Local changePanel 1. Metrics of climate change within a grid cell. From period t1 to t2, the climate within a given cell (lower left corner) is altered on a scale that can represent average or extreme climates, or the timing of climatic events.
Examples of metricsExamples of ecological applications
MAGNITUDE
Anomalies: the difference in climate parameters at a given locality over time.Examining the influence of Quaternary climate changes on European dung beetle (14) and amphibian and reptile (12) diversity patterns, and of future climate changes across global mountain systems (116).
Standardized anomalies*: the Euclidean distance between baseline and future climate at a given locality, standardized by historical interannual climate variability (23).Examining the exposure of different localities (cells) worldwide to future climate changes in relation to existing biodiversity (23, 24).
Change in the probability of extremes*: the difference over time, at a given locality, in the magnitude of extreme climatic events, or in the probability of occurrence of the most extreme historical climatic event (117).Examining the influence of extreme climates on invasion susceptibility of plant communities in north-central Chile over the past decades (26).
TIMING
Change in seasonality: the difference over time in the timing of climatic events.Assessing the role of delayed snowmelt on the hibernation emergence date of ground squirrels in Canada (33).
Regional changePanel 2. Metrics of change across grid cells. Between periods t1 and t2, the climate of a given cell (lower left corner) becomes less available across the entire region (from four to two cells), and more distant (longer arrows). The lightest shade in t1 corresponds to disappearing climates, whereas the darkest shade in t2 emerges as a novel climate.
Examples of metricsExamples of ecological applications
AVAILABILITY
Change in area of analogous climates*: the change over time in area experiencing similar climates [defined with reference to the difference between climates (23, 34), classification rules (118), histograms (35), or clustering analysis (119)].Exploring climate determinants of centers of rarity for Northern Hemisphere plant, bird, and butterfly species (8), and assessing the role of changes in Late Quaternary climate availability on mammal extinctions (21).
Novel climates*: emergence of future climatic conditions not found at present [future conditions that are most dissimilar to baseline climates (23), that do not overlap with present conditions in environmental space (29), or that lack baseline-analogs as defined above]. Conversely, disappearing climates refer to the disappearance of extant climates.Examining plant associations in eastern North America over the past 18,000 years, and testing whether the associations most dissimilar to today’s associations occur in areas where past climates were also most dissimilar to today’s climates (76, 77).
POSITION
Change in distance to analogous climates*: the change over time in the distance to similar climates (as defined above for the change in area of analogous climates).Assessing the role of Late Quaternary climate movements on mammal extinctions (21).
Climate change velocity*: the ratio of the temporal climatic gradient at a given locality to the spatial climatic gradient across neighboring cells (9).Predicting climate residence time in global protected areas (9), and comparing past climate velocities to Australian bird distribution shifts (19) and to global vertebrate endemism (16).
*Climate change metric implemented in our global comparison of climate change patterns.