2015-06 studium generale leemans...17/06/2015 2 prof. dr. rik leemans s7 as average global...

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Prof. Dr. Rik Leemans S1

Why has Climate change not allready been stopped?Evidence from projections and observations

Prof. Dr. Rik Leemans Environmental Systems Analysis Group

Wageningen University16th June 2015


People have been concerned about the rise in carbon dioxide in our atmosphere, the result of human activity, since what period of time?

1 2 3 4

0% 0%0%

100%

In 1896, Svante Arrhenius published the first study measuring how CO2 contributes to the greenhouse effect. CO2 warms the Earth by trapping heat near the surface, a bit like swaddling the planet in an extra blanket. Arrhenius also speculated about whether changes in atmospheric CO2 have contributed to long‐term variations in Earth’s climate. He made the link between burning fossil fuels and global warming, a link we are clearly seeing today.

1. 18th century2. 19th century3. 20th century4. 21th century


Which of the following gases do not trap heat (i.e. contribute to the greenhouse effect)?

1 2 3 4

0%8%8%

85%

Heat‐trapping greenhouse gases absorb and emit radiation within the thermal infrared range. Water vapour, carbon dioxide and methane are Earth's most abundant greenhouse gases. Nitrogen, which makes up 80 percent of Earth's atmosphere, is not a greenhouse gas. This is because its molecules, which contain two atoms of the same element (nitrogen), are unaffected by infrared light.

1. Carbon dioxide 2. Nitrogen 3. Water vapour 4. Methane


We produce more than 30 billion tons of carbon dioxide per year. Where does the majority of it end up?

1 2 3

13%

42%46%

Forty to 50 percent of the carbon dioxide stays in the air, and almost 30 percent is dissolved in the oceans. Scientists are not fully sure about the rest. They believe it is absorbed by forests, soil and crops.

1. It is inhaled by trees for photosynthesis.

2. It enters our oceans. 3. It lingers in the

atmosphere.


In the 10,000 years before the start of the industrial Revolution in 1750, carbon dioxide levels in the air rose by less than 10 percent. Since then they’ve risen by:

1 2 3

4%

68%

28%

Since 1750, humans added 590 ± 75 billion tons of carbon to the atmosphere in the form of carbon dioxide. In 2012, 92 percent of all human‐produced carbon dioxide originated from burning coal, natural gas, oil and gasoline. In 1750 the Co2 concentration was c. 280 ppm. Now it is 400 ppm (i.e. a 43% increase).

1. 21 percent 2. 43 percent 3. 62 percent


Melting sea ice could raise sea level by several meters.

1 2

42%

58%

Melting sea ice cannot raise global sea level since the ice is already floating. (Think of an ice cube melting in a glass full of water, which doesn't raise the water level.) However, Arctic sea ice is thinning and the long‐term summer average cover has decreased by 34 percent in 1979. Ice from glaciers and ice sheets, which form on land, does add water to Earth's oceans when it melts and does contribute to sea level rise.

1. True2. False

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As average global temperature rises,

1 2 3

41% 41%

18%

A higher temperatures give rise to a more active water cycle, which means faster and greater evaporation and precipitation and more extreme weather events.

1. Average precipitation increases

2. Average precipitation decreases

3. Average precipitation is unchanged


Where have some of the strongest and earliest impacts of global warming occurred?

Some of the fastest‐warming regions on the planet include Alaska, Greenland and Siberia. These Arctic environments are highly sensitive to even small temperature increases, which can melt sea ice, ice sheet and permafrost, and lead to changes in Earth’s reflectance (or “albedo”).

