Climate Change

Climate change refers to fluctuations in the Earth’s climate over a long period of time. Defined as the average of global or of a locale’s weather patterns over an extended period of time, climate is different from normal variations in weather, which can change on a regional scale, hour to hour, day to day, season to season. 

Current estimates geologically date the Earth to about 4.5 billion years, and it is important to note that the Earth’s climate has changed over time. In more recent history, the northern hemisphere experienced above average temperatures from the eleventh century through the fifteenth century, while the seventeenth through mid-nineteenth century experienced temperatures that were colder than normal. Climate can also vary on a short term basis due to volcanic eruptions or certain shifts in the Earth’s system, for example, El Niño, La Niña, or North Atlantic oscillation patterns.   

It is common knowledge that greenhouse gases, such as carbon dioxide, methane, ozone, and water vapor, absorb radiation in the atmosphere, naturally heating the Earth's surface. Without this greenhouse effect, the Earth would be inhabitable for most forms of life. However, scientists are attributing the record rate of warming of the twentieth century and present day to a human activity-enhanced greenhouse effect. As humans create and release more man-made greenhouse gases into the atmosphere, the natural greenhouse effect is magnified, trapping more heat than is released into space and causing more warming of the Earth’s surface. 

This amplified level of warming is a concern. Scientists all over the world are studying the occurrence of climate change over the past century and the impacts it will have on the Earth in the future. Calls for adaptation at all levels - internationally, nationally, and locally - are being sounded. The discussion of climate change has been brought out of the laboratory and into the forefront.

Local climate change impacts for the Delaware River Basin include increased temperature, changes in precipitation patterns, and sea level rise, all of which affect water supply and water quality. Increased temperatures will affect evapotranspiration rates and stream water quality; turbidity levels will likely increase, and dissolved oxygen levels decrease. Precipitation is predicted to occur in the form of fewer, more intense storms occurring in the winter months. This means a potential increase in flood events coupled with extended drought cycles.  The seasonality of flows may also change, for example, less snowpack may cause lower flows in the spring. Sea level rise may require increased releases from storage to augment river flows to repel salinity and/or costly modifications by water suppliers to treat increases in dissolved solids. Climate change could also affect instream flow and temperature conditions for aquatic biota. These potential impacts have been discussed in DRBC's 2019 State of the Delaware River Basin Report - see pages 16-18 (pdf 5.3 MB).

The effects of climate change are being considered as DRBC plans for future water supply availability. Modeling and other analyses are already underway to further define the range of risks due to climate change as well as evaluate future water demands for different purposes. Once this work has been completed, different approaches and mitigation measures will be needed to develop robust plans and resources to address the risks posed by climate change.

DRBC Presentations:

Climate Change Links of Interest


Intergovernmental Panel on Climate Change

Center for Climate and Energy Solutions (formerly PEW Center on Global Climate Change)

United Nations Environment Programme

United Nations Gateway to Climate Change

World Meteorological Organization


Adaptation Clearinghouse

Advisory Committee on Water Information's Water Resources Adaptation to Climate Change Workgroup

American University School of International Service: Finding Hope in Climate Engineering

Climate Central and its Surging Seas Sea Level Rise Risk Finder Tool

Milken Institute School of Public Health (of George Washington University): 53 Sources for Climate Change News and Realistic Ways You can Combat Climate Change, Today 

National Aeronautics and Space Administration (NASA) - Global Climate Change

National Oceanic and Atmospheric Administration (NOAA)

NOAA's Climate Program Office

NOAA Tides and Currents: Sea Level Trends

Natural Resources Defense Council

Sea Level Rise and Coastal Flood Web Tools Comparison Matrix

Union of Concerned Scientists (UCS)

United States (U.S.) Global Change Research Program

U.S. Department of Energy

U.S. Department of State

U.S. EPA: Addressing Climate Change in the Water Sector

U.S. Geological Survey (USGS): Northeast Climate Adaptation Science Center

USGS Climate and Land Use Change: FAQ

USGS: Land Resources

USGS: Sea Level Change

USGS Report: "Climate Change and Water Resources Management - A Federal Perspective"

Water Environment Research Foundation

Regional and Local

Carol Collier, former DRBC Executive Director: "Climate Change Impacts: Actions Needed to Protect the Water Resources of the Delaware River Basin" - presented at an Union of Concerned Scientists-sponsored event held at the John Heinz National Wildlife Refuge, January 2010 (pdf 3.97 MB).

City of Philadelphia: Growing Stronger - Toward a Climate Ready Philadelphia

Clean Air Cool Planet

Common Waters Partnership/Pinchot Institute for Conservation: "Adapting to a Changing Climate: Risks and Opportunities for the Upper Delaware River Region" (pdf 13 MB)

Consortium for Climate Risk in the Urban Northeast

Delaware Department of Natural Resources and Environmental Control (DNREC)

DNREC - Climate Change and Delaware

Delaware Valley Regional Planning Commission: Energy and Climate Change Initiatives

Dr. Anthony Broccoli, Rutgers University: "Future Changes in Climate, Sea Level, and Hydrology" - presented at the July 19, 2006 DRBC Meeting (pdf 7 MB). Click here for more information on Rutgers University's climate change research.

Dr. Michael Oppenheimer (Co-author), Princeton University (2005): "Future Sea Level Rise and the New Jersey Coast: Assessing Potential Impacts and Opportunities"

Graduate Students, University of Pennsylvania's School of Design, Fall 2008: "Climate Change: Impacts and Responses in the Delaware River Basin" (pdf 60 MB; powerpoint presented at the December 10, 2008 DRBC Meeting). This project was made possible by grant funding from the William Penn Foundation.

New Jersey Climate Adaptation Alliance

New Jersey Department of Environmental Protection: Adapting to a Changing Environment


New York City Department of Environmental Protection's Climate Change Program

New York City Mayor's Office of Recovery and Resiliency

New York State Department of Environmental Conservation's (NYSDEC) Office of Climate Change

NYSDEC Energy and Climate - Climate Change

Northeast Regional Climate Center

Office of the Delaware State Climatologist

Office of the New Jersey State Climatologist

Office of the Pennsylvania State Climatologist


Partnership for the Delaware Estuary (PDE) - Climate Change

PDE: Technical Report for the Delaware Estuary and Basin - Chapter 7 Climate Change (2017)

PDE: Additional Climate Change Data and Reports

Penn Future: Climate Change

Pennsylvania Department of Conservation and Natural Resources (PA DCNR): Addressing Climate Change on Public Lands

Pennsylvania Department of Environmental Protection: Climate Change

Pennsylvania Environmental Council - Pennsylvania Climate Roadmap

Union of Concerned Scientists Global Warming Regional Information - Northeastern States

U.S. Army Corps of Engineers' North Atlantic Coast Comprehensive Study

U.S. EPA Report (2009): "Coastal Sensitivity to Sea Level Rise: A Focus on the Mid-Atlantic Region" (pdf 7.2 MB)

U.S. EPA/DRBC Joint Report (1986): "Greenhouse Effect, Sea Level Rise, and Salinity in the Delaware Estuary"

USGS Report (1994): "Sensitivity of Water Resources of the Delaware River Basin to Climate Variability and Change"