Murphy administration launches projection tool for extreme precipitation

TRENTON, NJ — As part of its commitment to making the state more resilient to the impacts of climate change, on April 19, during Earth Week, the New Jersey Department of Environmental Protection launched an online tool that will help planners, local governments, developers and residents better understand that extreme precipitation events are increasing, as confirmed by recent studies by the Northeast Regional Climate Center. Improved understanding will help decision-makers and the public take informed actions necessary to adapt to a changing climate.

The New Jersey Extreme Precipitation Projection Tool allows users to view a range of rainfall depths, with options for frequencies, emission scenarios and time periods. Due to increasing greenhouse gas emissions and a changing climate, extreme precipitation events are expected to increase in frequency and intensity throughout the century.

The tool allows users to zoom in to local areas and view a depiction of the likely precipitation depth that would occur with various storm scenarios. It also allows users to compare this projection with the values currently published in the National Oceanic and Atmospheric Administration Atlas 14 reference report. 

“While Earth Week is certainly a time to celebrate our planet and our environment, it is also a time to commit to making hard choices to adapt to a changing planet and become more resilient,” NJDEP Commissioner Shawn M. LaTourette said. “This Extreme Precipitation Projection Tool is an investment in our planet by helping to open our eyes to the realities of climate change–induced flooding and helping us make better decisions on how and where we build. This tool will help all of us make informed choices to ensure that development is able to withstand the test of a changing planet.”

The tool incorporates the important findings detailed in two New Jersey–specific studies by the Northeast Regional Climate Center at Cornell University and in partnership with NJDEP. The studies, released in November, found that extreme precipitation events have been increasing for the past 20 years and are going to continue to increase throughout the end of the century.

The studies found that precipitation expectations that long guided state policy, planning and development criteria, and which rely upon data obtained through 2000, do not accurately reflect current precipitation intensity conditions. By including additional data through 2019, extreme precipitation amounts are 2.5-percent higher, and some parts of the state have seen a 10-percent increase from the outdated data. The studies also found that precipitation is likely to increase by more than 20 percent from the historical baseline, which is 1950 to 1999, through 2100, and projected changes will be greater in the northern part of the state than in the southern and coastal areas, with upper likelihood projections for some northwestern counties seeing the greatest increases, by as much as 50 percent. 

NJDEP will be using the Extreme Precipitation Projection Tool in planning and decision-making processes and encourages local government agencies, planners and developers to use the tool when assessing needs for flood hazard and stormwater management permits.

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