Climate Science Context

Brian Hoskins

Director Grantham Institute for Climate Change, Imperial CollegeProfessor 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 Published estimates of of NH temperature in the past 1000 yearstemperature in the past 1000 years

Since 1970, rise in: Decrease in: Global surface temperatures NH Snow extent Tropospheric temperatures Arctic sea ice Global ocean temperatures Glaciers Global sea level Cold 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”

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

IPCC 2007

IPCC (2007) Surface Temperature Projections 2020s & 2090s relative to 1980-99

Global mean2020s 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 21st century: Change (%) in precipitation for one scenario

Dec-Feb June-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

Dangerousclimatechange?

© Crown copyright Met Office

70 %99 %550 ppm

20 %80 %450 ppm

10 %60 %430 ppm

For 3 ºC target

For 2 ºC target

CO2 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 CO2 Emissions for 450ppm Stabilisation

10

15

20

25

30

35

40

45

2005 2010 2015 2020 2025 2030

Gt o

f CO 2

CCS in industryCCS in power generationNuclearRenewablesSwitching from coal to gasEnd Use electricity efficiency

End Use fuel efficiency

Reference Scenario

450 Stabilisation Case27 Gt

42 Gt

23 Gt

Energy-Related CO2 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