes mainly from fossil fuel used for agricultural machinery.

In July 2013, INRA, the French Agency for the Environment and Ma-nagement of Energy (ADEME) and the agriculture and ecology ministers pre-sented the results of a study indicating how a series of measures would make it possible to reduce greenhouse gas emissions from agricultural activities of nearly 32 million tons of equivalent carbon dioxide per year.

A third of the recommended ac-tions would lead to financial profit for farmers. They correspond mainly to technical adjustments, notably impro-ving the use of nitrogen fertilizers, which would reduce emissions by approximately 25 percent. Similarly, more sustained energy saving efforts (for example, better insulation of hea-ted greenhouses and livestock buil-dings) would lead to a reduction by 20 percent of carbon dioxide emissions for a total gain estimated at 170 euros per avoided ton.

Evolution in the beginning of the harvest in Chteauneuf-du-Pape

Since 1945, the date of the first harvest in Chteauneuf-du-Pape vineyards, in Vaucluse, has advanced by close to 3 weeks. The development cycle of vines shifted due to a gradual increase in ambient temperatures.

1st Sept .1950

6 Sept .11 Sept .16 Sept .21 Sept .25 Sept .1st Oct .

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References

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In northern Europe, sugar beet yields (for sugar, alcohol or biofuel production) are increasing with global warming.

A second series of actions is fore-seeable and for a limited cost: less than 25 euros per avoided ton of carbon dioxide. Examples include reducing the frequency of plowing (expensive in energy), producing biogas from livestock manure (through the pro-cess of methanisation), developing agroforestry to foster carbon storage in soil and biomass, and increasing cultivation of legumes (species that fix nitrogen) which would reduce the need for fertilizers. Some of these measures would require investment. They could also cause a moderate decrease in production, which would be only partially offset by a decrease in expenses. Subsidies proportional to tons of reduced carbon dioxide will be influential and a deciding factor in the implementation of these actions.

Finally, the third series of measures will necessitate higher spending, more than 25 euros per ton of reduced car-bon dioxide. It calls for the purchase of particular inputs such as nitrifica-tion inhibitors to reduce nitrous oxide emissions, or taking extra measures like cultivating carbon-fixing hedges. While costly, these measures would contribute to a reduction in emissions, but also to erosion mitigation and to the enhancement of landscape quality and biodiversity.

If agriculture must reduce its emissions, it must also manage the soils that act as carbon reservoirs. On the global level, the first meter of soil sequesters some 2,000 giga-tons of organic carbon, which is more than plant biomass and the atmosphere combined, making it the largest carbon pool in the biosphere. Organic material, plant debris or soil organisms are the main actors in the balance between storage and release of this reserve. Carbon stock corres-ponds to the balance between inputs (plant litter, crop residue, manure) and outputs (respiration by soil orga-nisms). It varies significantly accor-ding to the soil type, climate and how the soil is used and managed. It is more elevated in high-altitude meadows, wetlands and grasslands but quite low in vineyards, and in Mediterranean or intensive cropping

areas. The challenge is therefore how to preserve the soils that contain this significant but fragile carbon stock.

In addition, as possible measures for both adapting crops and mitiga-ting the effects of climate change are often compatible, they could be im-plemented simultaneously. However, this is not always the case: the cultiva-tion of legumes would reduce nitrous oxide emissions but these plants are

highly sensitive to the lack of water. Similarly, practices aimed at increa-sing carbon stocks in soils or biomass, with more important plant cover, may be challenged if the demand for water for the primary crop increases. Imple-menting and monitoring measures for climate change adaptation and mitiga-tion will require clear definition and careful examination of a set of parame-ters to ensure their compatibility.

S . Pellerin et L . Bamire (coord.), Quelle contribution de lagriculture franaise la rduction des missions de gaz effet de serre ?, INRA, 2013.N . Brisson et F . Levrault (d.), Le Livre Vert du projet CLIMATOR (2007-2010). Changement climatique, agriculture et fort en France : Simulations dimpacts sur les principales espces, Ademe, 2010.


Livestock systems produce a significant amount of greenhouse gases. They contribute to climate change, and conversely, are exposed to its effects. It is therefore urgent to implement adaptation measures, some of which already exist.

Should we reduce our consumption of animal products (meat, milk, eggs) to fight against climate change? This question has been the subject of debate for over a decade. The issue: greenhouse gas emissions caused from livestock supply chains which, according to the Food and Agriculture Organization (FAO), account for nearly 15 percent of total human contribution to greenhouse gas emissions. This share could increase: while meat consumption has started to decline in some Western countries, the demand for animal products will grow in developing countries. By 2050, global consumption could increase by 70 percent. But what would hap-pen if climate change, summer heat waves and droughts continue to affect livestock production a bit more every day?

