Wildfires’ Unexpected Impacts on Oceans
Over the years, research by Nicolas Cassar has yielded some eye-opening findings about carbon cycling and the oceanic food web.
But a study he published earlier this year may have triggered the biggest “aha" moment yet.
Cassar’s research showed that emissions from wildfires that ravaged Australia in 2019 and 2020 triggered widespread algal blooms in the Southern Ocean, thousands of miles downwind to the east.
Tiny aerosol particles of iron in the windborne smoke and ash fertilized the water as they fell into it, providing nutrients to fuel carbon dioxide-absorbing blooms at a scale unprecedented in the region. The study—which is the first to conclusively link a large-scale response in marine life to fertilization by iron aerosols from a wildfire—raises intriguing new questions about the role wildfires may play in spurring the growth of microscopic marine algae known as phytoplankton, which absorb large quantities of climate-warming carbon dioxide from Earth’s atmosphere through photosynthesis and convert it into organic matter, forming the foundation of the ocean’s food web.
The algal blooms triggered by the Australian wildfires were so intense and extensive that the subsequent increase in photosynthesis may have temporarily offset a substantial fraction of the fires’ CO2 emissions, Cassar says. But it’s still unclear how much of the carbon absorbed by that event, or by algal blooms triggered by other wildfires, remains safely stored away in the ocean and how much is released back into the atmosphere. Determining that, Cassar says, is the next big challenge.
Technology is the New Geology
Earth has entered a new era, the Anthropocene, or Age of Humans, and one of its defining characteristics, says Peter Haff, professor emeritus of earth science, is that technology is now shaping our environment in ways that geological forces such as wind, water, fire or ice shaped past ages.
Haff’s influential scholarship on the matter, summarized in papers published in 2013 and 2014, has been a powerful force for advancing the scientific validity of the Anthropocene, building consensus on when it began, and conceptualizing the far-reaching impacts technology will have in this new age.
Humans have invented technologies that can now think and communicate with each other and react in real time to the world around them, Haff argues, and wireless connectivity has allowed these technologies to form new types of hybrid ecosystems that turn our farms, factories, homes and cities into a semi-autonomous network of responsive environments. This network, which he calls the technosphere, has its own definable behaviors and internal dynamics, which humans currently drive but don’t really control.
The lines between biology, geology and technology are blurring, he says, and although it’s a world of humans’ own making, we’re no longer flying solo at its helm.
If Soil Could Talk ...
What the Calhoun Experimental Forest tells us about nature’s ability to renew after dire conditions and the soil’s carbon storage capabilities.
Why Coastlines Change
By applying the lessons of chaos and complexity research to shorelines, a 2001 study by Brad Murray revealed how simple interactions between sand and incoming waves can cause a shoreline to change in surprising ways.
Using computer simulation powered by an advanced mathematical model, Murray and his team showed that when waves approach the shore at angles greater than 45 degrees, they cause “bumps” in the shoreline, areas of erosion or beach buildup that, though isolated at first, can grow and interact with each other. Over time, the model showed, this can lead to the development of large capes and broad bays, or the building up of one stretch of shoreline at the expense of another located tens of kilometers away.
Those findings—now so widely accepted they seem like simple truths—laid the foundation for a new theoretical framework for understanding large-scale coastal change. Follow-up studies, many led or co-led by Murray, professor of geomorphology and coastal processes, have shed light on how coastlines change in response to a changing climate, underscoring the need for a new approach to coastal management planning.
Read more stories featured in the Duke Environment Magazine Fall 2021: 30th Anniversary Issue.