As the U.S. Senate continues debate on climate change legislation to reduce carbon emissions, a panel of top experts at a Capitol Hill briefing co-sponsored by AAAS warned that coastal communities will be forced to adapt to climate change.
Even with effective mitigation efforts that drastically reduce global greenhouse gas emissions, the current levels of atmospheric carbon commit the globe to consequences of climate change including severe weather, sea-level rise, and ocean acidification, the panel said.
Among the hardest hit will the coastal communities, they warned, which could experience property damage, loss of habitable and arable land, and regional economic disruption.
A Shishmaref home tumbled onto the beach after rising seas undermined the bluff where it sat.
David Kennedy, an acting deputy assistant administrator at the National Oceanic and Atmospheric Administration (NOAA), said that the consequences of climate change are already being felt in the United States. Kennedy recently traveled to coastal Alaska, where he saw communities being forced to decide if they want to remain on land that is vulnerable to the rising sea-level and erosion or retreat away from the coasts.
“Many coastal communities in the United States are already being affected by the changing climate,” said Kennedy. “With so many people located in areas vulnerable to sea-level rise and extreme coastal weather, undoubtedly more communities will be forced to develop adaptation plans.”
Kennedy estimated that coastal watershed counties, which constitute only 17% of total land area in the United States, are responsible for 57% of U.S. gross domestic product and contain 53% of the nation's population.
Because the stakes are so high, Kennedy called on scientists to work with policy makers to provide information on precipitation patterns, ocean temperatures, and sea-level rise in a way that is compatible with the important decisions that need to be made about how to protect residents of coastal areas.
Held in the Russell Senate Office Building, the 9 November briefing featured Kennedy alongside Virginia Burkett, chief scientist for global change research at the U.S. Geological Survey; Ken Caldeira, senior scientist at the department of global ecology at the Carnegie Institution of Washington; and Vicki Arroyo, executive director of the Georgetown State and Federal Climate Resource Center. Co-sponsored by the AAAS Center for Science, Technology, and Congress and the Communication Partnership for Science and the Sea (COMPASS), the briefing was geared for congressional staffers and focused on climate change impacts and adaptation options.
Kasey White, senior program associate at the AAAS center, said that while states and the federal government have begun to develop mitigation plans, very little attention has been paid to adaptation.
“Policymakers and the public are going to look to scientists for expert advice on which areas are most threatened, and which adaptation methods bring the highest chance of success,” said White. “Scientists once again have an important issue in which their expertise can help develop policy.”
The briefing was held just days after the first of several Senate committees to review climate change legislation approved the Clean Energy Jobs and American Power Act. Authored by U.S. Senators Barbara Boxer (D-California) and John Kerry (D-Massachusetts), the bill proposes a mitigation cap-and-trade program where polluters can buy and sell a finite number of allowances to discharge greenhouse gases.
In June this year, the U.S. House of Representatives passed its version of a climate change bill (H.R. 2454), authored by U.S. Representatives Henry Waxman (D-California) and Edward Markey (D-Massachusetts).
Burkett, who was a lead author on the United Nations Intergovernmental Panel on Climate Change Third (2001) and Forth (2007) Assessment Reports, said that the changing climate appears to have increased the pace of sea-level rise to dangerous levels—from around 1.7 millimeters per year over the past century—to a current rate of 3.1 millimeters.
Sea-level rise is caused by an increase in ocean temperatures due to the expansion of water molecules and melting of polar ice.
As saltwater creeps into freshwater and brackish estuaries and wetlands, many plants are unable to survive the increase in salinity—leading to ghost forests which contain little plant life.
Beyond sea-level rise, climate change is also blamed for an increase in extreme weather patterns like hurricanes that destroy ecosystems and cause coastal erosion. Burkett estimates that Louisiana lost 217 square miles of land following Hurricane Katrina in 2005.
Burkett cited the Biloxi-Chitimacha tribe's decision to abandon the Isle de Jean Charles as a real-life example of how climate change is affecting communities. For more than 170 years, the tribe, which is related to the Choctaw and part of a larger confederation of Muskogees, lived on a narrow patch of land between Bayou Terrebonne and Bayou Pointe-aux-Chene in southeastern Louisiana's Terrebonne Parish.
Burkett said that the tribal chief recently announced that they are going to abandon their ancestral homeland for higher ground because their homes have flooded five times in the past six years. While climate change is not solely responsible for the flooding, Burkett said it is a contributing factor.
“People are going to need to retreat or adapt their homes because a lot of land on which people live is just not sustainable for residency,” said Burkett. Adaptation methods include halting development in vulnerable areas, building houses on stilts, flood-proofing homes, or restoring natural ecological buffers.
Caldeira, a coordinating lead author of a 2005 IPCC report chapter on ocean carbon storage, said that most carbon in the atmosphere is eventually absorbed by the world's oceans, which causes the ocean to become more acidic. As oceanic pH drops, the ecosystem becomes less hospitable for many forms of marine life including corals, and organisms like clams and oysters that use calcium carbonate in their shells. The acidity makes it more difficult for corals to build their skeletons, and in high enough concentrations can cause shells to dissolve.
He warned that the warming effect of carbon released today will not be fully felt for another 40 years. “There are a lot of emissions in the pipeline,” he said, noting that mitigation and adaptation are both necessary to address these impacts.
Mitigation is also important because there are some consequences of climate change—ocean acidification, for example—for which there are few effective adaptation methods.
Caldeira also spoke about ocean acidification at an event in the evening at AAAS headquarters alongside Steve Murawski, director of scientific programs and chief science advisor at NOAA Fisheries. The event, co-sponsored by AAAS, Georgetown University, and the American Chemical Society and entitled “Acid Bath: The Impact of Increased Carbon on the Oceans” was the first of three installments of the Global Challenges series at AAAS in November.
“We need to come to the point-of-view where we stop using the world's oceans and atmosphere as a waste dump,” Caldeira said at the evening event.
Murawski said that ocean acidification greatly affects biodiversity, which in turn can have tremendous implications for local economies. He said that more than 50% of U.S. marine catch is a bivalve or crustacean, which has difficulty building shells in low-pH water. In addition, he warned that a decrease in biodiversity will lead to other vulnerabilities that scientists have not yet discovered.
“We hope that over generations, organisms will adapt,” said Murawski. “But failing that, this is a doomsday scenario. Oceans are reaching their capacity.”
In the afternoon, Arroyo said that with 12 states developing or having completed an adaptation plan looking at climate change impacts to infrastructure, private property, public health, wildlife habitat, industry, and tourism, local officials are beginning to take the threat seriously.
Public officials in California estimate that a sea-level rise of 55 inches—forecast in some models by 2100—could put 480,000 people at risk, cause $100 billion in damage, and lead to a $46 billion loss in the coastal economy. In the Bay Area alone, 270,000 would be at risk with $62 billion dollars in property damage. In Maryland, a rise of two to three feet in sea-level could have a major disruption to the state's economy due to the Chesapeake Bay's tidal shoreline. Arroyo pointed out that the Chesapeake Bay's shoreline (Maryland, Virginia, and Delaware) is more extensive than California's coastline.
Arroyo cited a Florida program that offers homeowners free wind inspection visits and small grants to harden their homes. She said the program was popular because the cost of hardening their homes was usually covered over time by the drop in home owners insurance.
“These successful strategies will hopefully show state and local governments that adapting to climate change can have immediate economic benefits,” she said.