A surge in natural gas supplies worldwide could halt any meaningful growth in the renewable energy sector over the next two decades if governments don’t take action, the International Energy Agency (IEA) warns. New technologies to extract natural gas, primarily from shale formations using a technique known as hydraulic fracturing, could triple production of unconventional gas globally between 2010 to 2035, to about 1.6 trillion cubic meters, according to a new IEA report. These new sources of supply will, in turn, help keep prices relatively low, posing an increased risk to renewable energy sources, which are more expensive in part because the costs of greenhouse gas emissions are not part of the calculation of energy costs. “Policy measures by governments for renewable energy have to be there for years to come, as it is not always as cost-effective as it could be,” Maria van der Hoeven, executive director of the IEA, told a conference in London, according to the Guardian. While natural gas drilling on its face produces about half of the carbon emissions of coal burning, some experts say the methane released during the drilling process may be enough to offset the global warming benefits of switching from coal to gas.