INTERACTIVE: The Paris Climate Accord, Explained?

[http_redir]On the campaign trail last May, then-candidate Donald Trump declared: "We're going to cancel the Paris climate agreement ... and stop all payments of the United States tax dollars to U.N. global warming programs."

As president, however, Trump now appears less determined to pull the U.S. out of the landmark 2015 international agreement that committed nearly every nation in the world to reduce planet-warming emissions. Contrary to his earlier statement, he doesn't have the power to "cancel" the multilateral U.N. accord, but could substantially weaken it by withdrawing the U.S., which is the world's largest economy and one of the biggest greenhouse gas emitters.)

As part of the deal, the U.S. promised to reduce its greenhouse gas emissions by at least 26 percent of 2005 levels within a decade.

Some of the most conservative members of his administration -- namely Steve Bannon and Scott Pruitt, head of the Environmental Protection Agency, still advocate walking away from the deal. But Trump's hesitation has grown recently as a number of his closest advisors, including son-in-law Jared Kushner and Secretary of State Rex Tillerson (the former head of Exxon Mobil), have urged him to stay the course in order to avoid diplomatic blowback. A host of major corporations, including several oil giants, have also endorsed the pact. The administration is expected to make a final decision at the end of May.

But even if Trump chooses to remain in the accord, it's highly unlikely his administration would adhere to the ambitious emission-reduction goals set by his predecessor; Trump has already made an aggressive push to peel back many of the energy regulations put in place by President Obama that would have helped achieve those goals.

In December 2015, representatives of 195 nations agreed to the landmark climate accord, which required each participating nation to significantly lower its greenhouse gas emissions as part of an  urgent international effort to stave off the worst consequences of climate change.

The agreement was the culmination of two intense weeks of negotiations between delegates from every corner of the globe, who gathered in a huge tent-city compound on the outskirts of Paris to iron out the countless details involved in one of the most complex international deals ever attempted.

The United Nations conference on climate change, or COP21 (Conference of Parties), followed nearly 20 years of largely failed efforts to forge a meaningful international agreement to lower GHGs. Many world leaders, including President Obama, considered these negotiations the last, best chance to prevent global temperatures from rising to catastrophic levels.

The goal: to stop global average surface temperatures from rising above 2 degrees Celsius (about 3.6 degrees Fahrenheit) above pre-Industrial Revolution temperatures (when we started burning large amounts of fossil fuels). Temperatures rising above that 2 degree threshold would likely result in irreversible, catastrophic environmental consequences around the world, according to broad scientific consensus. That could include rapid sea level rise and devastating flooding and drought.

To keep global average temperatures a bay, each of the participating nations -- which are collectively responsible for almost 98 percent of global emissions -- have to dramatically reduce their own greenhouse gas (GHG) emissions (including carbon dioxide, nitrous oxide and methane). But that's a tricky proposition: Some countries have been emitting GHGs for decades, even centuries, and reaping huge economic benefits, while many other "developing nations" are just beginning that process.

The deal, therefore, not only requires rich countries to significantly cut their emissions, it also mandates that they pay poorer countries to also cut emissions and adapt to the impacts of a changing climate.

As the New York Times noted:

"The new deal will not, on its own, solve global warming. At best, scientists who have analyzed it say, it will cut global greenhouse gas emissions by about half what is necessary to stave off an increase in atmospheric temperatures of 2 degrees Celsius, or 3.6 degrees Fahrenheit. That is the point at which scientific studies have concluded the world will be locked into a future of devastating consequences, including rising sea levels, severe droughts and flooding, widespread food and water shortages, and more destructive storms."

The deal also came under fire by some environmental activist groups who argue it's too weak to effectively prevent environmental disaster. They deal, they note is largely voluntary, lacking the necessary legally binding emissions reduction requirements.

Although the U.S. pledge to reduce emissions by 26 percent of 2005 levels is more ambitious than some large carbon emitting nations like Russia, it pales in comparison to many other developed countries, including the 28 European Union nations, who have all committed to at least a 40 percent GHG reduction below 1990 levels by 2030.

Signatories are legally required to meet every five years -- beginning in 2020 -- with updated emissions goals, but the goals themselves are not legally binding.