The past ten years have not necessarily been the best for the environmental and clean energy movement.  International progress on addressing climate change stalled within the United Nations Framework Convention on Climate Change, attempts on the Federal level to cap carbon emissions, implement a carbon tax, or institute a renewable energy standard were decisively defeated, and oil and gas companies recorded stratospheric profits and continued to enjoy billions in tax breaks while getting slapped on the wrist for causing multiple eco-disasters.  All this while global CO2 output continued to increase essentially unabated.  

Despite the deck being stacked against its favor, the share of electricity generation sourced from renewable energy increased dramatically in many states during this time period. 

In fact, wind power has been the fastest growing source of energy for electricity in the United States for most of the past ten years - even outpacing natural gas.

What has contributed to this high growth rate in renewable energy generation?  It's mainly come down to good environmental policy.  Twenty-four states, along with the District of Columbia, have enacted a renewable portfolio standard, which requires that a certain percentage of electricity be generated from clean sources.  A Federal production tax credit and associated grants have also contributed to these increases in renewable capacity and generation between 2001 and 2011. 

Unfortunately, many of these grants and rebates have expired or face expiration, and the growth rate of wind power is now in peril due to the continuing uncertainty surrounding extending the production tax credit for wind power generators.  Backlash from the failed Dept. of Energy loan to Solyndra has also given subsidies for green energy a bad name, which in turn has weakened interest from the private sector in financing it.

(Image above from U.S. Energy Information Administration)

So even as federal support of renewables is on the rocks, the majority of the American public continues to support expanded development of renewable energy resources.  And while the growth of renewables in the U.S. over the past ten years has been impressive, its current growth trajectory is insufficient to reduce greenhouse gas emissions to the extent that scientists say is necessary to avoid the worst impacts of global warming. 

Deployment of wind, solar, and other alternatives at a much faster rate will be needed to result in any meaningful reduction in atmospheric CO2.

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