Across the world, animals including bears, moose, lynx, squirrels and frogs are leaving their homes as the planet warms. 

A study was done of more than 4, 000 species from around the world. It showed that about half of them are on the move, according to National Geographic. They are moving up slopes and away from the equator toward the poles to seek cooler environments. The ones on land are moving an average of more than 16 kilometers per decade, while marine species are moving four times faster. 

Mountain species in particular, "are struggling to keep pace" with global warming, said Shaye Wolf, climate science director at the Center for Biological Diversity in the US. In North America, for example, pikas used to climb an average of 13 meters per decade but it has gone up to 145 meters per decade since the late 1990s. Similarly, moths on Mount Kinabalu in Borneo, an island in the Pacific Ocean, moved up 67 meters in altitude to escape rising temperatures. "We're concerned many species won't be able to move quickly enough, or that they will run out of mountaintop to flee, " said Wolf.

In some cases, moving species can lead to big changes in the whole ecosystem, as such areas aren't able to deal with it. In Australia's seas, kelp forests are being destroyed by tropical fish that have come in to eat them, threatening the survival of rock lobster, which also feeds on help forests.

And this is just adding fuel to the fire, making climate change worse. Take the pole ward spread of bark beetles in northern hemisphere forests as an example. The beetles attack trees that might already have been weakened by warmer, drier conditions, leading to more pest outbreaks and tree deaths. These, in turn, provide more fuel for forest fires, releasing more planet-warming carbon dioxide. 

Climate-driven species' movement shouldn't be a concern only for scientists — it should worry everyone, Nathalie Pettorelli, at the Zoological Society of London, UK, told the Guardian. "The world as a whole isn't fully prepared to deal with the range of issues emerging from species moving across local, national, and international boundaries".