The year has already produced three alarming reports involving climate change.

The United Nations Intergovernmental Panel on Climate Change reaffirmed the overwhelming consensus among scientists that the planet is warming, that humans and the burning of fossil fuels are largely responsible, and that the world must take aggressive, concerted action.

The federal National Climate Assessment described frightening changes, including unusually severe and persistent droughts, already occurring in the United States. And two weeks ago, two groups of scientists reported that the West Antarctic ice sheet had begun to disintegrate irreversibly, a process that, over centuries, could cause a large and destructive rise in the oceans.

Despite all this, many leading politicians continue to dispute the science and resist any effort to regulate and reduce the emissions of carbon dioxide, the main greenhouse gas. Among the prominent deniers are two Floridians — Senator Marco Rubio and Gov. Rick Scott — whose state is greatly at risk from even modest and relatively short-term increases in sea levels.

Some of this is to be expected in a political season, when politicians will do almost anything to prey on the public’s fear of job losses. What is truly depressing is the news that Wyoming’s State Legislature has become the first in the nation to reject the new national science standards for schools, standards that include instruction on the human contribution to climate change.