Wednesday, July 12, 2017

Climate change: Companies responsible for most greenhouse gas emissions, trillion ton iceberg breaks off in Antarctica

Here are a pair of reports on climate change from The Guardian. The first is noted by FiveThirtyEight’s Significant Digits email.

71 percent
A new report claims that 100 companies are responsible for 71 percent of greenhouse gas emissions since 1988. [The Guardian]

So, if we could convince just 100 companies to change their energy habits, we could significantly cut greenhouse gas emissions. Check out The Guardian report for details.

In the other Guardian report: Iceberg twice size of Luxembourg breaks off Antarctic ice shelf. Satellite data confirms ‘calving’ of trillion-tonne, 5,800 sq km iceberg from the Larsen C ice shelf, dramatically altering the landscape.

Read the report for photos and maps - which can be found in reports of this event in several other news sources, like this one from the NY Times: An Iceberg the Size of Delaware Just Broke Off a Major Antarctic Ice Shelf. Snippets follow.

A chunk of floating ice that weighs more than a trillion metric tons broke away from the Antarctic Peninsula, producing one of the largest icebergs ever recorded and providing a glimpse of how the Antarctic ice sheet might ultimately start to fall apart.

“The remaining shelf will be at its smallest ever known size,” said Adrian Luckman, a lead researcher for Project Midas. “This is a big change. Maps will need to be redrawn.”

Some climate scientists believe the warming in the region was at least in part a consequence of human-caused climate change, while others have disputed that, seeing a large role for natural variability — and noting that icebergs have been breaking away from ice shelves for many millions of years. But the two camps agree that the breakup of ice shelves in the peninsula region may be a preview of what is in store for the main part of Antarctica as the world continues heating up as a result of human activity.

At the remaining part of Larsen C, the edge is now much closer to a line that scientists call the compressive arch, which is critical for structural support. If the front retreats past that line, the northernmost part of the shelf could collapse within months.

“At that point in time, the glaciers will react,” said Eric Rignot, a climate scientist at the University of California, Irvine, who has done extensive research on polar ice. “If the ice shelf breaks apart, it will remove a buttressing force on the glaciers that flow into it. The glaciers will feel less resistance to flow, effectively removing a cork in front of them.”

According to Dr. Rignot, the stability of the whole ice shelf is threatened, as the shelf front thins.

"As climate warming progresses farther south,” Dr. Rignot said, “it will affect larger and larger ice shelves, holding back bigger and bigger glaciers, so that their collapse will contribute more to sea-level rise.”

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