This post is by Fred Krupp, president of the Environmental Defense Fund.

A few weeks ago, I returned from a voyage called the Arctic Expedition for Climate Action. Sponsored by the Aspen Institute, the National Geographic Society, and Lindblad Expeditions, our group [PDF] included over 100 business leaders, scientists, environmentalists, journalists, politicians, religious leaders, and community activists.

In a word, it was sensational. We set out by ship from Svalbard - almost the closest land to the North Pole, and a three hour plane flight from Oslo, Norway. This is by far the closest to the North Pole I've ever been. My prior trips to the north shore of Alaska at Prudhoe Bay and the north coast of the Arctic National Wildlife Refuge were much further south.

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This post is by James Wang, Ph.D., a climate scientist at Environmental Defense Fund.

This month, while Arctic sea ice hits its annual wintertime high (such as it is - see last week's post), Antarctic sea ice reaches its summertime low.

We've already posted about the British Antarctic Survey's report of a vast ice berg on the verge of breaking off the Wilkins Ice Shelf. Here's more on what's happening at the South Pole from NASA's recent briefing on polar sea ice.

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This post is by James Wang, Ph.D., a climate scientist at Environmental Defense Fund.

Last summer we saw record-shattering shrinkage of Arctic sea ice caused, in part, by human-induced global warming. Last week I listened in on a NASA briefing on polar sea ice, and this year looks no better.

This winter was relatively cold due to a strong La Niña, so the Arctic saw a modest increase in overall sea ice (slightly above the record low of 2005-2006, but still below the long-term average). However, the older, thicker ice that lasts through the summer has declined sharply, and this is very worrying.

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This post is by Sheryl Canter, an Online Writer and Editorial Manager at Environmental Defense Fund.

A huge Antarctic ice berg - seven times the size of Manhattan - is close to breaking off, supported only by a thin strip of ice hanging between two islands.

Part of the Wilkins Ice Shelf, the berg was captured in satellite and video images by British Antarctic Survey (BAS), which said, "It is another identifiable impact of climate change on the Antarctic environment."

This post is by Lisa Moore, Ph.D., a scientist in the Climate and Air program at Environmental Defense.

On January 13, Nature Geoscience published an article that reports large increases in ice loss from West Antarctica over the past 10 years. It's a sobering result that's in line with earlier, independent studies.

But then why do some people say that Antarctic ice is growing?

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The author of today's post, Sheryl Canter, is an Online Writer and Editorial Manager at Environmental Defense.

Researchers have been expecting Arctic ice to melt and shrink, but not this fast! The National Snow and Ice Data Center, part of the University of Colorado at Boulder, reports that Arctic sea ice has shrunk to a 29-year low, significantly below the previous record low set in 2005.

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The author of today’s post, Lisa Moore, Ph.D., is a scientist in the Climate and Air program.

A frame from an Environmental Defense ad campaign about the danger of unchecked global warming.

"Most Polar Bears Gone by 2050". You may have seen that headline in the news this week. The study behind this depressing conclusion could land polar bears on the list of threatened species under the Endangered Species Act.

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The author of today's post, Sheryl Canter, is an Online Writer and Editorial Manager at Environmental Defense.

If you had any doubts that the globe is warming and the Arctic is melting, this month's flag incident should put them to rest. A Russian submarine dove to the bottom of the Arctic Ocean to plant a flag in the seabed. Why? There's oil and gas in the Arctic seabed, which is now becoming accessible due to global warming.

Russia is not the only country vying for Arctic rights. Canada and Denmark are arguing about rights to the Northwest Passage, and the U.S. is getting into the act as well. But unfortunately, more than just oil and gas will be exposed as the Arctic melts.

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The author of today’s post, Lisa Moore, is a scientist in the Climate and Air Program.

Most people don't realize it, but "black carbon" or soot - the same stuff that dirties up chimney flues and car mufflers - is a significant contributor to global warming. Today's best estimates place it next in line behind the greenhouse gases CO₂ and methane (see Table 2.13 in the IPCC report).

Soot particle under a microscope. Credit: D.M. Smith, University of Denver.

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Guest blogger Lisa Moore, Ph.D., is a scientist in the Climate and Air Program.

There's always something new in climate change research. This week, scientists described the risks of geo-engineering, proposed an efficient way to reduce Arctic climate change, and discussed options for decreasing deforestation in developing countries.

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