Transcript Imperial College London

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:
 Global surface temperatures
 Tropospheric temperatures
 Global ocean temperatures
 Global sea level
 Water vapour
 Rainfall intensity
 Precipitation in extratropics
 Hurricane intensity
 Drought
 Extreme high temperatures
 Heat waves
Decrease in:
NH Snow extent
Arctic sea ice
Glaciers
Cold temperatures
20th Century Continental Temperatures:
Observed & Modelled with & without anthropogenic forcings
IPCC 2007
IPCC (2007) Surface Temperature Projections
2020s & 2090s relative to 1980-99
Global mean
2020s
2090s
Projected patterns at end of 21st 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?
© Crown copyright Met Office
Risk of significant
loss of rainforest.
Few ecosystems
can adapt.
+? °C
+3 °C
Melting of
Greenland ice
sheet may
become
irreversible
+2 °C
Some marine
ecosystems suffer
irreversible
change. Ocean
acidification is
already a risk.
+1 °C
Possible targets for stabilisation levels
Percentage likelihood of warming exceeding 2
and 3 ºC above pre-industrial levels
Today
Stern
target
CO2 equivalent
stabilisation level
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 CO2 Emissions for 450ppm Stabilisation
45
Energy-Related CO2 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 CO2
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
MetO Hadley Centre