Slide 1: GLOBAL DIMMING WHAT IS GLOBAL DIMMING?? : WHAT IS GLOBAL DIMMING?? Global dimming is the gradual reduction in the amount of global direct irradiance at the earth's surface that was observed for several decades after the start of systematic measurements in the 1950s. The effect varies by location, but worldwide it has been estimated to be of the order of a 4% reduction over the three decades from 1960–1990. PAN EVAPORATION METHOD : PAN EVAPORATION METHOD As the global climate warms, all other things being equal, evaporation will increase and as a result the hydrological cycle will accelerate. The downward trend of pan evaporation has been linked to Global Dimming. CAUSES OF GLOBAL DIMMING… : CAUSES OF GLOBAL DIMMING… Use of fossil fuels creates by-products such as sulphur dioxide, soot and ash.
Aerosol Sprays CAUSES OF GLOBAL DIMMING… : CAUSES OF GLOBAL DIMMING… Nuclei for cloud droplets
Increased pollution-more number of small droplets
Clouds become more reflective CONTRAILS : CONTRAILS VARIATION IN GLOBAL DIMMMING : VARIATION IN GLOBAL DIMMMING IMPACTS OF GLOBAL DIMMING : IMPACTS OF GLOBAL DIMMING Billions are likely to be affected in Asia
Massive famines between 1970-1980 in Ethiopia
Million people dead,50 million affected Impact on mountain glaciers : Impact on mountain glaciers Swiss Glaciers area reduction:
1973 - 1985: -1 %
1985 - 2000: -18 %
-Paul et al. 2004, GRL Does Global Dimming counteract with Global Warming? : Does Global Dimming counteract with Global Warming? It has slowed down the effects of global warming.
The rate of global warming is been underestimated due to global dimming, and this will accelerate the effect of global warming giving us less time to take action. Global dimming-Tool to decrease global warming? : Global dimming-Tool to decrease global warming? Human health problems from the soot/smog
Environmental problems such as acid rains
Ecological problems such as changes in rainfall patterns which can kill millions, if not billions.
The roots of both global dimming causing pollutants and global warming causing greenhouse gases have to be dealt with together. CONCLUSION : CONCLUSION The overriding concern expressed by climate scientists in this program is that our climate will be radically altered, rendering many parts of the planet uninhabitable - unless concerted action is taken to combat both global dimming and global warming. Question?? : Question?? Slide 14: Thank You !!