Nature: Last week’s UN Intergovernmental Panel on Climate Change (IPCC) report briefly mentions geoengineering as potentially necessary to slow or stop the rise of the global average temperature. Geoengineering takes many different forms but primarily focuses on increasing reflection of sunlight or removing greenhouse gases. However, the concept has only ever been tested on small scales. Most suggested projects face strong resistance. The potential for unforeseen consequences of intentionally attempting to alter the climate has stirred both the public and the scientific community against large-scale tests. Geoengineering projects are also criticized for distracting from efforts to directly reduce emissions. However, the mention in the report appears to have given some geoengineering researchers hope that more support, both publicly and financially, for further research may be forthcoming.