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  • CO2 levels are on the rise but they've been way higher before.

  • Soclimate, we cool?

  • Hello everyone, Julian here for DNews.

  • Antarctic CO2 levels finally caught up with the rest of the world and have an average

  • concentration of 400 parts per million.

  • So for every 1 million particles in the air, 400 of them are Carbon dioxide.

  • It's the highest those levels have been in 4 million years.

  • If you're a person who watches DNews regularly you might recognize this as a bad thing, but

  • if you're a “climate change is baloneytype, you may have heard that sentence differently.

  • If this is the highest Antarctic CO2 has been in 4 million years, then 4 million years ago

  • things were like they are now and we still turned out ok, right?

  • Boom, climate change busted.

  • Actually if you ascribe to that argument, I have even better news for you!

  • At certain points in earth's history, like during the mesozoic in the time of the dinosaurs,

  • CO2 concentrations were as high as ten times what they are now.

  • So why's everybody freaking out about a measly 400 parts per million?

  • We asked University of Northridge geochemist Jenn Cotton exactly that.

  • Cotton explained that there are still a lot of things that separate our current situation

  • from the extreme carbon dioxide levels of the past.

  • For one thing, our concentrations are ramping up a lot faster than they ever did before.

  • For most of earth's history the biggest emitter of CO2 was volcanic activity, both

  • on land and below the ocean, but volcanic CO2 emissions are fairly slow and steady.

  • Even during the Paleocene-Eocene Thermal Maximum, temperatures rose 5 to 8C over millennia,

  • not centuries.

  • Of course, as a geologist Cotton describes this as, “a really really rapid warming

  • event,” but her sense of timing is a bit out of whack.

  • This is why there are no geologist comedians.

  • But over that long period of warming organisms adapted to their changing environment and

  • indeed few species went extinct during this period, which some climate change deniers

  • use to downplay the impact of modern climate change.

  • But in fact, the current rise in temperatures is happening much much faster than it did

  • 55 million years ago, and many organisms likely won't be able to survive.

  • Another issue is the average global temperatures do not increase linearly with CO2, there are

  • diminishing returns.

  • Bumping up concentrations by 100 parts per million when it's already at 3000 is not

  • going to cause nearly as drastic a change as if concentrations were at 300 parts per

  • million, like they were in 1910.

  • We're actually at the lower end of atmospheric carbon concentrations right now compared to

  • most of earth's history, which means that the climate is much more sensitive that it

  • has been historically.

  • But if it was so high in the past, won't it just come down again?

  • Yes, climate change denier it will, but again, on a geological time scale.

  • CO2 is taken out of the air when it mixes with water in atmosphere and forms carbonic

  • acid.

  • It's why rain doesn't have a neutral ph of 7, it's typically closer to 5.5 even

  • in the absence of any other pollutants.

  • The carbonic acid reacts with rocks, breaking them down, turning them into soil, and being

  • converted itself into carbonate.

  • So, yes, atmospheric CO2 has been more abundant in the past, but not for millions of years.

  • That Paleocene-Eocene Thermal Maximum probably took 10,000 years to hit its peak, and didn't

  • drop to previous levels until 150 thousand years later.

  • Some people refuse to believe climate change is real because it used to be called global

  • warming, and changing names means scientists must be lying!

  • Unless climate change is used because it's the more accurate name.

  • Trace explains here.

  • What do you think?

  • Think we can turn this climate change thing around in less than 150 thousand years?

CO2 levels are on the rise but they've been way higher before.


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B1 中級 美國腔

全球变暖正在自我重演 400万年后(Global Warming Is Repeating Itself...4 Million Years Later)

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    joey joey 發佈於 2021 年 04 月 17 日