The situation is complicated by the fact that livestock production occupies 30 percent of the Earths land surface: 3.4 billion hectares of grass-lands and pastures and half a billion hectares for feed crops. More than 800 million of poor people depend on livestock farming for their survival and the sector contributes to the employment of more than 20 percent of the total worlds popu-lation. Ruminants are able to produce food on non-arable lands (due to slope, altitude or cli-mate) and to transform resources not used for human consumption, such as grass and fodder, into edible products.

Through grazing and sustainable use of grasslands, extensive livestock farming, if it is well managed, can contribute to protecting bio-diversity, soils and surface water and to limit the

Adapting livestock systems

to climate change

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Anne MottetLivestock Policy Officer FAO Animal Production and Health Division.

David RenaudeauResearch Scientist INRA-Agrocampus Ouest Physiology, Environment, and Genetics for the Animal and Livestock Systems Joint Research Unit.

Jean-Franois SoussanaINRA Scientific Director Environment.


development of scrubs. Livestock also accounts for 40 percent of the economic agricultural sector and is experiencing dynamic growth (more than 3 percent per year).

Meat, milk and eggs provide 18 percent of calories for human consumption and close to 40 percent of essential proteins and micronu-trients (for example, vitamins, mine-rals and unsaturated fatty acids).

Causes of the footprintGiven the diversity of producers and situations, quantifying greenhouse gas emissions from agricultural acti-vities, especially livestock produc-tion, is complex and subject to many uncertainties. In addition, micro-biological processes at the source of methane or nitrous oxide emissions are highly variable and we do not yet know how the global carbon stocks in soil organic matter is changing.

Despite these uncertainties, the FAO estimated livestock emissions, from land use for feed production to the processing and transport of animal products, through several economic sectors. The livestock sup-ply chains were found to represent globally 7.1 gigatons of equivalent carbon dioxide per year, i.e., 14.5 percent of anthropogenic green-house gas emissions. In a separate assessment, the Intergovernmental Panel on Climate Change (IPCC), showed in its fourth report that the entire agricultural sector contributes directly to more than 14 percent of emissions, while changes in land use like tropical deforestation, contri-bute as much as 17 percent.

The main sources of emissions identified by the FAO are related pri-marily to the production and proces-sing of animal feed: this corresponds to 45 percent of total emissions, 9 of which are related to the expansion of grazing and crop areas at the ex-pense of forests. Next come methane emissions from the digestive process in ruminant animals (39 percent), fol-lowed by emissions from manure (10 percent). The remainder comes from the processing and transportation of animal products.

Climate change resulting from ac-cumulated greenhouse gas emissions impacts agricultural and livestock production. Between 1980 and 1999, severe droughts were estimated to cause the disappearance of 20 to 60 percent of herds in several sub-Saha-ran African countries. In the summer of 2003, an exceptional heat wave hit Europe resulting in a drop of crop yields of 20 to 30 percent and a fo-rage deficit of 60 percent in France.

The number of hot summers is predicted to increase over the next 40 years. Changes in the water cycle related to climate warming is expec-ted to lead to an even more uneven

distribution of rainfall, more intense in some regions, more rare in others, which will lead in turn to prolonged droughts with increased risks of soil erosion and a reduced capacity to store water and provide nutrients.

In France, the VALIDATE project, coordinated by the French National Institute for Agricultural Research (INRA), proved through experimen-tation that climate change could re-duce production in temperate grass-lands by 20 to 30 percent. However, its impact would be less pronounced in grasslands based on resistant Me-diterranean grass varieties, as would also be the case in the Alps where variations in temperature are already

significant. An increase in atmosphe-ric carbon dioxide should also limit the impacts of drought on vegetation as an increase in the concentration of this gas in the atmosphere causes partial stomatal closure at the level of leaves. Partially closed stomatal pores reduce water loss in plants.

Most livestock animals are homeotherms: their survival de-pends on their capacity to maintain a constant internal temperature. When exposed to heat, they reduce their feed intake with subsequent nega-tive effects on their performance and health. Summer heat waves result in a significant number of animals

deaths. In California, heat weaves in 2006 resulted in the death of 700,000 poultry and more than 25,000 dairy cows.

Emergence or re-emergence of diseases affecting livestock animals is another risk associated with cli-mate change, which could have se-rious health, ecological, socio-econo-mic and political consequences. An example is the bluetongue virus, a viral disease affecting sheep, which has already begun to spread to tem-perate zones in Europe.

