This report investigates whether the evidence supports the reasons given by the Trump Administration to justify its decision to withdraw the United States from the 2015 Paris Agreement on climate change.

The Administration has not published any formal analysis to support its decision, so this report examines the substantive public arguments on the issue made by the President and other members of his team, particularly his speech in the Rose Garden of the White House on 1 June 2017 and associated material

The report first dissects President Trump’s speech, examining the sources he quoted from, and then goes on to discuss some important issues to which it did not refer, including the net benefits of the previous Administration’s proposals for reducing emissions; the use of inappropriate estimates of the ‘social cost of carbon’; the mounting evidence on the likely impacts of climate change on the American people; and the possible consequences of a US withdrawal from the Paris Agreement.

Main findings

  • The United States’ full withdrawal from the Paris Agreement will become effective from 4 November 2020 unless the Trump Administration relents. It is therefore a matter of urgency to assess whether that withdrawal is warranted so that the decision can be reviewed, either by the current Administration or, failing that, by whichever policymakers are responsible after the November presidential election.
  • The Administration has not provided any detailed analysis to support the decision to withdraw. The most substantive attempt at justification was made by President Trump during a speech in the Rose Garden of the White House on 1 June 2017. He relied on a consulting report and a newspaper article that were inaccurate or misleading, and he misrepresented the findings of researchers from the Massachusetts Institute of Technology.
  • Examples of the Trump Administration’s actions and inactions that have set back the United States’ progress on combatting climate change include: changes made to estimates of the ‘social cost of carbon’ (SCC); cancellation of measures to reduce greenhouse gas emissions proposed by the Obama Administration; and a lack of action in response to evidence about the growing risks to American lives and livelihoods from the impacts of climate change.
  • The Trump Administration has redefined the SCC in a way that is inconsistent with the established methods of researchers and ignores the damage that emissions by the United States cause to other countries. It also uses an inappropriate discount rate, which places much less value on impacts that occur at the end of the century and beyond. The overall effect of these changes is to significantly downplay the real costs of climate change.
  • The Administration abandoned the Clean Power Plan that was introduced by the Obama Administration and replaced it with the Affordable Clean Energy rule, which is expected to have a far weaker effect on emissions from the power sector.
  • The Administration has ignored major assessments by experts about the impacts of climate change on the United States, including the Fourth National Climate Assessment, mandated by Congress, which warned of growing economic damage.
  • Based on our assessment, we conclude that the decision by the Trump Administration to start the withdrawal of the United States from the Paris Agreement is irrational and does not promote the best interests of the American people.
  • Even though no other country has followed the example set by the Trump Administration, there is a danger that other countries will be encouraged to lessen their climate actions as well. There should be stronger challenges to the decision, from within and outside the United States, including from the United Kingdom, which is due to co-host the COP26 United Nations climate change summit in November 2021.

An 8-page policy brief by a number of leading academics from the United States and UK is also available: The economic case for the United States to remain in the Paris Agreement on climate change

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