US President Barack Obama on Friday signed an executive order requiring government departments to take steps to prepare for "extreme weather" and other impacts of climate change.

The order set up a task force for recommendations on how American states and cities can best prepare for the environmental impacts of global warming.

"The impacts of climate change .... are already affecting communities, natural resources, ecosystems, economies and public health across the nation," Obama said in the order.

"These impacts are often most significant for communities that already face economic or health-related challenges, and for species and habitats that are already facing other pressures."

Obama named symptoms of climate change as an increase in long periods of excessively high temperatures, more heavy downpours, more wildfires and severe droughts, permafrost thawing, ocean acidification, and rising sea levels.

The task force includes seven Democratic state governors and the Republican governor of Guam, a US territory that is vulnerable to rising sea levels in the Pacific Ocean.

Also on the panel are the mayors of a group of major American cities.

The order may be unpopular with some politicians in the Republican Party where skepticism of global warming runs high, and where there is opposition to other executive actions Obama has taken as part of his climate change agenda.

Obama tasked the panel with finding ways to modernize federal programs to support climate resistance investments and to prepare and manage land and waterways to resist climate change.

He also called on the panel to provide data and tools to measure preparedness for climate change and to sum up plans for various scenarios.