> For example, at the end of the last ice age, when the Northeast United States was covered by more than 3,000 feet of ice, average temperatures were only 5 to 9 degrees [Fahrenheit] cooler than today.
If 4 degrees Celsius of global cooling (relative to the current climate) can cause large parts of the US to be covered by 3,000 feet of ice, then it's not unreasonable to think that 4 degrees Celsius of global warming could have an equally destructive effect on agriculture and society.
If 4 degrees Celsius of global cooling (relative to the current climate) can cause large parts of the US to be covered by 3,000 feet of ice, then it's not unreasonable to think that 4 degrees Celsius of global warming could have an equally destructive effect on agriculture and society.