Brendan Smialowski, Associated Press
This Aug. 4, 2015, file photo shows U.S. Secretary of State John Kerry waving after delivering a speech at Singapore Management University in Singapore. Kerry says history will not look kindly on climate change skeptics who fail to take action to curb warming. Speaking Sunday, Aug. 30, 2015, in Anchorage, Alaska, Kerry says scientists are overwhelmingly unified in the conclusion that humans are contributing to global climate change and that steps must be taken to reduce the carbon in the atmosphere.

ANCHORAGE, Alaska — Secretary of State John Kerry kicked off a conference on the challenges of climate change by comparing it to the crisis faced by world leaders last century.

"Seventy-five years ago, our predecessors faced a world that was literally engulfed by strife, where seemingly all of Europe was overrun by evil, and civilization itself seemed in peril," Kerry said Monday at the State Department's Conference on Global Leadership in the Arctic.

The serious risks and overwhelming uncertainty brought on by climate warming may seem like "a pretty high mountain to climb," he said, but it can be tackled. Leaders rose to the occasion of World War II, he said. The urgent need for global cooperation now is the same as in the 1930s and '40s, Kerry said.

"The threat caused by climate change is obviously entirely different in character, but it is not different in its global reach or its potential to do harm," Kerry said.

Kerry and President Barack Obama, the final speaker at the conference, hope the Alaska gathering will lay groundwork for an international pact on carbon emissions in December at a United Nations conference in Paris.

Obama's science adviser, John Holden, spelled out research findings on warming's harmful effects, starting with global annual average surface temperature increasing by 1.6 degrees Fahrenheit from the end of 19th century to the last decade. Accompanying that is a higher percentage of precipitation as rain instead of snow, higher losses to evaporation and flood runoff and earlier snowmelt, leaving many regions drier.

Sea ice in Arctic waters, Holden said, covers 40 percent less ocean than when satellite monitoring began in 1970. Thawing of permafrost has led to land subsidence and the release of methane from previously frozen soil. Wildfires have become more frequent and are burning more area.

Changes in Northern Hemisphere atmospheric circulation patterns have led to "waviness" of the jet stream, bringing the cold "polar vortex" phenomenon to mid-latitudes, Holden said.

Opportunities to address climate change are "staring us in the face," Kerry said, and could create millions of jobs, improve the economy, improve health while avoiding the long-term costs of doing nothing.

The energy market, he said, is an opportunity to be grabbed and could dwarf the wealth creation the United States experienced during the technology and personal computer surge in the 1990s.

"Energy policy is the solution to climate change," he said.