Paragraph on Global Warming ~ Ofuran

Paragraph on Global Warming

Global Warming

Global warming is the observed increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation. Global average air temperature near Earth's surface rose 0.74 ± 0.18 °Celsius (1.3 ± 0.32 °Fahrenheit) in the last century. The Intergovernmental Panel on Climate Change (IPCC) concludes, "most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations," which leads to warming of the surface and lower atmosphere by increasing the greenhouse effect. The climate system varies through natural, internal processes and in response to variations in external forcing factors including solar activity, volcanic emissions, variations in the earth's orbit (orbital forcing) and greenhouse gases. Models referenced by the IPCC predict that global temperatures are likely to increase by 1.1 to 6.4 °C (2.0 to 11.5 °F) between 1990 and 2100. About three-quarters of the anthropogenic [man-made] emissions of CO2 to the atmosphere during the past 20 years are due to fossil fuel burning and the rest of the anthropogenic emissions are predominantly due to land-use change, especially deforestation that reflects the long average atmospheric lifetime of carbon dioxide (CO2). An increase in global temperatures can, in turn, cause other changes, including a rising sea level, changes in the amount and pattern of precipitation and increases in the frequency and intensity of extreme weather events. Other consequences include repercussions to agriculture glacier retreat, possible slowing of the thermohaline circulation, reductions in the ozone layer, increased intensity and frequency of hurricanes and extreme weather events, lowering of ocean pH, reduced summer streamflows, species extinctions and increases in the ranges of disease vectors. The broad agreement among climate scientists that global temperatures will discontinue increasing has led nations, states, corporations and individuals to implement actions to try to curtail global warming or adjust to it. A hotly contested political and public debate also has yet to be resolved, regarding whether anything should be done, and what could be cost-effectively done to reduce or reverse future warming, or to deal with the expected consequences. Most national governments have signed and ratified the Kyoto Protocol aimed at combating greenhouse gas emissions.