President Trump’s energy agenda calls for drilling more oil and gas, something that could take years. But he took other actions this week that could more quickly affect the way the country prepares for and adapts to climate changes driven by the burning of fossil fuels.

In 2021, President Biden ordered the Pentagon and Department of Homeland Security to study the security implications of climate change and to incorporate them into defense strategy and other national security plans.

Hours after his inauguration on Monday, President Trump signed a barrage of executive orders to grant his administration new powers to promote fossil fuels and to withdraw support for renewable energy, signaling that the United States government would no longer fight climate change.