7 April 2011

1

The Science of Climate Change:The Science of Climate Change:The Challenges for HumanityThe Challenges for Humanity

11

Don WuebblesDepartment of Atmospheric Sciences

University of IllinoisUrbana, IL

April 7, 2011

The Science is Clear: The Science is Clear: Climate change is one of the most Climate change is one of the most important issues facing humanityimportant issues facing humanity

22

The scientific evidence clearly indicates The scientific evidence clearly indicates that our climate is changing, and that that our climate is changing, and that human activities have been identified as human activities have been identified as the primary cause.the primary cause.

One of Many ExamplesOne of Many Examples

May 2009May 2009National Academies of Sciences from the National Academies of Sciences from the G8 + 5 other countriesG8 + 5 other countries

33

G8 5 other countriesG8 5 other countries““The need for urgent action to address The need for urgent action to address

climate change is now indisputable.climate change is now indisputable.””

ThreeThree independent independent analyses ofanalyses of temperature temperature record record –– TrendsTrends in in close agreementclose agreement

44

2010 Tied with 2005 for Warmest Year

55

The warming is not uniform, nor do we expect it to be

66From Tom Karl, NOAA NCDC

7 April 2011

2

Conditions today appear to be unusual Conditions today appear to be unusual in the context of the last 2,000 years …in the context of the last 2,000 years …

77Mann et al., 2008 PNAS

© Finnish Meteorological Institute

FinlandFinland ----Annual Mean Annual Mean TemperatureTemperature

88

The annual mean temperatures for 1901–2010 are marked in blue and the mean temperatures for each decade in red.

According to the Finnish Meteorological Institute the first decade of the 21st century was the warmest decade in recorded history (records go back to the 1840s).

Temperature riseTemperature riseSeaSea--level riselevel riseIncrease in heavy downpoursIncrease in heavy downpoursRapidly retreating glaciersRapidly retreating glaciersThawing permafrostThawing permafrost

Observed Signatures of Changing Observed Signatures of Changing ClimateClimate

99

g pg pLengthening growing seasonLengthening growing seasonLengthening iceLengthening ice--free season in the ocean and on lakesfree season in the ocean and on lakesand riversand riversEarlier snowmeltEarlier snowmeltChanges in river flowsChanges in river flowsPlants blooming earlier (1Plants blooming earlier (1--3 days per decade earlier) 3 days per decade earlier) Animals, birds and fish moving northwardAnimals, birds and fish moving northward

Relative SeaRelative Sea--Level Changes Level Changes on U.S. Coastlineson U.S. Coastlines

1010

Observed changes in relative sea level from 1958 to 2008 for Observed changes in relative sea level from 1958 to 2008 for locations on the U.S. coast. Some areas along the Atlantic and Gulf locations on the U.S. coast. Some areas along the Atlantic and Gulf coasts saw increases greater than 8 inches over the past 50 years. coasts saw increases greater than 8 inches over the past 50 years.

Glacier National Park: 25 out of 150 left Glacier National Park: 25 out of 150 left

1111

Arctic Sea Ice is DecreasingArctic Sea Ice is Decreasing

Arctic Sea Ice Volume

1212

Arctic Summer Minimum Area

7 April 2011

3

Natural factors affect climateNatural factors affect climate

Variations in the Earth's orbit Variations in the energy

1313

Variations in the Earth s orbit(Milankovic effect)

Stratospheric aerosols from

energeticvolcanic eruptions

Variations in the energyreceived from the sun

Chaotic interactions inthe Earth's climate

(for example, El Nino, NAO)

Human factors also influence climate

NonNon--natural mechanismsnatural mechanisms

•• Changes in atmospheric Changes in atmospheric concentrations ofconcentrations of radiativelyradiativelyimportant important gasesgases

•• Changes in aerosol particles Changes in aerosol particles

1414

g pg pfrom burning fossil fuels and from burning fossil fuels and biomassbiomass

•• Changes in the reflectivity Changes in the reflectivity ((albedoalbedo) of the Earth’s surface) of the Earth’s surface

Smoke from fires in Guatemala and Mexico (May 14, 1998)

Why does the Earth warm?Why does the Earth warm?1. Natural causes1. Natural causes

THE GREENHOUSE EFFECT…THE GREENHOUSE EFFECT…

•• …is 100% natural. …is 100% natural. –– Heat is trapped in the atmosphere.Heat is trapped in the atmosphere.

1515

•• …sustains life on Earth.…sustains life on Earth.–– Keeps average temperatures at Keeps average temperatures at 12.812.8ooC, instead of C, instead of ––2929ooC.C.

THE THE ENHANCED ENHANCED GREENHOUSE GREENHOUSE EFFECTEFFECT

(or GLOBAL WARMING)(or GLOBAL WARMING)

Why does the Earth warm?Why does the Earth warm?2. Human causes2. Human causes

1616

•• … is primarily human… is primarily human‐‐inducedinduced–– We’re increasing heatWe’re increasing heat‐‐trapping trapping gases in the atmosphere.gases in the atmosphere.

