The evidence for climate change has become too great to ignore, said Eugene Robinson in The Washington Post. The polar ice caps are now melting three times faster than in the 1990s, and heat waves are withering crops from Kansas to Russia. A new study warned this week that runaway carbon emissions may leave the earth a staggering 9 degrees Fahrenheit warmer by 2100, with consequences that are “beyond bleak”—a sea-level rise of three feet, mega-storms that ravage coastal cities, and droughts of biblical proportions. But all the president has offered so far to tackle climate change is a “big lump of meh,” said Monika Bauerlein in As the U.N. begins climate-change talks in Doha, Qatar, this week, Obama needs to show that the U.S. will do its part to forge a global treaty to cut carbon emissions beginning in 2015. As Hurricane Sandy and this summer’s record wildfires proved, “we can’t afford to keep paying the price of inaction.”

It’s not true that Obama has done nothing on climate change, said Kim Chipman in His policies on gas mileage, new power plants, and clean-energy development should help cut carbon emissions by 17 percent by 2020. “Without fanfare,” he has paved the way for the 2015 treaty to become a reality. U.S. carbon emissions have fallen to their lowest level in 20 years, said Charles C.W. Cooke in, but credit market forces, not Obama, for that decline. “Fracking, that bête noire of progressives everywhere,” now provides so much clean, cheap natural gas that it’s replacing carbon-dense coal in the nation’s electrical power plants.

We’re still on the road to disaster, said Coral Davenport in Global carbon emissions will rise 2.6 percent this year, to a record high. A global treaty in 2015 is only possible if Obama comes with a “new U.S. climate law in hand,” showing China—now the world’s worst polluter—and other developing countries that real action is possible. “One attractive solution” might be a $20 a ton carbon tax, said David Frum in Besides cutting emissions, it would raise $1.5 trillion in revenue that could be earmarked for payroll tax reductions and deficit reduction, and spur market changes “that would accelerate U.S. economic growth,” such as encouraging the trend of people moving back into energy-efficient cities. A better economy, smaller deficits, and a brake on climate change—“what’s not to love about a carbon tax?”