PITTSBURGH -- PITTSBURGH (AP) — Some of the world's top climate scientists say wind and solar energy won't be enough to head off extreme global warming, and they're asking environmentalists to support the development of safer nuclear power as one way to cut fossil fuel pollution.


Four scientists who have played a key role in alerting the public to the dangers of climate change sent letters Sunday to leading environmental groups and politicians around the world. The letter, an advance copy of which was given to The Associated Press, urges a crucial discussion on the role of nuclear power in fighting climate change.


Environmentalists agree that global warming is a threat to ecosystems and humans, but many oppose nuclear power and believe that new forms of renewable energy will be able to power the world within the next few decades.


That isn't realistic, the letter said.


"Those energy sources cannot scale up fast enough" to deliver the amount of cheap and reliable power the world needs, and "with the planet warming and carbon dioxide emissions rising faster than ever, we cannot afford to turn away from any technology" that has the potential to reduce greenhouse gases.


The letter signers are James Hansen, a former top NASA scientist; Ken Caldeira, of the Carnegie Institution; Kerry Emanuel, of the Massachusetts Institute of Technology; and Tom Wigley, of the University of Adelaide in Australia.


Hansen began publishing research on the threat of global warming more than 30 years ago, and his testimony before Congress in 1988 helped launch a mainstream discussion. Last February he was arrested in front of the White House at a climate protest that included the head of the Sierra Club and other activists. Caldeira was a contributor to reports from the Intergovernmental Panel on Climate Change, Emanuel is known for his research on possible links between climate change and hurricanes, and Wigley has also been doing climate research for more than 30 years.


Emanuel said the signers aren't opposed to renewable energy sources but want environmentalists to understand that "realistically, they cannot on their own solve the world's energy problems."


The vast majority of climate scientists say they're now virtually certain that pollution from fossil fuels has increased global temperatures over the last 60 years. They say emissions need to be sharply reduced to prevent more extreme damage in the future.


In 2011 worldwide carbon dioxide emissions jumped 3 percent, because of a large increase by China, the No. 1 carbon polluting country. The U.S. is No. 2 in carbon emissions.


Hansen, who's now at Columbia University, said it's not enough for environmentalists to simply oppose fossil fuels and promote renewable energy.


"They're cheating themselves if they keep believing this fiction that all we need" is renewable energy such as wind and solar, Hansen told the AP.


The joint letter says, "The time has come for those who take the threat of global warming seriously to embrace the development and deployment of safer nuclear power systems" as part of efforts to build a new global energy supply.


Stephen Ansolabehere, a Harvard professor who studies energy issues, said nuclear power is "very divisive" within the environmental movement. But he added that the letter could help educate the public about the difficult choices that climate change presents.


One major environmental advocacy organization, the Natural Resources Defense Council, warned that "nuclear power is no panacea for our climate woes."


Risk of catastrophe is only one drawback of nuclear power, NRDC President Frances Beinecke said in a statement. Waste storage and security of nuclear material are also important issues, she said.


"The better path is to clean up our power plants and invest in efficiency and renewable energy," Beinecke said.


The scientists acknowledge that there are risks to using nuclear power, but say those are far smaller than the risk posed by extreme climate change.


"We understand that today's nuclear plants are far from perfect."


___


Full letter online: http://bit.ly/1fc6Dpu


___


Follow Kevin Begos at https://twitter.com/kbegos





Loading Slideshow...



  • Top Renewable Energy Sources


    Renewable energy made up 9 percent of all energy consumed in 2011, according to the <a href="http://www.eia.gov/">U.S. Energy Information Agency</a>, and that number is <a href="http://www.eia.gov/forecasts/aeo/er/pdf/0383er(2013).pdf">predicted to grow throughout the next decade</a>. Here's a breakdown of the top sources of renewable energy in the country, from wind to water and everything in between. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>




  • Solar Power - 2 Percent


    Solar power and photovoltaic cells make up the smallest percentage of U.S. renewable energy production, but its future looks fairly promising. Warren Buffett's Berkshire Hathaway <a href="http://www.huffingtonpost.com/2013/01/03/warren-buffett-solar-power_n_2398816.html">invested $2.5 billion in Calif. solar company SunPower</a> earlier this year. Also, unlike other sources of renewables, energy can also be generated by small-scale solar installations (like on the rooftop of a home or business), and<a href="http://www.eia.gov/todayinenergy/detail.cfm?id=8570"> declining costs</a> have made solar much more affordable. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>




  • Geothermal - 2 Percent


    Geothermal power captures naturally occurring heat from the earth to turn it into power. The renewable source is geographically dependent, <a href="http://www.eia.gov/todayinenergy/detail.cfm?id=3970">but the Western half of the U.S.</a> has many promising locations for power plants, <a href="http://www.geysers.com/">like The Geysers in Calif.</a>, the largest geothermal power plant in the world. The U.S. is the largest producer of geothermal power on the planet, but growth hasn't kept up with wind or solar development in recent years. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>




