Christina+Harrison



**What's Known**
Scientists know with virtual certainty that: For years, global warming was dismissed as an apocalyptic vision dreamt up by cranks and hippies. But recently consensus has been growing that the climate is indeed changing and humans are directly responsible. Now the United Nations has concluded that humans are almost certainly responsible for global warming and issued its strongest-ever warning about the consequences . ( ** http://www.spiegel.de/international/0,1518,463888,00.html  ** ) The UN Intergovernmental Panel on Climate Change (IPCC) has reached a conclusion, human activity are lending a hand in global warming, a bigger hand than ever thought. We can expect to see more droughts, stronger storms and rising sea levels by some time around 2100. We are most likely the main cause of global warming over the last 45 years. Human’s producing greenhouse gases can be blamed for fewer cold days, hotter nights, heat waves, floods and heavy rains, droughts, and increased hurricanes and tropical storms strength. Predictions say that the temperature should rises 2 to 11.5 degrees Fahrenheit by the year 2100, and rising sea levels, the report projects jumps of 7 to 23 inches by the end of the century. An additional 3.9 to 7.8 inches are possible if polar ice sheets continue to melt. The report warns that no matter how much civilization slows or reduces its greenhouse gas emissions, global warming and sea level rise will continue for centuries.
 * Human activities are changing the composition of Earth's atmosphere. Increasing levels of greenhouse gases like carbon dioxide (CO 2 ) in the atmosphere since pre-industrial times are well-documented and understood.
 * The atmospheric buildup of CO 2 and other greenhouse gases is largely the result of human activities such as the burning of fossil fuels.
 * An “unequivocal” warming trend of about 1.0 to 1.7°F occurred from 1906-2005. Warming occurred in both the Northern and Southern Hemispheres, and over the oceans (IPCC, 2007).
 * The major greenhouse gases emitted by human activities remain in the atmosphere for periods ranging from decades to centuries. It is therefore virtually certain that atmospheric concentrations of greenhouse gases will continue to rise over the next few decades.
 * Increasing greenhouse gas concentrations tend to warm the planet. ( **  http://www.eoearth.org/article/Causes_of_climate_change  ** )