Waterworld: The Radcliffe Lectures

Around the Institute
Illustration by David Pohl
By Steve Nadis

Radcliffe unofficially deemed 2012 the year of water. The Institute hosted a “Future of Water” symposium in October and ran a Water Lecture Series throughout the fall, featuring four Harvard professors. The theme for 2012 was timely, given the extreme drought in the United States—where more than half the nation’s counties were declared “disaster areas” by the Agriculture Department—and the extreme flooding inflicted upon New Jersey and New York by Hurricane Sandy.

James McCarthy, the Alexander Agassiz Professor of Biological Oceanography at Harvard, kicked off the series with a broad introduction to the subject, describing the hydrological cycle and the general distribution of water. The vast majority of the earth’s water—more than 97 percent—is in the ocean; only about 2.5 percent is freshwater, most of which is locked up in the ice sheets of Antarctica and Greenland, leaving just 0.4 percent as surface freshwater and water vapor. In the summer of 2012, the extent of Arctic sea ice hit a record low. And for four straight days in July, Greenland’s entire surface remained above water’s melting temperature, “which has never been seen before,” McCarthy said. “This set off alarm bells that gave us all pause.”

As the oceans warm, water expands, triggering a rise in sea level; the melting of ice sheets and glaciers contributes to that rise. If humans fail to curb global emissions of greenhouse gases, the earth could become as warm as it was 30 million years ago, when sea level was 20 to 30 meters higher, McCarthy said. “But back then we didn’t have cities like Boston sitting just a meter or so above sea level.”

Pollutants Disrupt Hormonal Function

Joan Ruderman—Radcliffe’s senior science advisor and the newly appointed president and director of the Marine Biological Laboratory in Woods Hole—talked about her current research focus, “environmental estrogens,” which she defined as “synthetic chemicals that are designed for one purpose but are later found to have the additional property of being able to mimic estrogen or antagonize estrogen.” Estrogen is a hormone that plays a critical role in human fetal development and in later stages of life.

Environmental estrogens pose an insidious problem, given that 200 chemicals—including one-fourth of the pesticides tested so far—are known to interfere with hormonal function. Meanwhile, the list of environmental contami­nants keeps growing. Complicating matters is the fact that the risk posed by a synthetic compound from its chemical structure can’t be determined. “More than 100,000 chemicals are used in agriculture, manufacturing, and consumer products, and very few of them have been tested for toxicity or the ability to mimic or disrupt estrogen,” Ruderman said. She advocates a large-scale screening program and recommends zebra fish—which reach maturity in about a day—as convenient and economical test subjects.

Climate Change Drives Disease

John Mekalanos, who heads Harvard Medical School’s Department of Microbiology and Immunology, discussed the biology of cholera—a disease that is spread by feces-contaminated water and has plagued humanity for at least 2,000 years. Cholera is an intestinal disease, caused by the bacterium vibrio cholera, which is often lethal if left untreated. Unfortunately, new and more deadly strains of the bacterium have emerged, including one that appeared in the 1960s and another in the 1990s. “These two strains cause basically all of the cholera today,” Mekalanos noted, adding that it’s a moving target. “As microbiologists, we’re faced with a challenge in the future as these organisms respond and adapt to their settings.”

A cholera pandemic broke out in Haiti in 2011, following the massive 2010 earthquake, and killed more than 7,000 people; 20,000 additional cases occurred in the neighboring Dominican Republic. Mekalanos and his collaborators sequenced the strain responsible for the Haiti outbreak and determined that it was practically identical to the strain behind a previous outbreak in Nepal. He suspects that a relief worker from Nepal brought the disease to Haiti, which had been cholera-free for roughly a century. “In the future,” Mekalanos said, “relief workers and security forces need to be treated with antibiotics or vaccines to prevent the introduction of cholera in regions that are at high risk for the disease.”

We’re All Test Subjects

In a sense, suggested Daniel Schrag, the Sturgis Hooper Professor of Geology at Harvard, we’re all test subjects in the ongoing experiment known as global warming. “Nobody understands the earth’s system well enough to predict what will happen,” he said, “and there are going to be surprises.”

Hurricane Sandy provided some indication of the surprises ahead. Late-October hurricanes normally die out quickly as they move into cooler northern waters. But Sandy gained strength as it went from North Carolina to New Jersey, because ocean temperatures were four to five degrees warmer than the long-term historical average. In addition, changes in the jet stream, stemming from the loss of Arctic sea ice, could be causing more hurricanes to make landfall rather than stay at sea—a phenomenon observed with increasing frequency since 2007. Storms like Sandy, Schrag warned, could become “the new normal.”

When a high school student in the audience asked Schrag what she and her classmates should do to make their school more sustainable, he said the most important thing would be “to educate each other, read and be aware, and educate your parents.” For every hour you spend trying to cut down on your school’s greenhouse gas emissions, he added, “you should spend 10 hours teaching each other the latest information on climate change.”


Illustrations by David Pohl

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2013