  • Waste - 5 Percent


    Believe it or not, burned garbage accounts for 5 percent of all renewable energy created in the U.S. each year. More than 29 million tons of municipal solid waste was burned in 2010 to create steam to spin turbines and generate power, <a href="http://www.eia.gov/todayinenergy/detail.cfm?id=7990"> and there are more than 75</a> waste-to-energy plants in the country. Emissions regulations have been in place at waste incineration plants since the 1960s, but the <a href="http://www.epa.gov/ncer/publications/research_results_needs/combustionEmmissionsReport.pdf">EPA warned in a 2006 report that the toxins released</a> during the process could pose a serious environmental risk if not strictly enforced. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>




  • Wind - 13 Percent


    The amount of wind power has grown for each of the past three years throughout the U.S. and accounted for the <a href="http://www.eia.gov/todayinenergy/detail.cfm?id=9931">largest growth in capacity</a> of any energy resource in the country last year. Wind turbines now supply more than <a href="http://www.reuters.com/article/2012/10/19/us-utilities-windpower-usa-idUSBRE89I0TX20121019">50,000 megawatts a year,</a> enough to power 13 million homes, according to Reuters. Federal tax credits, which were set to expire at the end of 2012, have made wind farms an attractive form of renewable energy. Congress <a href="http://www.forbes.com/sites/davelevitan/2013/01/02/wind-power-tax-credit-survives-fiscal-cliff-deal/">approved an extension of the credits</a> through the end of 2013. After production, wind turbines are net zero, meaning they require no energy and produce no emissions. The only problematic thing generated in some cases other than clean power has been <a href="http://www.huffingtonpost.com/2011/05/24/wind-power-noise-pollution-maine_n_866182.html">a whole lot of noise</a>. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>




  • Biofuel - 21 Percent


    Biofuels, like ethanol, are created from organic matter like corn or soybeans. Gasoline in the U.S. contains 9 percent of the resource by federal mandate under the <a href="http://www.epa.gov/otaq/fuels/renewablefuels/index.htm">Renewable Fuel Standard program,</a> and more than <a href="http://www.huffingtonpost.com/2012/08/10/us-should-change-biofuel-_n_1764735.html">40 percent of the corn crop</a> last year was turned into biofuel. The resource is slightly more unstable than other renewables because it depends on the productivity of farms - <a href="http://www.huffingtonpost.com/2012/08/10/us-should-change-biofuel-_n_1764735.html">drought or other environmental problems</a> can significantly lower yields and increase prices. On average, <a href="http://www.afdc.energy.gov/vehicles/flexible_fuel_emissions.html">ethanol has 20 percent fewer emissions</a> than traditional gasoline but some types, like <a href="http://en.wikipedia.org/wiki/Cellulosic_ethanol">cellulosic ethanol,</a> cut greenhouse gas emissions more than 85 percent, according to the U.S. Department of Energy. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>




  • Wood - 22 Percent


    Timber accounts for nearly a quarter of all renewable energy created in the country. <a href="http://news.nationalgeographic.com/news/energy/2012/10/121022-wood-for-heating/">Rising energy costs </a>have led to an upswing in wood burning over the past decade, and nearly <a href="http://www.eia.gov/forecasts/steo/report/winterfuels.cfm">20 percent of New England homes </a>use wood for heating, according to a National Geographic report. Although it may be a cheaper alternative, wood burning stoves and fireplaces<a href="http://www.epa.gov/burnwise/energyefficiency.html"> release more emissions of fine particles </a> than other home heating methods, according to the EPA. Burning <a href="http://www.epa.gov/burnwise/bestburn.html">good wood in an efficient burner</a> lowers toxic emissions and lost energy. Oh, and always have working smoke and carbon monoxide detectors handy. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>




  • Hydroelectric - 35 Percent


    Almost all of the current hydroelectric power plants in the U.S. were <a href="http://www.eia.gov/energy_in_brief/article/hydropower.cfm">built before the mid-1970's</a>, but it's still the highest producing renewable energy source in the country. In 2011, 8 percent of all power created in the U.S. came from hydroelectric sources, but it's also one of the most geographically dependent sources of energy. The Pacific Northwest gets more than half of all power via hydroelectric due to prime geography. <em>Information courtesy of the <a href="http://www.eia.gov/totalenergy/data/annual/perspectives.cfm">U.S. Energy Information Agency</a>.</em>




  • How To Really Go Renewable


    Watch this TED talk on the missing link in the future of renewable energy.