On Tuesday, President Obama is expected to announce a couple major new steps to address global warming, including a plan to limit carbon-dioxide emissions from existing  power plants.

But what's the goal here? To put this all in context, take a look at this chart from the most recent Economic Report of the President, which shows the United States is nowhere near on pace to meet its short-term climate targets by 2020.

Over the past few years, U.S. carbon-dioxide emissions have been falling rapidly, thanks to the recession, improved energy-efficiency, and a shift from coal to natural gas. But those trends have bottomed out recently, and coal started making a comeback in 2013.

That means the United States is no longer on track to reduce its carbon-dioxide emissions 17 percent below 2005 levels by 2020, as Obama pledged under the Copenhagen Accord. To hit that target, the White House report argued, new "policy steps" will be needed. (These cuts are seen as a necessary first step, but far from sufficient to tackle global warming— there are still longer-term cuts, China needs to get on board, etc.)


So are the actions that Obama is unveiling Tuesday enough to reach that 17 percent cut by 2020? That all depends on the details. Here's how my colleague Juliet Eilperin previews the big speech:

President Obama will announce his intention to limit greenhouse gas emissions from existing power plants, increase appliance efficiency standards and promote renewable energy development on public lands in a speech Tuesday outlining his plan to use executive powers to address climate change.

The biggest piece here is the proposal to have the Environmental Protection Agency place limits on greenhouse-gas emissions from the nation's 1,142 coal-fired power plants and 3,967 natural gas plants. As I've discussed before, there are aggressive and less-aggressive ways to do this.

If Obama wanted to be aggressive, the EPA could adopt something like the Natural Resources Defense Council proposal to cut power-plant emissions 26 percent by 2020. That would certainly get the United States close to its near-term climate targets.

But there are downsides. This plan — which would let states take creative approaches to cut emissions — could also prove legally risky. And it might encounter sharp resistance from industry groups and even state governors. So, alternatively, the EPA could end up settling on less-stringent limits (requiring modest efficiency improvements at power plants, say). The fine print matters a lot here.

Further reading:

--Juliet Eilperin's detailed preview of Obama's climate speech Tuesday. Note that, in addition to emissions cuts, it will also include measures to "prepare the United States for the near-term impacts of global warming."

--How the White House thinks about climate change, in seven charts.

--Here's a detailed description of the Natural Resources Defense Council's plan to cut emissions from power plants 40 percent by 2020. And here's a look at why Obama's plans for climate action will likely be constrained by the courts.

--And here's a more detailed look at what the Obama administration could do to tackle climate change, particularly when thinking beyond short-term cuts.