Global warming what is it? Global warming refers to an average increase in theEarth's temperature, which in turn causes changes in climate. So what's the big deal you ask? Well the big deal is, if temperatures rise above normal levels for a few days, it's no big deal, the Earth will stay more or less the same, but if temperatures continue to rise over a longer period of time, then the Earth may experience some …showed first 75 words of 345 total…

…showed last 75 words of 345 total…century. The 20th century's 10 warmest years have all occurred in the last 15 years of the century. Worldwide precipitation over land has increased by about one percent and globally, sea level has risen 4-8 inches over the past century. Global warming has also decreased snow cover in the northern hemisphere,and melted glaciers. Changing regional climate could alter crops yields, water supplies,and forests. It could also affect the health of ecosystems, animals and even humans.