From Dimming to Brightening: Decadal Changes in Solar Radiation at Earth's Surface

Abstract

Treelines have long been recognized as important ecotones and likely harbingers of climate change. However, over the last century many treelines have been affected not only by global warming, but also by the interactions of climate, forest disturbance and the consequences of abrupt demographic and economic changes. Recent research has increasingly stressed how multiple ecological, biophysical, and human factors interact to shape ecological dynamics. Here we highlight the need to consider interactions among multiple drivers to more completely understand and predict treeline dynamics in Europe.

Decadal changes in shortwave irradiance at the surface in the period from 1960 to 2000 estimated from Global Energy Balance Archive Data

“…As a surrogate for the calibration, the records were adjusted to some reference, thus wiping out any decadal changes [Forgan, 2005]. Since 1988, however, positive trends were observed [Wild et al, 2005].…”

“…[7] In the present paper, we (1) provide an update of the SWIR data in the GEBA for the period from 1990 through to 2000, (2) critically discuss all SWIR data made available in the GEBA, and (3) reanalyze the trends in the SWIR data for the period from 1960 through to 2000 with the aim to reevaluate, including in the analysis the data that have been available in the GEBA version 2006 and using a uniform method, our earlier results as reported by Wild et al [2005]. This effort is justified, since, via the surface energy balance, decadal changes in SWIR affect the surface temperature, the hydrological cycle, and ecosystems [e.g., Wild et al, 1996Wild et al, , 2004Wild et al, , 2007Wild et al, , 2008Ramanathan et al, 2001a;Liepert et al, 2004;Robock and Li, 2006].…”

“…In this paper we did not attribute the decadal changes in SWIR to changes in the cloud cover and/or atmospheric clear-sky transmission since it is not possible to separate monthly SWIR values into values for clear-sky and all-sky conditions (unlike in the case of daily values [Liepert et al, 1994] or high-frequency measurements [Long and Ackermann, 2000;Dutton et al, 2004;Wild et al, 2005]). …”

“…[6] As soon as pyranometer measurements for the 1990s had become available, the SWIR was reanalyzed: Wild et al [2005] found a widespread increase of SWIR since the late 1980s and Dutton et al [2006] found, in the period from 1976 through to 2004, a decrease followed by an increase in three records of SWIR (those for South Pole, American Samoa and Boulder, Colorado).…”

Cloud and aerosol contributions to variation in shortwave surface irradiance over East Asia in July during 2001 and 2007

“…For example, Mallet et al [2] evaluated the impact of dust aerosols on the radiative budget, surface heat flux, and other parameters over West Africa. The solar dimming and brightening phenomenon has also received a great deal of attention [3] and has been investigated actively for various locations worldwide. Riihimaki et al [4] studied the contribution of aerosols to the direct irradiance in Oregon, USA, for almost three decades.…”