Evidence That Humans Caused Today's Global Warming
Here's an interesting climate change observation reported by the BBC—over the last 800,000 years, up until industrial revolution times, the concentration of carbon dioxide in the atmosphere never rose above 300 ppm. Since then, and particulary from the 20th century on, CO2 concentration has steeply climbed to where it is today, nearing 400 ppm. Many scientists believe significant global warming consequences are inevitable above 350 ppm.
The historical data cited by the BBC come in part from ice core samples taken in Antarctica and Greenland. Bubbles of air trapped in the ice show cycles of 100,000 years, during which air temperatures and CO2 levels fluctuate in parallel. As humankind grew in population and started heavily relying on fossil fuels, the cyclical pattern was broken. Now, CO2 and temperatures are simply going up.
This bad news is actually good news of a sort as the world prepares to meet next week in Copenhagen to deal with climate change. The recent hacked email scandal is being used by deniers and contrarians to weaken the chances of getting anything done at the conference. A good dose of solid science like this could help keep things on track.