© 2011 Martin Beniston Climatic change in the light of scientific knowledge Martin Beniston Institute for Environnemental Sciences University of Geneva

© 2011 Martin Beniston

Climatic change in the light of scientific knowledge

Martin BenistonInstitute for Environnemental SciencesUniversity of Geneva


The functionning of the climate system


Energy exchange around the planet

Solar

Reflectedenergy

Infrared


Volcanic eruptions


Fluctuations ofsolar

irradiance

Weak activityJanuary 2005

Stronger activityMarch 2001


ENSO (El Niño/Southern Oscillation)

February 2011 La Niña


Human perturbations to the climate system


CO2 and CH4 concentrations

10’000 5’000 0 10’000 5’000 0Years before present

250

300

350

500

1000

1500

CH4 ppbvCO2 ppmv

Years before present


Attribution of recent trends to anthropogenic forcing


Human responsibility…?

1900 1950 2000

0.0

0.5

1.0

T w

ith r

espe

ct t

o19

61-1

990

[°C

]

Observations

Natural forcing

Natural + Greenhouse-Gas Forcing

IPCC, 2007


Future warming will be linked to emissions

- and thus to the choices we make in terms of

policy, economics and technology


Global warming futuresIP

CC

, 200

7

-0.4-0.2

00.20.40.6

1.0

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

T r

esp

ect t

o 2

0th c

en

tury

me

ans

[°C

]

0.8

2.0

3.0

4.0

5.0

6.0

2050 2100

A2

B2


Glo

bal t

empe

ratu

re c

hang

eby

210

0


Heatwave days: Exceedance of 40°C threshold in Europe

5 10 15 20 251Days

EU

-FP

6 « EN

SE

MB

LE

S » P

roject, 2009

1961-1990

2021-2050

2071-2100

PrecipT CH


Changes in seasonal temperatures (at 2,500 m asl)

Beniston, 2006:Geophysical Research Letters

15

Winter Spring Summer Autumn

Te

mp

era

ture

[°C

] 10

5

0

-5

Ben

iston, 2004: Clim

atic C

hange and Im

pacts, S

pringer

1961-1990

2071-2100


Global precipitation change

(IPC

C A

R4, 2007)


Changes in summer precipitation (june-july-august)(Differences in % between 2071-2100 and 1961-1990)

(HIRHAM RCM; A-2 Scenario)

Christensen and C

hristensen, Nature, 2003

Seasonal precipitation Events greater than

50 mm/day

-40 -30 -20 -10 0 +10 +20 +30 +40

% change

Accelerated warming Impactsp CH


Changes in seasonal precipitation

Beniston, 2006:Geophysical Research Letters

-40.0

-30.0

-20.0

-10.0

0.0

10.0

20.0

30.0

40.0

Winter Spring Summer Autumn

Pre

cip

ita

tio

n c

ha

ng

e2

071

/21

00

vs

19

61/1

99

0 [

%]

ImpactsAccelerated warming


Since the 2007 IPCC reports, climate has shown signs of

accelerated change…


IPCC projections with respect to observations

19901995 2000 2005 2010

0

0.25

0.50

Cha

nges

in t

empe

ratu

re[°

C]

Projections (IPCC 3rd

Assessment Report )

Observed Updated from

Rahm

storff, 2007 in « S

cience »


Feedback mechanisms stronger than expected

Certain irreversible thresholds may be reached earlier than expected changes in Arctic sea ice release of methane in polar permafrost changing patterns of land-use

Whatever we achieve in terms of policy, climate is likely to warm by at least 1.5-2°C compared to the 1990 baseline levels

This is the upper bound of the EU policy limits brought to the COP-15 negotiations in Copenhagen in December, 2009…

ImpactsPolar ice decline


One probable cause of accelerated warming: Arctic Ocean

processes


Some reasons to address issues related to climatic change quickly…


Distributionof impacts

Aggregateimpacts

Tippingpoints

Naturalsystems

Climatic impacts…

Extremes

0 1 2 3 4 5T compated to 1980-1999

Risks to some Risks to many

Increase Large increase

Negative for somePositive for others

Negative foralmost all

Positive and negativemarket impacts

Negative inall metrics

Low risk High risk

CostsExamples of impacts


Coastal-zone vulnerability by 2100IPCC, 2007


Water availability

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Japan Spain India

2000

2050, without climatic change

2050, with climatic change

m3/p

erso

n/ye

arIP

CC

, 200

1

Haiti


Possible future discharge by 2100(m3/s, River Rhone)

Be

nis

ton

, 20

10

: Jo

urn

al o

f Hy

dro

log

y

0

50

100

150

200

250

300

350

400

J F M A M J J A S O N D

Ave

rag

e m

on

thly

dis

ch

arg

e [m

3/s

]

1961-1990

2071-2100(B2)

2071-2100(A2)


Tropical storms

0

40

80

120

160

960 940 920 900 880

Pressure at center of system [hPa]

Num

ber

of e

vent

s

Cat 3 Cat 4 Cat 5

1961-1990

2071-2100

K. E

mm

anuel, S

cience

: 2006


Vector-borne and water-borne diseases (WHO, 2005)

Diseases Relation to Populationsclimate at risk

(2050)

Malaria Temp., humidity (moskitos) 2.2 billionDengue Temp., humidity 2.5 billionSchistosomiasis Water for the snails 600 millionSleeping sickness Temp., humidity (flies) 55 millionChagas disease Temp., humidity (flies) 100 millionLeishmaniasis Temp., humidity (flies) 350 millionRiver blindess Water for the black flies 120 million


Even in today’s world, climate is a costly business


Costs related to natural hazards

4 11 1424 47

88

160

345

103

495

050

100150200250300350400450500

56-65 66-75 76-85 86-95 96-05

GeologicBillions ofUSD/decade

Decade

Climatic

Swiss Re, 2007

EndThe way forward


The way forward


Where we should be going… In view of the long inertia of environmental and

climatic change, it will not be possible to stop current trends rapidly

While addressing the long-term issues of emission abatements, adaptation strategies need to be implemented in order to ensure access to: Health Clean water and food Sustained biodiversity conservation Shelter Education

This raises ethical questions of equal access to resources and technologies, and a genuine move towards the eradication of poverty


Climatic change in the light of scientific knowledge

www.unige.ch/climate

[email protected]

Many thanks foryour attention!

Documents

© 2011 Martin Beniston Climatic change in the light of scientific knowledge Martin Beniston Institute for Environnemental Sciences University of Geneva