Melting Arctic sea ice mostly man-made

An aerial view of icebergs floating in the Jacobshavn Fjord, August 29, 2007 near the town of Ilulissat, Greenland. The latest study on the unprecedented loss of ice covering the Arctic says it is 70 percent the result of human-caused climate change.

Tess Vigeland: So here's the watercooler and dinner party topic of the week: That massive ice sheet that's melting really, really fast in Greenland.

It seems every day brings more clarity on the warming climate and the Arctic. A study out today by climate scientists in England and Japan puts a number on how much of it is caused by humans.

From the Marketplace Sustainability Desk, Scott Tong reports.

Scott Tong: Some Arctic melting comes from what’s called natural variability -- regular cycles of warm and cold. Strip that out, and the study suggests human behavior -- our fossil fuel lifestyles -- cause 70 to 95 percent of the problem.

Kevin Trenberth: That’s a very large number.

Climate scientist Kevin Trenberth is with the National Center for Atmospheric Research.

Trenberth: It certainly suggests that we’re headed for an ice-free Arctic in the summer, somewhere in the 2030s.

That’s in two decades. Most environment effects are tragic. But it does speed up the investment timeline for companies seeking northern exposure to warmer waters. Thirteen percent of the world’s undiscovered oil, and 30 oercent of the gas, is believed to be there.

Energy professor Dan Kammen at Berkeley attended an oil conference not long ago.

Daniel Kammen: They were denying the climate change story in public. On the other hand, they were saying ‘well, the data says there’ll be less ice. It’ll be easier for us to drill.’

And a host of other industries see gold in the warmer Arctic. Heather Conley ticks them off. She’s with the Center for Strategic and International Studies.

Heather Conley: Mineral extraction, huge numbers of iron ore, potential rare earth minerals. Fisheries, huge economic driver. Also, we’re seeing a growth in eco-tourism.

Already, the Arctic hosts one and a half million chilly tourists every year. And a million tons of cargo steam across each summer; we now have our Northwest Passage from east to west. This is a climate change market signal; the faster the ice melts, the sooner the New Great Game begins.

I’m Scott Tong for Marketplace.

About the author

Scott Tong is a correspondent for Marketplace’s sustainability desk, with a focus on energy, environment, resources, climate, supply chain and the global economy.
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If humans are the cause of global warming, when did this start? The glaciers started melting 10,000 years ago. If the ice was 1 mile thick, that is quite a 'storage' of cold - how much heat would there have to be to melt them and what could cause that? Does it not make sense that, even if everything stayed the same, as the ice melted and there was less avalable to 'store' the cold, the heating process would speed up?

I heard this report when it aired and searched out the website to see the wording:

"Some Arctic melting comes from what’s called natural variability -- regular cycles of warm and cold. Strip that out, and the study suggests human behavior -- our fossil fuel lifestyles -- cause 70 to 95 percent of the problem."

What does that mean? "Strip that out and..." 70 to 95 percent of the *remaining* variance is believed traceable to human behavior? That natural variability explains as little as 5%?

Surely there's significance in the "strip that out" clause, but its significance is lost in the rush to attach to humans a large -shockingly large- explanatory percentage. That statement wouldn't pass muster in a statistics class.

I gaze upon pictures of the beautiful fjords of Norway and wonder if the disappearance of the ice sheets that formed them is due to the hand of man since the onset of the Industrial Age. I think not.

A little confusion about what the Arctic is in this story, which starts talking about the ice sheet, which is Greenland and glaciers, then pivots to the new report, which is about sea ice. The "ice free" summer Arctic by 2030 and high level of human attribution is referring to the sea ice. Yes, Greenland's melting rapidly, too, but it there's still, well, tons of ice-- 12,000 feet at the summit-- that certainly won't be melted away in the coming decades: http://www.pbs.org/newshour/rundown/2012/07/sudden-freak-ice-melt-in-gre...

Amazing and terrifying that you put a positive spin on this. So we humans are just going to burn up the planet and then burn it up some more? So depressing. It's so simple to stop driving, stop using air conditioning, stop heating your house, stop barbequing, etc. Everyone can do this starting right now. I have.

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