In this context, reducing emis-sions is a priority for the livestock sector. This is reflected in a variety of international initiatives, such as

39 .1 %

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2 .9 %

16 .4 %7 .7 %

0 .4 %

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N2O: nitrous oxide; CH

4: methane; CO

2: carbon dioxide

Distribution of greenhouse gases produced by livestock

N2ON2O

CO2

CO2

CH4

CH4

N2O

N2O Applied and deposited manure

for fertilizationN

2O Fertilizers and crop residues

CH4 Rice fields for feed

CO2 Feed (energy used for production

or transport) CO

2 Expansion of soybean cultivation

CO2 Expansion of pastures

CH4 Enteric fermentation

CH4 Manure management

N2O Manure management

CO2 Indirect energy

(equipment and buildings) CO

2 Energy used directly on farm

CO2 Postfarm (transportation,

processing and distribution of products)


AnimalChange, a project funded by the European Union involving more than 100 scientists from 21 European countries for coordinated research on livestock, climate change and food security. In France, a study conducted by INRA highlighted the potential for important mitigation in the French agricultural sector: by 2030, emissions could be reduced by 32 million tons of equivalent carbon dioxide per year. Several measures target livestock in this study: grass-land and waste management, fee-ding practices and methanisation (see box on this page).

A study conducted by the FAO found that greenhouse gas emissions vary considerably between neighbo-ring farms. This finding is encoura-ging as it implies that by applying cleaner farming techniques we could reduce the carbon footprint by about 30 percent. In theory, emis-sions could be reduced in all systems, from industrial poultry farming in Asia to transhumant sheep and goat farming in arid zones in Africa. This objective could be achieved by using techniques that currently exist but which are not yet widely used. For example, extensive sheep and goat farming systems in western Africa could produce more while emitting fewer greenhouse gases by increa-sing the use of crop residues, by improving the health of the animals with vaccinations and deworming treatments and by implementing improved pasture management. This study also highlights the glo-bal potential for carbon storage in grassland soils via root systems and aboveground biomass. This could be achieved through moderately in-tensified farming in certain regions and taking restorative actions for degraded grasslands in others, and through the development of agro-pastoral systems.

Research for adaptationCan we make the livestock farming sector less vulnerable to the effects of global climate change? Complex stra-tegies are beginning to take shape. The first focuses on livestock feeding.

It is aimed at limiting fluctuations in productivity through, on one hand, the selection of more resistant forage species for temporary grasslands and, on the other, improving mana-gement of grazed permanent pas-tures. It also addresses, notably for poultry and pigs, strengthening the use of resources that do not com-pete with human food (industrial by-product meals, for example). At the same time, it will be necessary to continue to improve how efficiently animals utilize their feed rations for

the production of meat, milk or eggs. One example of the various possible pathways would be to improve the ration quality or to breed and select animals with a high efficiency of feed use and/or with a high ability to digest alternative feed resources.

A second strategy consists of developing selection programs for animals less susceptible to harsh conditions (heat, restriction of water or food). Due to their high capacity for adaptation, hardy local breeds are the main focus of these breeding

Under the actions of microorganisms and in the absence of oxygen, anaerobic di-gestion degrades organic matter from livestock manure . This process leads to two by-products . The first is the digestate: an organic substance rich in nutrients, it is gene-rally used as fertilizer . The second is a gaseous mixture (biogas) composed mainly of methane and carbon dioxide . Part of the methane in manure is converted into carbon dioxide, for which the warming potential is 25 times lower than that of methane .

The biogas produced in methanisation plants can be used in several ways: in com-bustion for heating or cooking, in cogeneration to produce electricity and heat, or used directly in the natural gas network . Methanisation can produce renewable energy, while diversifying revenues for farmers and reducing their carbon footprint .

In France, this process is developing rapidly with support from public authorities . Nearly 160 methanisation plants currently use livestock manure: whether privately or collectively owned, they produce an estimated at 650 megawatt-hours of primary energy . By 2030, the French Agency for the Environment and Management of Energy (ADEME) estimates that primary energy from methanisation will multiply by more than 100,000, and will reach as much as 69 terawatt-hours - or 3 percent of total energy production . It is estimated further that up to 78 percent of this energy will come from agriculture . In 2050, ADEME suggests, this could rise to 104 terawatt-hours: methani-sation would then become the third source of renewable energy in the country .

Marc Bardinal and Julien Thual, ADEME

Methanisation (or anaerobic digestion) is becoming increasingly important all over the world

These methanisation plants (in Germany, left, and in Ghana, right), considerably different in size, both produce renewable energy (biogas) from livestock manure.

