Global Warming

  2010 JUN 7 - (VerticalNews.com) -- According to recent research published in the journal Nonlinear Processes in Geophysics, "We revisit a recent claim that the Earth's climate system is characterized by sensitive dependence to parameters; in particular, that the system exhibits an asymmetric, large-amplitude response to normally distributed feedback forcing. Such a response would imply irreducible uncertainty in climate change predictions and thus have notable implications for climate science and climate-related policy making. ...read more

  2010 MAR 8 - (VerticalNews.com) -- "Absorbing aerosols supplements the global warming caused by greenhouse gases. However, unlike greenhouse gases, the effect of absorbing aerosol on climate is not known with certainty owing to paucity of data," researchers in India report.

  "Also, uncertainty exists in quantifying the contributing factors whether it is biomass or fossil fuel burning. Based on the observations of absorption coefficient at seven wavelengths and aerosol optical depth (AOD) at five wavelengths carried out at Gadanki (13.5 degrees N, 79.2 degrees E), a remote village in peninsular India, from April to November 2008, as part of the 'of Atmospheric Forcing and Responses (SAFAR)'' pilot campaign we discuss seasonal variation of black carbon ( BC) concentration and aerosol optical depth. Also, using spectral information we estimate the fraction of fossil-fuel and non-fossil fuel contributions to absorption coefficient and contributions of soot ( Black Carbon), non-soot fine mode aerosols and coarse mode aerosols to AOD. BC concentration is found to be around 1000 ng/m(3) during monsoon months (JJAS) and around 4000 ng/m(3) during pre and post monsoon months. Non-fossil fuel sources contribute nearly 20% to absorption coefficient at 880 nm, which increases to 40% during morning and evening hours. Average AOD is found to be 0.38 +/- 0.15, with high values in May and low in September. Soot contributes nearly 10% to the AOD. This information is further used to estimate the clear sky aerosol direct radiative forcing. Top of the atmosphere aerosol radiative forcing varies between -4 to 0 W m(-2), except for April when the forcing is positive. Surface level radiative forcing is between -10 to -20 W m(-2)," wrote H. Gadhavi and colleagues ...read more

  2009 DEC 7 - (VerticalNews.com) -- According to recent research from Paris, France, "In the absence of earthquakes, oceanic microseisms are the strongest signals recorded by seismic stations. Using the GEOSCOPE global seismic network, we show that the secondary microseism spectra have global characteristics that depend on the station latitude and on the season."

  "In both hemispheres, noise amplitude is larger during local winter, and close to the equator, noise amplitude is stable over the year. There is an excellent correlation between microseism amplitude variations over the year and changes in the highest wave areas. Considering the polarization of the secondary microseisms, we show that stations in the Northern Hemisphere and close to the equator record significant changes of the secondary microseism source azimuth over the year. During Northern Hemisphere summer, part or all of the sources are systematically located farther toward the south than during winter. Stations in French Guyana (MPG) and in Algeria (TAM) record microseisms generated several thousand kilometers away in the South Pacific Ocean and in the Indian Ocean, respectively. Thus, secondary microseism sources generated by ocean waves which originate in the Southern Hemisphere can be recorded by Northern Hemisphere stations when local sources are weak. We also show, considering a station close to Antarctica, that primary and secondary microseism noise amplitudes are strongly affected by changes of the sea ice floe and that sources of these microseisms are in different areas," wrote E. Stutzmann and colleagues ...read more