Peter Mumby has an article today in the Guardian which discusses an underreported consequence of rising CO2 levels, namely, ocean acidification, which wrecks havoc with the the formation of calcium-based structure. Bye bye shrimp, lobster, and coral reefs.
An article in the New York Times, “Before It Disappears,” discusses “the tourism of doom,” for people who want to see natural sites they expect won’t be around for very long. Add coral reefs (at least healthy ones) to the list. The story also touches on one of my pet peeves, that so-called eco-tourism damages the environment:
Almost all these trips are marketed as environmentally aware and eco-sensitive — they are, after all, a grand tour of the devastating effects of global warming. But the travel industry, some environmentalists say, is preying on the frenzy. This kind of travel, they argue, is hardly green. It’s greedy, requiring airplanes and boats as well as new hotels.
Please, stay close to home and make a donation instead.
From the Guardian:
My mother used to tell me that drinking too much Coca-Cola was bad because it’ll ‘rot your teeth’. In fact, my first science experiment involved dissolving my baby teeth in a stagnant glass of Coke. Little did I know that this experiment would simulate one of the most serious consequences of global climate change on my favourite ecosystem – coral reefs!
Human beings have been burning fossil fuels for around 200 years, and the rate of increase in atmospheric CO2 is 100 times faster than has occurred in the past. Half of this CO2 has been absorbed into the surface layers of the ocean, making it increasingly acidic. This spells potential disaster for the thousands of animals in the oceans that create chalk skeletons. The list is a long one and includes many plankton species, lobsters, some of the prettiest sea shells, and corals. As water becomes more acidic, corals find it increasingly hard to extract calcium from the water and create calcium carbonate or chalk. Laboratory experiments have shown that a doubling of atmospheric CO2 beyond pre-industrial levels can lead to a 50% reduction in the growth rate of coral. But what does that really mean?
Corals have a very narrow environmental tolerance and are easily stressed if the temperature becomes too warm, or if the water becomes too murky. If growth becomes more energetically demanding, it is likely that corals will become far more susceptible to disease. The skeletons of corals will also become less dense (lighter) as growth rate declines and this means that corals are more likely to break apart when struck by hurricanes. All in all, the rise in ocean acidity as CO2 levels continue to increase, spells many acute problems for reefs – and this is a global problem.
Talking about ocean acidity is difficult because its effects are slow and largely invisible from day to day. However, rising acidity is not the only problem facing reefs as a result of climate change. In 1998, the world’s oceans became unusually warm, with average summer temperatures rising around 2C above normal. This doesn’t sound very impressive, but it killed vast areas of coral worldwide. This phenomenon is called coral bleaching and occurs because corals can only harness the sun’s energy for photosynthesis within a very narrow range of temperatures: if it becomes too warm, the corals effectively get ‘sunburn’. I witnessed these events around the globe, and was devastated to see some of the most beautiful reefs in the world (video) become transformed from a bewildering array of colour to a monotonous shade of brown. And all within three months. If the oceans continue to warm at the predicted rate, these coral bleaching events could occur every year within our lifetimes. This is a dire state of affairs when you consider that reefs can take more than a decade to recover from just a single bleaching event.
My concern is that the current trend of rising CO2 spells disaster for coral reefs and the many millions of people that depend on them for food, shelter from storms, and livelihoods. We must go further in reducing CO2 emissions and do everything possible to reduce the local insults to these systems from over-harvesting and pollution. Local action may buy vital time for the most diverse ecosystem on Earth.