•• … is like wrapping an extra … is like wrapping an extra blanket around the Earth.blanket around the Earth.

1.1. “Basic“Basic physics”physics” evidenceevidence–– PhysicalPhysical understandingunderstanding ofof thethe climateclimate systemsystem andand thethe heatheat--

trappingtrapping propertiesproperties ofof greenhousegreenhouse gasesgases2.2. QualitativeQualitative analysisanalysis evidenceevidence

–– QualitativeQualitative agreementagreement betweenbetween observedobserved climateclimate changeschangesandand modelmodel predictionspredictions ofof humanhuman--causedcaused climateclimate changeschanges

Many lines of evidence for conclusion of Many lines of evidence for conclusion of a “discernible human influence”a “discernible human influence”

1717

andand modelmodel predictionspredictions ofof humanhuman causedcaused climateclimate changeschanges(warming(warming ofof oceans,oceans, landland surfacesurface andand troposphere,troposphere, waterwatervaporvapor increases,increases, etcetc..))

3.3. PaleoclimatePaleoclimate evidenceevidence–– ReconstructionsReconstructions ofof pastpast climatesclimates enableenable usus toto placeplace thethe

warmingwarming ofof thethe 2020thth centurycentury inin aa longerlonger--termterm contextcontext4.4. FingerprintFingerprint evidenceevidence

–– RigorousRigorous statisticalstatistical comparisonscomparisons betweenbetween modeledmodeled andandobservedobserved patternspatterns ofof climateclimate changechange

There is strong evidence that the climate There is strong evidence that the climate change occurring is primarily human inducedchange occurring is primarily human inducedHuman fingerprints have been identified in many aspects of climate change

•Surface and vertical temperature•Stratospheric and tropospherictemperature change

•Height of the tropopause

1818

g p p•Precipitation•Vertical structure of upper-ocean temperature changes

•Ocean heat content•Atmospheric moisture•Arctic sea ice•Sea-surface temperature changes in hurricane formation regions

7 April 2011

4

Climate models: Natural processes do not account for observed 20th century warming after 1965

Models with natural effects (volcanoes and solar) onlyModels with human and natural effects

1919 2020

Blue is the model predictions without anthropogenic forcingPink is the model prediction with anthropogenic forcingBlack are the observations

We have Moved Outside the Range of Historical VariationWe have Moved Outside the Range of Historical Variation800,000 Year Record of Carbon Dioxide Concentration800,000 Year Record of Carbon Dioxide Concentration

Future climate and its impacts depends on choices made today

2121

The climate future?The climate future?

Future temperature projected to increase at an unprecedented rate.

2222

From IPCC AR4, WG1, Ch. 11

2323

Observed temperature anomalies with respect to 1901-1950 (black line) and as simulated (red envelope) including all known forcings ; and as projected to 2100 by the A1B scenario (orange envelope).

From IPCC AR4, WG1, Ch. 11

2424

Observed temperature anomalies with respect to 1901-1950 for the Arctic (black line) as simulated (red envelope) including known forcings; and as projected to 2100 for the A1B scenario (orange envelope).

7 April 2011

5

Mean Annual TemperatureMean Annual Temperature1961-1990 1991-2020 2021-2050 2070-2099

2525

Mean annual temperature in Finland for the present day (a) and for the near-term (1990–2020), mid-term (2021–2050) and long-term (2070–2099). Numbers in maps refer to the Forest Centres

From Kilpeläinen et al. (2010)

Mean Annual PrecipitationMean Annual Precipitation

1961-1990 1991-2020 2021-2050 2070-2099

2626

Mean annual precipitation in Finland for the present day (a) and the predicted precipitation change for the near-term (1991–2020), mid-term (2021–2050) and long-term (2070–2099).

From Kilpeläinen et al. (2010)

Extreme weather events Extreme weather events become more commonbecome more common

•• Rare events likely to become commonplace.Rare events likely to become commonplace.•• Heat waves will likely become longer and more severeHeat waves will likely become longer and more severe•• Increasing risk of floods because of heavier rainsIncreasing risk of floods because of heavier rains•• Summers are warmer and dryer, so the level of the soil Summers are warmer and dryer, so the level of the soil

2727

moisture and groundwater likely to decrease moisture and groundwater likely to decrease •• Winter storm tracks are shifting northward and the Winter storm tracks are shifting northward and the

strongest storms are likely to become stronger and strongest storms are likely to become stronger and more frequent.more frequent.

