Discussions of our proximity to a "global tipping point" on climate have now become commonplace. Today the carbon dioxide concentration in the atmosphere is about 385 parts per million -- more than 100 parts per million higher than before the Industrial Revolution. Just when and where the climate will begin to change in large, unpredictable ways remains a threat that all our environmental models say is coming, even if they cannot be forecast with any real accuracy. James Hansen, the tremendously well-respected climate scientist and director of the NASA Goddard institute for Space Studies, has often been quoted on this topic. "We don't understand how fast ice sheets can respond," Hansen said in a podcast interview with Earth & Sky. "But what we're learning

At a recent Capitol Hill hearing I was surprised to learn that it was far from common knowledge just how competitive wind power has become. As a result, a bit of a data and price update memo may be of use, even to those who follow the industry. In addition, I will summarize the data on a few of the least cost wind farms in the nation.

Wind energy in the United States has continued to grow, and represented 19 percent of the new nameplate capacity added to the electrical grid in 2006 . With a total cumulative U.S. capacity of 11,575 MW (1 percent of total U.S. nameplate capacity) at the end of 2006, wind energy is now often directly cost competitive with fossil-fuel generation, and at times is a least-cost supply option.

Representative Wind Project and Wind Power

The risks of climate change and, of course, high oil prices have unleashed a wave of interest and commitment to changing our energy economy that, perhaps, could safeguard the planet. City, state, federal and international proposals and legislation are today all in play -- and in flux -- to lay out targets for greenhouse gas reductions.

Some of the most notable are the 25 percent reduction in GHG emissions by 2025 and the 80 percent reduction by 2050 that California has adopted, the 70 percent or more reductions proposed in the United Kingdom, New Zealand, and the Japanese proposals, and the 100 percent fossil-fuel-free plans of Sweden, and a number of progressive cities intent on making climate-wise statements.

How these diverse and ambitious plans pan out is anybody's