Climate Science Context Brian Hoskins Director Grantham Institute for Climate Change, Imperial College Professor of Meteorology, University of Reading
The Earth’s energy budget Kiehl and Trenberth 1997 Green house gases: water vapour, carbon dioxide, methane, ozone, … Fourier (1827), Tyndall (1861)
The Earth’s energy budget Kiehl and Trenberth 1997 Extra GHGs: heat lost from higher levels where it is colder warming
IPCC (2007) Changes in Greenhouse gases in the atmosphere from Ice-Core and Modern Data
Causes of the current imbalance in the energy budget IPCC 2007
Published estimates of of NH temperature in the past 1000 years
IPCC 2007 Fourth Assessment Report: “Global Warming is unequivocal” Since 1970, rise in: v Global surface temperatures v Tropospheric temperatures v Global ocean temperatures v Global sea level v Water vapour v Rainfall intensity v Precipitation in extratropics v Hurricane intensity v Drought v Extreme high temperatures v Heat waves Decrease in: NH Snow extent Arctic sea ice Glaciers Cold temperatures
20 th Century Continental Temperatures: Observed & Modelled with & without anthropogenic forcings IPCC 2007
IPCC (2007) Surface Temperature Projections 2020 s & 2090 s relative to 1980 -99 Global mean 2020 s 2090 s
Projected patterns at end of 21 st century: Change (%) in precipitation for one scenario Dec-Feb June-Aug Stippled areas are where more than 90% of the models agree in the sign of the change Precipitation increases very likely in high latitudes Decreases likely in most subtropical land regions This continues the observed patterns in recent trends IPCC 2007
Risk of large changes in ocean circulation and the release of methane cathrates Dangerous climate change? Risk of significant loss of rainforest. Few ecosystems can adapt. +? °C +3 °C Melting of Greenland ice sheet may become irreversible Some marine ecosystems suffer irreversible change. Ocean acidification is already a risk. © Crown copyright Met Office +2 °C +1 °C
Possible targets for stabilisation levels Percentage likelihood of warming exceeding 2 and 3 ºC above pre-industrial levels CO 2 equivalent stabilisation level Today Stern target For 2 ºC target For 3 ºC target 430 ppm 450 ppm 550 ppm 60 % 80 % 99 % 10 % 20 % 70 % © Crown copyright Met Office
Possible CO 2 Emissions for 450 ppm Stabilisation 45 Energy-Related CO 2 Emissions 42 Gt CCS in industry CCS in power generation Nuclear Renewables Switching from coal to gas End Use electricity efficiency Reference Scenario 40 Gt of CO 2 35 30 25 End Use fuel efficiency 27 Gt 450 Stabilisation Case 20 23 Gt 15 10 2005 2010 2015 2020 2025 2030 RCEP (2000): Energy in a changing climate © OECD/IEA 2007
Conclusion Urgent need to really start • Adaptation • Mitigation • Geo-engineering? It is difficult to conceive that any significant reduction in the level of “dangerous” climate change realised by the end of the century can be achieved without CCS being a major player.
Greenland Ice Sheet Projections Met. O Hadley Centre
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