1 2 3 4 5

25%

36%

0%

7%

32%

1. In the tropics 2. In northern latitudes3. Over the oceans4. Over mountains5. global warming is distributed

equally all over the planet


http://www.skepticalscience.com/


Forecasts: Opiate for decision makers

http://www.theguardian.com/environment/climate‐consensus‐97‐per‐cent/2013/oct/01/ipcc‐global‐warming‐projections‐accurate


Union of Concerned Scientists Infographic

"It's not known for sure whether (a) climate change is actually occurring or (b) if it is, whether humans really have any influence on it." American Petroleum Institute, 1998

"...current indirect CO2 benefits clearly outweigh any hypothesized cost by literally orders of magnitude; the benefit-cost ratios range up to more than 200-to-1." Peabody Energy, 2014


Eminent US climate scientist, Kevin Trenberth

The answer to the oft-asked question of whether an event is caused by climate change is that it is the wrong question. All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be.

This calls on us to reframe how we think about human-induced climate change. We can no longer place some events into the boxes marked “Nature” and “Human”.

Inventing these two boxes was the defining feature of modernity, founded on Cartesian and Kantian philosophies. Climate science now shows that such a separation can no longer be sustained, that the natural and the human are mixed up, and their influences cannot be neatly distinguished.

Trenberth, K.E., 2012: Framing the way to relate climate extremes

to climate change. Climatic Change, 115, 283-290.

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Climate scenarios of the IntergovernmentalPanel on ClimateChange (IPCC)


Temperature change in the SRES scenarios


The IPCC scenarios: GHG emissions

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Complete globalisation

Strong regionalisation


The final figure from IPCC’s synthesis report

Emissions

Narratives

Concentrations

Climate change Impacts


o Global GHG emissions increase in all scenarios in the next 10-50 years

o After 2050, emissions can increase fivefold but also be halved in world futures without climate policy

o GHG emissions are strongly related to developments and policies in other areas than climate change

o Large co-benefits between sustainable development, energy efficiency, land use and climate change policies

Summary of IPCC SRES scenarios


New scenarios development process: A time-saving parallel versus sequential approach

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Representative Concentration PathwaysRepresentative Concentration Pathways (RCPs) are greenhouse gas concentration trajectories (i.e. not emission scenarios like SRES) adopted by the IPCC in 2014. The RCPs supersede the SRES Scenarios (IPCC, 2000).The RCPs are used for climate modelling and research. They describe four possible climate futures, all of which are considered possible depending on how much greenhouse gases are emitted in the years to come. The four RCPs (i.e. RCP2.6, RCP4.5, RCP6 and RCP8.5) are named after a possible range of radiative forcing values in the year 2100 relative to pre-industrial values (i.e. +2.6, +4.5, +6.0, and +8.5 W/m2, respectively).

More information on: http://www.theguardian.com/environment/climate-consensus-97-per-cent/2013/aug/30/climate-change-rcp-handy-summary


Representative Concentration Pathways

RCP8.5

RCP6.0

RCP4.5

RCP2.6


RCPs also provide opportunities for the longer term

http://www.iiasa.ac.at/web‐apps/tnt/RcpDb


The 90th and 98th percentiles are indicated by the dark and light grey areas respectively.

Emissions that comply with the various Representative Concentration Pathways


The main effects of the different RCPs


Observed emission and the IPCC scenarios

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Circ

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Brysse, Oreskes, O’Reilly & Oppenheimer, 2013.

Climate change prediction: Erring on the side of least

drama? Global Environmental Change (in press).

Observed emission (X) follow the top

of all IPCC scenarios (●)

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Understandingtemperaturetrends


If you removed the atmosphere's natural greenhouse effect, and everything else stayed the same, Earth's temperature would be:

1 2 3 4

4%

44%

52%

0%

The greenhouse effect is a naturally occurring physical process that warms the Earth's surface with energy from the atmosphere. Without the effect, Earth's average surface temperature would be well below freezing, i.e. 28 to 33°C cooler.

