For about 2.5 years the world’s weather has fluctuated, starting from ice ages to warmer climates. In the last century the world’s weather has fluctuated fast, to about 1.1 to 1.5 farinheight. Scientists believe that the world’s weather is rising up from the people’s activity that is making the weather go crazy, that is known by global warming. Industrial activities started factories, power plants & cars burn fossil fuels, such as coal and oil revealing lots of carbondioxied into the atmosphere. Green House gases trap heat near the earth called the "Green House Effect." It starts with the sun and the energy it rates to the earth. Some of the earth collects the heat, and then warms up the earth. Scientists say that 1998 was the warmest year through history, then 2005 coming in 2nd. Green House carbon dioxide and methane their highest level in the past 420,000 years. The Arctic ice is melting, according to NASA studies. The Arctic ice has declined about 10%, in the last 30 years.