Vulnerability is the extent to which natural, built and human systems are at risk due to exposure to and consequences of climate hazards. Vulnerability is also modulated by adaptive capacity, which is a community or system's ability to respond to or recover from climate impacts. Physical, social, political and economic factors can all contribute to community adaptive capacity. Legacies of systemic racism, economic underinvestment, and legacies of extractive or polluting land uses in communities mean that not all communities or populations are equally vulnerable to the same climate risks. Learn more.

Representative concentration pathways, or RCPs, portray possible greenhouse gas and aerosol emissions scenarios.  For looking at emissions scenarios in the nearer term (by 2050 or sooner), emissions projection pathways are not dramatically different, and as our current national and international framework supports us following a high (RCP 8.5) emissions scenario, its generally suggested for both these reasons that RCP 8.5 be used for nearer-term projections. For longer term projections, conservative analyses argue for the use of RCP 8.5, but it may be relevant depending on your goals to look at moderate pathways (RCP 4.5) at the same time, thinking of each pathways as a distinct possible future. There is no crystal ball for projections but a precautionary approach would argue for seriously considering the higher emissions scenario for future pathways analysis. Learn more with Cal-Adapt.

The relevant timeframe for evaluating climate change projections for your community will depend on several factors, including what climate hazards present the highest risk in your community and the availability and certainty of the data that supports projections of those risks; the lifespans of built infrastructure that may be vulnerable to climate change impacts; and jurisdictional planning cycles that inform how long policies and planning objectives may be in effect. For example, if you are building climate adaptation into a comprehensive planning process to address urban flooding that impacts road access and infrastructure, relevant timescales for evaluating climate projections could include over the period during which the comprehensive plan is implemented (e.g., within 10 years), as well as longer-term projections that can inform capital expenditures for road infrastructure that may have a much longer lifespan than a single planning cycle (e.g., several decades).

Exposure is the extent to which people, infrastructure, natural resources, or other community assets could be harmed by a climate hazard. For example, if a building is located near a river which is expected to see increased frequency and intensity of flooding, that building may have a high risk of exposure to the flooding hazard, particularly relative to a building placed higher or farther away from the floodplain.

A good place to start is with Climate Explorer, which provides interactive graphs and maps showing past and projected climate conditions for counties and county-equivalents across the United States. Start by entering the city or county for which you want climate information. Result panels that can be explored include climate maps, which provide visualizations of climate data (e.g., average daily maximum temperature; days with >2" of preciptation) that can be viewed by historic and/or future projected conditions under multiple emission projection scenarios. These data can also be viewed with graphs that can help visualize the trends and variance associated with climate projections. For coastal regions, high-tide flooding maps are available.