1. 6 to 11°C warmer 2. 17 to 22°C warmer 3. 6 to 11°C cooler 4. 28 to 33°C cooler


The six hottest years on record occurred during the last:

1 2 3

7%

67%

26%

According to NASA, 2009 was only a fraction of a degree cooler than 2005—the warmest year on record—and was tied with a cluster of other years—1998, 2002, 2003, 2006 and 2007—as the second warmest year since record‐keeping began. January 2000 to December 2009 was the warmest decade on record.

1. 100 years 2. 50 years 3. 10 years


Where have some of the strongest and earliest impacts of global warming occurred?

Some of the fastest‐warming regions on the planet include Alaska, Greenland and Siberia. These Arctic environments are highly sensitive to even small temperature increases, which can melt sea ice, ice sheet and permafrost, and lead to changes in Earth’s reflectance (or “albedo”).

1 2 3 4 5

0%

100%

0%0%0%

1. In the tropics 2. In northern latitudes3. Over the oceans4. Over mountains5. global warming is distributed

equally all over the planet


No place on Earth is colder today than it was 100 years ago.

1 2

68%

32%

Although most locations on the planet have recorded increased temperatures since 1900, changes in global ocean and atmospheric circulation patterns have created small‐scale temperature decreases in a few local regions.

1. True2. False


Confusion on data

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Globally averaged increase in temperature anomaly (oC from 1951-80)


The temperature anomalies for different latitudinal bands


Globally averaged increase in January-February temperature anomaly (oC from 1951-80)

Increasing temperatures are observed, but what is/are the causes (i.e. explaining

the patterns or attribution of causes)

http://www.columbia.edu/~mhs119/Temperature/T_moreFigs/


Seasonal temperature anomalies

Prof. Dr. Rik Leemans S35 Prof. Dr. Rik Leemans S36

Does the long-term warming trend continue?

From: IPCC AR5

The hiatus1998 - now

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The climate hiatusSome claim that after 1998 (a strong El Niño year) the global mean surface temperatures have not increased anymore. However, IPCC shows that the nineties were warmer than the eighties, and the first decade of this century is warmer again than the nineties.


Climate sensitivityClimate sensitivity is the equilibrium temperature change in response to changes of the radiative forcing (or CO2concentrations). The climate sensitivity depends on the initial climate state. It can be inferred from palaeo-climate data, observed temperature change and climate models. Slow feedbacks, especially change of ice sheet size and atmospheric CO2, amplifythe total climate sensitivity by an amount that depends on the time scale considered.

The cost common value ranges from 1.5‐ 4.5oC at a doubling of CO2


The climate hiatus and natural variability

Natural variability is an important aspect of climate change. They include volcanic eruptions, solar variability, dust storms, and ocean circulation (El niño/La nina, PDO, NAO).

Grant, F., and R. Stefan. 2011. Global temperature evolution 1979–2010. Environmental Research Letters 6:044022.


How much of Earth's surface is covered by water?

1 2 3 4

0%

8%

88%

4%

Earth is often referred to as the "Water Planet" because you can see water in all three forms as you gaze at Earth from space. As we search for life elsewhere in the cosmos, we look for places that have liquid water, as it seems to be the primary requirement for life as we know it. About 70% of Earth is covered by water, and most of that water (97%) is found in our vast oceans.

1. 30% 2. 50% 3. 70%4. 85% or more


What role do the oceans play in the carbon cycle?

1 2 3 4

4%

11%

37%

48%

Oceans both release carbon dioxide into the air and absorbs or stores it. One‐third of all carbon dioxide emitted by humanity has been absorbed by the world’s oceans. This is making them more acidic than they have been for tens of millions of years. Warmer oceans are less able to store carbon.

1. a major source of carbon dioxide

2. a major absorber of carbon dioxide

3. Both 1 and 24. Neither 1 nor 2


What percentage of heat from global warming has the ocean absorbed in the past 40 years?

1 2 3 4

0%

11%

59%

30%

Water resists changes in temperature; it is slow to heat up and slow to cool down. In scientific terms, water has high heat capacity. This means that, so far, Earth's ocean has been able to absorb and hold a majority (i.e. 93%) of the heat from Earth's atmosphere.

