[MUSIC] This episode is sponsored by Dropbox. Your body is about ⅔ water. Earth’s surface
is about ⅔ oceans. This is not a coincidence. All of our lives began in water.
Every plant and animal living on dry land today can trace its family tree back to the
sea. Each of us, in every salty cell of our bodies,
are a bit of the ocean that grew legs, walked up on shore and learned to build sports cars,
skyscrapers, and spaceships. But in taking over the land, we’ve put a
lot of extra carbon in the air, and that’s having serious effects on our climate.
Much of that change isn’t happening in the atmosphere. It’s in the oceans, and for
one colorful group of creatures that could spell disaster. Coral reefs. Can they survive climate change? [MUSIC] Animal. Vegetable. And mineral. Coral reefs
are a little hard to classify, because, they’re kind of all three.
The animal bits come in the form of tiny invertebrates called polyps, that use tentacled arms to
feed on plankton and other small sea creatures. But living inside each polyp are single-celled,
plant-like algae. These can make up as much as a third of the polyp’s body, and they’re
what give coral reefs their colors. These organisms have a sort of cooperative
living arrangement called symbiosis. During photosynthesis, the algae consumes
the polyp’s waste CO2 and in return burps out oxygen and nutrients to feed its host.
The coral says thanks by giving the algae a nice, safe place to live: inside its own
body. Together, massive colonies of these symbionts
secrete calcium carbonate exoskeletons, building up the multicolored megastructures that we
call coral reefs. Marine biologist Sylvia Earle called coral
reefs the “jeweled belt around the middle of the planet.”
Because they rely on photosynthesis, we mostly find ‘em anchored between the tropics, where
Earth receives the most sunlight. Unfortunately, thanks to the extra carbon
dioxide and other greenhouse gases we’ve pumped into the atmosphere, more and more
of that sunlight’s heat is being trapped in Earth’s atmosphere. But most of it hasn’t
stayed there. Since 1955, 90% of the atmosphere’s excess
heat has been absorbed by the oceans. And in addition to all that energy, it’s
estimated that oceans have soaked up half of all CO2 emissions since the industrial
revolution. And that’s not like a bubbly soda, instead
much of that CO2 gets chemically converted into acid. If climate change is stressing you out, you’re
not alone. These warm waters, acidic conditions and increased
pollution are straining the delicate symbiotic relationships between algae and their coral
hosts, and many coral are kicking their colorful roommates to the curb.
Now, ejecting the algae leaves reefs looking rather blah and colorless, so the phenomenon
is called coral bleaching. Bleaching leaves polyps without nutrients and susceptible to
disease, and if it lasts long enough, the coral will die. Losing coral reefs would mean losing the most
diverse ecosystems that our planet has to offer.
Even though they cover just a tenth of a percent of the ocean floor, reefs provide a home to
a quarter of all ocean species. In some tropical reefs, a thousand different species can live
in a single square meter. In many places, this change already happening.
Half of all tropical reefs have disappeared in the past 30 years, and if the ocean continues
to get warmer like it is today, coral may die off completely by 2050.
It’s reefer badness out there. “Carl, Carl, Carl, Coral? Carl, Coral…” Right now, we’re changing the planet faster
than coral can adapt, but there is hope. Some scientists from Australia and Hawaii
have figured out how to breed coral in the lab, and similar to how farmers cross plants
to select for bigger fruit or drought resistance, they think that they can accelerate the evolution
of polyps and their algae accomplices to create stress-resistant super coral. We’ve changed a lot since our ancestors
left the shore, but from the air we breathe to the water within us, each of our lives
is still connected to the ocean. Helping coral will help us all. That way, next time we take a visit to where
we came from, looking for sea life, there will still be life to see. “Coral!” If you want to learn more about climate science,
we’ve got a bunch of other great videos here on It’s Okay To Be Smart, and coral is not
the only thing being put at risk by our changing climate. Check out the rest of the #OursToLose
campaign and you’ll find out a bunch of different ways that climate change is already impacting
all of our lives. Stay curious.