“There have been and will continue to be changes in precipitation amounts, frequency of storms, and intensity of storms. These changes will present
challenges to the turfgrass industry in the establishment of turfgrass stands and the maintenance of stands. Awareness of the potential changes creates an opportunity to develop adaptation and management strategies to cope with the changing precipitation regime for any location. These will be site-specific practices;
however, they will all involve management of the water that comes from precipitation in the most effective manner to ensure the viability of the turfgrass industry."
Figure 2. Trends in precipitation throughout the remainder of the 21st century. Te higher emission scenario projects precipitation trends if the carbon dioxide concentrations continue with the same rate of increase as observed today. Figure published in the National Climate Assessment 2014 (
https://www.globalchange.gov/nca4).
Changes in Precipitation Observations throughout the continental U.S. have shown that there are areas that have gotten wetter, e.g., the upper Midwest, and areas that have decreased in precipitation, e.g., the Southwest, as shown in Figure 1 from the National Climate assessment. Te cautionary tale is that when we talk about changes in precipitation or trends in precipitation, these have to be location specific. If you study the picture, the changes over the past 20 years are quite variable across the United States. What is consistent across all regions is that precipitation amounts have changed either in a positive or negative direction.
Te projection of future trends shown above in Figure 2 as estimated from climate models depicts that autumn, winter, and spring will become wetter in the upper half of the United States while the southern states will have drier conditions. Inversely, summers in the United States are projected to become drier compared to our current amounts. Estimation of changes in precipitation is one of the most difficult processes to predict in climate models; however, the ensemble of models used agree on these general trends. Te observed data from the U.S.
TPI Turf News September/October 2019
meteorological observation network reinforces these diagrams because the observed data also show these trends in precipitation patterns.
Shifts in Precipitation Patterns Annual precipitation amounts have been increasing as depicted in the long-term observations from Ohio since 1895 (Fig. 3). Te 30-year normals have shown an increase since the decades of the 1930s with a three percent increase each decade. Furthermore, the annual precipitation totals have shown there is a decrease in years with abnormally low precipitation totals. For the upper Midwest, these trends in increasing precipitation are evident but in the southeast, the trends are towards declining precipitation. Tese data are available for every state through the National Oceanic and Atmospheric Administration (NOAA) and the normal precipitation amounts by month and year are available on several sites. I recommend
https://statesummaries.ncics.org where you can find state level information on various climate parameters along with a discussion about the data. In Georgia for example, there has been a slight increase in annual precipitation with a marked decrease in summer precipitation amounts.
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