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Climatic change in the light of scientific knowledge

Climatic change in the light of scientific knowledge. Martin Beniston Institute for Environnemental Sciences University of Geneva. The functionning of the climate system. Energy exchange around the planet. Infrared. Solar. Reflected energy. Volcanic eruptions.

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Climatic change in the light of scientific knowledge

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

  2. The functionning of the climate system

  3. Energy exchange around the planet Infrared Solar Reflected energy

  4. Volcanic eruptions

  5. Fluctuations ofsolarirradiance Weak activity January 2005 Stronger activity March 2001

  6. ENSO (El Niño/Southern Oscillation) February 2011 La Niña

  7. Human perturbations to the climate system

  8. CO2 and CH4 concentrations CO2 ppmv CH4 ppbv 1500 350 1000 300 500 250 10’000 5’000 0 10’000 5’000 0 Years before present Years beforepresent

  9. Attribution of recent trends to anthropogenic forcing

  10. IPCC, 2007 Human responsibility…? Observations Natural forcing 1.0 Natural + Greenhouse-Gas Forcing DT with respect to 1961-1990 [°C] 0.5 0.0 2000 1950 1900

  11. Future warming will be linked to emissions - and thus to the choices we make in terms of policy, economics and technology

  12. Global warming futures 6.0 A2 5.0 IPCC, 2007 4.0 3.0 DT respect to 20th century means [°C] B2 2.0 1.0 0.8 0.6 0.4 0.2 0 -0.2 -0.4 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2050 2100

  13. Global temperature changeby 2100

  14. Heatwave days: Exceedance of 40°C threshold in Europe 1961-1990 2021-2050 2071-2100 EU-FP6 « ENSEMBLES » Project, 2009 Days 1 5 10 15 20 25 T CH Precip

  15. Beniston, 2006: Geophysical Research Letters Changes in seasonal temperatures (at 2,500 m asl) 15 1961-1990 10 2071-2100 Beniston, 2004: Climatic Change and Impacts, Springer 5 Temperature [°C] 0 -5 Winter Spring Summer Autumn

  16. Global precipitation change(IPCC AR4, 2007)

  17. Changes in summer precipitation (june-july-august) (Differences in % between 2071-2100 and 1961-1990)(HIRHAM RCM; A-2 Scenario) Events greater than 50 mm/day Seasonal precipitation Christensen and Christensen, Nature, 2003 % change -40 -30 -20 -10 0 +10 +20 +30 +40 p CH Impacts Accelerated warming

  18. Beniston, 2006: Geophysical Research Letters Changes in seasonal precipitation 40.0 30.0 20.0 10.0 Precipitation change 2071/2100 vs 1961/1990 [%] 0.0 -10.0 -20.0 -30.0 -40.0 Winter Spring Summer Autumn Impacts Accelerated warming

  19. Since the 2007 IPCC reports, climate has shown signs of accelerated change…

  20. IPCC projections with respect to observations 0.50 Observed 0.25 Changes in temperature [°C] Updated from Rahmstorff, 2007 in « Science » Projections (IPCC 3rd Assessment Report ) 0 1995 1990 2000 2005 2010

  21. 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… Polar ice decline Impacts

  22. One probable cause of accelerated warming: Arctic Oceanprocesses

  23. Some reasons to address issues related to climatic change quickly…

  24. DT compated to 1980-1999 Climatic impacts… 0 1 2 3 4 5 Extremes Increase Large increase Natural systems Risks to some Risks to many Distribution of impacts Negative for some Positive for others Negative for almost all Positive and negative market impacts Negative in all metrics Aggregate impacts Tipping points Low risk High risk Costs Examples of impacts

  25. Coastal-zone vulnerability by 2100 IPCC, 2007

  26. Water availability 2000 4500 2050, without climatic change 4000 2050, with climatic change 3500 3000 2500 m3/person/year 2000 1500 1000 500 IPCC, 2001 0 Japan Spain India Haiti

  27. Possible future discharge by 2100(m3/s, River Rhone) 400 1961-1990 350 300 250 200 2071-2100 (B2) Average monthly discharge [m3/s] 150 Beniston, 2010: Journal of Hydrology 100 2071-2100 (A2) 50 0 J F M A M J J A S O N D

  28. Tropical storms 160 Cat 4 Cat 3 Cat 5 120 1961-1990 Number of events 80 2071-2100 40 0 K. Emmanuel, Science: 2006 880 960 940 920 900 Pressure at center of system [hPa]

  29. Vector-borne and water-borne diseases (WHO, 2005) Diseases Relation to Populations climate at risk (2050) Malaria Temp., humidity (moskitos) 2.2 billion Dengue Temp., humidity 2.5 billion Schistosomiasis Water for the snails 600 million Sleeping sickness Temp., humidity (flies) 55 million Chagas disease Temp., humidity (flies) 100 million Leishmaniasis Temp., humidity (flies) 350 million River blindess Water for the black flies 120 million

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

  31. Swiss Re, 2007 Costs related to natural hazards Billions of USD/decade Geologic 495 Climatic 500 450 345 400 350 300 250 160 200 103 88 150 24 47 100 14 11 4 50 0 56-65 66-75 76-85 86-95 96-05 Decade End The way forward

  32. The way forward

  33. 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

  34. Many thanks for your attention! Climatic change in the light of scientific knowledge www.unige.ch/climate Martin.Beniston@unige.ch

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