Video 3.8: Why the Arctic is Crucial to Earth's Climate - Dr. Bart Van Dongen and Dr. Robert Sparks

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Do curso por University of Manchester

Nossa Terra: Clima, História e Processos

91 classificações

University of Manchester

Nossa Terra: Clima, História e Processos

91 classificações

Develop a greater appreciation for how the air, water, land, and life formed and have interacted over the last 4.5 billion years.

Na lição

Water in Earth’s Climate System: Oceans, Atmosphere, and Cryosphere

Video 3.1.1: Where Did the Oceans Come From?6:55

Video 3.1.2: Are the Oceans in Steady State?13:36

Video 3.2.1: How the oceans work - Dr. Gregory Lane-Serff9:36

Video 3.2.2: The oceanic conveyor belt - Dr. Gregory Lane-Serff12:57

Video 3.3.1: What is the Atmosphere Made Of?6:41

Video 3.3.2: What Controls the Temperature Profile of the Atmosphere?5:49

Video 3.3.3: Three Radiation Laws4:48

Video 3.3.4: What if the Earth had no Atmosphere?7:37

Video 3.4.1: How does the Atmosphere Work?9:04

Video 3.4.2: How do the Jet Streams Control the Weather?7:05

Video 3.5: Extratropical cyclones8:11

Video 3.6: The Rise and Fall of Ice on Earth12:44

Video 3.7: How do Glaciers Control the Height of Mountains? – Dr. Simon Brocklehurst10:46

Video 3.8: Why the Arctic is Crucial to Earth's Climate - Dr. Bart Van Dongen and Dr. Robert Sparks 7:48

Conheça os instrutores

Prof. David M. Schultz
Professor of Synoptic Meteorology
School of Earth, Atmospheric and Environmental Sciences
Dr Rochelle Taylor
Postdoctoral Research Associate
School of Earth, Atmospheric & Environmental Sciences
Dr Jonathan Fairman
Postdoctoral Research Associate
School of Earth, Atmospheric and Environmental Sciences

Hi.

We're here at the University of Manchester.

I'm joined by Dr. Bart Van Dongen, who is a senior lecturer at the university, and

Dr. Robert Sparkes, who's a research associate.

Bart and Robert are both researchers working on how

the changing global climate has led to changes in the Arctic.

So guys, climate warming is occurring globally but

why the special focus on the Arctic?

>> The Arctic is one of the areas in the world that is heating up the fastest.

If you compare it, for instance,

to the equator region it is warming up like two or three times faster.

That is mainly caused by what we called the albedo effect.

That means that radiation comes in in the Arctic.

There's normally a wide surface, snow, ice, which is covering it,

and that is reflecting the radiation back into the atmosphere, and back into space.

When you get small patches of ice retreating, you get a surface which is

much darker, water or just ground, and that's absorbing the heat,

absorbing irradiation and heating up and because of that, you get this effect,

which is accelerating and that causes extend warming in the Arctic.

>> And that's called Arctic amplification, am I right?

>> Yep. >> Okay.

>> Absolutely. >> Very good.

So Robert, what are the consequences then, for this warming in the Arctic?

What will happen because of it?

>> Well, the Arctic, especially in Siberia and

Canada, the ground has a lot of carbon stored in the soils.

This is call permafrost, it's completely frozen solid.

It has been for thousands of years but

as the temperatures rise, that soil warms up, the permafrost starts to thaw out and

all that carbon has the potential to be released into the atmosphere.

Some of that can be direct release, so the soils can just break down and

the gas can escape but also, once the ice is gone and the permafrost is gone,

then the rivers can erode that soil, transport the material out into the ocean.

When it's in the ocean, again, there's a chance for the carbon to break down,

become greenhouse gases and get released into the atmosphere.

>> So Bart, what's happening to all this carbon that's sitting off the shelf

of the Arctic?

>> As Robert already explained, you have an increased release of carbon and

when this carbon enters the water body,

so it enters the shelf, two things can potentially happen.

One, it could be just being transported and dumped on the ocean floor.

