But Really, A Mass Extinction? Really – A Mass Extinction.
Not Just Another Conference
In April of 2011, the International Program on the State of the Ocean convened 27 experts from 6 different countries “to determine the net effect of what is already happening to the ocean and is projected to do so in the future.” The workshop follows in a long line of international summits about our oceans. Even a cursory Google search shows a Sustainable Ocean Summit in 2010, a Global Oceans Conference in 2010, 2008, 2006, and 2003, the Clean Oceans Conference in 2007, 1998, 1997, and 1996, the Ocean Policy Summit in 2005, the Global Oceans Forum in 2001 – and the list goes on.
But this time there were some things different.
This particular meeting had two highly original qualities about it: its approach for studying the ocean, and the findings that resulted from said approach. This time, somebody had the wonderful idea of gathering experts from across traditionally separate disciplines, thus forming a cumulative understanding of the ocean’s condition, rather than studying one aspect of ocean health at a time.
And the findings were equally original. When experts on every little corner of the ocean came to Oxford University and put their individual pieces of the puzzle together, they saw a startling picture: a mass extinction of ocean life (to begin with) more imminent than anyone had previously thought.
The workshop’s report “leads to the conclusion that we have underestimated the overall risks and that the whole of marine degradation is greater than the sum of its parts.” So what, exactly, was underestimated?
Many of the ‘worst-case-scenarios’ laid out by the Intergovernmental Panel on Climate Change (IPCC) are already being met in the following areas: rate of decrease of Arctic Sea ice, Greenland and Antarctic ice sheets; sea level rise; and the release of methane from the ocean floor. Furthermore, these conditions are making things worse for other indicators that have so far only matched – and not yet exceeded – the already bleak predictions. These include the distribution and abundance of marine life, degradation of ecosystems, distribution of algal blooms, simplification and destabilization of food webs, and the ability of marine life to survive stresses on the ocean.
The Imperfect Storm
A long-suspected fact about human pollution has finally been born out. Human-induced carbon dioxide emissions, the dumping of waste, run-off from agriculture, over-fishing, the destruction of environments from industry and transportation – all of these things are now known to compound each other. As the report explains, different stresses on the ocean can interact in ways that are either “synergistic” (increasing their overall effect) or “antagonistic” (decreasing their overall effect).
For example, the warming of the ocean, nutrient run-off from human activities, and the introduction of non-native species can together create the conditions for an algal bloom, which removes diluted oxygen from the water (hypoxia) and creates ‘dead zones’ where most sea life cannot survive.
Or take coral reefs. The state of coral reefs may be one of the most important indicators of overall species health in the ocean. They represent the most diverse ecosystem on the planet and directly support an estimated 500 million people with food and economic livelihood. They also act as barriers that protect our coastlines.
But the last century has been bad for coral reefs. In the past 50 years, about 40% of them have disappeared. And the increasing pressure from carbon dioxide emissions is speeding things up. Whereas the original perceived threats were overfishing and direct pollution through chemicals and plastics, now, warmer and more acidic oceans are causing coral bleaching, making it harder for reefs to recover. “A recent study,” professor and conference-participant Ove Hoegh-Guldberg explains, “has revealed that reef building corals are more sensitive to temperature stress when exposed to acidified ocean waters. This suggests that existing scientific projections of how coral reefs will respond to global warming have been highly conservative.”
The new projections are something a little less conservative: scientists are now trying to figure out how to gauge the clock that counts down to the next mass extinction.
Indeed, coral reefs bare out a disturbing truth about the state of the ocean and its resemblance to conditions present in most (if not all) of the past mass extinctions. Paleobiologists have pinpointed five mass extinctions – defined as the loss of at least 75% of species over 2 million years – over the last 540 million years. The common thread that runs through most of them is what’s called “the deadly trio,” or three conditions that were present when mass extinctions occurred: global warming, ocean acidification, and ocean anoxia (the absence of oxygenated water).
These conditions are also present today, but moving at a rate unprecedented in Earth’s history. To illustrate: whereas carbon perturbation during the End Permian mass extinction (about 251 million years ago) and the Paleocene Eocene Thermal Mass extinction (about 55 million years ago) was on the scale of one to two gigatons (Gt) per year, “both these estimates are dwarfed by today’s emissions of roughly 30 Gt of CO2 per year.” As the sink drain for atmospheric carbon dioxide, the ocean is absorbing gargantuan amounts of human pollution – about one third of it over the last two decades
Even our most primitive data suggest that a global mass extinction is not far. Anthony D. Barnosky, a UC Berkeley professor of integrative biology, suggests that “if currently threatened species – those officially classed as critically endangered, endangered and vulnerable – actually went extinct, and that rate of extinction continued, the sixth mass extinction could arrive within as little as 3 to 22 centuries.”
Three to twenty-two centuries is not a very long time to head off a mass extinction, in the scheme of things. But that doesn’t mean that humanity should not try. One of the most important conclusions of the workshop last April was “to strengthen the case for greater action to reduce anthropogenic emissions of carbon dioxide” (Rogers & Laffoley 2011, 4). Other recommendations call to reduce fishing to the point of sustainability; establish a world-wide system of conserving ocean biodiversity; reduce and prevent inputs of other pollutants and nutrients into the ocean; and create a United Nations body to govern international waters, where no one is responsible for the conservation of biodiversity. Still, it is far from clear that any of these solutions will be worthwhile as long as civilization is still pumping so much CO2 into the atmosphere. In other words, the ocean is seriously changing – and humans are going to have to seriously adapt.
Photo credit: Matthew Dell
Photo credit: rst.gsfc.nasa.gov/Sect16/_45552631_ocean_acidification02_466in.gif