Downscaling the IPCC: The 2008 and 2014 Colorado Climate Assessments

The last two years have seen the release of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) and the third US National Climate Assessment (NCA). In addition to these high profile climate assessments, many regional, state, and municipal entities are leveraging the emerging climate science and scaling the process and the data to develop climate assessments relevant to decision making at sub-national scales. One such example is the assessment Climate Change in Colorado: A Synthesis to Support Water Resources Management and Adaptation. The report (released in August 2014) expands and updates an earlier Climate Change in Colorado assessment that was published in October 2008.

The 2008 Colorado assessment took a hybrid approach to assessment, marrying the IPCC Working Group I focus on physical science, with the adaptation components raditionally embedded within Working Group II. The Colorado assessment approach included the transparency and open review that underpin the credibility of the IPCC and NCA processes. A modest amount of original research was undertaken, which is a slight deviation from the IPCC and NCA processes. The state-based process also used a co-production model that engages users directly at the outset of the process. The 2008 and 2014 reports used the same process, but the newer assesment is vastly expanded in scope.

The efficacy of the process is demonstrated by the use of the Colorado assessments by decision makers. The science in the 2008 report supported the Colorado State Drought Plan, Climate Adaptation Plans for several Colorado Counties, and the State Water Supply Initiative. Components of the 2014 assessment have been used as the science basis for Denver's Climate Adaptation Plan.

Decisions that involve climate adaptation tend to happen at sub-regional scales. Consequently, IPCC and NCA documents are not as informative for adaptation planning at regional and state scales as localized assessments. This does not diminish the importance of the IPCC and NCA. Without concerted effort at larger scales, the rich pool of climate science available to inform efforts at smaller scales would not exist. Ensuring that processes are implemented that connect climate assessment at multiple scales will ensure the value of climate assessments in decision making.