Satellite Observations and Climate Modeling: What They Can and Cannot Reveal About Future Climate

Transcription

1 Satellite Observations and Climate Modeling: What They Can and Cannot Reveal About Future Climate INCOSE Chesapeake Chapter JHU/APL March 21, 2012 Albert Arking Dept of Earth and Planetary Sciences Johns Hopkins University Baltimore, MD 21218

2 Overview of the global warming over the last few decades, within the context of past climate variability Basic physics of global-scale climate and identify areas where knowledge is lacking: Water vapor feedback Aerosol effects Solar irradiance variations Role of satellite data and numerical models in expanding our knowledge IPCC assessment: Climate scenarios and future projections Concluding remarks and a suggestion on how to lessen the human impact on climate

3 Overview of a global warming over the last few decades, within the context of past climate variability Basic physics of global-scale climate and identify areas where knowledge is lacking: Water vapor feedback Aerosol effects Solar irradiance variations Role of satellite data and numerical models in expanding our knowledge IPCC assessment: Climate scenarios and future projections Concluding remarks and a suggestion on how to lessen the human impact on climate

4

5

6 IPCC/AR4 FAQ 3.1 Fig. 1

7

8

9 EARTH - 18,000 years ago Fig. 16 2, p. 441

10 Fig. 16 5, p. 443

11 Antarctica Vostok

12

13

14

15 IPCC 2007

16 Overview of a global warming over the last few decades, within the context of past climate variability Basic physics of global-scale climate and identify areas where knowledge is lacking: Water vapor feedback Aerosol effects Solar irradiance variations Role of satellite data and numerical models in expanding our knowledge IPCC assessment: Climate scenarios and future projections Concluding remarks and a suggestion on how to lessen the human impact on climate

17 Energy Balance INCOMING SOLAR RADIATION 342 W/m 2 REFLECTED RADIATION 101 W/m 2 EMITTED TERRESTRIAL (THERMAL) RADIATION 241 W/m 2

18 SURFACE TEMPERATURE EXTREMES ( F) AVERAGE LOWEST HIGHEST Earth (Vostok, Antarctica) +136 (El Aziza, Libya) Mars Venus +900 Mercury

19 shortwave radiation longwave radiation

20 Fig. 2 15, p. 45

21 Fig. 2 16, p. 47

22 The climate system Climate Change in a Nutshell Atmosphere (mostly the troposphere, but the stratosphere could be important) Oceans Land surface Cryosphere: frozen water (on earth or ocean) and permafrost (frozen soil) Biosphere: vegetation + General state of the climate system determined by a balance between incoming energy (solar radiation) and outgoing energy (terrestrial radiation). Outgoing energy is determined by the temperature and composition of the atmosphere and surface. Especially important are the physical, chemical, and thermodynamic proceseses that change with any change in the general state of the climate system these are internal processes that which can amplify or dampen any imposed or external change and are called feedbacks. For example, any imbalance between incoming and outgoing energy causes the state of the climate system to change. The direct effect is a change in temperature to restore the balance. The indirect effects are due to feedbacks, which include every other feature of the climate system that is influenced by temperature (e.g., winds, atmospheric humidity, precipitation, cryosphere, and biosphere).

23 Overview of a global warming over the last few decades, within the context of past climate variability Basic physics of global-scale climate and identify areas where knowledge is lacking: Water vapor feedback Aerosol effects Solar irradiance variations Role of satellite data and numerical models in expanding our knowledge IPCC assessment: Climate scenarios and future projections Concluding remarks and a suggestion on how to lessen the human impact on climate

24 K 0 ~ 0.3 deg/(w/m 2 ) Arking, BAMS, v. 72, 1991

25 f i Arking, BAMS, v. 72, 1991

26 f i /K o Bony et al, J. Climate, 2006

27 Overview of a global warming over the last few decades, within the context of past climate variability Basic physics of global-scale climate and identify areas where knowledge is lacking: Water vapor feedback Aerosol effects Solar irradiance variations Role of satellite data and numerical models in expanding our knowledge IPCC assessment: Climate scenarios and future projections Concluding remarks and a suggestion on how to lessen the human impact on climate

28 AEROSOLS Most aerosols have an overall cooling effect on the climate system, but highly absorbing aerosols (e.g., soot) could contribute to a warming. The magnitudes are highly dependent on the optical properties of the aerosols, their level in the atmosphere, the underlying surface, and how they interact with clouds. Within a column of air, there could be cooling in some layers and warming in others. In any event, the magnitude of the contribution of aerosols to climate change is highly uncertain. Direct effect: reflectance of SW radiation > cooling absorbtion of SW rad > decrease reflectance > warming absorbtion of LW > increase of atmospheric opacity > warming Indirect effect: more aerosols > smaller particles > brighter clouds > cooling absorbing aerosols > heating > fewer clouds > warming

29 Outbreak of desert dust off the coast of Africa

30 Sunspot Cycle Length Temperature Friis Christensen andlassen (1991)

31 NH Land Air Temperature vs Length of Solar Sunspot Cycle Lassen and Friis Christensen (1995)

32 Moberg et al (2005)

33 Contribution of the Sun to Global Warming ( ) Scafetta and West (2006c)

34 Contribution of the Sun to Global Warming ( ) Scafetta and West (2006a)

35 Monitoring of the solar irradiance from space since 1976 shows ~0.1% 11 year cycle variation. That could not account for more than ~0.1 C change in temperature. However, empirical relationships between solar activity e.g., magnetic storms and surface phenomena such as UV emission, flares, and variations in the solar wind estimated using proxy measurements (e.g., tree rings, isotopes) as well as sunspot counts have provided proxy data for total solar irradiance variations on much longer time scales over the past few centuries. These data are then matched to actual measurements of solar flux from satellites since 1976 to produce a proxy data set representing total solar irradiance. The result is a remarkable correlation between total solar irradiance and global surface temperature going back hundreds of years. These results have led to the belief that the earth s climate has been influenced by long term variations in solar luminosity. But over the last 3 or 4 decades, the variations have been small and consequently unable to explain the recent warming.

36 Overview of a global warming over the last few decades, within the context of past climate variability Basic physics of global-scale climate and identify areas where knowledge is lacking: Water vapor feedback Aerosol effects Solar irradiance variations Role of satellite data and numerical models in expanding our knowledge IPCC assessment: Climate scenarios and future projections Concluding remarks and a suggestion on how to lessen the human impact on climate

37 Overview of a global warming over the last few decades, within the context of past climate variability Basic physics of global-scale climate and identify areas where knowledge is lacking: Water vapor feedback Aerosol effects Solar irradiance variations Role of satellite data and numerical models in expanding our knowledge IPCC assessment: Climate scenarios and future projections Concluding remarks and a suggestion on how to lessen the human impact on climate