Power outages over the last six years have more than doubled in number compared to the previous six years, according to a Reuters examination of federal data. In the past two years, power systems have collapsed in Gulf Coast hurricanes, West Coast wildfires, Midwest heat waves and a Texas deep freeze, causing long and sometimes deadly outages.

Compounding the problem, the seven regional grid operators in the United States are underestimating the growing threat of severe weather caused by climate change, Reuters found in a review of more than 10,000 pages of regulatory documents and operators’ public disclosures. Their risk models, used to guide transmission-network investments, consider historical weather patterns extending as far back as the 1970s. None account for scientific research documenting today’s more extreme weather and how it can disrupt grid generation, transmission and fuel supplies simultaneously.