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1、Click to edit Master title style*Name of speaker1To what extent is geo-engineering the solution to the climate change problem?Brian HoskinsDirector, Grantham Institute for Climate ChangeImperial College& Professor of Meteorology, University of Reading“Greenhouse” gases determine height of layer from
2、 which heat escapesMore greenhouse gases: higher levelcolder temperatureless heat lostglobal warming (water vapour) carbon dioxide, methane,Temperature and greenhouse gases in past 650,000 yproxy for tempmethanecarbon dioxidenitrous oxidetodaytimeIPCC 2007Causes of the current imbalance in the energ
3、y budgetIPCC 2007Since 1970, rise in:Decrease in: v Global surface temperatures NH Snow extentv Tropospheric temperatures Arctic sea icev Global ocean temperaturesGlaciersv Global sea levelCold temperaturesv Water vapour v Rainfall intensityv Precipitation in extratropicsv Hurricane intensityv Droug
4、htv Extreme high temperaturesv Heat wavesIntergovernmental Panel on Climate Change Fourth Assessment Report (2007): “Global Warming is unequivocal”Estimates of NH temperatures in the past 1000 yearsProjections of globally averaged surface warmingIPCC 2007Different scenariosIPCC (2007) Surface Temper
5、ature Projections 2020s & 2090s relative to 1980-992020s2090sEstimates of impacts in different sectors for increasing global warming (IPCC 2007)Tackling the anthropogenic climate change problemBy emitting greenhouse gases to the atmosphere we are perturbing the climate system in a dangerous way. Wha
6、t can we do?1.Adapt to whatever happens: adaptation2.Move towards a drastic reduction of the emissions of greenhouse gases: mitigation3.Do something else to compensate: geo-engineeringTwo basic kinds of geo-engineering1. Reduce the content of greenhouse gases in the atmosphere2. Alter the climate sy
7、stemGeo-engineering 21. Reduce the atmospheric greenhouse gas content2.plant trees3.develop & grow special biological organisms4.fertilise the oceansOceanic carbon cycleSeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE.Biological activity in the oceanGeo-engineering 22. Alter the clima
8、te systemRestore the global energy balance by the management of solar radiationIn terms of the global energy budget a reduction of the solar energy absorbed in the climate system by about 2% might balance a doubling of atmospheric carbon dioxideKiehl and Trenberth 1997The Earths energy budget12341.
9、In Space: Solar InterceptorCloud of many small independent spacecraft.Each one has small solar sails to set its orientation to face the sun and to stay within the cloud, in line with sun (Angell, 2007)At a point where gravitational and centrifugal forces are in equilibrium (Lagrange point)2. In the
10、stratosphere, mimicking a volcanic eruption e. g. Mount Pinatubo in 1991Pitari and Mancini (2002)Reduction in radiationEruption1-year laterProposal: put SO2 at about 25km in the equatorial region3. Increase the reflection by low-level cloudAverage amount of low-level (stratocumulus) cloud3. Spray Tu
11、rbine Concept Latham Salter (2006) 4.Increase the reflectivity (albedo) of the surface1.Whiten the desserts2.Enhance reflectivity of human settlements3.Develop & use more reflective grassesManagement of net Solar Radiation:Opportunities at 4 levels in the atmosphereComments:1.The restored energy bal
12、ance through a reduction in solar radiation would be only in the annual and global average, not in a particular region or time of year2.Solar and thermal radiation act on the climate system in different ways3.Increasing acidification of the ocean would continue4.Feasibility, cost, unintended impacts
13、Discussion1.Our understanding of likely climate change due to increased greenhouse gases is limited. In general it is more so for geo-engineering “solutions” .2.Need to be able to evaluate the actual impacts 3.Ability to stop quickly is an important consideration4.Some private companies are already
14、planning to start ocean fertilisation on a commercial basis, offering it as an off-setting mechanism 5.Is it a “solution”? Is it possible to compensate for any increase in atmospheric greenhouse gases? 6.Necessity for legal and political framework7.Might it take the pressure off the imperative to re
15、duce greenhouse gas emissions?8.Is it a good way of buying time until serious greenhouse gas emission reductions have been agreed and executed?Stabilisation CO2 Concentrations and EmissionsCO2 concentration (ppm)CO2-equivalent concentration (ppm)Global mean temperature increase above pre-industrial
16、level at equilibrium* (C)Peaking year for CO2 emissionsGlobal change in CO2 emissions in 2050 (% of 2000 emissions)350 400445 4902.0 2.42000 2015-50 to -85400 440490 5352.4 2.82000 2020-30 to -60440 485535 5902.8 3.22010 2030+5 to -30485 570590 7103.2 4.02020 2060+10 to +60570 660710 8554.0 4.92050 2080+25 to +85660 790855 1 1304.9 6.12060 2090+90 to +140* Based on the “best estimate” of climate sensitivity.Source: IPCC (2007). OECD/IEA 2007Stippled areas are where more than 90% of the models ag
