Countries commit to putting forward their best efforts to reduce greenhouse gas emissions.

PARIS — Representatives of the world’s nations, after four years of negotiations, on Dec. 12 reached an agreement on how to address the challenges presented by climate change. The treaty, negotiated under the United Nations Framework Convention on Climate Change (U.N.F.C.C.C), provided a framework that commits all countries to put forward their best efforts to reduce their greenhouse gas emissions and included requirements that all parties report regularly on their emissions and implementation efforts, and undergo international review.

Under the Paris Agreements, the nations agreed to do the following:

1. Reaffirm the goal of limiting global temperature increase well below 2 degrees Celsius, while urging efforts to limit the increase to 1.5 degrees.
2. Establish binding commitments by all parties to make “nationally determined contributions” (N.D.C.s) with regard to reducing greenhouse gas emissions, and pursue domestic measures aimed at achieving them.
3. Commit all countries to report regularly on their emissions and “progress made in implementing and achieving” their N.D.C.s, and to undergo international review.
4. Commit all countries to submit new N.D.C.s every five years, with the clear expectation that they will “represent a progression” beyond previous ones.
5. Reaffirm the binding obligations of the developed countries under the U.N.F.C.C.C. to support the efforts of developing countries, while for the first time encouraging voluntary contributions by developing countries, too.
6. Extend the current goal of mobilizing $100 billion a year in support to developing countries’ climate change efforts by 2020 through 2025, with a new, higher goal to be set for the period after 2025.
7. Extend a mechanism to address “loss and damage” resulting from climate change that explicitly will not “involve or provide a basis for any liability or compensation.”
8. Require parties engaging in international emissions trading to avoid “double counting.”
9. Call for a new mechanism, similar to the Clean Development Mechanism under the Kyoto Protocol, enabling emission reductions in one country to be counted toward another country’s N.D.C.

The Center for Climate and Energy Solutions noted, “The Paris Agreement is a treaty under international law, but only certain provisions are legally binding. The issue of which provisions to make legally binding (expressed as ‘shall’ as opposed to ‘should’) was a central concern for many countries, in particular the United States, which wanted an agreement the president could accept without seeking congressional approval. Meeting that test precluded binding emissions targets and new binding financial commitments.”

The treaty is scheduled to take effect in 2020 after ratification of the party states.

Secretary of Agriculture Tom Vilsack said, “The historic COP21 deal (referring to official name of the Paris conference, i.e. the 21st Session of the Conference of the Parties to the U.N.F.C.C.C.) supports a better-nourished, stable, secure future for the United States and every nation. Thanks to a coalition of global leaders led by President Obama, our world is now working together to aggressively address climate change with action and results. The benchmarks outlined in the deal build on the ambitious climate smart strategy being implemented by U.S. farmers, ranchers and foresters in partnership with the U.S.D.A. and the Obama administration. Our efforts to boost productivity, reduce greenhouse gas emissions, and share best practices with counterparts around the world will help to address climate change and improve global resilience while continuing to meet global demand for food, fiber and fuel.”

The treaty encountered a cold response from Republican congressional leaders. Representative Lamar Smith, chairman of House Committee on Science, Space, and Technology, said, “The Obama administration’s Paris climate deal will increase the control of the federal government over the lives of Americans, all for little environmental benefit. The cornerstone of the president’s pledge, the so-called Clean Power Plan regulation, would cost billions of dollars and risk thousands of jobs.