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P . Gerber et al ., Tackling climate change through livestock. A Global assessment of emissions and mitigation opportunities, FAO, 2013.M . Mathieu et al ., Intensive grazing system for small ruminants in the Tropics : The French West Indies experience and perspectives, Small Ruminant Research, vol. 77, n 2, pp. 195-207, 2008.

References

programs. On this topic, INRA is currently running several ambi-tious programs mainly focused on pigs and poultry.

A third adaptation strategy is based on controlling the increase in animal health risks associated with climate change. To do this, it will be necessary to anticipate changes in the geographical dis-tribution and the virulence of pathogens and limit their effects on livestock animals. This can be achieved through early diagnos-tic methods and/or vaccination and/or by promoting new far-ming systems based on, among other things, the association of several animal species. As an example, to fight against gas-trointestinal nematode infections in small ruminants, it is possible to use integrated control manage-ments such as the mixed grazing of animal species (small and large ruminants) bearing different gas-trointestinal nematode species.

In agriculture, adaptation also requires better management of climate risks, often necessitating the diversification of crops and farming systems. Small farms, particularly those in harsh envi-ronment, have developed strate-gies that make them less vulne-rable to climatic shocks and help them to manage the impacts. Risk-sharing within families and rural communities, anticipation measures (feed storage), and insurance mecha-nisms are part of these autonomous strategies, which are, however, not sufficient to deal with large-scale climate change.

A number of innovations will be necessary: increased use of biologi-cal diversity and breeds, environ-mental technologies for improved water collection and storage, seaso-nal weather forecasts... However, the success of these technologies will depend on their technical efficiency and their adoption rate, two factors limited, in many developing regions, by poverty, hunger, lack of financial resources, environmental degrada-tion and conflicts.

Reducing emissions and increa-sing adaptation to climate change are both achievable goals: for example, by avoiding overgrazing we can restore carbon stocks in soil while fostering better resistance to drought. That said, while synergies exist, trade-offs should also be consi-dered: selecting animals to improve their production potential tends to increase their sensitivity to external

factors (such as heat). Solutions for combining adaptation and mitigation are therefore that much more difficult to identify as they need to be adjustable according to livestock farming systems and climatic contexts.

Rapid responseNow aware of the urgency, the livestock sector is reacting. Many initiatives involving public and private actors have emerged over the past ten years. Whole sectors are taking action, such as the French dairy sector, which launched the Carbon Dairy pro-ject in late 2013 with the goal of reducing greenhouse gas emis-sions of 3,900 farms by 20 percent over the next 10 years.

Beyond international politi-cal frameworks and negotiations, such as the Kyoto Protocol or the United Nations Framework Convention on Climate Change, it is essential to support concer-ted actions that bring all stake-holders together: producers, processors, governments, NGOs, civil society and the scientific community.

Scientists must evaluate the potential of different approaches to reduce greenhouse gas emis-sions and adaptive measures for

livestock farming, in order to define priorities. It is also their responsibili-ty to assess possible actions, to conti-nue to develop innovations capable of reducing the carbon footprint and to develop tools to precisely predict the impacts climate change will have on livestock farming over the next 50 years while defining measures that can be implemented... as soon as possible.

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Like all ruminants, sheep release methane during digestion.


Forests are sensitive to climate change. Observation networks, new genetic data and numerical simulations will give the opportunity to define forest change scenarios and to identify optimal conditions for adaptive forest management practices.

Forests will not be spared by climate change. While some effects have proven to be benefi-cial, climate change on the whole will probably cause significant damage. Since the first research programs aimed at understanding the effects of cli-mate change began in the 1990s, the magnitude of current changes and their impacts have always been revised upward. However, it is the multiplication of extreme events, such as the series of storms and droughts that occurred in early 2000s, which raised awareness of the need to act quickly.

It has also become evident that adaptive stra-tegies for forests will require flexibility over time. These measures need to be considered as dynamic processes rather than a means to reaching a stable equilibrium to adapt to local conditions in a given moment. Indeed, forests will be faced with climatic conditions that will continue to change over seve-ral decades, possibly over a century. To anticipate future climatic hazards, we need to be prepared to manage many uncertainties. This will require a

thorough reexamination of models currently gui-ding forest management.

Forest dynamicsForests are complex and diverse ecosystems, which vary depending on their climatic zones. Their functioning and dynamics are governed by a multitude of interacting organisms, which exhi-bit very different life cycles - from fungi to trees, insects or large herbivores. Forests actively impact their environment, affecting temperature changes, precipitation, soil, wind, and even influence at-mospheric water vapor pressure.

