Earth's atmosphere now has 400 parts of carbon dioxide for every million parts of air.
What does this number mean?
Earth's global average temperature is 1.3º hotter than it was in 1895.
Why is this small number a big deal?
The area of the Arctic Ocean covered by sea ice is only 66% as large at the end of summer 2009 as in 1979.
What is happening to the ice?
The global average sea level has risen 2 inches in the past 17 years.
What if it keeps rising this fast?