From Wikipedia:Climate Change BIG FAT BALLS!
- Beginning with the industrial revolution in the 1850s and accelerating ever since, the human consumption of fossil fuels has elevated CO2 levels from a concentration of ~280 ppm to more than 370 ppm today. These increases are projected to reach more than 560 ppm before the end of the 21st century. Along with rising methane levels, these changes are anticipated to cause an increase of 1.4–5.6 °C between 1990 and 2100
In 2005 there were a record number of hurricanes. In Europe winters and summers have been more extreme. Large chunks of the polar ice caps are melting. There is talk of the gulf stream shifting as a result of the changes in ocean currents. Apparently small changes in temperature can lead to large changes in the environment.
Shift of Gulf Stream
A shift of the gulf stream would have serious consequences for both agriculture and fishing. Arable land might cease to be suitable for farming. A massive drop in plankton levels would lead to an equally large drop in fish.
We have the know-how to reverse these changes. What is missing is the political will to do so. The problem is not so much a technological problem as a social one.