It is important to stress that current forests only offer snapshots of these more or less rapid dynamics. Some forests are changing quickly, for example those subjected to fire or mountain forests dating from major reforestation actions in the nine-teenth century, or even riparian forests where cycles governing colonization, maturation and extinction are subject to flooding. Forests, which we consider

Towards adaptive forest management

Franois LefvreResearch Director INRA Ecology of the MediterraneanForests Research Unit.

Denis LoustauResearch Director INRA-Bordeaux Sciences Agro Atmosphere Plant Soil Interactions Joint Research Unit.

Benot MaraisResearch Director INRA-Universit de Lorraine Tree-microbe interactions Joint Research Unit.

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to be stable, are also experiencing their own slower dynamics. Climate change may have cascading effects that will modify these dynamics. Milder winters and drier summers have, for example, favored the massive outbreak of the mountain pine beetle, a small insect which colonized the North American continent moving from west to east, progressively adapting itself to dif-ferent species of pine trees. As a result, pine trees died which in turn facilitated the spread of forest fires, and effecti-vely caused the destruction of entire sections of forests. In a more general sense, climate change and the spread of forest pests and diseases have modified both the number and the nature of ene-mies which pose a threat to forests. The distribution areas of certain pests have become significantly larger, either due to decreased constraints on their win-ter survival, or to improved breeding conditions during the warmer seasons.

The most well documented case is that of the pine processionary moth, but there exist a number of other examples such as oak ink disease and the red band needle blight afflicting laricio pines, both of which are caused by pathogenic fungi.

While parasites generally tend to strive in warmer temperatures, this is not always the case. The growth of the fungus Chalara fraxinea is in fact slowing due to increasingly hotter summers occurring in some parts of Europe, such as for example, in Slove-nia or the Po valley in Italy. This could be a hopeful sign that this epidemic affecting ash trees in temperate forests could be alleviated in warmer regions.

More than the gradual change in global temperatures, it is the recurrence of extreme events, such as droughts and severe storms that will play a decisive role in the future of forests. The impacts of drought have prolonged effects that can last for several years and it is often the cumulative effects resulting from several successive dry years that have serious consequences. In the Southern Alps, for example, the drought that

occurred in 2003 and its impacts over the following years resulted in the mas-sive dieback of fir trees. On Mount Ven-toux, the fir trees that died are those that benefited from good conditions when they were young, initially growing in soil with high water content.

Such a finding suggests that, despite their vitality, these fir trees were less ac-climatized to drought than neighboring trees that survived. Such a relationship, however, between the vitality of young trees and latter stage mortality, has not been found in other forests where different mechanisms occur. As this example illustrates, it is often difficult to identify the causes of tree dieback, which are multifactorial processes with intervening physicochemical (abiotic) and parasitic (biotic) factors.

The question of how rapidly these changes take place is all the more im-portant for the different components within the forest ecosystem (trees, fun-gi, insects) as their reaction times vary. For example Diplodia pinea, a para-sitic fungus of pines, which strives in drought conditions and high summer

Forest biomass, a renewable energy source

The term biomass refers to the total mass of biological material derived from living orga-nisms, plant or animal . In France, biomass is the primary source of renewable energy, well ahead of wind turbines, photovoltaics or geothermal systems . Today it is consumed mainly by private individuals for wood heating . In the framework of a French policy aimed at developing renewable energy by 2020, one of the main biomass resources could come from forests; it would be much more widely used over the next several years for central and industrial wood heating systems . Indeed, today, only half of the annual production is used in materials and energy sectors .

However, increased use of forest biomass raises two difficulties . The first is in its collection, as French forests (16 .3 million hectares, or 30 percent of the territory) are frequently the property of private owners with surfaces often too small to lead to any pro-fitable activity, wood energy being only one of several possible applications . One of the challenges is therefore determining the best way to exploit the French forests . The other difficulty is the environmental agenda . It will be essential to integrate all of the environ-mental issues in the use of biomass in order to maintain equilibrium within ecosystems . This will be possible notably by putting in place forest management strategies combining two objectives: adaptation to climate change and mitigation of if its negative effects . Re-search will provide tools to guide this decision to allow local decision makers to optimize forest management while considering multiple environmental issues .

Caroline Rantien, ADEME

Pine trees infested with Diplodia pinea, a fungus which strives in drought conditions and which has become major threat in southwestern Europe.

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temperatures, was once considered to be a minor disease and has become, in less than 20 years, one of the major health problems that pine forests face today.

