by Roger Payne
It is generally accepted by scientists that the worst threat humanity faces, and has ever faced, is global warming. So widespread is this assumption that I suspect anyone suggesting a different worst-threat would be dismissed out of hand. Nevertheless, I have long believed that ocean acidification is a worse threat than global warming, simply because the time it will take for ocean acidification to reach a point where it can wreak its maximum havoc is apparently much shorter than the time it will take for global warming to raise the temperature of the earth enough to unleash its worst effects. (Ocean acidification is estimated to require decades to do its worst, whereas Global warming is estimated to require a century or centuries.) The reason for focusing on the oceans is that they are the principle force that stabilizes the conditions on this planet that enable life. So even if you live at the center of this continent, say, in Kansas, and have never even seen the ocean, it’s a fair bet that if the oceans die you will die too, because of the loss of stability in the natural world that surrounds you.
We have all heard that global warming is largely the result of burning fossil fuels and that humans have already caused the greatest increase in carbon dioxide (CO2) in nearly 3 million years (and probably much longer, although that can’t be confirmed until several gaps in the temperature record get filled in).
Global warming is caused by CO2trapping heat, whereas ocean acidification is caused by CO2combining chemically with water to produce carbonic acid—a reaction that produces highly reactive hydrogen ions that combine readily with the very chemicals that shellfish and corals need to make their protective coverings. When ocean acidity is increased it becomes increasingly difficult or impossible for shellfish to secrete their shells and corals to form reefs. However, these structures are what protect molluscs and corals from an ocean’s worth of crafty, awe-inspiring, sometimes microscopic, predators.
Although global warming is caused by CO2trapping heat, and ocean acidification is caused by CO2combining chemically with water to produce carbonic acid, there is a third problem that is caused when the interiors of living cells are exposed to carbonic acid. This problem is called metabolic drag.
A great deal of research in the past 30 years has refined our understanding of the effects of CO2on global warming but research on ocean acidification has been under-funded and lags far behind. However, an even greater hole in our understanding of how the global buildup of CO2affects all life are the consequences of CO2entering live cells and increasing their acidity.
Very recent research shows that the higher the CO2concentration in a cell, the more it affects such important cellular functions as oxygen transport and protein synthesis. Furthermore, in dealing with these effects the organism has to use energy it would otherwise have available for doing, well… everything else it does. The result is a reduction in vigor, which, even if it doesn’t kill a cell outright (or the owner of that cell), makes cells and their owners more susceptible to a long list of stresses that reduce any organism’s fitness (and often kill it following a suitable delay). This process is called metabolic drag.
The worst effect of CO2on humans will not be the flooding of coastal cities caused by melt-water from glaciers and ice caps, or the increase in extreme weather events. Far worse damage will be caused by changes in the courses and strengths of oceanic and atmospheric currents that will move the boundaries of the habitats within which animals and plants can live and crops can grow, poleward by tens, hundreds and in some cases even thousands of miles. Such shifts will take decades to complete during which the cells within all ocean life will be experiencing a kind of chemical chaos from the increased CO2 and carbonic acid inside them.
The warming of this planet, along with the behavioral processes I have described, takes place much more slowly than do the fatal effects of ocean acidification. But acids don’t mess around; even very modest increases in acidity can weaken microscopic plants and zooplankton. That’s because the more acidic the seawater, the more species it kills, and the quicker it does so.
Although zooplankton are tiny, their importance is massive: for they are the food of the small fish, that are food of the larger fish, that are the food for the fish we depend on. So when a plankton species dies, its food chain dies, and the victims may include people who depended on the fish that lived at the top of that plankton’s pyramid.
Unfortunately, even the most important plankton species turn out to be so little-known that almost no one can recognize or name them. An example is the pteropods—a group of planktonic species that are major food sources for many species of ocean fish, as well as for baleen whales. Even their common names: sea butterflies and sea angels, are unfamiliar to most biologists. They are tiny, free-swimming, open-ocean snails and sea slugs, that are present in staggering numbers, worldwide, and at all latitudes. They are usually found less than 500 meters below the surface and are most abundant over continental shelves, where they form dense groups—a behavior that whales exploit to capture them. It is because of the staggering abundance of some of these little-known species that it is sometimes said that they control ocean productivity.
