To meet energy demands without escalating the problem of global warming, humankind must embark on a research effort as grand in scale as the Apollo project to put a man on the moon, say scientists in a study published today in the journal Science. The 18 researchers — coming from government, universities, and even such traditional climate change naysayers as ExxonMobil — conclude that within 50 years, clean energy technologies will need to produce up to three times the energy now generated by coal, oil, and other fossil fuels. Without that kind of output, and unless the use of fossil fuels also declines, emissions of carbon dioxide, the leading greenhouse gas, will not stabilize. The scientists contend that existing clean energy technologies “have severe deficiencies” and limited potential, and they took a dig at current U.S. policy, noting that it “emphasizes domestic oil production, not energy technology research.” One author of the report, Haroon Kheshgi of ExxonMobil, says, “You need a quantum jump in technology.”