1. 11%2. 35% 3. 56%4. 93%

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Increased heat in de Oceans (1022 Joules)


Where is the heat generated by the ‘greenhouse’?


Effect of natural variability in de Pacific Ocean (IPO)

In periods with a positive (negative) IPO, the temperature trend is positive (negative)


Data adjusted for:o lack of data in polar regions, Africa,

Asia and Latin Americao Climate variabilityo Ship measurementso Ocean heat uptake

Estimated rate of warming:0.086oC per decade and 0.116oC per decade for 2000-2014 (IPCC: 0.039oC per decade)

Bias adjustments to the data


Understanding how to keep thetemperaturetrends within the internationally accepted 2oC


To stabilize CO2 concentrations in the atmosphere, the emissions should be:

1 2 3 4

17%

67%

17%

0%

The greenhouse effect is a naturally occurring physical process that warms the Earth's surface with energy from the atmosphere. Without the effect, Earth's average surface temperature would be well below freezing, i.e. 28 to 33°C cooler.

1. The increase in recent CO2emission must be stopped

2. Current CO2 emissions must reduced by 25%

3. Current CO2 emissions must reduced by 50%

4. CO2 emissions must peak before 2020 and then be reduced by at least 90% before 2050.

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What are the allowed future emissions if all countries agree to the 2o target (i.e. the Copenhagen accords)?

Q1: What are the current cumulative CO2

emissions in GtC since 1870?

Q2: What are the allowable future cumulative

CO2 emissions in GtC?


What are the current cumulative CO2 emissions in GtC since 1870?

1 2 3 4 5

6%

22%

6%

17%

50%

1. 150 GtC2. 300 GtC3. 450 GtC4. 600 GtC5. 750 GtC


What are the allowable future cumulative CO2emissions in GtC to keep temperatures within 2oC?

1 2 3 4 5 6

12%

28%

12%

16%

20%

12%

1. 100 GtC2. 200 GtC3. 300 GtC4. 400 GtC5. 500 GtC6. 600 GtC


The urgency of emission reduction to stay within the 2o target

IPCC 2013Maximally allowable

emissions are 400 Gt C

Current worldwide annual emissions are

10.5 Gt C

That is (400/10.5)38 jaar of the current

emissions

(with a reduction of 3% per year, still 75 year)

How do we distribute these 400 Gt C between

countries, people and generations?

450 Gt C 850 Gt C

What are the allowed future emissions if all countries agree to the 2o target (i.e. the Copenhagen accords)?


Consider national differences!


If humans stopped emitting carbon dioxide tomorrow, what would happen to global temperatures?

When we stop all carbon emissions right now, the hundreds of billions of tons of CO2 that have been pumped into the atmosphere and absorbed by the oceans since the Industrial Revolution would continue to warm the planet. For how long? No one knows, but estimates range from hundreds to thousands of years.

1. They would immediately begin to drop.

2. They would continue to rise.

3. They would stop rising, flatten out and then drop.

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Sherwood, S. (2011). Science controversies past and present. Physics Today, 64, 39‐44.

There can be long time lags between scientific consensus and societal consensus



Climate policies will get strong support from the Pope this week!


Conclusions

The climate system consist of many interacting components and its precise behaviour is complex and difficult to predict Although new scientific insights continue to emerge, science

has developed the necessary skills to understand and predict the system’s course behaviour Human influence is unequivocal (c.f. IPCC) and global mean

temperature continues to increase Many societal actors do not accept this robust science

because of political, lobbyest and post-modern motivations: “Science has become another opinion” or “Do you believe in climate change?”

To limit climate change to 2oC and address other global-change challenges is not yet impossible but requires political courage, guts and nowadays immediate action


2015-06 studium generale leemans...17/06/2015 2 prof. dr. rik leemans s7 as average global...

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