Adaptations and their limitsOver the next century, the fate of fo-rests will depend on, above all else, their capacity for adaptation to cli-mate change: physiological resistance, genetic diversity and evolution of forest stands, migration to more favo-rable environments, both altitudinal and latitudinal, and forestry practices. Plasticity and biodiversity in forests are considered to be strong assets, but we do not yet know how or to what extent these two parameters will allow tree populations to adapt to such rapid changes. Climatic conditions for the current distribution range for a tree species will change much more rapi-dly than the rate of their spontaneous migration. Therefore, the capacity for spontaneous migration will likely not be sufficient to maintain all of the eco-systems and their biodiversity in the same climate. It is adaptation to new climatic conditions that will determine their persistence.

It is here that forestry - a set of prac-tices and methods aimed at improving growth management, maintenance and forest exploitation - can intervene. A first planned adaptive method is to increase biodiversity, particularly in European fo-rests, characterized by relatively few spe-cies compared to other temperate areas. Certain parasites, which strive with climate changes, will limit the options available to forest managers. Caused by two fungi, the red band needle blight led to the suspension of laricio pine planta-tions in Great Britain and has limited its use in western France. In some cases, this may justify considering the use of exotic forest species.

Another planned adaptive measure aims at promoting genetic evolution within specific forest species. Fores-ters have for many years resorted to the practice of transplantation, which has provided valuable indications

related to the speed of possible genetic changes. They found that the Monterey Pine, Pinus radiata, is able to survive, to flourish and reproduce in environ-ments that are very different from its native range (the California coast), demonstrating a high potential for adaptation following several genera-tions during which time the varieties had been improved. Another example concerns the spruce provenances trans-planted from Germany to Norway at the beginning of the twentieth century. Trees from Germany were poorly adap-ted to the cold Nordic climate: they entered dormancy three weeks later than local trees rendering them more vulnerable to early frost. Some trees nevertheless survived and the cycles of their offspring synchronized with those of indigenous trees. Several processes contributed to this rapid evolution: the selection of more resistant trees, the effects of the environment on gene

expression and pollen contribution of indigenous trees for reproduction. It is therefore important to avoid the rapid and systematic eradication of the trees that survive massive dieback. These surviving trees are the product of inten-sive selection pressure, which promotes the evolution of new genetic resources, when it does not lead to the complete disappearance of the population. Natu-rally, limits to adaptive potential exist. In many regions, adaptive capacities are not sufficient to maintain forests in their current state. Nonetheless, it is important to exploit these evolutionary changes wherever they occur.

A challenge for forestryAll of these examples confirm that it will be necessary to take an adaptive approach to forest management based on continuous adjustment of tested practices. This adaptive management will allow us to build on previous

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Sensors placed at top of a 55 m tower located in a forest in French Guiana. They allow for the measu-rement of carbon dioxide fluxes, in order to assess if the ecosystem gains or loses carbon over time.


References

P. F

rey,

INRA

advances in research, such as develo-ping technology for measuring envi-ronmental variables. For example, we know today how to detect subtle changes in climatic variables (tempe-rature, humidity or light radiation), as well as concentrations of carbon dioxide and air pollutants (ozone le-vels and nitrogen deposits).

Organized networks of standar-dized and integrated observation in-frastructures covering the greater part of the continents allow us to conti-nuously monitor the biogeochemical functioning of forests with a resolu-tion of 30 minutes. Sensors on aircrafts and satellites complement these obser-vation networks and offer global cove-rage. Data collected by these networks are used to model the impacts of cli-mate change and to organize more ac-curate monitoring of terrestrial ecosys-tems. Infrastructures in Europe such as ICOS (Integrated Carbon Observa-tion System) and ANAEE (Analysis and Experimentation on Ecosystems), and NEON (National Ecological Observatory Network) in the United States, were designed for this purpose. Through the use of robust calculation power, these infrastructures focus on revealing the current extent of ecolo-gical disruptions and anticipating the most critical situations.

Mathematical models are used to simulate the current and future role of forests in the carbon cycle. On the global scale, forests contain nearly 50 percent of carbon stored in terres-trial ecosystems. Any variation of this stock would change the atmospheric concentration of carbon dioxide. Tro-pical deforestation and changes in land use release carbon. Conversely, the renewal of the vegetative cover of one part of deforested surfaces combi-ned with the plantation of trees tem-porarily trap carbon in the biomass. Undisturbed tropical forests, as well as temperate and boreal forests which are currently expanding, accumulate carbon. The net combined result of these phenomena corresponds today to a fixation of 4.4 gigatons of carbon dioxide per year, or roughly 15 percent of the release of fossil carbon in the atmosphere. Consequently, the reduc-tion of net carbon dioxide emissions will largely depend on our ability to restrict deforestation. With regard to the soils that also store carbon, it is

not known if climate change will al-ter their organic matter composition, which effectively determines their sto-rage capacity.

