Recently a publication in " Science" magazine says that according to NASA(National Academy for Space and Administration) the aerosols present in the earth's atmosphere is thinning since 1990 causing a brightening effect. The aerosols consists of dust, volcanic ash and man made pollution act like a global sun screen by blocking parts of the sunlight.
“When more sunlight can get through the atmosphere and warm Earth’s surface, you’re going to have an effect on climate and temperature,” said lead author Michael Mishchenko of NASA’s Goddard Institute for Space Studies.
It has been stated in the science journal "Science" that in year 2005 that the amount of aerosol has decreased by 20% from the levels found between 1986 to 1990.That resulted in more sunlight reaching the earth's surface.
Scientists are not sure whether amount of aerosols amount in the atmosphere will continue to decrease or not as the particle's are available at different levels around the globe and the come from different sources both man made or natural.
According to a study Winter this year was warmest along the globe. That
may be a cause of the above effect.