After the petition appeared, the National Academy of Sciences said in a 1998 news release that "The NAS Council would like to make it clear that this petition has nothing to do with the National Academy of Sciences and that the manuscript was not published in the "Proceedings of the National Academy of Sciences" or in any other peer-reviewed journal." It also said "The petition does not reflect the conclusions of expert reports of the Academy." The NAS further noted that its own prior published study had shown that "even given the considerable uncertainties in our knowledge of the relevant phenomena, greenhouse warming poses a potential threat sufficient to merit prompt responses. Investment in mitigation measures acts as insurance protection against the great uncertainties and the possibility of dramatic surprises."