Katie White said the new UK taskforce will track climate and nature threats, assess their national security impact and review existing resilience projects.
The 8-member panel was launched to stop climate change from escalating into a national security emergency, with White saying it is already reshaping the world.
Its remit also includes backing clean-energy investment and supporting an 87% emissions cut between 2038 and 2042.
The government said the effort is meant to limit the risk that climate shocks overseas spill into major domestic pressures in the UK.