research on climate impacts in hamburg and schleswig holstein

20.04.23

Hans von StorchInstitute of Coastal Research, Helmholtz Zentrum Geesthacht

and KlimaCampus HamburgGermany

Research on Climate Impacts in Hamburg and Schleswig Holstein

Many thanks to Jacobus Hofstede, Heinke Schlünzen, Benno Hain, Insa Meinke, Jörg Knieling, Grit Martinez and Olaf Müller for helpful comments.

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• Introduction: Exchange between climate (impact) research and stakeholders in Hamburg und Schleswig-Holstein

• Issues- the 2o goal and the need for adaptation- challenges- tools: scenarios and temporal consistency

• Example: Storm surges in the Elbe estuary and along the German Bight coast

• Regional climate servicing

Overview

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Climate knowledge demand, supply and brokers in Hamburg and Schleswig-Holstein

Municipalities/regions- coastal defense- urban and regional planning- water management

Landscape oriented: - agri- & horticulture - forestry- tourism- nature conservation

Technology oriented: offshore operations (marine/coastal) transport

Universities:Hamburg (UHH, HCU, TUHH) CAU Kiel

Max-Planck Society: MPI of Meteorology

Helmholtz Association: HZ Geesthacht, Kiel; Bremerh.

Federal agencies:BSH, DWD (SWA), BAW

National climate service: CSC, DWD

Regional climate service: IfK@HZG

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Overview

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2oC goal

In the last decade, CO2 emissions are not only continuing to increase, but accelerating.

Also the growth of CO2 concentations in the atmosphere is acceleratimg.

A tendency towards limiting the rate of increase does not exist at this time.

Chances for reaching the 2o-goal are small; a goal below 2o is unrealistic.

20.04.23 GISS estimate, 2011

A robust expectation

Global air temperature will increase in 2100 at least by 2oC.

The effects of man-made climate change will become more distinct and more consequential in the next decades.

The need for adapting to the non-avoidable change will grow – the more the less effective a global climate protection policy will

become.

2o goal and adaptation

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Overview

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Conceptual challengesissue manifestationUncertainty Lack of knowledge is not an issue of inaccuracy.

Knowledge about future takes the form of corridors, ranges, not of precise numbers. Some aspects will become less uncertain, other sources of uncertainty will emerge.Sum of non-knowledge does not necessarily become smaller

Instationarity Change will continue; traditional methods of estimating risks (extreme value analysis) become inadequate.

Diversity of influences

Other, also so far unknown, factors will become essential for designing adaptation measures.

Changing conditions

New problems will show up. Social preferences, technologies and governance will change.

Medial-cultural constructions

The public discourse is based not on contemporary scientific knowledge but to large extent on perceptions rooted in cultural mental models maintained by the dynamics of media and interest groups.

Time horizons Different measures must be implemented on different time horizons

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Overview

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tools: scenarios

Future anthropogenic climate change, or Global Warming, is described by scenarios.

Alternative scenarios about economic and social developments in the coming 100 years are made; from these assumptions emissions of greenhouse gases are estimated; the climatic effect of these are assessed by running climate models.

The resulting knowledge are not predictions, but projections conditional upon certain emission scenarios.

If, however, all scenarios point to the same development, then they collectively become predictions – namely that temperatures as well as sea level will rise.

IPCC SRES scenarios

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Tools: temporal consistency

Are present changes indicators of future changes?

To do so, one may compare the change in the past, say, 30 years with the change envisaged by the scenario calculations.This has not often been done systematically - one case being temperature and precipitation in the Baltic Sea catchment.

It is found that the ongoing temperature change is broadly consistent with the future expectation, but that the consistency is limited for precipitation.

Bhend, pers. comm, 2011

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Overview

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For the low-lying Northern Germany, storm surges represent the greatest geophysical hazard

In the past, very strong storm surges have breached coastal defense, with many dead and much damage.

However, after the 1962 flood, the hazard seems mostly checked by an efficient coastal defense, even if a remaining (albeit small) risk prevails

Which effect will climate change have on this hazard?

Christmas flood 1717

Hamburg flood, 1962

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Graphik: Michael Schrenk

The bath tub

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Example: Storm surges

Storm surges are a threat for the low-lying areas along the (not only) German coasts (both North Sea and Baltic Sea)

• Climate Change as well as the improvement of waterways and of coastal defense are associated with changes of the storm surge hazard.

• The North Sea is one of the best observed marginal seas. Here, an accelerated increase in sea level has not (yet?) been identified in the observed data; also storm activity remains mostly stationary, albeit undulated by decadal variation.

