Frequently we read commentary of the sort:
“Yes, global warming is occurring. But humans have proven themselves capable of developing technology to counter physical threats such as climate change.”
The element of faith in this statement is amazing. Because in the past technology has overcome problems we need not fear the future.
James Hansen has pointed out two things that undermine such optimism. First: we may not accurately estimate the extent of the risk. Secondly, there may be causative elements not yet correctly identified that will undermine reasonable projections.
The United Nations Intergovernmental Panel on Climate Change (the Panel) proposed that the world accept a global warming limit of 2 degrees Celsius . Scientific advisors to the Panel have suggested that pressure was applied by national representatives to accept this limit. Hansen says that it “was pulled out of a hat”.
Many other scientists participating in the have warned us that limiting global warming to 2 degrees may not prevent a catastrophic sea level rise that would leave major cities from Miami to Mumbai at risk of drowning.
Yet the efforts of the Panel remains focused on this limit. The Panel concluded that a target within reach is to be preferred to a target beyond the present level of political will.
Hansen observed that “[countries] need to understand that the issue is most urgent and the required rate of reduction of emissions is much greater than that which has been achieved.”
Hansen is to be thanked for his research, disturbing though it is, as the warming limit cannot simply be determined by political will.