Seattle Mayor Jenny Durkan joined dozens of mayors from around the world Tuesday in signing a "Chicago Climate Charter" at a summit designed to address concerns following President Donald Trump's rejection of the Paris climate accord.

“We cannot let the President and his climate change-denying administration block progress on this critical issue,” Durkan said in a statement. “Seattle is a city that leads, and my administration will work to make protecting our planet a central goal. Taking action on climate is important for the future of Seattle and generations to come.”

Chicago Mayor Rahm Emanuel says climate change can be solved by human action.

The charter calls for mayors to achieve a percent reduction in greenhouse gas emissions that's equal or more than outlined in the Paris agreement. It also calls for them to work with scientific and academic experts to find solutions.

Some mayors have specifically agreed to commitments to expand public transportation and invest in natural climate solutions such as tree canopy and vegetation.