Bob Howarth doesn’t go looking for fights, but he doesn’t hide from them, either. Howarth, the David R. Atkinson Professor of Ecology and Environmental Biology in the College of Agriculture and Life Sciences, has been a leader in the field of biogeochemistry for almost 40 years. His pioneering research has focused on ocean dead zones caused by nutrient pollution, methane’s role in climate change, the environmental impact of hydraulic fracturing for natural gas and the high carbon footprint of “blue” hydrogen. These groundbreaking studies have influenced policy and often sparked controversy; most recently, a lobbyist for a U.K. hydrogen group resigned just days after Howarth’s blue hydrogen study was published.
“When I decided I wanted to be a scientist, I could see biogeochemistry as a way to do science that was fun but was also something that mattered and had immediate, public impact,” Howarth said. “I’ve never set out deliberately looking for confrontation, but I have deliberately taken on questions that are challenging and where the answers matter.”
The key to answering questions that matter lies in the field itself. Biogeochemistry is inherently interdisciplinary, Howarth says, and serves as a bridge between life and earth sciences by studying the ways that biological life interacts with environmental chemistry, including the ways that humans impact those processes. When Howarth began his career in the early 1980s, biogeochemistry was still a new discipline, with few universities teaching courses in the subject and no journal devoted to the field.
Although the American Geophysical Union did not formally recognize biogeochemistry as a discipline “section” until 2000, it has been taught at Cornell continuously for 65 years, longer than at any other university in North America. Howarth founded the field’s first journal, Biogeochemistry, 35 years ago, and the field has grown dramatically since then, owing much to its critical role in understanding climate change.
‘Icon of biogeochemistry’
Among those who raised the visibility and credibility of biogeochemistry was Gene Likens, who joined the Cornell faculty in 1969. Likens, with Yale Professor Herbert Bormann, had established the Hubbard Brook Ecosystem Study, a world-renowned project in New Hampshire that has been researching the long-term interactions among air, water, soil, plants and animals for over 60 years. Likens is also credited as one of the first scientists to discover acid rain. His research and advocacy on the negative impacts of polluted rainwater informed public understanding and brought about legislative change.
“When you talk about Cornell’s long-term impact in this field, you have to include Gene Likens, the icon of biogeochemistry,” said Kate Lajtha, a professor at Oregon State University and editor-in-chief of Biogeochemistry since 2004. “When I earned my Ph.D. in the 1980s, the word ‘biogeochemistry’ was still rarely used – my degree was in botany, which is ridiculous, but they didn’t know where to put people like me that didn’t fit into the traditional academic silos."
Explore the timeline
Click on the milestones to learn more about Cornell CALS’s leadership in biogeochemistry.
‘Bob was a pioneer’
As the discipline of biogeochemistry began to blossom, it ran into the institutional walls of those academic silos. Howarth recalls having papers rejected by geology journals for being “too biological” and by biology journals for being “too geochemical.” In 1984, just four years out from earning his Ph.D., Howarth launched Biogeochemistry. Four years later Howarth and his wife, fellow biogeochemist Roxanne Marino, began the Biogeochemistry Seminar Series, featuring lectures by prominent researchers.
“Even as an absurdly young person, Bob was pushing theories, pushing boundaries, posing new ideas and causing scientific controversy,” Lajtha said. “He wasn’t afraid to throw out new theories or take on huge projects that no one before him had done.”
The excitement around the discipline led to several more faculty hires in the 1990s and to the first-ever graduate training grant for a biogeochemistry program.
“This opened up the gateway, the floodway, for multiple generations of students to be trained in biogeochemistry, including me,” said Sujay Kaushal ’97, professor at the University of Maryland and an undergraduate mentee of Howarth’s. “Bob was a pioneer. People forget, now that it’s a mainstream discipline and respected, that you had to have somebody stick their neck out to get the discipline to this point. Bob stuck his neck out there for biogeochemistry; he believed in it so much as a field.”
Howarth took a radical approach for his trailblazing 1996 study that demonstrated how nutrient pollution can cause ocean “dead zones,” where aquatic life can’t exist. He and his colleagues applied principles devised by biogeochemists like Likens to a far bigger ecosystem than previously had been studied: Howarth assembled a multidisciplinary team to investigate every natural and man-made nitrogen source in the North Atlantic, including sewage treatment plants, agricultural runoff and power plants. The series of studies the team published demonstrated a near-linear correlation between human activities and nitrogen pollution in oceans. The research was critical, not just for understanding and informing policy around nutrient pollution, but in pioneering methods of measuring large-scale human impacts – methods that are now widely used in understanding human-caused climate change.
A bright future
The work of Likens and Howarth paved the way for dozens of other Cornell researchers in biogeochemistry, and for hundreds of undergraduate and graduate students. There are now 31 biogeochemists working across disciplines at Cornell, including Ben Houlton, the Ronald P. Lynch Dean of the College of Agriculture and Life Sciences (CALS), whose research focuses on global ecosystem processes, climate change solutions and agricultural sustainability. Many of the university’s biogeochemists belong to the Department of Ecology and Evolutionary Biology, which is housed in both CALS and the College of Arts and Sciences.
Assistant Professors Xiangtao Xu and Meredith Holgerson are two of the newest biogeochemists hired by Cornell in 2019 and 2020, respectively. Xu studies global carbon modeling and ecosystem ecology in the context of climate change. Holgerson explores how ponds respond to environmental change and the role they play in the global carbon cycle. One of Holgerson’s first academic publications was in Howarth’s Biogeochemistry, on cycling of carbon dioxide and methane in small ponds.
“Usually, you’re pegged as either an aquatic or a terrestrial researcher, but Bob has influenced both fields,” Holgerson said. “By studying biogeochemistry across ecosystem types and geographic regions, he has advanced our knowledge of biogeochemical cycling in a diversity of ways.”
Howarth said he’s hopeful about the next 65 years of biogeochemistry at Cornell.
“With the hiring of these world-class researchers, I’m so excited about where we stand moving forward,” he said. “If and when I retire, I’m quite confident that there will be a long, ongoing tradition of strength in biogeochemistry at Cornell.”
Krisy Gashler is a writer for the College of Agriculture and Life Sciences.
Meet some of our biogeochemists
There are 31 researchers studying biogeochemistry across disciplines at Cornell. Meet a few of them below:
Joe Yavitt focuses on the biogeochemistry and ecology of forest, wetland and desert ecosystems.
Lou Derry studies biogeochemical processes at multiple time scales, from modern environments to the evolution of biogeochemical cycles over Earth’s history.
Christy Goodale, the Frank H.T. Rhodes Professor of Environmental Science, studies cycling of water, carbon and nitrogen through forest ecosystems.
Ben Houlton, the Ronald P. Lynch Dean of the College of Agriculture and Life Sciences, focuses on global ecosystem processes, climate change solutions and agricultural sustainability.
Xiangtao Xu studies global carbon modeling and ecosystem ecology in the context of climate change.
Meredith Holgerson explores how ponds respond to environmental change and the role they play in the global carbon cycle.
Explore the Biogeochemistry Seminar Series
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