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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L04702, doi:10.1029/2006GL028031, 2007

Impact of global dimming and brightening on global warming

Martin Wild

Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland


Atsumu Ohmura

Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland


Knut Makowski

Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland


Abstract

Speculations on the impact of variations in surface solar radiation on global warming range from concerns that solar dimming has largely masked the full magnitude of greenhouse warming, to claims that the recent reversal from solar dimming to brightening rather than the greenhouse effect was responsible for the observed warming. To disentangle surface solar and greenhouse influences on global warming, trends in diurnal temperature range are analyzed. They suggest that solar dimming was effective in masking greenhouse warming, but only up to the 1980s, when dimming gradually transformed into brightening. Since then, the uncovered greenhouse effect has revealed its full dimension, as manifested in a rapid temperature rise (+0.38°C/decade over land since mid-1980s). Recent solar brightening cannot supersede the greenhouse effect as main cause of global warming, since land temperatures increased by 0.8°C from 1960 to 2000, even though solar brightening did not fully outweigh solar dimming within this period.

Received 8 September 2006; accepted 27 December 2006; published 20 February 2007.

Keywords: solar dimming/brightening; global warming; radiation and climate.

Index Terms: 0360 Atmospheric Composition and Structure: Radiation: transmission and scattering; 1610 Global Change: Atmosphere (0315, 0325); 1620 Global Change: Climate dynamics (0429, 3309); 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513); 3359 Atmospheric Processes: Radiative processes.

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Citation: Wild, M., A. Ohmura, and K. Makowski (2007), Impact of global dimming and brightening on global warming, Geophys. Res. Lett., 34, L04702, doi:10.1029/2006GL028031.