NEIWPCC member states have identified climate change, specifically the threats posed by climate change to water resources in the Northeast, as a cross-programmatic priority. Because past and current greenhouse gas emissions have committed the region and the nation to some level of climate change over the next several decades we must as decision-makers deal with the consequences. Informed policies and actions are necessary to not only reduce emissions but to adapt to the consequences of past and present conditions. NEIWPCC will track this issue and keep our member states apprised of all relevant developments.
The Earth’s climate is variable and changes over vast timeframes due to natural factors, such as changes in the earth’s orbit, solar intensity variation, changes in ocean circulation patterns, and natural events such as volcanic eruptions. However, over the past century human greenhouse gas emissions through the burning of fossil fuels and other activities have resulted in global climate change that goes far beyond natural climate variability.
Life on Earth is made possible by a system known as the “greenhouse effect” (see Figure 1), which controls the absorption of the sun’s energy by the Earth’s surface. However, the increase in atmospheric concentrations of carbon dioxide (CO2) and other greenhouse gases has enhanced the natural greenhouse gas effect, leading to increases in global average temperatures.
The 2007 IPCC Fourth Assessment Report found that “Warming of the climate system is unequivocal. As is evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.” (IPCC, 2007) The report also stated that it was “very likely”—indicating a greater than 90% certainty—that human activity is the cause for global warming seen over the past 50 years.
According to the July 2007 Union of Concerned Scientists report Confronting Climate Change in the Northeast, the Northeast has seen a 0.05°F increase in temperature annually since 1970 and average annual rainfall has been increasing in the Northeast since the 1900s.
What does the future hold for us? According to IPCC predictions of future greenhouse gas emissions scenarios, atmospheric concentrations of CO2 will either triple under the worst case scenario (continued heavy dependence on fossil fuels) or double under the best case scenario (rapid deployment of technologies that reduce our reliance on fossil fuels). According to a 2007 Union of Concerned Scientists report, both low- and high-emissions scenarios will translate into warmer summers and winters for the Northeast. By the end of the century, under the high-emissions scenario winter temperatures in the Northeast are projected to rise between 8°F to 12°F and summer temperatures anywhere from 6°F to 14°F. Under the low-emissions scenario, which requires significant reductions in atmospheric concentrations of CO2 and other greenhouse gases, winter temperatures are projected to rise between 5°F to 8°F and summer between 3°F to 7°F (UCS, 2007).
In addition, annual precipitation will likely continue to increase in the northeastern United States. According to the UCS report, by the end of the century, precipitation in the Northeast will increase by 10% or 4 inches per year. In addition, as temperatures rise, winter precipitation will increasingly fall as rain rather than snow, and snow season length and snow depth are very likely to decrease. An increase in the frequency and severity of extreme precipitation events are also projected, which would contribute to more severe flooding due to increases in runoff.
Expected climatic changes to the Northeast, including changes in precipitation patterns and amounts, temperature rise, sea level rise, and the increased frequency and severity of extreme events will have an impact on Northeast water resources. The degree of these changes will determine the severity of the impacts to water resources, such as increased water demand, altered stream flow, degraded water quality, saltwater intrusion of coastal aquifers, drought, and coastal flooding.
IPCC Fourth Assessment, 2007
Working Group I Report – Physical Science Basis http://www.ipcc.ch/ipccreports/ar4-wg1.htm
Working Group II Report – Impacts, Adaptation and Vulnerability http://www.ipcc.ch/ipccreports/ar4-wg2.htm
Working Group III Report – Mitigation of Climate Change http://www.ipcc.ch/ipccreports/ar4-wg3.htm
Union of Concerned Scientists - Northeast Climate Impacts Assessment 2007
Confronting Climate Change in the U.S. Northeast: Science, Impacts, and Solutions