Hibernation is about more than just  bears curling up in a den all winter.

It can also be this little guy, a fat tailed  dwarf lemur sleeping through the dry season in   Madagascar.

Hibernation is really a response  to hostile environments where food and water   are scarce.

Think bitter, cold winters or  super hot summers.

If hibernation were just   about escaping the cold, you might expect that  climate change warming up the earth would mean   fewer animals would hibernate.

But because  hibernation is actually about a lack of food,   is there a scenario in which a warmer earth might  push animals who didn't hibernate before to start?

What is that?

Before we figure out if climate change is going  to change hibernation, let's get straight what   hibernation is.

Because hibernation isn't a deep  sleep, it's a type of dormancy where animals go   through periods of torpor, also known as decreased  activity interspersed with short awake periods.

It usually includes slowed breathing and heart  rate, a slowed down metabolism and decreased   body temperatures.

There are actually lots  of different types of hibernation.

The two   main types are obligatory and facultative.

Obligatory hibernators hibernate on a fixed   yearly rhythm.

These guys are  the Usain bolts of hibernation.

That's Sarah Moore.

She studies 13 lined ground  squirrels.

And not only are they adorable,   there are also some of those Usain  bolt hibernators she's talking about.

They drop their body temperature,  metabolic rate, and heart rate   way down to go dormant each year, no  matter the environmental conditions.

Facultative hibernators on the other hand,  only hibernate when day get short and nights   get longer.

When temperatures get colder  and when food and water become more scarce.

Remember that that's gonna be important  later.

The crazy thing about hibernation   is that it can be due to super cold temperatures  or super hot temperatures.

Animals might undergo   hibernation in cold climates or estimation in  warm climates.

But no matter when they hibernate,   how do animals actually stay in  one place, basically without moving   for months without going hungry?

I'd be hungry.

First thing first–fat storage.

Lots  of hibernating animals build up   big fat stores when food is plentiful so that  they can use them up.

When they're hibernating,   fat tail lemurs can hibernate for up to  seven months at a time.

So being able to   pull energy from big fat stores in their tails is  important.

This is one of the first ways we might   see climate change mess up hibernation.

Warmer  summers could bring droughts, drying up food   sources that could prevent animals from storing  up enough fat to survive their winter hibernation.

But hibernating can't just rely on a bunch of fat.

They also have to regulate their energy levels.

If   an animal isn't eating much for months on end,  they need to dramatically reduce the amount of   energy that they're spending otherwise they'll  starve.

And that means that they have to slow   down their metabolism.

Metabolism describes  the network of all of the chemical reactions   taking place in your cells.

This includes  breaking molecules from food down to make   energy and building new molecules that your  cells need.

A lot of hibernating animals   slow their metabolisms by adding or removing tiny  phosphate tags to proteins to turn them on or off.

For example, removing these tags from certain  carbohydrate munching enzymes turns them off,   reducing the speed at which the body breaks down  stored carbs into sugars.

Many small mammals can   save 90% of the energy they would otherwise spend  by turning off parts of their metabolic network.

And that decreased metabolism drops the animal's  body temperature too, but when they need to an   animal can quickly ramp up its metabolism by  adding or removing those same phosphate groups   to turn proteins back on.

While turning metabolism  on or off, like this might sound like a hibernator   superpower, the genes needed for dormancy and  hibernation are actually found in many animals,   including humans.

The’re usually  genes that we and other animals use   for everyday stuff like fat breakdown,  circadian rhythms, and normal homeostasis,   but when they're turned on or off in just the  right pattern, they can cause hibernation.

This   means that the potential to hibernate could be  right inside the genomes of lots of animals,   just waiting to be turned on when the  conditions, right.

So if all of this has to do   with temperature and food availability, will  climate change impact how animals hibernate?

Yes.

Especially the facultative of hibernators  whose hibernation patterns change based on the   environment.

And it's already happening.

As  the winters get warmer, scientists have already   seen squirrels and bears emerge from hibernation  sooner.

This means they might wake up when their   food sources just aren't ready yet, or in periods  where they have to fight other species for food.

Warmer weather in some years has prevented  chipmunks from entering hibernation at all.

In one study, tracking a group of nine free  ranging chipmunks during a particularly warm year,   only one chipmunk entered hibernation.

And by the  end of the winter, the scientists were pretty sure   that all of the rest of them were dead.

We can  also get a sneak peek at how environmental changes   are gonna affect hibernators by looking at species  that live spread out across multiple habitats.

Northern Idaho ground squirrels that live at lower  warmer elevations emerge from hibernation sooner   than squirrels who experience deeper snow and  lighter later snow melt at higher elevations.

So   as temperatures rise across the whole region, all  of the squirrels might emerge sooner and sooner.

When it comes to survival of hibernators  and probably all animals when it comes to   climate change, the question is really  how fast is the change gonna happen?

How extreme is the change going to be, and  how consistent is that change going to be?

But could climate change cause animals that don't  currently go dormant to start or to stay dormant   longer?

Maybe.

Over the past 20 years, Columbian  ground squirrels living near the Rocky mountains   have actually emerged from their hibernation  later and later as late spring snowfalls have   become more prevalent due to the changing climate  and adult female survival rate has dropped by 20%.

The scientists think it's because the later  emergence reduces the amount of time the   squirrels have to fat up before their next  hibernation.

Piute ground squirrels have also   started to estimate earlier and earlier  in the summer due to increased drought.

If the summers keep getting hotter, they may  keep hibernating for longer and longer.

And   while dormancy in insects isn't quite the finely  tuned homeostatic machine that it is in mammals,   dormancy patterns in these tiny organisms  might give us some insight into the future.

For example, the great banded grayling, a  butterfly common to much of Europe that has an   amazing name, used to have one main flight  peak between June and September, but in more   recent hotter summers scientists see two active  flight peaks separated by a period of inactivity.

They think that the new inactive period  is actually the butterfly is going dormant   and estimating for three to four  weeks in the dry summer months,   waiting it out until cooler temperatures return.

This is a new phenomenon in the past two decades   that correlates with warmer summers,  warmer weather, new hibernation.

So are warmer temperatures gonna lead to  more animals going dormant in the summer?

Maybe we're not sure yet, but the hotter it  gets, the more I'm sure that I'm gonna wanna   take a page out of the banded grayling's book  and just sleep right on through the summer.