Climate Change
Climate change is considered by many scientists to be the most serious threat facing the world today.
The pollutants we pump into our atmosphere are changing its composition and preventing heat from escaping the earth’s surface. Today’s atmosphere contains 32% more carbon dioxide, one of the main greenhouse gases, than at the start of the industrial era.
The result is climate change — altered long-term weather patterns. Global warming, a rise in the average global temperature, is one measure of climate change; and it has already begun. Global average temperature has risen by 0.6 degrees Celsius since 1900 and the northern hemisphere is substantially warmer than at any point during the past 1000 years.
Recent climate change research has uncovered a disturbing feature of the earth’s climate system: it is capable of sudden, violent shifts. This is a critically important realization. Climate change will not necessarily be gradual, as assumed in most climate change projections, but may instead involve sudden jumps between very different states.
No such shift has occurred over the duration of human civilization, yet records of prehistoric shifts are clear. A mounting body of evidence suggests that continued greenhouse gas emissions may push the oceans past a critical threshold and into a drastically different future. Abrupt, hard-to-predict climate change will present an enormous challenge to human societies and the global environment as a whole.
Sources:
http://www.davidsuzuki.org/Climate_Change/
http://www.davidsuzuki.org/Climate_Change/Science/
http://www.davidsuzuki.org/Climate_Change/Science/Abrupt_Change.asp