Remember the ozone hole in Antarctica?  Discovery that CFCs used for refrigerators, air conditioning and a variety of manufacturing processes were creating a hole in the earth's protective ozone layer led to a worldwide ban on these chemicals. Well the good news is that since the ban the ozone layer in Antarctica has been recovering. The bad news is that scientists think that re-establishing the ozone layer will contribute to warming in Antarctica.  "While Earth's average surface temperatures have been increasing, the interior of Antarctica has exhibited a unique cooling trend during the austral summer and fall caused by ozone depletion", said Judith Perlwitz of the Cooperative Institute for Research in Environmental Sciences, a joint institute of CU-Boulder and NOAA. "If the successful control of ozone-depleting substances allows for a full recovery of the ozone hole over Antarctica, we may finally see the interior of Antarctica begin to warm with the rest of the world," Perlwitz said.  more...

At the White House on Wednesday President Bush made a speech on climate change. Here are excerpts:

"I have put our nation on a path to slow, stop, and eventually reverse the growth of our greenhouse gas emissions. In 2002, I announced our first step: to reduce America's greenhouse gas intensity by 18 percent through 2012. I'm pleased to say that we remain on track to meet this goal even as our economy has grown... When I took office seven years ago... a number of nations around the world were preparing to implement the flawed approach of Kyoto Protocol. In 1997, the United States Senate took a look at the Kyoto approach and passed a resolution opposing this approach by a 95 to nothing vote. The Kyoto Protocol would have required the United States to drastically reduce greenhouse gas emissions. The impact of this agreement, however, would have been to limit our economic growth... while allowing major developing nations to increase their emissions... We're working toward a climate agreement that includes the meaningful participation of every major economy -- and gives none a free ride... Today, I'm announcing a new national goal: to stop the growth of U.S. greenhouse gas emissions by 2025.

... To reach our 2025 goal, we'll need to more rapidly slow the growth of power sector greenhouse gas emissions so they peak within 10 to 15 years, and decline thereafter. By doing so, we'll reduce emission levels in the power sector well below where they were projected to be when we first announced our climate strategy in 2002. There are a number of ways to achieve these reductions, but all responsible approaches depend on accelerating the development and deployment of new technologies... The wrong way is to raise taxes... The right way is to set realistic goals for reducing emissions consistent with advances in technology, while increasing our energy security and ensuring our economy can continue to prosper and grow.

...The strategy I have laid out today shows faith in the ingenuity and enterprise of the American people -- and that's a resource that will never run out. I'm confident that with sensible and balanced policies from Washington, American innovators and entrepreneurs will pioneer a new generation of technology that improves our environment, strengthens our economy, and continues to amaze the world.

Here's the full speech.

Earlier this week a 160 square mile section of Antarctica's Wilkins Ice Shelf collapsed into the sea.  "Hard to believe that 500 billion tonnes of ice sheet has disintegrated in less than a month," said British Antarctic Survey glaciologist David Vaughan.  The collapse has been attributed to global warming.  Ice shelves ringing Antarctica hold back land-based glaciers and keep them from from flowing into the sea.  Because they float on the water, like ice cubes in a glass, disintegrating ice shelves do not raise sea levels.  However, if land based glaciers flow into the sea more quickly there could be consequent rises.  Even as this event demonstrates that the earth is warming some contrary events are taking place at Antarctica itself.  This year there's higher than normal snowfall in parts of Antartica and greater than normal amounts of sea ice are forming.

Christian Science Monitor
Images of shelf collapse at National Geographic
CNN
NPR

What is the best way to combat global warming?  Reducing C02 output is the goal because C02 is emitted whenever any of our most popular fuels are burned: coal, diesel (including biodiesel), gas, oil , wood, etc.  Public policy offers two options. Output reductions can be mandated by governments in the manner of fuel economy standards.  Alternatively, a tax can be imposed on carbon fuels to raise the cost of those fuels and create an incentive to use alternatives such as wind or hydrogen. Focusing on industrial output is preferable to focusing on consumers for obvious reasons. Carbon taxes on industry have been used in Europe with mixed success. For a carbon tax to work the proceeds of the tax need  to be allocated directly toward conservation and alternative energy development.  Doing this requires real restraint on the part of government. It's hard, nearly impossible, for politicians to keep their hands out of a new tax revenue cookie jar.  Here's a good editorial on the subject by Monica Prasad in the NYT.