Climate Science Context Brian Hoskins Director Grantham Institute for Climate Change, Imperial College Professor of Meteorology, University of Reading

Kiehl and Trenberth 1997 The Earth’s energy budget Green house gases: water vapour, carbon dioxide, methane, ozone,… Fourier (1827), Tyndall (1861)

Kiehl and Trenberth 1997 The Earth’s energy budget Extra GHGs: heat lost from higher levels where it is colder warming

Changes in Greenhouse gases in the atmosphere from Ice-Core and Modern Data IPCC (2007)

Causes of the current imbalance in the energy budget IPCC 2007

Published estimates of of NH temperature in the past 1000 years

Since 1970, rise in:Decrease in:  Global surface temperatures NH Snow extent  Tropospheric temperatures Arctic sea ice  Global ocean temperaturesGlaciers  Global sea levelCold temperatures  Water vapour  Rainfall intensity  Precipitation in extratropics  Hurricane intensity  Drought  Extreme high temperatures  Heat waves IPCC 2007 Fourth Assessment Report: “Global Warming is unequivocal”

20 th Century Continental Temperatures: Observed & Modelled with & without anthropogenic forcings IPCC 2007

IPCC (2007) Surface Temperature Projections 2020s & 2090s relative to Global mean 2020s 2090s

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 Projected patterns at end of 21 st century: Change (%) in precipitation for one scenario Dec-FebJune-Aug IPCC 2007

© Crown copyright Met Office Risk of large changes in ocean circulation and the release of methane cathrates Risk of significant loss of rainforest. Few ecosystems can adapt. Melting of Greenland ice sheet may become irreversible Some marine ecosystems suffer irreversible change. Ocean acidification is already a risk. +1 °C +2 °C +3 °C +? °C Dangerous climate change?

© Crown copyright Met Office 70 %99 %550 ppm 20 %80 %450 ppm 10 %60 %430 ppm For 3 ºC target For 2 ºC target CO 2 equivalent stabilisation level Percentage likelihood of warming exceeding 2 and 3 ºC above pre-industrial levels Today Stern target Possible targets for stabilisation levels

Possible CO 2 Emissions for 450ppm Stabilisation Gt of CO 2 CCS in industry CCS in power generation Nuclear Renewables Switching from coal to gas End Use electricity efficiency End Use fuel efficiency Reference Scenario 450 Stabilisation Case 27 Gt 42 Gt 23 Gt Energy-Related CO 2 Emissions © OECD/IEA 2007 RCEP (2000): Energy in a changing climate

Conclusion Adaptation Mitigation Geo-engineering? Urgent need to really start 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 MetO Hadley Centre