Global Warming
Global warming is the increase in the average temperature of the Earth's near-surface air and oceans since the mid-20th century and its projected continuation. Global surface temperature increased 0.18°C (0.32°F) during the last century. Temperature increase since the middle of the 20th century was caused by increasing concentrations of greenhouse gases resulting from human activity such as fossil fuel burning and deforestation. One natural cause is the release of methane gas from arctic tundra and wetlands. Methane is a greenhouse gas, which is very dangerous for our environment.
Pollution is one of the biggest man-made problems. Pollution comes in many shapes and sizes. Burning fossil fuels is one thing that causes pollution. Fossil fuels are fuels made of organic matter such as coal or oil. When fossil fuels are burned, they give off a green house gas called CO2. Also, mining coal and oil allows methane to escape. Another major man-made cause of global warming is population. More people means more food and more methods of transportation. That means more methane because there will be more burning of fossil fuels and more agriculture.
The effects of global warming include Arctic shrinkage, Arctic methane release, releases of terrestrial carbon from permafrost regions and Arctic methane release in coastal sediments, and sea-level rise. Global average temperature is predicted to increase over this century, with a probable increase in frequency of some extreme weather events, and changes in rainfall patterns. Moving from global to regional scales, there is increased uncertainty over how climate will change. The probability of warming having unforeseen consequences increases with the rate, magnitude, and duration of climate change. Sea level is expected to rise 18 to 59 cm (7.1 to 23.2 inches) by the end of the 21st century.
Some regions and sectors are expected to experience benefits while others will experience costs. With greater levels of warming (greater than 2-3°C, relative to 1990 levels), it is likely that benefits will decline and costs will increase. Low-latitude and less-developed areas are probably at the greatest risk from climate change. With human systems, adaptation potential for climate change impacts is considerable, although the costs of adaptation are largely unknown and potentially large. Climate change will likely result in reduced diversity of ecosystems and the extinction of many species.