Up to half of plant and animal species in the world’s most naturally rich areas—including the Amazon and the Galápagos—could face extinction by the turn of the century due to climate change if carbon emissions continue to rise unchecked.

A new study examines various climate change scenarios—from 4.5°C rise in global mean temperatures if we don’t cut emissions to a 2°C rise if we meet the upper limit for temperature set in the Paris Agreement—and their impact on nearly 80,000 plant and animal species in 35 of the world’s most diverse and naturally wildlife-rich areas. Researchers selected each area for its uniqueness and the variety of plants and animals found there.

The findings point to an urgent need for action on climate change:

We’ll see almost 50% species loss in areas studied if global temperatures rise by 4.5°C

in areas studied if global temperatures rise by 4.5°C We’ll see less than 25% species loss in areas studied if we limit global temperature rise to 2°C

“Hotter days, longer periods of drought, and more intense storms are becoming the new normal, and species around the world are already feeling the effects,” said Nikhil Advani, lead specialist for climate, communities, and wildlife at WWF. “While we work to ratchet down emissions, it’s critical we also improve our understanding of species response to climate change and develop strategies to help them adapt.”

If wildlife can move freely to new locations, then the risk of extinction in these areas decreases from around 25% to 20%—but only in a scenario in which we keep global mean temperature rise to 2°C. And if species cannot move or evolve, they may not be able to survive.