Emissions billow from smokestacks at the NTPC Ltd. Badarpur coal-fired power plant as the sun sets in Badarpur, Delhi, India, on Tuesday, April 28, 2015. Barely 16 miles from central Delhi, the 40-year-old coal-fired power plant stands testament to the bargain struck by India's capital city: The world's dirtiest air for electricity. Bloomberg AFP/Getty

On Friday, the U.S. and China will unveil their “common vision” for the major new pact on climate change that negotiators from countries worldwide hope to reach in Paris late this year, a senior U.S. official said.

China, as part of the joint announcement, will also describe plans to launch a national cap-and-trade system for greenhouse-gas pollution in 2017.

Administration officials touted the joint statement as a success story ahead of two days of talks between President Obama and Chinese President Xi Jinping that begin Thursday night. The bilateral talks arrive at a time of tension on other issues, including Chinese currency practices and suspected computer hacking.

“Tomorrow we will release a far-reaching joint presidential statement on climate change. This is a statement that has been worked closely on and negotiated closely by our respective teams over the course of many months,” a senior official told reporters Thursday ahead of the U.S.-China summit.

Officials said a key element of the agreement will be the alignment of U.S. and Chinese stances on major issues that will be under negotiation at the wider United Nations talks in Paris in December.

“We have a long way to go, a lot of work to do to get to a successful agreement in Paris. But this document and this statement reflects what our two countries thought we could put forward to be as constructive as possible in moving that process to a successful resolution,” an official said.

The joint statement will address issues including: development of strategies for transitioning to low-carbon economies by mid-century, which means looking beyond the nearer-term emissions pledges the two nations have already made for the 2025-2030 time frame; “transparency” to ensure nations are implementing the carbon-emissions pledges that are part of the U.N. process; joint principles on adaptation to climate change and assistance to poor nations, and more.

The latest joint initiative comes after China and the U.S.—the world’s No. 1 and 2 greenhouse-gas polluters—reached a major deal on emissions in late 2014.

Last November, China agreed to a peak in its soar­ing car­bon emis­sions in 2030 at the latest, and also vowed to sharply in­crease use of car­bon-free fuels to reach 20 per­cent of its en­ergy con­sump­tion by 2030. The U.S. pledged to cut green­house-gas emis­sions by 26-28 per­cent be­low 2005 levels by 2025, build­ing on the ex­ist­ing tar­get of a 17 per­cent cut by 2020.

On Friday, the nations are slated to announce a suite of measures that build on that pledge, officials said. A big one will be what U.S. officials called a first-time confirmation from China that it will launch a national emissions-trading system in 2017, and the specifics of the initiative.

“China will detail some of the components of that strategy, including the number of sectors that the [emissions-trading system] will cover, including power generation, iron and steel, chemicals, building materials, including cement, papermaking and nonferrous metals. These sectors together produce a substantial percentage of China’s climate pollution, and this reflects a significant policy move that the Chinese are announcing they will take,” a U.S. official said.

Other efforts address the two nations’ plans for regulations to cut emissions from heavy-duty vehicles (think big trucks). The Environmental Protection Agency and the Transportation Department are already working on carbon-pollution and mileage standards, but an official said the joint effort will “encourage greater emissions reductions earlier" and "send a signal to the global industry that our two countries are harmonizing those regulations.”

The wide-ranging statement will also have provisions on appliance-efficiency standards, ways that China will increase the prioritization of greener power sources in its electrical grid, finance for global efforts to combat climate change, and more.

This story has been updated.

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