  Among the scientific community it is no longer controversial that anthropogenic climate change is real and a significant threat to the well-being of both current and future generations.  But it is also widely acknowledged that human development is an important way to address high levels of global poverty, that such development is energy intensive, and the cheapest sources of energy available are not likely to be clean energy types. These considerations significantly affect efforts to deal with problems presented by climate change. There is much discussion about the principles that should inform a fair treaty aimed at dealing with addressing climate change that also gives appropriate weight to concerns for human development. Some of the main contenders include principles that recognize causal responsibility for high emission levels, principles that are sensitive to ability to pay, and ones according to which those who have benefited from emissions should now be expected to absorb more costs.