Achim Steiner is the Executive Director of the United Nations Environmental Programme (UNEP) and the Under-Secretary-General of the UN.

Prior to joining UNEP, Steiner was the Executive Director of the International Union for Conservation of Nature. He has spent his professional career working to address environmental sustainability, social equality, and economic development through international policy-making.

An active speaker on climate change, Steiner remarked in a 2012 interview, "I think we have not even begun to understand how serious are the underlying trends that we have brought to bear on the sustainability of the planet."

One of UNEP's primary missions is to develop sustainable solutions to climate change.