none of above
The basic science of climate change is more than 150 years old. Back in 1859, Irish physicist John Tyndall predicted that winters would warm faster than summers, and nights faster than days. Now we see it borne out.
The bad news: we are causing it.
The good news: we can stop it.
Climate change will have major impacts on the availability of water for growing food and on crop productivity in the decades to come. Increased temperatures will lengthen the growing season in northern temperate zones but will reduce the length almost everywhere else. The livelihoods of rural communities as well as the food security of city populations are at risk.