Obama committed the United States to reduce carbon emissions by at least 26 percent by 2025.
Sue Biniaz, a former State Department legal adviser who supports the accord, admitted Trump does not need to make a binary choice between leaving or staying.
U.S. President Donald Trump attends the U.S. Holocaust Memorial Museum's "Days of Remembrance" ceremony in the Capitol Rotunda in Washington, U.S, April 25, 2017. His chief strategist, Steve Bannon, has pressed Trump to uphold his campaign promises to withdraw from the plan and thereby signal a commitment to American energy producers, including coal miners. At the same time, he has also been dismantling the regulatory mechanism put in place by his predecessor Barack Obama to enable the United States to fulfil its commitments under the accord.
In March, Spicer had said that the decision would come before the G-7 summit. Another co-signer of the letter, the Heartland Institute, was recently exposed for sending materials to school teachers that questioned the veracity of climate change science.
China has called on the U.S. to honour its commitments to tackle climate change.
However, the group found, 21 percent of that achievement - or roughly one-fifth of the emissions cuts - depend on the United States.
The American participation during the Bonn talks may indicate whether the U.S. will actually withdraw from the Paris Agreement before the July G20 summit as speculated, if not before the meeting of the G7 heads of state that is scheduled for later this month in Italy.
She was confident, though, that these challenges would not be "unsurmountable", noting that businesses, cities and individual USA states were firmly on track to a green energy future.
"Federal ethics rules distinguish between specific party matters such as an individual permit or lawsuit and matters that apply generally such as a nationally applicable regulation", said Kevi Minoli, the EPA lawyer who advises Pruitt on ethics issues. Yates said it was clear from news reports that Flynn had explained his transition contacts with the Russian ambassador to Vice President Pence in a way that was not backed up by evidence gathered by U.S. Intelligence, and that the Russians obviously knew that as well.
"The United States is contributing 21 percent of the pledged global reductions in greenhouse gas emissions", said Ellie Johnston, the climate and energy lead at Climate Interactive.
"Global investors are eager to open their wallets to a low-carbon future", said Mindy Lubber, president of CERES, a non-profit organisation that works with North American companies on sustainability projects.
"Obviously we want the USA to stay in the Paris Agreement, for its own good as well as for the rest of the world".