Triangulation in climate change vulnerability assessment: examples from Colorado, USA

Climate change vulnerability assessment is a key first step for land managers attempting to address the potential impacts of future climatic conditions on important vegetation types. We compared outcomes of three vulnerability assessments focused on major vegetation types in Colorado. Assessments differed in methods and scale, but overlapped in both qualitative and quantitative techniques, and in vegetation types assessed. Agreement on vegetation type vulnerability was 47–50% between the regional scale southwestern Colorado assessment and either of two statewide assessments. Disagreements were due to regional sampling bias, qualitative vs. quantitative climate exposure analysis, or lack of information about the vegetation type in question. The two statewide-scale assessments were in agreement on 75% of vegetation types assessed in both studies; differences were due to choice and interpretation of climate projection data. Sources of variation are categorized in relation to a taxonomy of uncertainty. We compare our iterative experience of climate change vulnerability assessment using methods adapted to the needs and means of various land management agencies to the technique of triangulation used to gradually home in on the location of an object. We clarify ways in which participant choices shape the end result and mitigate the common perception that climate science is too difficult for the lay person to use or understand.