The National Research Council summary of warnings associated with climate change:
“Core features of the climate change situation are known with confidence. The greenhouse effect associated with the carbon dioxide molecule has been measured, as has the dwell time of that molecule and its concentration in the atmosphere. We also know that the rate at which carbon dioxide is currently being added to the atmosphere substantially exceeds the natural rate that prevailed before the rise of human societies. That means that a large and unprecedentedly rapid thermal impulse is being imparted to the earth’s ecology that will have to be balanced in some fashion. We know beyond reasonable doubt that the consequences will be extensive. We do not, however, know the timing, magnitude, or character of those consequences with sufficient precision to make predictions that meet scientific standards of confidence.
In principle the thermal impulse could be mitigated to a degree that would presumably preserve the current operating conditions of human societies, but the global effort required to do that is not being undertaken and cannot be presumed. As a practical matter, that means that significant burdens of adaptation will be imposed on all societies and that unusually severe climate perturbations will encountered in some parts of the world over the next decade with an increasing frequency and severity thereafter. There is compelling reason to presume that specific failures of adaptation will occur with consequences more severe than any yet experienced, severe enough to compel more extensive international engagement than has yet been anticipated or organized.
This report has been prepared at the request of the U.S. intelligence community with these circumstances in mind. It summarizes what is currently known about the security effects of climate perturbations, admitting the inherent complexities and the very considerable uncertainties involved. But under the presumption that these effects will be of increasing significance, it outlines the monitoring activities that the intelligence community should be developing in support of improved anticipation, more effective prevention efforts, and more decisive emergency reaction when that becomes necessary.” [Emphasis added]