PS374.Climate.Change.Oct.20.2009

PS374.Climate.Change.Oct.20.2009 -...

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Unformatted text preview: http://www.vanityfair.com/politics/features/video/2007/knut_video200705 http://www.youtube.com/watch?v=4amBtVFaBlg http://flood.firetree.net/ PS 374 (Oct. 20, 2009) Global Temperature Evidence 1 PS 374 (Oct. 20, 2009) Global Temperature Evidence 2 PS 374 (Oct. 20, 2009) Global Temperature Evidence 3 PS 374 (Oct. 20, 2009) Global Temperature Evidence 4 PS 374 (Oct. 20, 2009) Global Temperature Evidence 5 Knut in December 2008 PS 374 (Oct. 20, 2009) Global Temperature Evidence 6 PS 374 (Oct. 20, 2009) Global Temperature Evidence 7 PS 374 (Oct. 20, 2009) Global Temperature Evidence 8 PS 374 (Oct. 20, 2009) Global Temperature Evidence 9 Charismatic Megafauna PS 374 (Oct. 20, 2009) Global Temperature Evidence 10 PS 374 (Oct. 20, 2009) Global Temperature Evidence 11 PS 374 (Oct. 20, 2009) Global Temperature Evidence 12 PS 374 (Oct. 20, 2009) Global Temperature Evidence 13 The Hockey Stick Graph PS 374 (Oct. 20, 2009) Global Temperature Evidence 14 The Hockey Stick Graph PS 374 (Oct. 20, 2009) Global Temperature Evidence 15 PS 374 (Oct. 20, 2009) Global Temperature Evidence 16 The upper graph shows an attempted reconstruction of global (Northern AND Southern) Hemisphere temperatures over nearly two millenia. The red curve that shoots up abruptly in the 20th century is based on surface and ocean instruments (confirmed by measurements of temperatures down boreholes). The rest, drawing upon countless hours of datagathering and analysis by thousands of people, averages a variety of "proxy" data ranging from tree rings to coral reef chemical analysis. The smoothed blue curve has been attacked by critics as misleading, since there may be significant leaps and falls of temperature hidden within the yellow uncertainty band. PS 374 (Oct. 20, 2009) Global Temperature Evidence 17 The expansion in this lower image compares a number of different estimates over the past 1150 years, including the 1999 "hockey stick" graph of Mann et al. (thin purple line). One recent reconstruction (in heavy blue) using a new method showed a warm Middle Ages, although only for the Northern Hemisphere; Mann replied with calculations indicating the method exaggerated long-term trends. While debate continues, even skeptics agreed with Mann and Jones's basic conclusion that "late 20th century warmth is unprecedented." The recent steep rise (black at far right) could only be explained as a result of the parallel rise of greenhouse gas emissions.1 Upper: Jones and Mann (2004), Rev. Geophys., 42, p. 16, doi:10.1029/2003RG000143. Copyright 2004 American Geophysical Union, reproduced by permission. Lower: Science 307 (2005) p. 828, adapted from K. R. Briffa and T. J. Osborn, Science 295 (2002), and (the recent heavy blue line) A. Moberg et al., Nature 322 (2005). 1. Mann and Jones (2003). "We find no evidence for any earlier periods in the last two millennia with warmer conditions than the post-1990 period... [computer] model experiments that use natural-only forcings fail to reproduce this warming,"according to Moberg et al. (2005). PS 374 (Oct. 20, 2009) Global Temperature Evidence 18 Wh a t is c a us ing G lo b a l Wa rm ing ? A. Caused by people and their activities? A. Not sure A. Reflects natural cycles of change PS 374 (Oct. 20, 2009) Global Temperature Evidence 19 R e p ub lic a n Me m b e rs o f C o ng re s s " Do y o u th ink it's b e e n p ro ve n b e y o nd a re a s o na b le d o ub t th a t th e Ea rth is wa rm ing b e c a us e o f m a nm a d e p ro b le m s ? " Na tio na l Jo u rn a l... 2007 2006 0% 50% 100% yes no IP C C : G lo b a l wa rm ing is b e ing c a us e d b y m a n is a t le a s t 9 0 % c e rta in... PS 374 (Oct. 20, 2009) Global Temperature Evidence 20 PS 374 (Oct. 20, 2009) Global