The phrase "environmental extremists" refers to individuals or groups who hold extreme views and take radical actions to protect and preserve the environment, often by resorting to aggressive or illegal means. Full definition
It is an excellent window into the lying and exaggerations frequently employed by environmental extremists in order to demonize coal. (globalwarming.org)
More on Fracking: Uranium Released by Fracking May Pollute Groundwater Mayor Bloomberg Warns Against Fracking in Delaware River Basin New York Governor Orders Moratorium on Fracking, But It's Only Sort of Good News Are Pennsylvania's Fracking Opponents Really Environmental Extremists? (treehugger.com)
I can assure you that scientists are NOT allied with environmental extremists, or even regular environmentalists (though secretly they may be using compact fluorescent bulbs). (realclimate.org)