Journal of Geophysical Research: Atmospheres

Introduction to special section on Global Warming and the Next Ice Age

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[1] This section of the Journal of Geophysical Research contains several of the papers presented at the Second International Conference on Global Warming and the Next Ice Age and at the workshop on Aerosols and Climate Prediction Uncertainty. Over 130 oral and poster papers were presented at the meeting, which was attended by over 120 climate and aerosols experts from 15 countries. The meeting was held in Santa Fe, New Mexico from 17 to 21 July 2006. It was hosted by the Los Alamos National Laboratory and cosponsored by the American Meteorological Society and the University of Washington.

[2] This was the second conference in the series, planned to take place every five years to provide an opportunity for scientific exchange of ideas between experts holding quite diverse points of view and research perspectives on the current climate change. Papers dealing with the current anthropogenic global warming as well as with longer-scale climate changes (ice ages) are welcome. The First conference took place at Dalhousie University in Halifax, Canada, in 2001. The following collection of papers contains some of reported new research. Many of the conference presentations (including those concerning the next ice age) were already in the reviewing process or published at the time of the conference. The first few papers of this collection provide an overview of recent IPCC climate modeling results related to decadal and multidecadal climate variability [Parker et al., 2007], discuss the contribution of solar variability to global surface air temperature changes [Scafetta and West, 2007], and consider general limitations on the prediction of climate from the principals of chaos theory [Essex et al., 2007].

[3] Climate sensitivity, which determines how top-of-atmosphere radiative forcing is translated into the changes in global average temperature, has been deduced from observational data during the last decade suggesting that an increasing carbon dioxide concentration occurred simultaneously with a decreasing aerosol optical depth [Chylek et al., 2007a]. A different approach deduces climate sensitivity using the ocean heat capacity and the time lag of the climate system response [Schwartz, 2007]. These results (between 0.29 K/Wm−2 and 0.48 K/Wm−2) based on observations are on the low end of the range of equilibrium climate sensitivities reported by the Intergovernmental Panel on Climate Change.

[4] The influence of biosphere on H2O and CO2 fluxes [Ferguson and Veizer, 2007], regional temperature changes [Reiter, 2007], and some remaining issues of climate temperature data [Pielke et al., 2007; McKitrick and Michaels, 2007] are subject of the following few papers. These are followed by a review of ground-based aerosol optical depth measurements in polar regions [Tomasi et al., 2007] and by aerosol remote sensing methods [Popp et al., 2007; Magi et al., 2007]. The next few papers include a model of inorganic and organic aerosols [Amundson et al., 2007], effect of cirrus clouds on radiation [Fusina et al., 2007] and an electron tomography method to determine the aerosol fractal structure and its effect on aerosol optical properties [Adachi et al., 2007]. The following papers develop process level models to capture activation of black carbon [Henson, 2007], probability distribution function method to improve description of subgrid details and to improve cloud treatment in climate models [Jeffery, 2007] and to treat aerosol indirect effects [Tao et al., 2007].

[5] A new high spatial resolution method of remote sensing of the Greenland ice sheet melt area has been developed [Chylek et al., 2007b] and applied to the southwestern part of the ice sheet. The results suggest that the melting has increased during the last decade; however, the largest extend of the melt area occured in 1930s.

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