Anthropocene physical basis of climate spring 2011 Introduction and UNEP reports Observations...
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Transcript of Anthropocene physical basis of climate spring 2011 Introduction and UNEP reports Observations...
Anthropocenephysical basis of climate spring 2011
• Introduction and UNEP reports• Observations
– Emissions and other natural forcings– Temperature record, SSTs– Precipitation, Sea level, ENSO, Severe storm
s
• Attribution• Models and predictions• Uncertainties
Svante Arrhenius (1859 -1927)
• Swedish• 1884 PhD dissertation electro-
chemistry – did not impress advisor, 150 pages, 85 theses.
• 1896 – Suggested that CO2 could warm the planet, from his work on ice ages. Emission of CO2 may prevent future ice ages.
• 1903 – Nobel prize in chemistry for work in his dissertation. Most of his these would be unquestioned today
Intergovernmental panel on climate change (IPCC)Established by WMO and UNEP and confirmed by UN general assembly
December 1988 Five reports issued, the latest in 2013
• 1990 human emissions are increasing atmospheric greenhouse gases, resulting increase 0.3 °C per decade 21st century.
• 1995 discernible human influence on global climate
• 2001 surface temperature projected to increase 1.4 - 5.8 C 1990 -2100, and sea level to rise by 0.1 - 0.9 meters
• 2007 (Nobel peace prize) Climate warming unequivocal. Most increase in global temperatures since mid-20th century is (>90%) due to increase in anthropogenic greenhouse gas concentrations.
• The fifth one is underway. 831 authors selected from 3000 nominations. 3-4 reviewers for each chapter.
Human activities have changed the composition of the atmosphere since the pre- industrial era
Watt’s steam engineBegin industrial period
Global mean surface temperatures have increased
http://www.atmosphere.mpg.de/enid/20c.html
Liou, 2002, pp 161Atmospheric heating rates
Precipitation patterns have changed
Annual mean precipitation change: 2071 to 2100 Relative to 1990
Climate-induced increases in sea level are caused by thermal expansion of the oceans and melting of
land ice and ice sheets
Sea Levels have risen
The El-Nino phenomena leads to floods and droughts throughout the tropics and subtropics
El Niño years
La Niña years
The frequency, persistence and magnitude of El-Nino events have increased in the last 20 years
Weather-related economic damages have increased
Most of the observed warming in the past 50 years is attributable to human activities
Atmosphere
Estimated Fossil Deposits
6.362.3
92.3
60
90
3.3
Plants
Soil
Oceans
750
500
2000
39,000
About 16,0001.6
This is the “greenhouse” problem
Driven by fossil fuel emissions
…and land clearing
The oceans and land vegetation are currently taking up 4.6 Gt C per year
The KP seeks to reduce total emissions by about 0.2
Humans are
perturbing the carbon
cycle
UnitsGt C for stores & Gt C y-1 for fluxes
There are fast and slow processes in the carbon cycle
More adverse than beneficial impacts on biological and socioeconomic systems are projected
Land areas are projected to warm more than the oceans with the greatest warming at high latitudes
Annual mean temperature change, 2071 to 2100 relative to 1990: Global Average in 2085 = 3.1oC
Some areas are projected to become wetter, others drier with an overall increase projected
Annual mean precipitation change: 2071 to 2100 Relative to 1990
2020s
2050s
2080s
Initially increased agricultural productivity in some mid-latitude regions & reduction in the tropics and
sub-tropics even with warming of a few degrees
Uncertainties
• Changes in atmospheric water vapor
• Changes in cloudiness
• Changes in albedo
• Aerosol particles– Direct effects– Impact on clouds– Black carbon