The natural world is changing more quickly than ever before in human history, fueled mainly by carbon dioxide emissions from human activities. And after years of debates and delays, U.S. government policy is finally starting to catch up — albeit slowly.

On Monday, the U.S. Environmental Protection Agency unveiled "the biggest, most important step we have ever taken" to combat climate change, according to President Obama. Known as the Clean Power Plan, the move will address the country's single largest source of climate-warming greenhouse gas emissions: power plants. The electricity sector is responsible for nearly one-third of U.S. carbon dioxide emissions, largely due to its traditional reliance on coal, the most carbon-heavy fossil fuel.

The Clean Power Plan is not Earth-shattering, and it won't come close to solving the global mess of climate change. Reviews so far are mixed, even among those who agree the move is a step in the right direction. While many environmental groups are cheering the plan as transformative, and the New York Times calls it "the strongest action ever taken in the United States to combat climate change," some observers say calling it "bold" or even a "big deal" would be an overstatement.

But while the plan may be pedestrian, it still has potential to be powerful. Not only can it help formalize the country's existing shift to safer, more sustainable energy sources, but it can help set the stage for something even bigger and more important: the potentially game-changing U.N. climate talks in Paris this December.

If you don't have time to study the 1,560-page plan, here are a few key points:

1. It sets the first CO2 limits on U.S. power plants.

The final version of the Clean Power Plan sets "flexible and achievable" standards to curb CO2 emissions 32 percent from 2005 levels by 2030, according to a White House fact sheet. That's 9 percent more ambitious than the proposal released in 2014.

Until this week, the U.S. had no legal limits on how much CO2 a power plant could dump into Earth's atmosphere. The Obama administration has set limits on CO2 emissions from other sources like vehicles — and on other pollutants emitted by coal, like mercury and arsenic — but this represents the first-ever regulation of the climate-altering gas from both new and existing power plants.

Coal use has already been fading for years, thanks to a mix of factors like cheap natural gas and shrinking costs of renewable energy. U.S. power-plant emissions fell 15 percent from 2005 to 2013, so they're already well on their way to the goal of 32 percent by 2030. The Clean Power Plan may only nudge along an existing trend, but it still offers a significant push — and a safeguard against backsliding.

2. It's customizable for each state.

The plan sets uniform CO2 limits for power plants nationwide, but it gives each state an individual goal based on its current energy mix. States can then customize their own plans for meeting those goals, including things like switching from coal to natural gas (which emits less CO2), using more renewable energy like solar and wind (which emits no CO2), improving energy efficiency or adopting carbon-trading programs.

"This plan reflects the fact that not everybody is starting from the same place," Obama said Monday during a press conference to unveil the Clean Power Plan.

The EPA has developed a proposed federal plan, which can serve as a model to help states develop their own plans. And as the White House explains, it will also provide a "backstop" to ensure every state complies. So if any state refuses to submit a plan of its own, the EPA can simply impose its federal version.

3. It's good for the climate and the economy.

The primary purpose of the plan is obviously to reduce the country's outsized contribution to climate change. But cleaning up the U.S. electricity sector offers a variety of other benefits to public and economic health. By meeting the emissions goals for 2030, the EPA estimates the U.S. will experience up to 3,600 fewer premature deaths, 90,000 fewer asthma attacks in children, 1,700 fewer hospital admissions, and 300,000 fewer missed days of school and work.

Switching from entrenched fuel sources will have an upfront cost, but the EPA's plan is widely expected to offset that with long-term savings. The agency forecasts it will add $8.4 billion to utility costs over the next 15 years, while providing four times that amount in various benefits. It will save consumers a total of $155 billion from 2020 to 2030, according to the White House.

"By 2030, the net public health and climate-related benefits from the Clean Power Plan are estimated to be worth $45 billion every year," EPA Administrator Gina McCarthy writes in a blog post. "And, by design, the Clean Power Plan is projected to cut the average American’s monthly electricity bill by 7% in 2030."

4. It helps pave the way to Paris.

Aside from its direct effects within the U.S., one of the most important aspects of this move is the tone it sets for international climate negotiations. U.N. climate talks are notoriously sluggish, having struggled for decades to produce a universally binding treaty for cutting CO2 emissions. China, the world's leading CO2 emitter, has long resisted emissions cuts and pointed to higher per-capita emissions in the U.S. But after the U.S. announced its Clean Power Plan, China responded with its own pledge to curb greenhouse gas emissions by 2030.

As the window for preventing catastrophic climate change closes, the international community has targeted this December's Paris climate talks as a pivotal moment for reaching the long-sought treaty. The U.N. held a summit in New York last year to build momentum for Paris, and the Obama administration hopes this plan will inspire other countries as it apparently has China.

"The release of the Clean Power Plan continues momentum toward international climate talks in Paris in December," the White House says in a statement, "building on announcements to-date of post-2020 targets by countries representing 70 percent of global energy based carbon emissions."

5. It's still not written in stone.

Although Monday's release is the final version of the plan, hurdles remain. Critics who oppose regulation of greenhouse gases are expected to mount legal challenges, even though the U.S. Supreme Court has already confirmed the EPA's authority to regulate CO2 under the Clean Air Act. (It's worth noting the Obama administration initially wanted Congress to pass a climate bill rather than using the EPA's authority, but that effort failed in 2009.) Still, as Resources for the Future recently pointed out, the plan's unorthodox use of the law does raise some legal uncertainty.

And perhaps even more importantly, Obama's successor could wield significant influence over how this plays out. States are supposed to submit their plans by 2016, but an extension to 2018 is available, which is well into the next president's term. So the Clean Power Plan could be a key point of debate in the 2016 presidential race.

That might be discouraging for anyone concerned about the unprecedented pace of climate change, but at least this means the topic might actually come up during the presidential debates this time around.

***

For more about the Clean Power Plan, see this list of details from the EPA and the promotional video below released by the White House:


Related on MNN:

Russell McLendon ( @russmclendon ) writes about humans and other wildlife.