Is it Too Late to Tackle Global Warming?

Global greenhouse-gas emissions rose to record levels in 2012, the International Energy Agency said in a report released last week. Especially disconcerting is the news from May that carbon-dioxide levels reached 400 parts per million "for the first time in several hundred millennia," the report states.

IEA predicts that the global temperature could rise between 6.84 and 9.54 degrees Fahrenheit, "with most of the increase occurring this century." This is significantly more than the 3.6-degree Fahrenheit temperature (2-degree Celsius) rise scientists have said the Earth must not surpass. The report sounds a dismal tone: "Despite the insufficiency of global action to date, limiting the global temperature rise to 2 degrees C remains still technically feasible, though it is extremely challenging."

The report recommends a suite of four policies countries must adopt by 2020 in order to stave off the worst impacts of the temperature rise. IEA selected these policies for two key reasons: They rely on existing technologies, and they would not, according to the agency, harm economic growth in any country. The policies, in order of the greatest impact on temperature rise, are: enacting more energy-efficiency practices, limiting construction and use of coal-fired power plants, minimizing methane emissions from oil and natural-gas operations, and phasing out subsidies to fossil-fuel industries. Notably absent from this list are a carbon tax or a cap-and-trade system to control the price of greenhouse gas emissions.

The IEA's report should carry significant weight. It's an independent agency that has 28 members, including the United States, Japan, and most of Europe. But notable nonmembers of the organization are two of the world's biggest greenhouse-gas emitters: China and India.

Does this report indicate it's too late for the world to do anything substantive to combat global warming? If so, what will the consequences be?

Which one of the four measures IEA recommends should the United States push the most? Or, should Washington instead push for a more ambitious policy that places a price tag on greenhouse-gas emissions?

Should adaptation measures--policies that address the impacts of climate change already being felt today, such as more-extreme weather--be a larger part of the conversation?