Temperature Evidence 21 S e a Le ve l R is e (O ne Me te r) PS 374 (Oct. 20, 2009) Global Temperature Evidence 22 S e a Le ve l R is e (T h re e Me te rs ) PS 374 (Oct. 20, 2009) Global Temperature Evidence 23 S e a Le ve l R is e (Five Me te rs ) PS 374 (Oct. 20, 2009) Global Temperature Evidence 24 S e a Le ve l R is e (Five Me te rs ) PS 374 (Oct. 20, 2009) Global Temperature Evidence 25 De lta S m e lt PS 374 (Oct. 20, 2009) Global Temperature Evidence 26 PS 374 (Oct. 20, 2009) Global Temperature Evidence 27 PS 374 (Oct. 20, 2009) Global Temperature Evidence 28 T h e Inte rna tio na l P a ne l o n C lim a te C h a ng e (IP C C ) R e c o g nizing th e p ro b le m o f p o te ntia l g lo b a l c lim a te c h a ng e , th e Wo rld Me te o ro lo g ic a l O rg a niza tio n (WMO ) a nd th e Unite d Na tio ns Enviro nm e nt P ro g ra m m e (UNEP ) e s ta b lis h e d th e Inte rg o ve rnm e nta l P a ne l o n C lim a te C h a ng e (IP C C ) in 1 9 8 8 . It is o p e n to a ll m e m b e rs o f th e UN a nd WMO . PS 374 (Oct. 20, 2009) Global Temperature Evidence 29 Direct Observations of Recent Climate Change Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level. DIRECT OBSERVATIONS OF RECENT CLIMATE CHANGE Since the TAR, progress in understanding how climate is changing in space and in time has been gained through: improvements and extensions of numerous datasets and data analyses broader geographical coverage better understanding of uncertainties, and a wider variety of measurements Direct Observations of Recent Climate Change Gobal mean temperature Global average sea level Northern hemisphere Snow cover Direct Observations of Recent Climate Change Global average air temperature Updated 100-year linear trend of 0.74 [0.56 to 0.92] oC for 1906-2005 Larger than corresponding trend of 0.6 [0.4 to 0.8] oC for 1901-2000 given in TAR Average ocean temperature increased to depths of at least 3000 m ocean has absorbed 80% of heat added > seawater expansion and SLR Global mean temperatures are rising faster with time Warmest 12 years: 1998,2005,2003,2002,2004,2006, 2001,1997,1995,1999,1990,2000 Period Rate 50 0.128 0.026 100 0.074 0.018 Years /decade Arctic vs Global annual temperature anomalies (C) Warming in the Arctic is double that for the globe from 19th to 21st century and from late 1960s to present. Warmth 1925 to 1950 in Arctic was not as widespread as recent global warmth. Note different scales Further Changes in Artic and Frozen Ground Annual average Arctic sea ice extent shrunk by 2.7 % per decade, decreases in summer 7.4 % Temperatures at the top of permafrost layer have generally increased since the 1980s by up to 3C The maximum area covered by seasonally frozen ground has decreased by about 7% in Northern Hemisphere since 1900, in spring of up to 15%. Changes in Precipitation, Increased Drought Significantly increased precipitation in eastern parts of North and South America, northern Europe and northern and central Asia. The frequency of heavy precipitation events has increased over most land areas - consistent with warming and increases of atmospheric water vapour Drying in the Sahel, the Mediterranean, southern Africa and parts of southern Asia. More intense and longer droughts observed since the 1970s, particularly in the tropics and subtropics. Other changes in Extreme Events Widespread changes in extreme temperatures observed Cold days, cold nights and frost less frequent Hot days, hot nights, and heat waves more frequent Observational evidence for an increase of intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures Proportion of heavy rainfalls: increasing in most land areas Regions of disproportionate changes in heavy (95th) and very heavy (99th) precipitation Land precipitation is changing significantly over broad areas Increases Decreases Smoothed annual anomalies for precipitation (%) over