Climate 411

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

The term "tipping point" refers to a critical threshold at which a small change can qualitatively alter the state of a system. For example, when temperature reaches 32°F, ice changes into water. There also are "tipping points" in global warming. The best known is the Greenland Ice Sheet, which could begin a slow, irreversible meltdown if global temperature passes a certain threshold.

Last week, climate researchers published a paper that examines Earth systems in danger of passing tipping points due to human activity. They call these "tipping elements", and highlight nine such systems from around the world. They say the greatest threat is to the Arctic, followed by the Greenland Ice Sheet. Here’s the list.

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

It’s not just an election year, it’s an historic election year. Every news outlet is filled with speculation and commentary. So why is it so quiet here, at Climate 411? How come we don’t talk about the election and the candidates?

It’s because of our tax status. Environmental Defense is incorporated as a 501c3 charitable organization. This means that donations to us are tax deductible, and we are allowed only limited lobbying and no electioneering whatsoever. Even commenting on candidates’ climate change plans could imply that we prefer one over the other and jeopardize our tax status. That’s why we talk about policies and not about candidates.

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

The U.S. Environmental Protection Agency (EPA) has come out with a neat new calculator that can make sense of all those arbitrary-sounding greenhouse gas numbers.

What does a metric ton of carbon dioxide look like? The calculator shows a dozen different equivalencies, such as 114 gallons of consumed gasoline, 2.3 barrels of oil, or 0.01 acres of forest preserved from deforestation. And it’s not limited to metric tons or CO₂. You also can try different amounts and different greenhouse gases.

The EPA developed the calculator to help people in communicating about reduction targets, but it’s useful to anyone trying to get a handle on the numbers.

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

The results are in for 2007, and it was a warm one. How warm? It depends who you ask. According to NASA, 2007 was the second warmest year on record. NOAA’s analysis put it in fifth place. The University of East Anglia’s Climatic Research Unit (CRU) ranked it eighth.

The results differ because it’s not as straightforward as you might think to take the temperature of the globe. There are many subtleties to consider.

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