National Geographic News

Christine Dell'Amore

National Geographic

Published June 9, 2014

The shrinking of the Arctic ice sheet in the upcoming 10th edition of the National Geographic Atlas of the World is one of the most striking changes in the publication's history, geographers say.

The reduction in multiyear ice—commonly defined as ice that has survived for two summers—is so noticeable compared with previous editions that National Geographic Geographer Juan José Valdés calls it "the biggest visible change other than the breakup of the U.S.S.R."

As the ocean heats up due to global warming, Arctic sea ice has been locked in a downward spiral. Since the late 1970s, the ice has retreated by 12 percent per decade, worsening after 2007, according to NASA. May 2014 represented the third lowest extent of sea ice during that month in the satellite record, according to the National Snow and Ice Data Center (NSIDC).

Ice loss is accelerated in the Arctic because of a phenomenon known as the feedback loop: Thin ice is less reflective than thick ice, allowing more sunlight to be absorbed by the ocean, which in turn weakens the ice and warms the ocean even more, NASA says.

Because thinner ice is flatter, it allows melt ponds to accumulate on the surface, reducing the reflectiveness of the ice and absorbing more heat. (See pictures of our melting world in National Geographic magazine.)

"You hear reports all the time in the media about this," Valdés said. "Until you have a hard-copy map in your hand, the message doesn't really hit home."

Arctic Mapping

The multiyear ice—or older ice—is shown on the map as a large white mass; the maximum extent of sea ice—the pack ice that melts and refreezes with the seasons—is depicted as a line on the map, according to Rosemary Wardley, National Geographic's senior GIS cartographer. In the 10th edition, which will be released September 30, the multiyear ice is much smaller in area than on previous maps. The 5th edition of the atlas, published in 1989, was the first to comprehensively map the Arctic.

Wardley and Valdés relied on two government resources that track Arctic ice data: NASA and the NSIDC. To map the multiyear ice, they took data from a 30-year study by NASA, published in 2012. "We wanted to have that comprehensive coverage," Wardley said.

But Walt Meier, a research scientist at NASA Goddard Space Flight Center's Cryospheric Sciences Lab, said he's concerned that the map leaves out some important details that might mislead the public.

He noted that the 10th edition should show the total area of the existing ice at the end of the summer, which would include the remaining ice that was newly formed over the previous winter.

Scientists call that the total minimum sea ice cover, and it's measured in September. (Total maximum sea ice cover is measured in March, at the end of winter.)

Without the minimum sea ice mapped, "ice that's one year old or less is not being shown," he said.

"Personally, my thought is that it would be best to show the entire end-of-summer ice cover in white—which is how it generally would appear in a photo from above [without clouds]—with the multiyear area outlines or maybe offset in a different shade to highlight it. At the least, I think it would be good to put a clear line [to] denote the minimum extent," he said.

"Ultimately," noted Meier, "it is an editorial decision as to what to show and how."

Confirms Wardley: "We do not show the minimum extent simply because there is only so much information we can put on the map before it becomes confusing to the user."

Variable Ice

Meier is also concerned about relying on a single year-the new Arctic map draws from 2012 data, an extremely low year for ice cover. (Related: "Arctic Sea Ice Hits Record Low—Extreme Weather to Come?")

"If 2012 is shown, it is the record low year and probably overemphasizes the long-term trends. But if 2013, a higher year relative to recent years, is shown, it underemphasizes the trend. A potential solution would be to do an average over a few years."

Valdés responded: "At the time of production of this map we were only able to find multiple sources from 2012, including the main source we used ... showing multiyear sea ice trends over a 30-year period." The 2012 source also fit better with the style of the map, he added.

Publication schedules have an impact as well.

"We are aware that the multiyear ice is constantly shifting and can change as often as every few months," he said. "That is certainly a challenge we have with these static maps, along with the fact that the production date is oftentimes many months earlier than the publication date of the map."

Representing a dynamic environment in fixed form is always a challenge, said Valdés. Even so, atlases "open people's eyes to what's happening the world." (Explore National Geographic's atlas puzzles.)

Follow Christine Dell'Amore on Twitter and Google+.

31 comments
Lineu Teixeira
Lineu Teixeira

O que os cientistas já vêem alertando à décadas e agora está a acontecer. No entanto será que estão a ser tomadas medidas? Está a ser feito alguma coisa que possa reverter o processo, isto é se ainda for reversível! Que estão a fazer os governos do mundo em concreto? As populações estão devidamente alertadas e preparadas para os cenários? Estas são algumas de muitas questões que deviam ser respondidas por aqueles que têm permitido o que vem acontecendo.

Dwayne LaGrou
Dwayne LaGrou

I would like to know why the maps cannot show what the conditions are like in near real time?! It seems like it would be an easy option to show what the caps have looked like at different intervals by using the NOAA satellite information. There could be lines drawn to show what it was like in summer and winter 100 years ago and again what it is like now.

If the people had a way to SEE how we are changing the weather conditions it would have a more direct effect on how they see the planet as a whole. The little guy is much less likely to change his own personal habits if he has no way of seeing the actual affects in the place where he lives. I know that by being able to see the effects of climate change on the Great Lakes personally, It has made me more aware of how my own actions are changing the map where I live.

