The climate-change conundrum isn't set by contending ideologies, whose adherents can argue about whether tax cuts create jobs or kill them. Political reality is hard to change, but physics and chemistry are impossible to shift.
It's hard to avoid the conclusion that while the world is far from ready to do what it must with the substance of the climate threat, it is also true that the process has become the enemy, rather than the facilitator, of progress.
It's going to be a long road ahead, but the resounding determination expressed by the nations of the world in Cancún to find a real and lasting solution to this pressing challenge has restored my optimism.
Across Africa, changing weather patterns and erratic rainfall are making farming more and more difficult, contributing to food crisis and famines in country after country. Support and leadership from the US is urgently needed in Cancún and beyond.
The diminished number of political figures is contrasted by the growing participation of the business community which is speaking in stronger terms than ever before about the need to find real solutions to human-induced climate change.
Now is the time to invest in women in vulnerable communities so they can fight climate change and feed their families. After all, empty promises don't protect from dangerous storm surges or help alleviate the impacts of drought.
All eyes will be focused on the U.S. in Cancun. But unlike in Copenhagen, where participants were optimistic that a newly elected, "environmentally friendly" president would ensure success, no such expectations will abound this year.