Current global climate change is the seventh climate change event in the past 650,000 years. Unlike past climate change episodes, many experts believe that human activity plays an important role in current global climate changes.
Tiny changes in the planet's orbit alter the amount of energy Earth receives from the sun, causing climate change events. However, human activity has a huge impact on current global climate change as well. Human activity produces high levels of carbon dioxide in the Earth's atmosphere, trapping heat from the sun and altering world climates at a faster rate than past climate changes. For example, the sea level increase in the last decade is twice what it was in the past century. As the oceans absorb some of the Earth's excess heat, the ocean's surface gradually rises in temperature. This warming trend is also causing the ice sheets in Greenland and Antarctica to shrink perceptibly. Research points to losses of over 36 cubic miles of both ice sheets between 2002 and 2006. Land-based glaciers also exhibit decreasing size.
In the Northeast and Midwest United States, climate change is causing more extreme heat events and wetter weather conditions, while the Southwest and Northwest are experiencing an increase in wildfires and outbreaks of damaging insects, as of 2015.