Last November, the Supreme Court heard arguments on whether the EPA can continue to refuse to regulate carbon dioxide emissions under the Clean Air Act. The petition was brought by 12 western and northeastern states. They argued that the Clean Air Act mandates the regulation of all pollutants that may endanger public health or welfare, including effects on climate and weather.

This hearing punctuated a remarkable shift in awareness and concern about global warming among the U.S. public and political and opinion leaders. A recent Zogby poll indicated that about 70 percent of Americans believe that global warming is happening, with most of them becoming more convinced in the last two years.

No wonder. The media coverage of Hurricane Katrina and the other Category Five hurricanes during 2005, news of disappearing glaciers, and the surprising box office reception for Al Gore’s “An Inconvenient Truth” all played a role.

In addition, week by week we have heard more scientific evidence of climate-related changes. The surface temperatures in all ocean basins have warmed. Category Four and Five cyclones have been more frequent globally. Global sea level rise was 50 percent greater during 1993-2005 than the earlier part of the century. The Greenland ice cap is melting; the ocean is being gradually acidified, the distribution of plants and animals is shifting toward the poles, and their cycles of reproduction and migration are changing.

Recently, the U.S. Department of Interior proposed listing polar bears as threatened species and the National Oceanic and Atmospheric Administration announced that 2006 was the warmest year for the 48 contiguous states since regular temperature records began in 1895, surpassing the previous champion, 1998. In the announcement, NOAA officially said for the first time that man-made greenhouse gasses contributed to the long-term warming trend.

In 2005, President Bush said: “Listen, I recognize that the surface of the Earth is warmer, and that an increase in greenhouse gases caused by humans is contributing to the problem.”

Long settled in the scientific community, it appears that debate on these points within the public and political arenas has ended for all but a few. The policy debate has shifted from whether the climate will change to how to address this change.

Allstate Insurance answered for itself when it announced recently it intended to stop writing new homeowner’s policies in coastal areas of Maryland and Virginia, citing concern that a warmer Atlantic Ocean will lead to an increase in severe storms.

California took similar unilateral action. Last September, Gov. Arnold Schwarzenegger signed into law the California Global Warming Solutions Act of 2006. The act requires a statewide greenhouse gas emissions limit equivalent to 1990 levels (a 25 percent reduction) to be achieved by 2020.

Efforts are under way in other states to follow this lead and I wonder what the states in the Chesapeake Bay watershed will do. Neither Maryland, Virginia nor Pennsylvania were among the petitioners to the Supreme Court, although New York, Washington, D.C., and Baltimore were.

Global warming is of immediate interest to the mid-Atlantic. In its 2002 report, Chesapeake Futures: Choices for the 21st Century, the Scientific and Technical Advisory Committee of the Chesapeake Bay Program, described the ways that potential changes in climate could affect the region and the achievement of Bay restoration goals.

These consequences included sea level rise and the attendant erosion of shorelines and loss of wetlands and islands; an exacerbation of summer “dead zones” (areas of low oxygen water that often cannot support aquatic life); loss of eelgrass, which provides critical underwater habitat; and opening the door to invasive species from warmer climes. The report argued that these effects should be taken into account in setting goals and directing management actions, thus adapting our strategies to potential climate-related changes.

The emerging policies requiring significantly reduced greenhouse gas emissions add a new dimension. They will shift the playing field for Bay restoration in profound ways because serious efforts to mitigate global warming will affect nearly everything we are trying to manage for the restoration of the ecosystem. For example, consider these questions:

How will higher energy prices, affecting everything from fertilizer production to operation of farm machinery to transportation, change agricultural practices? What role will the production of biofuels and carbon sequestration play? Will technologies applied to reduce carbon dioxide emissions from power plants and vehicles also reduce emissions of nitrogen oxides? Will energy conservation requirements prompt more mass transit and compact development patterns?

Each of these questions has the potential to help or hurt Bay cleanup efforts, depending on how it is answered. As we think about protecting and restoring our mid-Atlantic environment, we need to look ahead and create a holistic environmental policy that restores the Bay while mitigating global warming.

Donald F. Boesch is chair of the Science Board of the Louisiana Coastal Area Ecosystem Restoration Project and was from late 2005 to 2006, the chair of the Working Group for Post-Hurricane Planning for the Louisiana Coast.

Distributed by the Bay Journal News Service