• For the future, changes are to be expected. Chiefly for mean sea level (until 2100: 20-80 cm), to a lesser extent for storms (until 2100: up to 30 cm).

A need for further improving coastal defense will emerge after 2030; until then, planning and discussion about options as well as maintaining the present levels of protection is needed. Building structures, which allow additional fortification at a later time is prudently done already now.

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Special: estuaries

• In the estuaries of Elbe, Weser and Ems the storm surge heights have grown - but since the 1960s more so upstream (e.g. Hamburg) than at the mouths (e.g., Cuxhaven).

• The upstream growths are best explained by water works, related to shipping and coastal defense (after 1962) .

• The coastal defense, which has been fortified since 1962, have provided security against these intensified hazards.

Differences of storm surge heights in Cuxhaven (mout of Elbe) and Hamburg (St. Pauli) since 1900

• Possibly, the expected intensification due to climate change may (partly) by met by other local modifications (“Tideelbeprojekt”).

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Technological optimization of flood protection infrastructures

Besides enforcing traditional measures of coastal defense, new adaptive options need to be developed. Candidates are

• constructing coastal defense measures such they may at a later time further be fortified.

• damping of tidal energy in estuaries („Tideelbeprojekt“)

• improved design for constructing dykes (more effective clay cover layer; increased allowance for wave overtopping)

Options for adaptation

Graphik: Michael Schrenk

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Strategy „living with water - paradigm shift in flood protection„

• River basin management to develop strategies and measures for the whole river• Enlargement of catchment areas to hold water back• Building on warfts (e.g. HafenCity)• Floating homes and cascade systems of flood protection • Flood proof spatial planning; building codes, such as cascading zoning for the case of defense failure, but also retreat.

Pasche et al., 2008

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Governance• urban planning• cross-regional and cross-national decision making (national, supranational)• stakeholder involvement / public participation/civic self-organization• adecision-making under uncertanties • cost-benefit analysis/ evaluation of measures

Research questions

Changes • urban thermal comfort & health• amount of rainwater to be managed• storm surge levels• level of groundwater• river discharge• wind conditions• coastal sea change• ecosystem services

Options• retention areas• damping of tidal energy• cascading zoning• live with change, social learning• business opportunities• controlled drainage

Social conditions• perceptions, mental models of climate change• media framing and coverage• acceptance of strategies and measures• cultural constraints

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Overview

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How strongly do you employ the following sources of information, for deciding about issues related to climate adaptation?

Survey among regional administrators in German Baltic Sea coastal regions.

Bray, 2011, pers. comm.

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The medial-cultural constructed mental model of climate change

„Klimakatastrophe“

Mankind is changing climate, mostly by excessive use of fossil energy, but also locally by deforestation.

The weather is less reliable than previously, the seasons are more erratic, storms more violent. Weather extremes have become catastrophic to an extent never seen before.

Almost all contemporary weather extremes are related to man-made global warming.

The cause of all this is „human greed“ and “stupidity“, the mechanism is „revenge of nature“. Damaging extremes are a warning for humankind.

Regional Climate Service

1. Analysis of cultural construct, including common exaggeration in the media.

- Determination of response options on the local and regional scale: mainly adaptation but also regional and local mitigation.

- Dialogue of stakeholders and climate knowledge brokers in „Klimabureaus“.

2. Analysis of consensus on relevant issues (climate consensus reports).

3. Description of recent and present changes.

- Projection of possible future changes, which are dynamically consistent and possible („scenarios“)

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Raw data from 12 regional climate projectionsAnalyzed for Northern Germany and the Odra estuary

regionInteractive user interface

„Klimaatlas“http://www.norddeutscher-klimaatlas.de

http://www.ujscieodry-atlasklimatu.pl/

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Conclusions

• Man-made climate change is real and emerging. Given our present knowledge, the present changes can only be explained consistently when employing elevated greenhouse gas concentrations as a major factor.

• Stakeholders must understand that the knowledge about climate change (incl. hazards) is different from the knowledge about present climate (incl. hazards): in particular uncertainty and instationarity.

• Climate science represents a key advisory capacity for decision processes, by - providing needed scientific knowledge, which allows embedding the complex issue of climate change into a social context,- explaining interdependences and efficiencies of measures used in the past and available for the future.

• For designing suitable and socially acceptable adaptation measures, other factors than climate change must be taken into account, among them emerging other stressors and other options.

• The major issue is knowledge, which is available in different, often competing types. Regional climate service is needed to align these different types.

• Decisions about adaptation to climate change are political, not scientific.

research on climate impacts in hamburg and schleswig holstein

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