Just a simple guys thoughts!

Paul OS
Paul OS

As part of the map. Will NG explian how much of the melt from global warming is due to anthropogenic CO2 and much is due to natural variability

M B
M B

Just another conspiracy from the scientists... the likes of evolution, electricity, space, the atom, gravity, what's next?  They always make stuff up to serve their political interests....


Damn you Newton!

John Smith
John Smith

So, the map has been changed from reality to fantasy by switching from the actual ice minimum to the multiyear ice extent, and by taking the measurements of the year with the modern minimum.. Looking down from space at the end of the melt season, would I see only multiyear ice? No, there would be much more ice cover than the new map shows. It's a distortion and a lie, plain and simple.


If the case for the need to do something about global warming is so strong on its face, why do people like National Geographic cartographers feel the need to exaggerate and to distort the facts to promote their case?

Jorge Del Corral Landeros
Jorge Del Corral Landeros

We need to change our attitudes for the next generation. All of us are responsible from our omission, I think

S Katz
S Katz

The perception of what changes in a map look like in relation to a recent map might jolt some folks out of their complacency. 


But if it takes a map to do this, we have to blame the media and educators for not doing a good enough job in explaining how dangerous Anthropomorphic Global Warming really is. 

David Gillespie
David Gillespie

Do scientists want to chime in yet on maybe the cause of global warming is the distance the globe is from its last caldera, (super volcano) eruption.  75,000 years now, I wouldn't worry over it too much the Yellowstone is long over due it will take care of all this warming talk, and we will be scrambling for arctic clothing soon.

Karlis Blums
Karlis Blums

Tev mājās ir pasaules karte? Tā vairs nav pareiza...

Dipanjan Mitra
Dipanjan Mitra

We (human beings) are cancer, spreading all over the body of earth. She is seriously ill and as a result our own fate is going to be fatally ill soon..

Kim Adigwe
Kim Adigwe

The Chinese are dumping CO2 into the air at a record pace.  Unless the Chinese stop what they are doing, there is nothing that can be done to slow global warming.  

David Swartz
David Swartz

The irony behind all this is humans are a contributing factor. We trash everything we touch. If we try to fix it through things like geoengineering, we're gonna mess it up more.

kevin le pape
kevin le pape

It'll not change anything. How many years I heard to be careful, it's almost irreversible but each year it's the same speech.
Stop preventing, unfortunately nobody listening ... It's too late that's all, it's very pessimistic, but for the moment humanity is too material and we can't move forward. Hope that our grandchildren will see the changes of our children who may have actually taken conscience.

Internet Policeman
Internet Policeman

Hopefully this drastic adjustment will get people to stop, collaborate and listen.

Joel Leek
Joel Leek

@Dwayne LaGrou Very good idea, I hope the editors and web-masters take your suggestions to heart.


In other sections of your post you seem to accept at least partial blame for the conditions that are causing this phenomenon. Unless you can take credit for major volcanic eruptions over the last 10 years, I think you can focus less on the cause and more on the effect of global warming.


Which, in m 6th grade elementary geology class (1973), we learned would be a decades long cycle of cooling that would usher in the next mini ice-age.

Geoff Price
Geoff Price

@John Smith The article does not say that this is a "switch" in policy in how ice is represented, are you pulling in some additional information from somewhere?


You would like the company to hold production until their schedule conveniently lines up with a local high for ice extent, to serve some political goal of yours?


In the face of the complete collapse over time of the arctic sea ice – more than half of its traditional ice volume gone, and dramatic reduction in ice coverage regardless of which way you visualize it (see the animations at NSIDC) – this sort of nitpicking is the only thing you're able to do, "John"? 

Geoff Price
Geoff Price

@Kim Adigwe The average U.S. citizen is responsible for several times as much emissions as the average Chinese citizen, and the U.S. in general is responsible for a much larger share of the existing emissions in the atmosphere than China.

Sendai Iicx
Sendai Iicx

@Kim Adigwe Curiously enough, the Chinese are doing far more than most think they are. China's looking to reduce coal use by half by 2020, that's a far greater reduction than the US, Australia, and many other countries that could easily afford to are doing.

Geoff Price
Geoff Price

@david schumer Pretty outrageous that National Geographic doesn't edit in a fictional larger ice cap to make us feel better about things. They are intentionally hurting our feelings, and should be boycott.

Liz R
Liz R

@david schumer I don't understand your comment. Obviously this *does* show how bad global warming is, and it isn't just "anything" but a sensitive indicator of the extent of the problem. Would you rather science didn't warn us about impending problems? Would you rather have a checkup that gave you early warning of a disease and perhaps allowed it to be cured, or would you prefer to continue in blissful ignorance until it was too late to do anything to save you?

J. Kingham
J. Kingham

@Sendai Iicx @Kim Adigwe  I agree that China are taking (or at least talking about) measure to reduce their carbon emissions but at the same time I don't think that's enough. Coal use is increasing around the globe in developing nations and we can't stop it. That's a hell of a lot of CO2 which will affect the climate in the future.

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