German President Frank-Walter Steinmeier and COP23 President Prime Minister Frank Bainimarama of Fiji greet teenager Timothy Naulusala from Fiji after his speech as U.N. Secretary-General Antonio Guterres looks on during COP23 U.N. Climate Change Conference in Bonn, Germany, November 15, 2017. Governments should put a price on carbon emissions to help combat global warming and stop making bad bets on fossil fuels, U.N. Secretary-General Antonio Guterres said on Wednesday at talks on a climate pact weakened by a U.S. pullout. REUTERS/Wolfgang Rattay

Patricia Espinosa, Executive Secretary of the United Nations Framework Convention on Climate Change, and U.N. Secretary-General Antonio Guterres arrive for the opening of the High-Level Segment of COP23 U.N. Climate Change Conference in Bonn, Germany, November 15, 2017. Guterres told almost 200 nations in Bonn, where they are working on details of the 2015 Paris climate agreement that aims to end the fossil fuel era this century, that a shift to cleaner energies would boost rather than hamper economic growth. REUTERS/Wolfgang Rattay

German Chancellor Angela Merkel, left, welcomes UN Secretary General Antonio Guterres during the 23rd Conference of the Parties (COP) climate talks in Bonn, Germany, Wednesday, Nov. 15, 2017. World leaders arrive at the global climate talks in Germany on Wednesday to give the negotiations a boost going into the final stretch. AP Photo/Martin Meissner

Patricia Espinosa, Executive Secretary of the United Nations Framework Convention on Climate Change, French President Emmanuel Macron, COP23 President Prime Minister Frank Bainimarama of Fiji, German Chancellor Angela Merkel and U.N. Secretary-General Antonio Guterres pose for a photo during the COP23 U.N. Climate Change Conference in Bonn, Germany, November 15, 2017. REUTERS/Wolfgang Rattay

French President Emmanuel Macron, COP23 President Prime Minister Frank Bainimarama of Fiji and U.N. Secretary-General Antonio Guterres attend COP23 U.N. Climate Change Conference in Bonn, Germany, November 15, 2017. The Nov. 6-17 meeting is trying to bolster climate action after U.S. President Donald Trump, who doubts that man-made emissions are the main cause of rising temperatures, decided to withdraw and instead promote domestic fossil fuels. REUTERS/Wolfgang Rattay

German President Frank-Walter Steinmeier, COP23 President Prime Minister Frank Bainimarama of Fiji, U.N. Secretary-General Antonio Guterres, Patricia Espinosa, Executive Secretary of the United Nations Framework Convention on Climate Change, pose for a family photo during COP23 U.N. Climate Change Conference in Bonn, Germany, November 15, 2017. Guterres urged governments to put a price on carbon to deter emissions and encouraged carbon trading as a way to restrict emissions. Last year, he said carbon pricing initiatives generated $22 billion. REUTERS/Wolfgang Rattay