Information about changing drought patterns and the impacts of drought on ecosystems in the Northeast. The fact sheet is the outcome of a May 2016 Northeast Climate Science Center workshop on ecological drought.
Cornell Institute for Climate Smart Solutions (CICSS)
A tool which shows maps of the Palmer Drought Severity Index. The tool is updated every month. Users can also find historical conditions going back to January of 1950 and time series plots from each county in NYS. A quarterly newsletter accompanies the tool.
Climate change is expected to alter the mean and variability of future spring and summer drought and wet conditions during the twenty-first century across North America, as characterized by the Standardized Precipitation Index (SPI). Based on Coupled Model Intercomparison Project phase 5 simulations, statistically significant increases are projected in mean spring SPI over the northern part of the continent, and drier conditions across the southwest. Dry conditions in summer also increase, particularly throughout the central Great Plains. By end of century, greater changes are projected under a higher radiative forcing scenario (RCP 8.5) as compared to moderate (RCP 6.0) and lower (RCP 4.5). Analysis of projected changes standardized to a range of global warming thresholds from +1 to +4 °C reveals a consistent spatial pattern of wetter conditions in the northern and drier conditions in the southwestern part of the continent in spring that intensifies under increased warming, suggesting that the magnitude of projected changes in wetness and drought may scale with global temperature. For many regions, SPI interannual variability is also projected to increase (even for regions that are projected to become drier), indicating that climate may become more extreme under greater warming, with increased frequency of both extreme dry and wet seasons. Quantifying the direction and magnitude of projected future trends from global warming is key to informing strategies to mitigate human influence on climate and help natural and managed resources adapt.
Climate impact analyses seldom examine temporal changes in the impacts and responses associated with climate anomalies. Newspaper reports, quantitative agricultural and water resource data and a survey of drought sensitive segments of society are used to compare the impacts and responses of a 1995 drought in the New York City metropolitan area to those experienced during five previous droughts. Impacts related to surface water supplies dominated each of the drought periods studied. Over time, however, changes in water consumption habits and available reservoir capacity lead to an increase in impact severity for similar meteorological conditions. To account for these non-climatic influences on water storage, a method to adjust for trends in available reservoir storage and water use is developed and implemented. Once adjusted, a fairly strong (R2 = 70.9%) exponential relationship exists between the minimum reservoir level and Palmer Drought Severity Index experienced during each drought period. Unadjusted levels exhibit a considerably weaker (R2 = 49.0%) relationship. Changes in water consumption and reservoir capacity also influenced the enactment of voluntary and ultimately mandatory water conservation measures. These restrictions were responsible for business and industrial impacts that varied through time as technology evolved and societal attitudes changed. Minor time-dependent changes were also evident in agricultural and wildfire impacts.
Droughts and heat waves have important impacts on multiple sectors including water resources, agriculture, electricity generation, and public health, so it is important to understand how they will be affected by climate change. However, there is large uncertainty in the projected changes of these extreme events from climate models. We compare historical biases in models against their future projections to understand and attempt to constrain these uncertainties. Historical biases in precipitation, near-surface air temperature, evapotranspiration, and a land-atmospheric coupling metric are calculated for 24 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) against the North American Land Data Assimilation System Phase 2 (NLDAS-2) as reference for 1979-2005. Biases are highly correlated across variables, with some models being hotter and drier, and others wetter and cooler. Models that overestimate summer precipitation project larger increases in precipitation, evapotranspiration, and land-atmospheric coupling over important agricultural regions by the end of the 21st century (2070-2099) under RCP8.5, although the percentage variance explained is low. Changes in the characteristics of droughts and heat waves are calculated and linked to historical biases in precipitation and temperature. A method to constrain uncertainty by ranking models based on historical performance is discussed but the rankings differ widely depending on the variable considered. Despite the large uncertainty that remains in the magnitude of the changes, there is consensus amongst models that droughts and heat waves will increase in multiple regions in the US by the end of the 21st century unless climate mitigation actions are taken.