Why animals are dying in their thousands across the world
Eighty thousand reindeer have starved to death in Siberia during the past decade and experts believe it's all due to climate change.
Around 20,000 died in 2006 and another 61,000 died in 2013 because they couldn't eat through the snow and ice.
That's been caused by sea ice melting in Siberia due to rising temperatures that in turn caused more rain which then froze on the ground.
It meant the reindeer couldn't break through the ice to reach their food.
The Biology Letter journal has shared its findings in a new report and says things are likely to get worse for reindeer.
The news comes weeks after huge numbers of tufted puffins were found dead on St Paul Island in the Bering sea.
Experts linked these deaths with the rise in ocean temperatures which resulted in a lack of food for the birds.
Earlier this year, scientists found sea temperatures in 2015 and 2016 had resulted in the deaths of millions of coral in and around the Great Barrier Reef in Australia.
Dr Stephen Cornelius, the World Wildlife Fund's chief adviser on climate change says this happens because these animals are unable to adapt or move - leaving them with only one alternative.
"Species have three options. When confronted with climate change animals can move, they can adapt or they can die," he tells Newsbeat.
"Moving is one option, so they can try and stay within the envelope of temperature and rainfall that they are used to.
"They can adapt - which could be a plant flowering earlier. It could be a caterpillar hatching a bit earlier to respond to that plant changing.
"There are various things they can do, but if they are unable to move or adapt they may become extinct in that locality."
Stephen says there are a number of things that can force wildlife populations to move, adapt or die - and they can all be caused by humans.
"Climate change has an impact on biodiversity but there are other things that also [affect it] such as habitat destruction due to agriculture, pollution or over-exploitation," he says.
Mass deaths among wildlife populations are just one physical result of these factors.
Humans are the ones causing the problems, and now we are facing major issues of our own.
"There's evidence that in the UK it's becoming rainier in the winter," says Stephen.
"There's evidence that droughts are becoming longer. There's evidence that storms are becoming more intense and there's new science that links climate change to those storms."
But to some people, that science isn't enough proof.
In May, Donald Trump pledged to withdraw from the Paris Agreement, which leading nations signed in April, to reduce greenhouse gas emissions.
He has previously said that global warming was invented by the Chinese to "make US manufacturing non-competitive".
His triumph in the US election has many people who are passionate about climate change worried for America's future involvement in these plans.
But Stephen doesn't think we need to worry about America making any hasty decisions when it comes to the environment and contributing to further mass deaths in wildlife populations.
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