Models capable of integrating adap-tive processes, interactions between various actors and even silvicultural operations are currently developed. The most likely scenarios, on local and global scales, will soon be available to foresters and policy makers.

Dynamic modelsModeling will also benefit from impor-tant methodological progress, notably new genomic tools which provide access to detailed information about a species genetic diversity. Such infor-mation is of key importance to unders-tand the current dynamics of species as well as their past evolution. The advent of high-throughput sequen-cing (NGS, Next Generation Sequen-cing technologies) also offers new perspectives. In theory, NGS technolo-gies provide access to the full genome information of any organism and no longer only for a limited number of model species. The genome of fungi and other poorly understood microor-ganisms could thus be characterized. This will be the case, for example, for agents responsible for emerging di-seases, notably ash dieback.

Innovation, however, does not only mean new technologies, analy-sis methods or numeric simulations. Forests adaptation to climate change will necessitate the use of new antici-patory practices and support systems. Adaptive forestry will allow forests to evolve taking into account ecological and socio-economic constraints. Every aspect of this evolution will be based on future scenarios and no longer on what we know from past experience.

A . Cheaib et al ., Climate change impacts on tree ranges : model intercomparison facilitates understanding and quantification of uncertainty, Ecology Letters, vol. 15, pp. 533-544, 2012.J . Stenlid et al ., Emerging diseases in european forest ecosystems and responses in society, Forests, vol. 2, pp. 486504, 2011.

Forest biomass is a source of energy, but fragmentation of French metropolitan forests, three-quarters of which are privately owned, makes its use difficult.


Freshwater is a vital resource. But subjected to the simultaneous effects of climate change, pollution and overexploitation, water resources have become fragile. Models are used to study the consequences of water preservation measures.

Rivers, lakes and wetlands, also referred to as freshwater hydrosystems, represent only 0.6 percent of the worlds water but host 6 percent of the total number of animal and plant species. As such, they are an important reservoir of biodiversity and play a key role in a variety of bio-logical cycles. But they are as susceptible to climate change as the terrestrial ecosystems with which they are connected. They are vulnerable because climate change is happening on a global scale and because they are also submitted to the impact of human activities.

Increasing air temperatures will contribute to warmer water temperatures and disrupt water transfers through for example, a change in the date of snow melt. These transfers control not only the quantity of water in transit, but also the organic and mineral components being transferred.

This will change the soil composition and vege-tation in the river watersheds (terrestrial systems with which the hydrosystem is connected). As a result of modifications in the volume, nature and intensity of rainfall, the quantity and availability of

water that reaches the hydrosystems will change. Aquatic organisms will face a variety of modified physicochemical conditions in their environment, for example declining concentrations of dissolved oxygen in water.

It is essential that we study and understand the impacts of climate change on hydrosystems to suggest either mitigation or adaptation strategies. However, the variety and complexity of these im-pacts hinder our ability not only to identify them, but also to predict their occurrence and intensity.

Presented here is a review of current research focusing on the adaptation of hydrosystems to cli-mate change, bearing in mind that aquatic systems did not benefit so far from as much attention as ter-restrial ecosystems.

Impacts on water quantityThe reduction of fresh water availability is one im-mediate consequence of climate change. In many regions, water resources are already insufficient or used too intensively to ensure replenishment of the stocks. In the future, agriculture will require even

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Jean-Luc Baglinire Research Director INRA-Agrocampus Ouest Ecology and Ecosystem Health Joint Research Unit.

Marie-lodie Perga Research Director INRA-Universit Savoie Mont Blanc Alpine Centre for Research on Lake Eco-systems and Food Webs Joint Research Unit.

tienne Prvost Research Director INRA-Universit de Pau et des Pays de lAdour Behavioural Ecology and Fish Population Biology Joint Research Unit.

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more water to satisfy an increasing hu-man population (19 percent increase by the year 2050). As a result, more intense competition for access to water resources for agricultural, industrial, household, recreational and environ-mental activities is anticipated.

Temperature increases stimulate both evaporation and evapotranspira-tion (water loss by plants), which, com-bined with a decline in precipitation, threatens hydrosystems with drought in temperate zones, for example in the marshes of western France. Water flow in rivers should decline by 20 to 25 percent by the end of the century and this is also expected to come with longer low water periods. At the same time, extreme rainfall events should multiply flood occurrence or periods of high water.

