The carbon and climate problem

Transcription

1 The carbon and climate problem What is the evidence? What are the caveats? What are the long-term implications? Prof. Ric Williams 1

2 1. What is the evidence? data/simple theory CO 2 (ppm) atmospheric CO 2 increase time (year) Simple theory suggests rise in atmospheric CO2 gives global rise in surface heat flux ~ 1 W m -2 ocean temperature rise ~ 0.4 o C

3 Summary for Policymakers global data CHANGES IN TEMPERATURE, SEA LEVEL AND NORTHERN HEMISPHERE SNOW COVER Signals of global warming (from IPCC, 2007)!"#$%&'(%)(*#+,-(',./ global warming of 0.6oC since 1950 surface warming since 1979: warming over most of globe land warming faster than ocean #$%&'()*+%,(-.*.'(/,*!010*234,(*.$+,55'+,*&,$.6%.4839 #$%&'()*,:,%;34,%,*$+*.6%<$/,*,=/,>+*'(*,$.+, A86+4,%(*B/,$(*$(-*>$%+.*8<*C(+$%/+'/$D E$(-*3$%&'()*.')('<'/$(+5;*<$.+,%*+4$(*8/,$(*8:, H'-I+%8>8.>4,%,*3$%&'()*/8(.'.+,(+*3'+4*+4$+*$+!"#$%&'(%)(*#+,-(',./", #$%&'()*+%,(-.*.'(/,*!010*234,(*.$+,55'+,*&,$.6%,&,(+.*.+$%+,-7* Figure SPM.3. Observed changes in (a) global average surface temperature, (b) global average sea level from tide gauge (blue) and.4839 Hemisphere snow cover for March-April. All changes are relative to corresponding averages for satellite (red) data and (c) Northern the period Smoothed curves represent decadal average values while circles show yearly values. The shaded areas are the uncertainty intervals estimated from a comprehensive analysis of known uncertainties (a and b) and from the time series (c). {FAQ 3.1, A86+4,%(*B/,$(*$(-*>$%+.*8<*C(+$%/+'/$D Figure 1, Figure 4.2, Figure 5.13} E$(-*3$%&'()*.')('<'/$(+5;*<$.+,%*+4$(*8/,$(*8:,%*5$.+*FG*;,$%.D H'-I+%8>8.>4,%,*3$%&'()*/8(.'.+,(+*3'+4*+4$+*$+*.6%<$/,J oc per decade 0.75!"

4 Other signals global /regional data retreat in summer rise in sea level Arctic sea ice 20th century sea level rise 1979 Satellite altimetry Holgate and Woodworth, /- 0.3 mm/yr 2003 Church et al., 2004,

5 Is the recent warming due to carbon dioxide? climate models data: black line climate model with only natural forcing: blue line (19 simulations, 5 models) climate model with anthropogenic forcing: red line (58 simulations, 14 models)

6 2. What are the caveats? models/regional data While globe is warming, regional signals are complex. How wet is each summer? In summer 2007, the jetstream is flowing further south allowing low pressure systems to sweep straight over the centre of the country. Pressure chart: 4/07/07. Source: Met Office 6

7 How has ocean warmed over last 50 years? 60 o N 48 o N 36 o N 24 o N 12 o N 0 o 75 o W 50 o W 25 o W 0 o Change in ocean heat content (10 20 J) between and data Decadal, natural variability might mask any local signal of greenhouse forcing Lozier, Leadbetter, Williams et al. (2008) Science

8 3. What are the long-term effects? data Ocean holds ~ 50 as much carbon as in the atmosphere 1/3 of the recent industrial emissions of carbon has gone into ocean Remotely-sensed picture of surface chlorophyll (NASA) What is the problem? Ocean takes up less carbon dioxide as it becomes more acidic

9 So what happens if we burn all our fossil fuels? simple theory (b) atmospheric CO years Time (years) Initial fast rise in atmospheric CO2 Eventually approach a steady state Final radiative heating varies linearly with size of carbon emissions (emit 1000 GtC implies extra heating of 1.5 Wm -2 lasting for millennia) Goodwin, Williams et al. (2009) Nature Geoscience

10 If burn all of conventional fossil fuels, 5000 GtC without carbon capture, then extra heating of 7.5 Wm -2 equivalent to heating given in a room (20m x 30m) by these 100 W light bulbs: 45 bulbs simple theory

11 Legacy for future generations speculations if release all the carbon in conventional fossil fuels, ~ 5 x present anthropogenic heating lasting for millennia tipping points: melting Greenland ice release methane stored in frozen tundra UAF researcher Katey Walter lights a pocket of methane on a frozen lake in Siberia in March of (Credit: Photo by Sergey Zimov) 11

12 Implications Personal : Institutional : National : International Energy policy Transport Use of resources Sustain ecosystems 12

13 Liverpool University is setting up an Energy Institute Tim Greenshaw (Physics) Real challenge to produce enough clean electricity Need to investigate feasible technologies (solar, wind, wave, tide, fission, fusion, clean coal) 13

14 Solar power (Peter Weightman, Chris Lucas, Physics) small fraction of Earth s deserts could provide global needs (but cannot make enough photoelectric cells) Tidal power (Richard Burrows, Engineering; Judith Wolf, POL) minimize environmental impact by extracting energy on part of tidal cycle continuous power supply if several schemes along UK coast La rance tidal power plant 14

15 Recycle concrete (Marios Soutsos, Engineering) develop concrete products from demolition waste Nuclear fission (Tim Greenshaw, Physics) investigate safer alternatives to standard approach possibly use thorium via sub-critical reactions 15

16 Conclusions 1. Science Global warming is happening. Large regional and inter-annual variability. 2. Implications Need to take long term and ethical perspective Requires co-ordinated planning Opportunity to develop new technologies and good practice 16