Climate Risk Score Calculator

This score follows the IPCC formulation in which climate risk arises from the interaction of three components rather than from climate change alone: hazard, the physical event or trend; exposure, the people and assets located where the hazard occurs; and vulnerability, the propensity to be harmed once exposed. The three are multiplied rather than added because risk collapses to near zero if any one is absent - a severe drought over uninhabited terrain, or a well-defended city facing no hazard, both score low. Here the hazard term is a weighted blend of temperature anomaly (40 percent), precipitation change (30 percent) and sea level rise (30 percent), each capped at 100 and scaled so that roughly 4 degrees C of warming, a 40 percent shift in rainfall or 100 cm of sea level rise saturates its sub-index. Precipitation uses absolute change because both drying and intensification are damaging; departures beyond about 20 percent from the historical baseline are conventionally treated as high hazard. Exposure is scaled logarithmically with population because impacts do not grow in proportion to headcount, and vulnerability is simply 100 minus adaptive capacity, which typically sits around 60 to 80 for high-income countries and 20 to 40 for least developed ones. The result is a comparative index, not a probability or a loss estimate. Its weakest point is linearity: tipping elements such as the West Antarctic ice sheet or Amazon dieback introduce threshold behaviour that no weighted sum reproduces. Results also depend heavily on the emissions scenario assumed, and local factors such as drainage, building stock and land tenure are invisible at this resolution.

The decomposition of risk into hazard, exposure and vulnerability came from the disaster risk reduction community rather than from climate science. Early IPCC reports, through the Third Assessment in 2001 and the Fourth in 2007, framed vulnerability as a function of exposure, sensitivity and adaptive capacity, which conflated the physical event with the social condition. The 2012 IPCC special report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation, generally abbreviated SREX, reconciled the two traditions by placing risk at the intersection of climate hazards, exposure and vulnerability. The Fifth Assessment Report Working Group II volume adopted that structure in 2014, and the Sixth Assessment Report retained it in 2022 while adding response risk from maladaptive actions. Operational indices followed the conceptual shift. The Notre Dame Global Adaptation Initiative country index, developed from the Global Adaptation Index founded in 2010 and moved to the University of Notre Dame in 2013, ranks countries by combining exposure, sensitivity and adaptive capacity across sectors such as food, water, health and infrastructure. The World Bank Climate Change Knowledge Portal made downscaled projections widely available for national and subnational screening. In parallel, the financial sector adopted similar scoring after the Task Force on Climate-related Financial Disclosures published its recommendations in 2017, which required firms to assess physical as well as transition risk and drove demand for asset-level hazard and vulnerability scores.