By reducing the quantity of water circulating in hydrosystems, climate change would also prompt a de-crease in the hydrological connection between the different parts of a river (upstream, downstream, estuaries and tributaries), therefore enhancing habi-tat fragmentation.

Ecological adaptationsIncreased average temperatures will cause a warming of water, the magni-tude of which will vary depending on the altitude and water supply to the watershed. Between 1977 and 2006, annual average water temperatures in the Rhone river increased by 1.5 C, and summer temperatures taken from the middle of the Loire river rose by 1.5 to 2 C. In Lake Geneva, as for a dozen of other Swiss lakes, deep waters have warmed by 1 C over 40 years; the winter temperature of the total water mass rose from 4.5 C in 1963 to 5.15 C in 2006.

Hydrosystems host numerous cold-blooded animal species, notably fish, whose physiology relates directly to temperatures. As such, global war-ming of water may induce cascading effects on the composition of fish communities. The maintenance of fish

populations faced with environmen-tal changes depends on the species capacity to adapt. Adaptation may come from phenotypic plasticity (as, for example a change in shape or size, without modifying their genetic cha-racteristics), or can arise from selection mechanisms triggering changes in the genetic composition of the population (provided the genetic variability wit-hin the population is sufficient).

For instance, triggers for reproduc-tion, egg development and fry survi-val in Arctic char (Salvelinus alpinus), require temperatures ranging between 3 and 7C. Warmer waters in winter

would jeopardize reproduction and maintenance of Arctic char popula-tions living in the Great Alpine Lakes in France, their southernmost habitat in Europe. In contrast, in these same lakes, the two-week delay in whitefish reproduction in December is compen-sated for by a shortening of the dura-tion of its embryonic development and finally whitefish populations appear to benefit from climate effects.

The decrease in individual sizes as observed for salmon population ap-pears to be related to changes in both environments they occupy, i.e., increa-sing temperatures and acidification

Monitoring salmon populationsA significant increase in the growth of juvenile Atlantic salmon population over the last 40 years has been observed in a small river in Brittany . It was initially attributed to the rise in water temperature due to climate change, but finally proved to be the result of an increase in productivity in the river correlated to inputs of nitrates . Additional studies over the past 20 years indicate that the primary factor affecting growth for salmonids in Brit-tany is definitely not water warming .

How consistently explore the effects of climate change on fish populations? Vir-tual experimentation through model simulation provides important new insight . INRA is currently developing a simulation tool to study Atlantic salmon populations currently at risk in French rivers . This simulator integrates a diverse range of modalities for envi-ronmental factors related to climate change and the processes linking the different life cycle phases . It will give the opportunity to explore how populations adapt both with and without genetic change .

First simulations showed that, in an initial phase, increasing river water temperature would promote the survival of individual fish, but that it can also lead to earlier sexual maturation, which tends to have a negative influence on survival rates . Virtual experimen-tation also offers the opportunity to prioritize the various components of climate change relative to their effects . As such, for the next 30 years, changes in the hydraulic regime (notably flow) in rivers should be a higher concern for the persistence of salmon popula-tions than rising temperatures .

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of the marine habitat combined with higher temperatures and altered water flow in rivers. In large water systems, species adapt by modifying their spa-tial distribution. Along the Rhone river, near Bugey nuclear power plant, thermophilic species, such as the bar-bel and the dace, are gradually repla-cing cold water species, such as chub, encountered further upstream. Al-though there are several evidences of the impacts of climate change on fish communities, predicting long-term consequences affecting populations in freshwater environments beyond

these selected examples remains a wide open field for research.

Changes in hydrosystemsBecause temperature affects water density (reaching a maximum at 4C, then lowering when tempera-tures increase), climate change also affects the dynamics of water masses in lakes. Stratification periods, when warmer water layers float on colder layers, alternate with periods when the lake water mixes. But the relative duration and intensity of each of these periods are affected by climate change.

Warmer springs have prompted stra-tification to occur one month earlier than it did 30 years ago, effectively ex-tending the duration of stratification.

The seasonal succession of plank-tonic species has in turn been modi-fied. Thirty years ago, algae or cyano-bacteria species, that are adapted to grow in deep waters where they face sedimentation, proliferated mainly in autumn. Nowadays, they appear at the end of the summer and have lon-ger life spans. As these are filamentous species, sometimes even toxic, they tend to accumulate at the bottom of

lakes and disturb the supply of drin-king water. Furthermore, changes in wind patterns and decreasing flows of tributaries also contribute to limiting the efficiency of water mass mixing in winter and oxygen replenishment in deep waters. As such, bottom deoxy-genation in the Great Alpine Lakes has increased over the past 20 years, threa-tening life in deep waters.

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