Why are gas prices rising? Drivers could soon be paying more at pump amid US extreme cold, experts say

Experts say drivers could soon be paying more at the gas pump, as the nation's largest oil refineries shut down to conserve power.

Natural gas prices rose more than 7% during this wave of extremely cold weather across large parts of the country.

Winter weather is overwhelming power grids unprepared for climate change, leaving millions without electricity in record-breaking cold.

RELATED: 3 million without power, 20 dead as 100 million Americans brace for more cold, ice and snow

At least 20 people have died, some while struggling to find warmth inside their homes. In the Houston area, one family succumbed to carbon monoxide from car exhaust in their garage; another perished after flames spread from their fireplace.

Blame the polar vortex, a weather pattern that usually keeps to the arctic, but is increasingly visiting lower latitudes and staying beyond its welcome. Scientists say climate change caused by humans is partly responsible for making its southward escapes longer and more frequent.

The Associated Press and ABC News contributed to this report.