"The environmentally responsible manner in which the extraction of natural gas from Marcellus Shale occurs will bring countless jobs to West Virginia," Tomblin said in announcing the task force.

But the Tyndall researchers report that "Evidence from the U.S. suggests shale-gas extraction brings a significant risk of ground- and surface-water contamination" serious enough to warrant "a precautionary approach to development" as the "only responsible action."

"The depth of shale gas gives rise to major challenges in identifying categorically pathways of contamination of groundwater by chemicals used in the extraction process," the report said.

"An analysis of these substances suggests that many have toxic, carcinogenic or hazardous properties," the report said. "There is considerable anecdotal evidence from the U.S. that contamination of both ground- and surface-water has occurred in a range of cases."

The Tyndall report noted that the Bush administration successfully pushed to exempt hydraulic fracturing from key water quality regulations, and that the Obama administration launched a major U.S. Environmental Protection Agency study of the potential impacts of the practice.

Following a "precautionary principle" adopted by members of the European Union, the report says, "shale gas exploitation should be delayed until at least after the EPA has reported and, depending on the findings, perhaps longer."

Tyndall researchers found "little to suggest that shale gas will play a key role as a transition fuel in the move to a low-carbon economy.

"There is little evidence from data on the U.S. that shale gas is currently, or expected to, substitute at any significant level for coal use," the report said. "By contrast, projections suggest it will continue to be used in addition to coal in order to satisfy increasing energy demand.

"It is important to stress that shale gas would only be a low-carbon fuel source if allied with as yet unproven carbon capture and storage technologies."

The report says that the "rapid carbon reductions" needed to deal with global warming "require major investment in zero-carbon technologies and this could be delayed by exploitation of shale gas."

"The investment required to exploit shale gas will be substantial," the report says. "In relation to reducing carbon emissions this investment would be much more effective if targeted at genuinely zero or very low carbon technologies. If money is invested in shale gas then there is a real risk that this could delay the development and deployment of such technologies."

Read the study.

Political and business leaders in West Virginia are furiously working to find ways for the state to cash in with jobs and spinoff industries from the boom in drilling for natural gas in the Marcellus Shale.

But in Great Britain, scientists are warning policymakers that the experience so far in the United States shows shale-gas drilling causes serious problems.

And, those scientists are cautioning that increased use of natural gas from the drilling boom is not likely to provide the reduced greenhouse emissions proponents say it will.

In a detailed report last month, researchers at the Tyndall Centre for Climate Change Research at the University of Manchester concluded that "in an energy-hungry world, any new fossil fuel resource will only lead to additional carbon emissions" and delay the introduction of renewable energy alternatives.

"Consequently, if we are serious about our commitment to avoid dangerous climate change, the only safe place for shale gas remains in the ground," said Kevin Anderson, an engineer and researcher director for Tyndall-Manchester's Energy and Climate Change Program.

The Tyndall report concludes that "While shale-gas extraction, at a global level, does not involve the high energy and water inputs at the scale of other unconventional fuels, such as oil derived from tar sands, it does pose significant potential risks to human health and the environment.

"Principally, the potential for hazardous chemicals to enter groundwater via the extraction process must be subject to more thorough research prior to any expansion of the industry being considered," the report said.

"Additionally, while being promoted as a transition route to a low-carbon future, none of the available evidence indicates that this is likely to be the case," the report said. "It is difficult to envisage any situation other than shale gas largely being used in addition to other fossil fuel reserves and adding a further carbon burden. This would be compounded if investment in shale gas were to delay the necessary investment in zero- and very low-carbon technologies."

In their push for more natural gas, drilling operators are increasingly using a process called hydraulic fracturing, which shoots vast amounts of water, sand and chemicals deep underground to break apart rock and release the gas. More frequently, this process also involves drilling down and then turning horizontally.

West Virginia leaders are hoping this practice expands as gas companies seek to tap into vast reserves contained in the Marcellus Shale, a formation that stretches across 95,000 square miles from southern New York and into eastern Ohio.

Last week, acting governor Earl Ray Tomblin formed a "Marcellus to Manufacturing" task force aimed at encouraging spinoff chemical plants related to the natural-gas boom.

"The environmentally responsible manner in which the extraction of natural gas from Marcellus Shale occurs will bring countless jobs to West Virginia," Tomblin said in announcing the task force.

But the Tyndall researchers report that "Evidence from the U.S. suggests shale-gas extraction brings a significant risk of ground- and surface-water contamination" serious enough to warrant "a precautionary approach to development" as the "only responsible action."

"The depth of shale gas gives rise to major challenges in identifying categorically pathways of contamination of groundwater by chemicals used in the extraction process," the report said.

"An analysis of these substances suggests that many have toxic, carcinogenic or hazardous properties," the report said. "There is considerable anecdotal evidence from the U.S. that contamination of both ground- and surface-water has occurred in a range of cases."

The Tyndall report noted that the Bush administration successfully pushed to exempt hydraulic fracturing from key water quality regulations, and that the Obama administration launched a major U.S. Environmental Protection Agency study of the potential impacts of the practice.

Following a "precautionary principle" adopted by members of the European Union, the report says, "shale gas exploitation should be delayed until at least after the EPA has reported and, depending on the findings, perhaps longer."

Tyndall researchers found "little to suggest that shale gas will play a key role as a transition fuel in the move to a low-carbon economy.

"There is little evidence from data on the U.S. that shale gas is currently, or expected to, substitute at any significant level for coal use," the report said. "By contrast, projections suggest it will continue to be used in addition to coal in order to satisfy increasing energy demand.

"It is important to stress that shale gas would only be a low-carbon fuel source if allied with as yet unproven carbon capture and storage technologies."

The report says that the "rapid carbon reductions" needed to deal with global warming "require major investment in zero-carbon technologies and this could be delayed by exploitation of shale gas."

"The investment required to exploit shale gas will be substantial," the report says. "In relation to reducing carbon emissions this investment would be much more effective if targeted at genuinely zero or very low carbon technologies. If money is invested in shale gas then there is a real risk that this could delay the development and deployment of such technologies."