In that case, you would have just a movement from one

section to another section and the effects on global warming would be minimal.

Unfortunately, that's not what's happening.

Most of the material is being degraded on transport.

So either already in the river or on the shelf in the water column and

bacteria get their hands on it and then degrade it and

ultimately, is releasing greenhouse gases, predominantly CO2.

>> Mm.

>> So that means that the material is not behaving, as we would call it,

conservatively but it actually being broken down and

that means that there is an increase in greenhouse gas releases and

that's what we call a positive feedback on climate warming.

So this means that what happens in the Arctic

is not solely restricted to the Arctic region but could have global effects.

>> Are there other sources of carbon that we should be worried about?

So, as well as the river erosion, then Siberia has thousands of kilometers of

coastline, and these coasts are mostly just soils and dusty

rocks that have been frozen together and have survived for a few thousand years.

But as the sea ice retreats, as the temperatures warn, the storms can come in,

can hit these cliffs, and erode the coastline very quickly.

It's one of the fastest places for coast erosion in the world and

these cliffs are full of carbon, just like the soil is and

as they erode, that material can also be transported onto the shelf.

So part of our work has been trying to calculate the balance between material

delivery from the rivers and the material delivered from the coastal erosion and it

seems like coastal erosion, in this part of the world, is a really important way

that carbon is being released out into the ocean, and then out into the atmosphere.

>> Okay, and then what about methane?

I mean I've heard a lot about methane release in the Arctic.

What do you know about that?

>> There are different sources of methane release.

There is already the direct release from land,

from when these permafrosts are warming up.

So we already see that when we go from winter to summer, we have ice and

we see that pockets of methane have been trapped below the ice and

when the ice is melting away, you see that methane being released.

But there's also a second source, which is probably far less known and

that is the submarine permafrost areas

on the East Siberian Arctic shelf that used to be land.

After the last ice age, when the water levels were rising,

that was covered by water, that's now below water and

in those submarine permafrost, there was also a lot of methane being captured and

because of submarine processes, that's also started to be released.

Slow heating up of that area also caused that

methane potentially becomes available, and is released into the water body.

When we were sailing there in 2008, we already measured the amounts of methane in

the water column there, to be about 1,000 times higher than what is normal.

>> Okay. >> Indicating that there is,

indeed, a release.

>> Hm. >> However,

the interesting point is that there is no connection yet

established between what is in the water column and what actually is in the air.

So there's still a lot of questions,

a lot of things unknown about what's happening to that methane.

>> I see, so that looks like a pretty serious problem.

Once the methane is in the water, does it enter the atmosphere?

So, if it were to enter the atmosphere,

what would we expect to happen to the earth's climate as a result?

>> Well, most of the carbon released we've been studying here in the Arctic,

we've formed part of a positive feedback loop.

So because there is increased CO2 in the atmosphere at the moment and

increased methane levels, then we're getting the warming in Siberia.

The warming is causing the permafrost to thaw, causing the release of methane from

the shelves and that will then go back into the atmosphere as increased CO2 and

increased methane, and so will lead to even further warming.

So you get this loop where more warming leads, to more greenhouse gas release,

leads to more warming, leads to more greenhouse gas release.

So the system can feed itself and can probably amplify how much

climate warming we might expect to see from this kind of region.

>> Wow, so it sounds like we've got a lot more to learn about this.

I mean, there's a lot of exciting research but also potentially,

large changes that could occur to the Arctic as a result of this.

>> Yes, absolutely, and just as an example, we have seen major

methane spikes in the past in our fossil records and that for

instance, has led to amplified global warming to a massive scale.

We're not saying that that's going to happen but

that's the potential that could have happened.

So, if we would study previous events,

we might get some ideas of what could happen to this sort of event.

>> Yeah. >> This sort of scenarios.

>> So further observations of this area are crucial to understanding what may or

may not happen to these buried carbon stores.

>> Absolutely.

>> Great.

Thanks, Bart.

Thanks, Robert.

Thanks for watching.

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