President Obama has placed an increasing focus on tackling climate change in the last 12 months, with a clear eye on his political legacy. On Monday, the Environmental Protection Agency released the Clean Power Plan, a framework under which the United States -- as in, each of the 50 states -- would cumulatively cut carbon dioxide emissions by 32 percent by the year 2030.

It's certain that the proposal -- almost without question the most aggressive greenhouse gas reduction plan the country has ever seen -- will result in harsh political backlash, particularly as the Republican presidential fight continues to roil. At a retreat sponsored by the oil-producing Koch brothers over the weekend, Texas Sen. Ted Cruz went on the offensive against the proposal. That's likely the tip of the iceberg.

That said, there are some important things to keep in mind about Obama's new proposal.

1. Coal was already in decline.

Our Steven Mufson has a good overview of coal's recent struggles and the role the new proposal will have in exacerbating them. It's important to remember, though, that coal's sharp decline is already several years old.

The graph below uses data on electricity generation by source from the Energy Information Administration.

Notice that coal's drop doesn't correlate to growth in wind power or solar. It's natural gas that's eating into coal's market, a function of improvements in hydraulic fracturing (better known as "fracking"). Only a few weeks ago, natural gas passed coal as a source of electricity. When burned, coal produces far, far more carbon dioxide than natural gas. But natural gas itself, which is mostly methane, often leaks from drilling sites -- and methane is a far more effective heat-trapping gas than carbon dioxide, meaning that it's worse for global warming on a ton-per-ton basis.

2. The carbon dioxide reduction goal is set against a recent high, not current emissions.

The drop in coal use shown above also means that there's been a drop in America's carbon dioxide emissions. Part of that is a function of the increased use of natural gas, but part of it was the economic collapse that led to the recession. A slower economy uses less electricity.

The new proposal sets a benchmark of 32 percent reduction of carbon dioxide emissions from power plants versus 2005 levels. Data from the EPA shows that emissions were already down steeply in 2013 versus 2005 (though they ticked up again in 2014).

Notice, too, that this only addresses one part of the total carbon dioxide emissions of the United States.

3. This rule won't solve the problem by itself ...

And it does nothing to address global emissions, naturally. The good news is that the world didn't see a big increase in carbon dioxide emissions in 2014. In recent years, though, we've seen a gigantic spike in China's emissions as the country's economy shifts. (Note that this data, from the Carbon Dioxide Information Analysis Center, only goes through 2011.)

That's why Obama's agreement with Chinese leader Xi Jinping is so important. It uses diplomacy to try and pressure other high-polluting countries to cut emissions, too.

4. ... But it should reduce how disproportionately the U.S. is responsible.

While we aren't the biggest polluters, we still produce the most carbon dioxide per person.

China's gaining in this regard, too, having recently passed the EU.

Obama's plan is ambitious enough that it will have an effect -- albeit a small one -- on climate change, and will inspire a ferocious political fight domestically. For environmentalists, having a president willing to engage in the latter is almost as noteworthy as one willing to attempt the former.