land from 1900 to 2005; other regions are dominated by variability. Circulation change Climate change is affecting storm tracks, winds and temperature patterns Anthropogenic forcing has likely contributed North Atlantic hurricanes have increased with SSTs N. Atlantic hurricane record best after 1944 with Marked increase aircraft after 1994 surveillance. (19442005) SST Global number and percentage of intense hurricanes is increasing Snow cover and Arctic sea ice are decreasing Spring snow cover shows 5% stepwise drop during 1980s Arctic sea ice area decreased by 2.7% per decade (Summer: -7.4%/decade) Glaciers and frozen ground are receding Increased Glacier retreat since the early 1990s Area of seasonally frozen ground in NH has decreased by 7% from 1901 to 2002 A Paleoclimatic Perspective Paleoclimate information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1300 years. The last time the polar regions were significantly warmer than present for an extended period (about 125,000 years ago), reductions in polar ice volume led to 4 to 6 metres of sea level rise. Global-average radiative forcing estimates and ranges Observed widespread warming Annual Trend 1979 to 2005 Surface Troposphere Global ocean extremely unlikely without external forcing very unlikely due to known natural causes alone 2005 1955 1980 Terms Sensitivity Testing PS 374 (Oct. 20, 2009) Global Temperature Evidence 48 Projections of Future Changes in Climate Best estimate for low scenario (B1) is 1.8C (likely range is 1.1C to 2.9C), and for high scenario (A1FI) is 4.0C (likely range is 2.4C to 6.4C). Broadly consistent with span quoted for SRES in TAR, but not directly comparable Time Preferences: How much would you be willing to give me, a year from now, if I gave you $100 today? A. $100 B. $105 C. $110 D. $125 E. $150 PS 374 (Oct. 20, 2009) Global Temperature Evidence 50 Terms Sensitivity Testing Discount Rate: "The Social Rate of Time Preference" PS 374 (Oct. 20, 2009) Global Temperature Evidence 51 PS 374 (Oct. 20, 2009) Global Temperature Evidence 52 PS 374 (Oct. 20, 2009) Global Temperature Evidence 53 PS 374 (Oct. 20, 2009) Global Temperature Evidence 54 Policy Instruments Command and Control Regulation "Technology Forcing" (The Clean Air Act) Does not allow weighing of costs and benefits Does not adapt to changing conditions... PS 374 (Oct. 20, 2009) Global Temperature Evidence 55 Policy Instruments "Cap and Trade" Establish global budget for carbon Permit existing emission rights Allow trading among users Allows market to establish the best use for limited allowable emissions... PS 374 (Oct. 20, 2009) Global Temperature Evidence 56 Policy Instruments Carbon Sequestration naturally Forestation... young forests, Oceans... CO2 dissolves into water... Soils... in colder climates... PS 374 (Oct. 20, 2009) Global Temperature Evidence 57 and Northern forests... biology... Policy Instruments Carbon Sequestration enhanced Forestation... Planting trees, but older forests... Use wood, not artificial products, but what happens to the wood eventually (burning?) PS 374 (Oct. 20, 2009) Global Temperature Evidence 58 Policy Instruments Carbon Sequestration enhanced Oceans... Iron fertilization... grows more plankton Soils notill farming, residue mulching, cover cropping, and crop rotation Global Temperature Evidence 59 PS 374 (Oct. 20, 2009) PS 374 (Oct. 20, 2009) Global Temperature Evidence 60 Policy Instruments Carbon Sequestration Carbon Capture at Power Plants Oceans direct injection or deposit of biomass residue Geological sequestration (storage) PS 374 (Oct. 20, 2009) Global Temperature Evidence 61 ...
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This note was uploaded on 06/22/2011 for the course POLI 374 taught by Professor Tompkins during the Fall '09 term at South Carolina.

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