Decision Making in a Changing Climate - World Resources Institute

xGlossary of Key TermsGlossaryAdaptation: “Adjustment in natural or human systems to a new or changingenvironment. Adaptation to climate change refers to adjustment in naturalor human systems in response to actual or expected climatic stimuli or theireffects, which moderates harm or exploits beneficial opportunities.” 1Adaptive capacity: “The ability of a system to adjust to climate change(including climate variability and extremes) to moderate potential damages, totake advantage of opportunities, or to cope with the consequences” 2Climate: “Climate in a narrow sense is usually defined as the ‘averageweather’ or more rigorously as the statistical description in terms of the meanand variability of relevant quantities over a period of time ranging from monthsto thousands or millions of years. The classical period is 30 years, as definedby the World Meteorological Organization (WMO). These relevant quantitiesare most often surface variables such as temperature, precipitation, and wind.Climate in a wider sense is the state, including a statistical description, of theclimate system.” 3Hazard: The physical manifestation of climate change/variability (e.g.precipitation increase) as it affects human systems. The outcome of a hazard isan impact. 10Heightened variability: Increases in climate variability(see climate variability).Hundred-year event: An event that has a 1 in 100 chance of occurring. 11Long-term change: A change in the mean climate system that persistsfor decades or longer. 12Maladaptation: “Any changes in natural or human systems that inadvertentlyincrease vulnerability to climatic stimuli; an adaptation that does notsucceed in reducing vulnerability but increases it instead.” 13Mean state of the climate system: Average state of the climateClimate change: “Climate change refers to a statistically significant variationin either the mean state (see definition below) of the climate or in itsvariability, persisting for an extended period (typically decades or longer).” 4system over a given period. 1Mitigation: “An anthropogenic intervention to reduce the sources orenhance the sinks of greenhouse gases.” 14Climate impacts: “Consequences of climate change on natural andhuman systems.” 5Climate system: “The climate system is the highly complex systemconsisting of five major components: the atmosphere, the hydrosphere (water),the cryosphere (ice), the land surface and the biosphere (living organisms),and the interactions between them.” 6Climate variability: “Climate variability refers to variations in the meanstate and other statistics (such as standard deviations, the occurrence ofextremes, etc.) of the climate on all temporal and spatial scales beyond that ofindividual weather events. Variability may be due to natural internal processeswithin the climate system (internal variability), or to variations in natural oranthropogenic external forcing (external variability).” 7Coordination: The process by which different levels of government anddifferent ministries, agencies and actors harmonize work on a common issue.Natural cycles: A process in which elements are continually cycled invarious forms through different compartments of the environment (air, water,soil, organisms). 15Resilience: “Amount of change a system can undergo without changingstate.” 17 Some view vulnerability as the opposite of resilience, meaningthat a reduction in vulnerability is the same as an increase in resilience, 18 butresilience could indicate an ability to return to the status quo whereas reducingvulnerability can lead to an improvement from the status quo.Risk: The probability of a hazard’s occurrence. 16Sensitivity: “The degree to which a system is affected, either adverselyor beneficially, by climate-related stimuli. The effect may be direct (e.g. achange in crop yield in response to a change in the mean, range or variability oftemperature) or indirect (e.g. damages caused by an increase in the frequencyof coastal flooding due to sea level rise).” 19World Resources 2010-2011Exposure: “The nature and degree to which a system is exposed to significantclimate variations.” 8Extreme event: “An extreme weather event is an event that is rare at aparticular place and time of year. . . . By definition, the characteristics of whatis called extreme weather may vary from place to place in an absolute sense.Single extreme events cannot be simply and directly attributed to anthropogenicclimate change, as there is always a finite chance the event in questionmight have occurred naturally. When a pattern of extreme weather persists forsome time, such as a season, it may be classed as an extreme climate event,especially if it yields an average or total that is itself extreme (e.g. drought orheavy rainfall over a season).” 9Vulnerability: “The degree to which a system is susceptible to, andunable to cope with, adverse effects of climate change, including climate variabilityand extremes. Vulnerability is a function of the character, magnitude, andrate of climate change and variation to which a system is exposed, its sensitivity,and its adaptive capacity.” 20