JUST BEFORE Republicans scored a big midterm-election victory two weeks ago, the authoritative Intergovernmental Panel on Climate Change (IPCC) released a report that underscored the severity of the risk global warming poses and the level of certainty scientists have about their warnings. Then, shortly following the GOP’s win, President Obama concluded a historic agreement with China on climate change, undercutting Republican arguments that cutting emissions here would be useless because China wouldn’t sacrifice along with the United States.

Despite all of this, since the election Republican leaders have continued to indulge in hysterical “war on coal” rhetoric, and they attacked the climate breakthrough in Beijing. They still appear determined to repeal the country’s climate policies rather than replacing those policies with cheaper and more effective options, such as the market-based carbon-pricing programs that authentic conservatives would favor.

Americans deserve leaders who will govern with clear eyes about a range of potential hazards, particularly those over which humans have direct control. Whether out of cynicism, callousness or ignorance, Republicans over the past decade have instead indulged and encouraged shortsighted naysayers and climate conspiracists in the face of grave climate forecasts. If they continue with this nonsense, they will risk disqualifying themselves with voters who expect rationality from their elected representatives.

Scientists could not be clearer about the need to act. Here are just a few of the IPCC’s conclusions:

“Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems.”

“Many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.”

“From 2000 to 2010 emissions were the highest in history. Historical emissions have driven atmospheric concentrations of carbon dioxide, methane and nitrous oxide, to levels that are unprecedented in at least the last 800,000 years.”

“Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, and in global mean sea-level rise; and it is extremely likely to have been the dominant cause of the observed warming since the mid-20th century.”

“In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans.”

“Changes in many extreme weather and climate events have been observed since about 1950. Some of these changes have been linked to human influences, including a decrease in cold temperature extremes, an increase in warm temperature extremes, an increase in extreme high sea levels and an increase in the number of heavy precipitation events in a number of regions.”

“Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks.”

During the campaign, soon-to-be Senate majority leader Mitch McConnell (R-Ky.) spoke a lot about the “war on coal” but dodged questions about the damage coal burning does to human welfare. “I’m not a scientist,” he told reporters. House Speaker John Boehner (R-Ohio) struck a similar note. Their scientific qualifications have never been the question. Their suitability for leadership still is.