June 5, 2019
Dr. David Trossman earned a BA in mathematics and a BA/MA in physics from Washington University in St. Louis, a MA in public policy from the University of Chicago, and a PhD in physical oceanography from the University of Washington-Seattle before moving on to do postdocs, work at NASA, and land at the Institute for Computational Engineering and Sciences at the University of Texas-Austin, where he currently works as a Research Associate. He is improving reconstructions of the ocean’s recent historical conditions and the representations of interactions between the ocean and other parts of the Earth system. David was a 2018 Fellow in AGU’s Voices for Science Program.
Over the past several decades, scientists have been able to better understand how the Earth’s climate is changing through the ocean. Since the mid-1950s, the oceans have taken up over 90% of the heat and 25% of the carbon accumulating on Earth. Because the ocean can sequester heat and carbon for up to thousands of years, uptake about 850 times more heat than the atmosphere before warming by the same amount, and redistribute heat to cause changes in the temperatures we experience, the impact of our carbon now will last well beyond the lifetime of any individual. The economic cost of inaction surrounding greenhouse gas emissions will accrue year after year, which scientists have begun to quantify. Unless global emissions are reduced, the world’s governments will incur substantial costs. The changes in our planet’s climate due to human emissions have already exacerbated global economic inequality, widening the gap by about 25% since the 1960s. The country with the world’s largest economy—the United States—has not been exempt from economic pain. Even if all emissions ceased immediately, the world economy will lose $54 trillion, and no action could cost more than a quadrillion dollars.
The ocean-related costs are significant and long-lasting. Many resources we would have otherwise had—such as seafood and minerals—will be lost, not to mention biodiversity, habitats, and history. The most visible disruptions to the ocean include plastic pollution and coral bleaching but the ocean is also losing oxygen—deoxygenation—and gaining carbonic acid—acidification. Plastic pollution harms not only tourism, but also ecosystems, for a net cost of $500 billion to $5 trillion per year, based on what’s already in the ocean, and an additional cost of $25 billion to $250 billion per year, based on the current rate of plastic output. The loss of coral reefs is caused by a combination of ocean warming and acidification. Their disappearance would cost $1 trillion each year from loss of biodiversity and tourism, and possibly more due to their role as the primary buffer between harsh waves and coastal communities. As time goes on, deoxygenation and acidification will reduce the habitats of many species of fish. This will affect fisheries economically and be felt by the nearly one billion people who depend on seafood for sustenance.
Perhaps the most profound oceanic shift is a rise in sea level caused by ocean warming and the melting of ice sheets and glaciers, a development that could turn entire cities from beachfront property into uninhabitable ruins. The price tag of our current emissions trajectory—between $14 trillion and $27 trillion each year by 2100 due to flooding alone—has likely been understated because experts now say that sea level changes from melting ice sheets have been underestimated by a factor of two. Already, rising sea levels on the coasts are being exacerbated by a simultaneous subsidence—sinking of the ground. While most environmental changes are incremental, human impacts on the ocean will eventually lead to life-altering events for more than 200 million people. These changes cannot be reversed over just a few decades.
It’s becoming increasingly important that policymakers and citizens alike take action to ensure that we reduce additional negative impacts on the ocean. Single tactics in isolation will not prevent the aforementioned problems from getting worse. One potential solution includes capturing carbon dioxide—and burying it in deep-sea sediments. Still, carbon capture alone cannot reliably address the underlying problem of human emissions, particularly for the ocean. Policymakers and citizens will need to consider other viable solutions to address our emissions, including renewable energy developments and infrastructure—potentially saving people of the world $160 trillion by 2050—as well as reforestation/avoided deforestation and other nature-based solutions. Because of the ocean, we will need to supplement short-term adaptations with long-term solutions if we don’t want to be stuck with a bill that will be difficult to pay.