It's the Greenhouse Gases

The greenhouse Gases is the most important factor cause of global climate change. The chemical compounds found in the earth’s atmosphere act as greenhouse gases. Some of them occur in natural, such as water, vapor, carbon dioxide, methane, and nitrous oxide, while others are exclusively human-made. The human actions cause mainly effect to the greenhouse gases. Human produced CO2 emissions by burning of fossil fuels in the past 20 years which will warm the earth. Rising temperature can produce change in weather, sea levels, and land use patterns, commonly referred to as climate change.
Our greenhouses gas emissions come mostly from energy use. Theses are driven largely by economic growth, fuel used for electricity generation, and weather patterns affecting heating and cooling needs. Showing by the source from Energy Information Administration Emissions of Greenhouse Gases in the United States, the energy related carbon dioxide emissions, resulting from petroleum and natural gas, represent 82 percent of total U.S human-made greenhouse gas emissions.
The climate of north and south poles became more extreme, human can not adapt the summer to winter temperature, which are caused by greenhouses gases.