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17/06/2015
1
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
Prof. Dr. Rik Leemans S2
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
Prof. Dr. Rik Leemans S3
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
Prof. Dr. Rik Leemans S4
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.
Prof. Dr. Rik Leemans S5
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
Prof. Dr. Rik Leemans S6
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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2
Prof. Dr. Rik Leemans S7
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
Prof. Dr. Rik Leemans S8
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
Prof. Dr. Rik Leemans S9
http://www.skepticalscience.com/
Prof. Dr. Rik Leemans S10
Forecasts: Opiate for decision makers
http://www.theguardian.com/environment/climate‐consensus‐97‐per‐cent/2013/oct/01/ipcc‐global‐warming‐projections‐accurate
Prof. Dr. Rik Leemans S11
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
Prof. Dr. Rik Leemans S12
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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3
Prof. Dr. Rik Leemans S13
Climate scenarios of the IntergovernmentalPanel on ClimateChange (IPCC)
Prof. Dr. Rik Leemans S14
Temperature change in the SRES scenarios
Prof. Dr. Rik Leemans S15
The IPCC scenarios: GHG emissions
Emph
asis
on
sust
aina
bilit
y an
d eq
uity
Emph
asis
on
mat
eria
l wea
lth
Complete globalisation
Strong regionalisation
Prof. Dr. Rik Leemans S16
The final figure from IPCC’s synthesis report
Emissions
Narratives
Concentrations
Climate change Impacts
Prof. Dr. Rik Leemans S17
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
Prof. Dr. Rik Leemans S18
New scenarios development process: A time-saving parallel versus sequential approach
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4
Prof. Dr. Rik Leemans S19
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
Prof. Dr. Rik Leemans S20
Representative Concentration Pathways
RCP8.5
RCP6.0
RCP4.5
RCP2.6
Prof. Dr. Rik Leemans S21
RCPs also provide opportunities for the longer term
http://www.iiasa.ac.at/web‐apps/tnt/RcpDb
Prof. Dr. Rik Leemans S22
The 90th and 98th percentiles are indicated by the dark and light grey areas respectively.
Emissions that comply with the various Representative Concentration Pathways
Prof. Dr. Rik Leemans S23
The main effects of the different RCPs
Prof. Dr. Rik Leemans S24
Observed emission and the IPCC scenarios
Cro
sses
(X
) : H
isto
rical
em
issi
ons
grow
th o
ver
the
perio
d in
hor
izon
tal
axis
Circ
les
(●)
: Sce
nario
em
issi
ons
grow
th o
ver
the
perio
d in
hor
izon
tal
axis
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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5
Prof. Dr. Rik Leemans S25
Understandingtemperaturetrends
Prof. Dr. Rik Leemans S26
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
Prof. Dr. Rik Leemans S27
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
Prof. Dr. Rik Leemans S28
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
Prof. Dr. Rik Leemans S29
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
Prof. Dr. Rik Leemans S30
Confusion on data
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6
Prof. Dr. Rik Leemans S31
Globally averaged increase in temperature anomaly (oC from 1951-80)
Prof. Dr. Rik Leemans S32
The temperature anomalies for different latitudinal bands
Prof. Dr. Rik Leemans S33
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/
Prof. Dr. Rik Leemans S34
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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7
Prof. Dr. Rik Leemans S37
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.
Prof. Dr. Rik Leemans S38
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
Prof. Dr. Rik Leemans S39
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.
Prof. Dr. Rik Leemans S40
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
Prof. Dr. Rik Leemans S41
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
Prof. Dr. Rik Leemans S42
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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8
Prof. Dr. Rik Leemans S43
Increased heat in de Oceans (1022 Joules)
Prof. Dr. Rik Leemans S44
Where is the heat generated by the ‘greenhouse’?
Prof. Dr. Rik Leemans S45
Effect of natural variability in de Pacific Ocean (IPO)
In periods with a positive (negative) IPO, the temperature trend is positive (negative)
Prof. Dr. Rik Leemans S46
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
Prof. Dr. Rik Leemans S47
Understanding how to keep thetemperaturetrends within the internationally accepted 2oC
Prof. Dr. Rik Leemans S48
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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9
Prof. Dr. Rik Leemans S49
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?
Prof. Dr. Rik Leemans S50
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
Prof. Dr. Rik Leemans S51
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
Prof. Dr. Rik Leemans S52
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)?
Prof. Dr. Rik Leemans S53
Consider national differences!
Prof. Dr. Rik Leemans S54
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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Prof. Dr. Rik Leemans S55
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
Prof. Dr. Rik Leemans S56
Prof. Dr. Rik Leemans S57
Climate policies will get strong support from the Pope this week!
Prof. Dr. Rik Leemans S58
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
Prof. Dr. Rik Leemans S59