How warmer winters affect our planet

Earth’s polar regions are sensitive enough that a difference of one or two degrees in temperature can thaw a world of ice. Polar scientist, Marco Tedesco of Columbia University’s Earth Institute has been studying these warmer winters that affect our poles and our planet. This segment is part of our ongoing series of reports Peril and Promise on the challenge of climate change.

TRANSCRIPT

Earth's polar regions are sensitive enough that a difference of 1 or 2 degrees in temperature can thaw a world of ice.

Polar scientist Marco Tedesco of Columbia University's Earth Institute has been studying these warmer winters that affect our poles and our planet.

This segment is part of our ongoing series of reports, 'Peril and Promise: The Challenge of Climate Change.'

Thanks for joining me.

Thank you.

So, you guys put out a report card.

What's in an Arctic Report Card?

Well, the Arctic Report Card is something sponsored by NOAA, which groups many scientists -- this year, 61 scientists -- to put out what is the state of the arctic in a very fast and quick way, right after when the data comes out fresh from the sensors, so that we can have a better picture of what the state of the arctic is, what's happening, and if things are changing.

So, what are the grades of the arctic, and what's been happening over time?

Well, the arctic has been warming, first of all, at a very fast pace.

Mostly twice the rate of the rest of the planet.

For 2016, for example, the arctic, just the land over the arctic, was up to about 3.5 degrees Celsius -- about 6.3 degrees Fahrenheit -- warmer than the average.

And the overall arctic was about 2 degrees Celsius -- about 4, 4.5 Fahrenheit -- warmer than the rest of the world.

So, is it happening at the pole more so than in the rest of the planet?

Well, when the rest of the planet warms up, there is something we call arctic amplification.

The arctic amplification is really the mechanism through which the arctic warms much faster than the rest of the world.

One example, there are all these feedback mechanisms -- so, mechanism that amplifies the effect of a warming world.

For example, this appearance of sea ice.

You replace a very bright surface that reflects all of sun radiation and keeps the planet cool with the dark ocean that absorbs a lot of solar radiation, it keeps warming more and more the arctic.

This, for example, and other aspects are all mechanisms.

They're amplifying the warming of the arctic, and this is what happens.

So, is it a bit of -- I hate to mix snow and ice here, but -- a snowball effect, where the more ocean you get, the more heat it absorbs, the faster it melts, the more ocean you get --

Correct. Correct.

The snowball effect.

Sometimes I'll describe it like a train running downhill, for example, right.

So if you put the temperature as your coal in the furnace, your train goes faster and faster if you put more coal.

But if your train is running downhill, like the amplifying mechanism on your speed, then even if you don't start putting more coal, the train will keep accelerating farther and farther.

And so that's what happens.

You put more coal, we're going downhill, and everything happens much faster.

So, let's talk a little bit about, what are the actual impacts on the surface?

So, places like Greenland.

They're not as green as they once were.

Or maybe you're seeing more green now than you used to see.

Well, we don't see a lot of green, but we see less ice.

And also we see more bare ice exposed.

You know, snow is one thing.

Pure snow, bright snow, it really reflects a lot of solar radiation.

The ice which is below the snowpack, is really what really puts water into the ocean, that contributes to sea-level rise, because this ice has been locked for a very long time on the ice sheet and is not part of the water cycle.

And so when we expose this bare ice, it's very dark, it contains dark material, and so it absorbs the sunlight much stronger, and it melts much faster.

And so we are starting to remove this ice that was locked for tens of thousands of years and putting it into the ocean, which is directly contributing to the sea-level rise.

And that sea-level rise can be felt globally.

It can be felt globally, yes.

So, everything you put into the ocean will be redistributed, but overall the impact that this might have is both local in terms of salinity, ecosystems, fishery, but also global in terms, of course, of sea-level rise in coastal regions.

So, if you put a cube of ice in a glass of water, it doesn't necessarily change, but it does start to expand, and over time, when that melts, you get a lift.

Right.

So, the reality is that the ice is not sitting in the water.

It's sitting on land.

So everything that we remove from land to the ocean, that actually is increasing our glass of water.

So that's the equivalent of adding more and more ice cubes in, right?

It's the equivalent of adding more and more ice cubes.

There are shelves, of course, ice is sitting into the water.

That does not add up.

But when those are removed, that is really the unplugging the cork of your champagne bottle, and then all the ice behind can start flowing much faster, and this increases sea-level rise.

So, as these changes are able to be measured...

Mm-hmm.

There are different scientists that say we're at a tipping point, we're nearing a tipping point, we're past a tipping point.

Can this be slowed?

Well, it can be slowed, but we don't know how fast it can be slowed.

And there are mechanisms that can counter-effect the acceleration that we're seeing.

Namely, putting more snow -- or cooling down the planet.

This is really the recipe.

There's no big other issue or big other thought to make.

And you can do this by reducing, of course, the CO2 emission.

So, the thing that is very important to think of is, the time it takes to destroy or to remove the ice from the ice sheet is much faster than the time it will take to build an ice sheet.

You can really see this like building slowly something that takes a long time to consolidate and take shape, and then suddenly you take away the base of the structure, everything collapses.

To build it back still takes the same time, which is a long time, and it's much longer than destroying it.

So, how do you measure the warming that's actually happening?

Well, the warming is measured through a series of things.

Satellites are observing the surface, the ocean and land surfaces, through a network of sensors on land, through models that try to replicate what happened in the past and is happening in the present to project what will happen in the future.

For example, satellites, they've been used to measure the mass of Greenland -- how much mass Greenland is losing.

They've been measuring, too -- they used to measure also how much snow is falling here, and how much melt is occurring.

We have all this beautiful set of sensors, which we didn't have until 10, 12 years ago, together with the advances of supercomputing and the possibility of exploring this data, and a new generation of scientists who's really focusing their effort on understanding better these processes through these great data sets.

And so we can have a better picture now than we had even just 10, 12 years ago.

And this is somehow much better for us, but it's also more frustrating, because the more we know, the more we think there's an action that needs to be taken.

Is there any question that humans are contributing to this?

Well, not on my point of view, and not to the opinion of the IPCC.

I think being skeptical is a good thing.

I do agree with people who say that being scientists means also being skeptical.

This doesn't also mean that you need to start attacking a lot of things that are easy to defend when you don't have the time to do it, or when you can do it in a fair way.

So, to me, there's really a little point to discuss about this.

Well, one of the things that even the head of the EPA says is it's really hard to measure the amount that humans contribute to all of this.

But given all of the work you're doing, all of your peers are doing... you're fairly certain that this is warming that is caused by humans, and you can see the impact on the arctic?

Right.

I do agree, it's very hard.

But I do think, also, that the scientific community is doing an excellent job.

Being hard doesn't mean it's wrong.

I do think that there's more need to better understand and refine the projections in which way.

We want to know, for example, whether there will be a problem for Battery Park in 20 or 40 years, if there is a storm surge coming with an increase in sea-level rise, instead of being out one week, we'll be out maybe a month, or a blackout in the subway like happened with Sandy.

So in this regard, yes, we need to refine better, but we need to do it because we need to provide our expertise and service to the public by refining our projections, and work with policy makers to basically give back what we take from the public, which is the federal taxes used for the good of the public.

All right.

Marco Tedesco, professor at Lamont-Doherty Earth Observatory at Columbia University.

Thanks for joining us.

Thank you very much.