93% of pteropods have shells; the remaining 7% lack them. The shelled species are vulnerable to ocean acidification. Exposure to seawater at acidity levels that the oceans are expected to reach by 2050 dissolve the shells of pteropods completely—which is fatal to them.
We may get used to (become inured to?) global warming, ocean acidification, and metabolic drag, but then, more research soon appears that offers a yet bleaker future, and underlines even more clearly the urgency of the need to act. And sure enough, just this week, a new threat was revealed in a paper by a group in Hawaii that studied the effects of the ultraviolet in sunlight on the more than 8 billion tons of plastics that humanity has produced since we started manufacturing it in the 1950s. (Yes, billion with a “b,” and yes, tons—in fact, metric tons, each of which is 2,200 pounds, not a measly 2000). The group in Hawaii studied the effects on seven kinds of plastics of exposure for several days to UV light, both in air and in water. Their sample included the most abundant plastic polymer: polyethylene (the polymer found in more than a third of all types of plastic). The group analyzed the gases that the plastics released, discovering thereby that the breakdown products of all seven of the plastics they tested produce greenhouse gases (principally methane, which is 30 times more powerful in trapping heat than CO2and persists in the atmosphere for centuries). They also found that the most abundant plastics, the polyethylenes, produce the most greenhouse gases by far.
All of the plastics tested also release ethylene—a gas that is the second most abundant hydrocarbon pollutant in the atmosphere and that is implicated in the creation of Carbon monoxide.
These rather grim results led the authors of the paper to conclude that: “Due to the longevity of plastics and the large amounts of plastic persisting in the environment, questions related to the role of methane and ethylene global budgets should be prioritized and addressed by the scientific community.” That is scientist-speak for… “Uh Oh, World; this looks serious.”
It is surprising that a problem that seems so obvious and was hiding in plain sight has been almost completely ignored until now, but it is always surprising how often that is the case. Furthermore, the contribution of the gases that we now know are released by deteriorating plastics has never yet been included in any climate models.
It is clear that global warming, ocean acidification, and metabolic drag are a triple threat. However, they are a triple threat of which most people are unaware and whose name most people don’t even know. But knowing a name is not enough; we need to understand what causes them if we are to stop the problem.
It is well to note that global warming, ocean acidification and metabolic drag are not causes, they are symptoms. Their main, underlying cause is the burden that CO2places on all life—the name for which is “the carbon burden.”
So… my concern as to whether ocean acidification or global warming is the bigger threat seems misplaced; both are symptoms of the carbon burden, though ocean acidification may become intolerable soonest. However, we must not lose sight of the fact that the biggest threat that we, along with all life on earth face is not just something called global warming, or ocean acidification or metabolic drag, but the mutually self-reinforcing, combined threat that is the sum of those three threats, a sum that is called the carbon burden. It is the carbon burden that is the biggest threat, but even though it is the biggest threat we face we don’t yet understand its full dimensions.
As Carl Safina put it so well; [ref.]
“It is and always has been about carbon. We need to place carbon back in the center of the equation. From atmosphere to ocean to cell, the carbon burden is the problem… and the more we learn, the more its dimensions appear ever more staggering.”
So how surprising: our greatest threat is not the economy, or congress, or the liberal agenda or the conservative agenda, or the nanny state, or terrorists, or the national debt, or the costs of the perpetual war on terror, or the ebola virus, or whether our president gets to build his wall, or no gun laws, or even, dare I say it… all-out nuclear war. In spite of how ghastly the devastation may be from any of those causes, time is likely, eventually, to reverse the misery they create. No… the main threat is not humans versus humans—us vs them. The worst threat comes when we trigger the mass destruction of the rest of life—the non-human species on which we are utterly dependent. And the most likely way we can achieve that threat is not through violent acts of aggression, but by failure to stop the slow and ponderous but effective imposition of the carbon burden on all life, simply because the carbon burden is such an effective way to devastate life on earth.
If the carbon burden is the greatest threat, what caused it? We caused it. In fact we’re still causing it; it’s our worst own-goal—a self-inflicted wound that we must staunch before we waste any more time or energy or treasure doing anything else. As Pogo, a beguiling cartoon character of the 1950s said; “We have met the enemy and he is us.”
We may be our own worst enemy, but we’re also our best hope. There are many things each of us can do, and if enough of us do them, it can make a difference. — Iain Kerr