Natural Causes
Natural causes are causes created by nature. One natural cause is a release of methane gas from arctic tundra and wetlands. Methane is a greenhouse gas that contributes to global warming. Cows can also produce Methane gas. Agriculture is responsible for an estimated 14 percent of the world's greenhouse gases. A significant portion of these emissions come from methane, is 23 times more powerful than carbon dioxide. The U.S. Food and Agriculture Organization say that agricultural methane output could increase by 60 percent by 2030. (Source: Times Online). They are about 98 million cause in the US and each producing lots of Methane gases very day. Agriculture has definitely had a great impact on global warming in the US. Another natural cause is that the earth goes through a cycle of climate change. This climate change usually lasts about 40,000 years.