Widespread climateWidespread climate--related impacts related impacts are occurring now and are expected to are occurring now and are expected to increaseincrease

2828

Water Water ResourcesResources

Energy Supply and Use

Transportation Agriculture

Ecosystems Human Health

Society

US Army Corps of Engineers

The benefits of strong, early action on The benefits of strong, early action on

2929Dave Saville, courtesy of FEMA

The benefits of strong, early action on The benefits of strong, early action on climate change outweigh the costsclimate change outweigh the costs

Energy Efficiency / Conservation

Use of renewable energy resources

Improve vehicle fuel

Some Solutions Some Solutions areare Already AvailableAlready Available

3030

Jupiter Images

efficiency

Craig Miller Productions and DOE, NREL

Steve H

all

Detroit Shoreway Community Development Organization

7 April 2011

6

Both Mitigation and Adaptation are Both Mitigation and Adaptation are importantimportant

3131

We Choose Our We Choose Our FutureFutureWe Choose Our We Choose Our FutureFutureA commonly heard myth: A commonly heard myth: Modern wealth is due to the subsidy of Modern wealth is due to the subsidy of cheap fossil fuel. If we stop burning oil cheap fossil fuel. If we stop burning oil and coal we’ll freeze in the dark!and coal we’ll freeze in the dark!

I prefer:I prefer:

3232

I prefer:I prefer:Modern Modern wealth results from ingenuity and wealth results from ingenuity and

hard work.hard work. We can We can inventinvent new energy new energy technologies for the 21technologies for the 21stst Century and Century and beyond. beyond.

Conclusion: We can succeed!Conclusion: We can succeed!

Forest Fire PotentialForest Fire Potential1961-1990 1991-2020 2021-2050 2070-2099

3333

Mean annual forest fire potential in Finland for the present day (a) and for the near-term (1990–2020), mid-term (2021–2050) and long-term (2070–2099).

From Kilpeläinen et al. (2010)3434From IPCC AR4, WG1, Ch

Temperature and precipitation changes over Europe for A1B simulations. Top row: Annual mean, DJF and JJA temperature change between 1980-1999 and 2080-2099, averaged over 21 models. Lower row: same but for fractional change in precipitation

An interesting note:

The overall warming is very likely to shorten the snow season in all of Europe. Snow depth is also likely to be reduced, at least in most areas, although increases in total winter precipitation may counteract the increased melting and decreased fraction of solid precipitation associated with the warming. The changes may be large, including potentially a one-to-three month shortening of the snow season in northern Europe (Räisänen et al., 2003) and a 50 to 100% decrease in snow depth in most of Europe (Räisänen et al., 2003; Rowell, 2005) by the late 21st century. However, snow conditions in the coldest parts of Europe, such as northern Scandinavia and north-western Russia (Räisänen et al 2003; Shkolnik et al 2006) and the highest peaks of the Alps (Beniston

3535

(Räisänen et al., 2003; Shkolnik et al., 2006) and the highest peaks of the Alps (Benistonet al., 2003) appear to be less sensitive to the temperature and precipitation changes projected for this century than those at lower latitudes and altitudes.

The Baltic Sea is likely to lose a large part of its seasonal ice cover during this century. Using a regional atmosphere-Baltic Sea model (Meier et al., 2004), the average winter maximum ice extent decreased by about 70% (60%) between 1961 to 1990 and 2071 to 2100 under the A2 (B2) scenario. The length of the ice season was projected to decrease by one to two months in northern parts and two to three months in the central parts. Comparable decreases in Baltic Sea ice cover were projected by earlier studies (Haapala et al., 2001; Meier, 2002).

From IPCC AR4, WG1, Ch. 11.3.3

Floods and dry spells will increase with climate change also in Finland. Especially in southern Finland, the snow cover and snowmelt floods will be reduced. Heavy rains will increase the flood risk, especially in urban areas and small catchments. The risk of winter floods will increase in large lakes like Saimaa and Päijänne during snowless and rainy winters. Increasing damage may also be caused by extreme high water situations at the coast. However, adaptation to these changes is possible, according to the water part of the FINADAPT summary report. The FINADAPT project was a comprehensive attempt to estimate the capacity of the Finnish society and environment to adapt to the climate change. The water part of the report was presented to the public on the World Water Day Eve in Helsinki.

The most significant hydrological effect of the climate change in Finland is the change of annual variation patterns of runoff and discharge. Snowmelt will occur throughout the winter and rainfall during winter months will be more common. Wintertime water levels in lakes will be higher than now. On the other hand, spring floods will be less extensive. Such a pattern has already become

3636

, p g p ymore common in southern and central Finland, and it will extend northwards if the climate develops according to the prognoses.

The less there are lakes in a river system, the less they can smooth out the variations in discharge. More heavy rainfall in summer means more floods, especially in catchments with few lakes. On the other hand, evaporation from soil and lakes will increase when the summer period becomes longer. As a consequence, discharges will decrease, droughts will be more severe, and groundwater will be more scarce, especially late in the summer.

Groundwater bodies are essential for water supply. Longer dry spells will decrease the groundwater resources and the quality of groundwater may deteriorate.

From the Finnish Environment Institute