climate change Contents CO 2 (ppm)

Transcription

1 climate change CO 2 (ppm) 2007 Joachim Curtius Institut für Physik der Atmosphäre Universität Mainz Contents 1. Summary 2. Background 3. Climate change: observations 4. CO 2 5. OtherGreenhouse Gases (GHGs): CH 4, N 2 O, CFCs, HCFCs, O 3 6. Aerosols and Clouds 7. Solar variability 8. Future climate change 9. Paleo-climate 10. Climate protection

2 6. Aerosols and Clouds Aerosols: background, light scattering natural and anthropogenic sources direct aerosol effect first indirect effect second indirect effect semi-direct effect aerosol source strength (kg km -2 hr -1 ) anthropogenic mineral dust from land-use change... [IPCC 2001]

3 aerosol source strength (kg km -2 hr -1 ) sea salt aerosol [IPCC 2001] Total optical depth Optical depth [IPCC 2007]

4 indirect climate forcing effects from aerosols natural background, clean air mass, few CCN cloud formation: water vapor condenses few large cloud droplets polluted air mass, many CCN many small cloud droplets change of optical properties, cloud becomes more white and reflects more solar radiation, Nomenclature: Twomey effect (Twomey, Tellus B, 1984) or cloud albedo effect, or first indirect aerosol effect change of hydrologic cycle : longer lifetime of cloud, suppression of precipitation, cloud droplets <14µm. Nomenclature: second indirect aerosol effect, or "lifetime effect" first indirect effect IR satellite image (wavelength 3.7 µm) Pacific, West Coast USA/California. Continuous cloud cover (grey) of marine stratocumulus with line-shaped ship tracks (white) with higher reflectivity caused by the ships aerosol emissions.

5 indirect aerosol effect Rosenfeld, Science, 2000: NOAA AVHRR satellite images : red: clouds with large droplets yellow: clouds with small droplets blue: ground A) 1) Istanbul, 2) Izmit 3) Bursa B) 4) Mining and Smelting, Flin-Flon, Manitoba, Canada C) 5) Port Augusta, power plants 6) Port Pirie, lead smelter 7) Adelaide port 8) oil refineries smaller droplets less/later precipitation less ice formation in clouds correlationof aerosolconcentration withconcentration of cloud condensation nuclei [Ramanathan et al., Science, 2001]

6 Schematic diagram of aerosoldirect and indirect effects [Haywood and Boucher, Rev Geophys., 2000, IPCC 2007] indirect aerosol effects and ice nuclei various influences on CCN and IN (currently not considered by GCMs and IPCC) Aerosol particles Human activity [Lohmann, 2005]

7 Semi-direct aerosoleffect Ackerman et al., Science, 2000; Sakteesh und Ramanathan, Nature, 2000; Venkataraman et al., Science 2005, uvm.: "Atmospheric Brown Cloud, ABC": soot emissions (firewood) above India and the Indian Ocean lead to strong absorption, heating of air layers, evaporation of clouds cooling at ground. strong impact on radiation balance and precipitation. Total effect about 10 x larger than the effect by greenhouse gases above the Indian Ocean! Andreae et al., Nature, 2005

8 Andreae et al., Nature, 2005 Aerosol effects are not sufficiently quantified, therefore estimate of climate sensitivity, with respect to temperature trend (+0.7 C): GHG-effects are well quantified as well as heat capacity of oceans. Climate sensitivity (K) represents the equilibrium rise in temperature resulting from a doubling of the preindustrial atmospheric CO 2 concentration. simple heat balance equation: c= Andreae et al., Nature, 2005

9 Andreae et al., Nature, 2005 T interglac.-ice age prediction IPCC-TAR "tolerable" Andreae et al., Nature, 2005: "... our analysis suggests that there is a possibilitythat climate change in the twentyfirst century will follow the upper extremes of current IPCC estimates, and may even exceed them. Such a degree of climate change is so far outside the range covered by our experience and scientific understanding that we cannot with any confidence predict the consequences for the Earth system. To reduce these uncertainties a multi-pronged approach is needed. First, there is a great need for in situ studies that investigate the response of cloud microphysics and dynamics to enhanced aerosol concentrations...."

10 Aerosol radiative forcing: Comparison of several models Anderson et al., Science, 2003: Compare aerosol forcing effects from GCM models using "forward calculations", i.e. calculate the aerosol effects based on knowledge of aerosol physics and chemistry, and "inverse calculations", i.e. infer aerosol forcing from the total forcing required to match climate model simulations with observed temperature changes. Then derive the aerosol forcing from the difference between required forcing and calculated (well-known) greenhouse-gas forcings. Aerosol radiative forcing: Comparison of several models Anderson et al., Science, 2003: Uncertainties of aerosol total radiative forcing (direct and indirect, etc.). Forward calculations: ~1.5 W m -2, inverse calculations: ~1 W m -2 ; reasons for difference? truth?...

11 climate impact of air traffic: AVHRR-satellite picture: a) contrails can evolve into "persistent contrails" b) influence on cirrus clouds (via ice nuclei, H 2 O, etc.) climate impact of air traffic: some numbers concerning air traffic 13% of the total CO 2 by traffic are caused by air traffic, and ~3% of total CO 2 emissions air traffic increased by a factor of 15 between 1960 and 1992; air traffic will grow by a factor of 6 until air traffic currently grows by 5% per year, kerosine consumption grows by 3% per year. Boing 747 "Jumbo-Jet": max. 175 t kerosine of 400 t take-off weight, fuel consumption: liters/km; FFM - NY - FFM: ~ 550 kg fuel/passenger

12 climate impacts of air traffic: climate impacts of air traffic: climatic effects currently relatively small, but stronglyincreasing!

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