I recommend reading this summary of the scientific evidence reported in 2009. Its summary is
Many of the predicted impacts of human-caused climate change are occurring much faster than anybody expected — particularly ice melt, everywhere you look on the planet.
If we stay anywhere near our current emissions path, we are facing incalculable catastrophes by century’s end, including rapid sea level rise, massive wildfires, widespread Dust-Bowlification, large oceanic dead zones, and 9°F warming — much of which could be all but irreversible for centuries. And that’s not the worst-case scenario!
The consequences for human health and well being would be extreme.
Many good links in this one.