UN spokesman Stephane Dujarric announced Solheim's appointment today and Ban's intention to appoint Espinosa as executive secretary of the United Nations Framework Convention on Climate Change after consulting its member nations.
Solheim will succeed Achim Steiner as executive director of the United Nations Environment Program known as UNEP. He currently heads the Organization for Economic Cooperation and Development's committee on development assistance and serves as UNEP's special envoy for environment, conflict and disaster.
Espinosa, a career diplomat, has been Mexico's ambassador to Germany since 2012 and was foreign affairs secretary from 2006 to 2012.
Dujarric said Espinosa has more than 30 years of experience at the highest levels in international relations, specializing in climate change, sustainable development, global governance and human rights. She would replace Christiana Figueres of Costa Rica.
Espinosa would head the secretariat that supports the United Nations Framework Convention on Climate Change - the international treaty agreed upon at the 1992 Earth Summit in Rio de Janeiro that set up negotiations for further treaties to try to control the rise of greenhouse gas emissions that cause global warming.