In four years, climate change has gone from the elephant that blind men are trying to describe to the elephant in the room.
No one wants to talk about it. With a few exceptions, voters don't ask. And presidential candidates don't tell.
Now that the 2012 presidential debates are over, commentators have begun to take notice. Not once during the three presidential encounters or the single vice-presidential debate did the subject come up.
"National elections should be a time when our nation considers the great challenges and opportunities the next President will face," opines the website ClimateSilence.org, a project of Forecast the Facts and Friends of the Earth Action aimed at pushing the issue into campaigns. "But the climate conversation of 2012 has been defined by a deafening silence."
The candidates talked about energy and green energy, but always with regard to jobs, never about the climate. Why?
The easy answer is that it's not good politics. What candidate wants to talk about emissions when voters are worried about jobs? Who wants to tackle carbon taxes when many Americans are struggling to pay the taxes they already owe?
The deeper question is: Do Americans want their candidates to talk about climate change? The answer seems to be: No.
It's probably not climate skepticism that's the main barrier here. Polls show that over time Americans are increasingly convinced by the science showing that the climate is warming, and they do see a link with human activity. The ranks of the "climate deniers" are thinning, albeit slowly.
The bigger challenge may be that to many voters the problem seems all too real and unsolvable – something to fear because we can't fix it.
"Climate change is disturbing," writes sociologist Kari Norgaard in her 2011 book, "Living in Denial." "It's something we don't want to talk about. So what we do in our everyday lives is create a world where it's not there, and keep it distant."
Dr. Norgaard isn't talking about the United States. She's writing about Norway. And if there's a place that knows about a warming planet, it's Norway. Winters are warmer, snows are coming later.
Yet during the unusually warm winter of 2001, when she spent a year living there, the percentage of Norwegians worried about climate change had dropped from 40 percent in 1989 to 10 percent. Despite all the evidence before their eyes, including extensive flooding, people in her community avoided talking about it.
So if first-hand experience with climate change won't push people to debate the issue, what will?
A real catastrophe can galvanize action, points out author biologist Glenn Croston in his new book, "The Real Story of Risk."
Real leadership, too, can show how global warming can be tackled and overcome. Since the problem is international, the solution will take leadership on the part of many nations. As the world's largest economy, the US would be expected to play a leading role.
So far, though, America's can-do spirit and optimism is a no-show.
"In 2008, both political parties nominated presidential candidates — Barack Obama and John McCain — who promised to address the climate crisis with mandatory caps on carbon pollution," says ClimateSilence.org. "For President Obama, climate change has gone from an 'urgent' challenge worthy of major speeches and comprehensive legislation, to an afterthought, fleetingly mentioned at occasional campaign events. Mitt Romney, meanwhile, has backpedaled from weak acknowledgement of the basic science to outright mockery of the carbon crisis."
Perhaps they're not telling us because we really don't want to hear.