Much of this nitrogen from fertilizers ends up in our oceans, where nitrogen is now 50 percent above normal levels. According to the journal Science, excess nitrogen "depletes essential oxygen levels in the water and has significant effects on climate, food production, and ecosystems all over the world."
Oysters to the rescue. One oyster filters 30-50 gallons of water a day -- and in the process filters nitrogen out of the water column. Recent work done by Roger Newell of the University of Maryland shows that a healthy oyster habitat can reduce total added nitrogen by up to 20 percent. A three-acre oyster farm filters out the equivalent nitrogen load produced by 35 coastal inhabitants (PDF).
There is an array of projects sprouting up that use a mix of seaweed and shellfish to clean up polluted urban waterways and help communities prepare for the effect of climate change. One initiative, spearheaded by Dr. Charles Yarish of the University of Connecticut, is growing kelp and shellfish on floating lines in New York's Bronx River to filter nitrogen, mercury, and other pollutants out of the city's toxic waterways, with the goal of making them healthier, more productive, and more economically viable.
Then there is the emerging field of "oyster-tecture," dedicated to building artificial oyster reefs and floating gardens to help protect coastal communities from future hurricanes, sea level rise, and storm surges. Architect Kate Orff from the design firm SCAPE is developing urban aquaculture parks that use floating rafts and suspended shellfish long-lines to build more urban green space while improving the environment. She envisions the new urban ocean farmer as part shell fisherman tending to oysters reefs, and part landscaper, tending the above-surface floating parks.
In Connecticut, advocates are pushing for an expansion of the state's existing nitrogen credit trading program to include shellfish farms, thereby reimbursing oystermen for the nitrogen they filter from Long Island Sound each year. With new oyster operations sprouting up all around the country, rewarding "green fishermen" for the positive effect their farms have on the environment could be a model for how to stimulate job growth while saving the planet.
Farm Your Fuel, Power the Planet
Finding a clean replacement for existing biofuels is becoming increasingly urgent. A report commissioned by the European Union found biofuels from soy beans can create up to four times more climate-warming emissions than equivalent fossil fuels. Biofuels have also forced global food prices up by 75 percent -- far more than previously estimated -- according to a confidential World Bank study. And a recent report from the International Food Policy and Research Institute, warned that U.S. government support for corn ethanol was a major factor behind this year's food price spikes.
Seaweed and other algae is increasingly looking like a viable substitute. About 50 percent of seaweed's weight is oil, which can be used to make biodiesel for cars, trucks, and airplanes. Scientists at the University of Indiana recently figured out how to turn seaweed into biodiesel four times faster than other biofuels, and researchers at the Georgia Institute of Technology have discovered a way to use alginate extracted from kelp to ramp up the storage power of lithium-ion batteries by a factor of ten.
But unlike land-based biofuel crops, seaweed farming does not require fertilizers, forest clearing, water, or heavy use of fuel-burning machinery -- and, as a result, according to the World Bank, has a negative carbon footprint. While the technology is still in development, farmers are eager to begin growing their own fuel and create some of the first closed energy loop farms on the planet.
The U.S. Navy has already developed the Riverine Combat ship and Seahawk helicopters powered by seaweed-based bio-diesel. The Pentagon views seaweed and other algae as a key component in their efforts to reduce their carbon footprint. According to Alan Shaffer, the Pentagon's principal deputy director of defense research and engineering:
The beauty with algae is that you can grow it anywhere and to grow it needs to absorb carbon dioxide, so it's not only a very effective fuel, in theory it's also a carbon sink. That's a pretty good deal.
Given the high oil yield from algae, some 10 million acres would be sufficient ... to replace the total petro-diesel fuel in the United States today. This is about one percent of the total amount of acreage used in the United States today for grazing and farming.
The world's energy needs could be met by setting aside three percent of the world's oceans for seaweed farming. "I guess it's the equivalent of striking oil," says University of California, Berkeley microbial biology professor Tasios Melis.
The Bitter Reality of Climate Change
These are urgent times, demanding creative and bold solutions. In his best-selling book Eaarth: Making Life on a Tough New Planet, Bill McKibben breaks the news that climate change is no longer a future threat -- it is here and now and we had better get our affairs in order.
Our oceans are already locked in a death spiral. According to the International Program on the State of the Ocean (IPSO) -- a consortium of 27 of the top ocean experts in the world -- the effects of climate change, ocean acidification, and oxygen depletion have already triggered a "phase of extinction of marine species unprecedented in human history." Simultaneously, greenhouse gas emissions are breaking records, exceeding even the worst-case scenario envisioned by scientists four years ago.
We face a bitter new reality: Mitigating the effects of climate change may force us to develop our seas to save them -- and planet. This re-imaging of the oceans will be heart-wrenching and controversial. Our waters are revered as some of the last wild spaces on Earth -- ungoverned and untouched by human hands. If we develop our oceans, farms will some day dot coastlines, mirroring our agricultural landscape. But in the face of the escalating climate crisis, we have little choice but to explore new ways of sustaining humanity while protecting the planet.
As we search for new solutions, we cannot afford to repeat the errors made on land, subsidizing industrial-scale factory farms at the expense of environmental and food quality. Simply substituting destructive fishing fleets with destructive fish farms will only hasten the demise of our oceans.
Instead, we can learn from our mistakes and chart a new course guided by principles of sustainability and meeting social needs. This means dedicating portions of ocean to farming -- while reserving large swaths for marine conservation parks. And rather than building sprawling ocean factories, we need create decentralized networks of small-scale food and energy farms growing food, generating power, and creating jobs for local communities. While no panacea, ocean farming -- carefully conceived -- could be a vital part of reversing course and building a greener future.
All of us who hold dear the deep blue sea need to confront the brutal reality that if we ignore the largest environmental crisis of our generation, our wild oceans will be dead oceans.