what are the main drivers of climate change?...global average sea level change september arctic sea...
TRANSCRIPT
What are the main drivers of climate change?
Professor John Mitchell FRSMet Office Hadley Centre
Long term perspective:Atmospheric CO2 concentrations over the last 800,000 years
© Crown copyright Met Office
© Crown copyright Met Office
Drivers of climate since1750
Natural- the sun- volcanoes
Human- greenhouse gases
and aerosols
Natural internal variations in the ocean and atmosphere
How sensitive is the climate?
Professor Keith Shine FRSUniversity of Reading
• A fundamental characteristic of the climate system• If we suddenly doubled the amount of carbon dioxide in
the atmosphere, by how much would the Earth eventually warm?
IPCC AR5 concludes it is:“likely between 1.5oC and 4.5oC”
and“extremely unlikely it is less than 1oC and
very unlikely greater than 6oC”
What is the evidence that climate change is due to human activity?
Professor Corinne Le QuéréTyndall Centre
Observed decadal mean warming
C. Le Quéré, Tyndall°Centrefor Climate Change Research
University of East Anglia
Observed warming inconsistent with that expected from natural factors
C. Le Quéré, Tyndall°Centrefor Climate Change Research
University of East Anglia
Observed warming consistent with that expected from greenhouse gases
C. Le Quéré, Tyndall°Centrefor Climate Change Research
University of East Anglia
It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th
century
C. Le Quéré, Tyndall°Centrefor Climate Change Research
University of East Anglia
The state of the climate system
Professor Brian Hoskins FRSImperial College London
Globally averaged surface temperature 1850-2012IPCC 2013Relative to 1961-90 mean
A warming climateIPCC 2013
Surface temperaturechange 1901-2012
in ºC/decade
Global average sea level change September Arctic sea ice area
Sept 2012
Projections of globally averaged surface temperature change from 1986-2005
IPCC 2013
Projections of regional surface temperature change1986-2005 to 2081-2100 for high emission scenario (RCP8.5)
IPCC 2013
Temperature
Precipitation
CO2already
emitted to the
atmosphere
about half the
historical emissions
about 3 x historical emissions
Emissions compatible with different futures
C. Le Quéré, Tyndall°Centrefor Climate Change Research
University of East Anglia
Thinking probabilistically about future projections
Professor Tim Palmer FRSUniversity of Oxford
F = ma
E = hω
Comprehensive climate models are based on the primitive laws of physics e.g.
Are Climate Models “Fundamentally Flawed”?• Only if the basic laws of physics are!
Can climate models be improved?• Certainly! Ability to represent small-scale processes
accurately (e.g. associated with clouds) requires bigger computers
How do we deal with uncertainties in current climate models?
• Make multiple predictions varying uncertain aspects of the representation of small-scale processes. Means (IPCC AR5) predictions are inherently probabilistic.
Extreme events and climate change
Professor Stephen BelcherMet Office Hadley Centre
© Crown copyright Met Office
AR5 update on extreme events
© Crown copyright Met Office
Recent extreme summers
• Summer 2012
• Wettest Summer since 1912
• Wheat yields down 15% on 5-yr average
• Cost insurers £800 million
• Likely part of a natural ocean-atmosphere cycle
• Summer 2003
• Hottest summer in Europe since 1540
• 20,000+ deaths
• Very likely that human influence at least doubled the risk of a heat wave such as 2003
• Normal by 2040s and cool by 2080s