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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Rod Fujita, Ph.D., is a scientist in the Oceans program at Environmental Defense Fund.

Coral reefs aren't just pretty places for scuba divers (although they do bring in billions of tourist dollars). These rich ecosystems supply the inhabitants of coral reef countries with the fish that they depend on as their main source of protein. Coral reefs, like rainforests, are also treasure troves of biodiversity that may hold the keys to fighting diseases like cancer and arthritis. Human wellbeing is tightly bound to the health of coral reefs.

Unfortunately, coral reefs are in trouble, and climate change plays a major role.

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

IPCC scientists have been saying for years that man-made global warming is likely to increase extreme weather events. A new report ("Weather and Climate Extremes in a Changing Climate") from U.S. government scientists confirms these findings, and focuses specifically on the U.S.

It's certainly timely, considering the devastating floods in the Midwest.

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

The record floodwaters in Iowa and other parts of the Midwest are claiming lives, destroying homes and crops, contaminating drinking water, and - as the AP puts it - spreading "a noxious brew of sewage, farm chemicals, and fuel that could sicken anyone who wades in." The cost in human anguish is incalculable.

But why is it happening? Is it just a freak of nature? One causal element, as reported in today's Washington Post, may be human reengineering of the landscape. Mary Kelly, who heads up EDF's rivers and deltas program, gives a good overview of these issues.

Another element may be global warming, which increases the probability of extreme weather events like torrential rain.

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This post is by Sheryl Canter, an online writer and editorial manager at Environmental Defense Fund.

Our own Scott Anderson is one of the experts featured in a new video on Carbon Capture and Sequestration (CCS). The video explains why CCS is an important tool in cutting emissions, and gives an animated description of how it works. It's a good companion to Scott's blog post on CCS.

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

In IPCC's Third Assessment Report (2001), scientists reported that carbon dioxide (CO₂) and methane levels were higher than at any time in the past 420,000 years. In their latest report (2007), IPCC scientists raised the number to 650,000 years.

Last week, scientists again revised the number upward. New research shows that CO₂ and methane levels are higher today than they have been in at least 800,000 years.

Here's how they know.

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

An article in this week's Nature predicts that Europe and North America will cool slightly over the next decade. No, this doesn't mean that global warming has stopped.

The new paper describes a climate model that makes short-term (decadal) predictions based on ocean dynamics. The decade-long cooling is just a temporary offset to warming from human activity. After it passes, temperatures will begin climbing again. By 2030, the model forecasts the same global temperatures as the IPCC.

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

Last week, NOAA released some disheartening numbers: both CO₂ and methane increased sharply last year. Growth rates are increasing (see graph to the right).

The CO₂ numbers weren't a surprise. A paper with similar findings was published last November by a team that included a NOAA scientist. I wrote a blog post summarizing the study, which analyzed the reasons behind the trend (see Rise of Atmospheric Carbon is Accelerating).

The methane numbers, however, were disturbing. Until this year, methane levels have been essentially unchanged since 1998.

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

There's an email making the rounds lately - an invitation to take a Global Warming Test. It starts off reasonably enough (yes, global warming is real), but then quickly devolves into ridiculousness - ridiculousness presented in a way that looks misleadingly "scientific".

For those interested in truth, here are the real answers to the Global Warming Test.

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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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