Credit: Corbis
OTHER STUDIES ARE starting to hint that the problem is going to hit a wider sweep of species than just those that have calcium carbonate shells or skeletons.
Research from the Monterey Bay Aquarium Research Institute in California, U.S., recently found that lowering the pH of the oceans allows sound to travel farther – potentially 70 per cent farther by 2050 – with knock-on effects for whales, which rely on sonar, and are already struggling with a cacophony of man-made noise pollution.
Another issue that could affect a range of marine invertebrates and fish is increased acidity of their body fluids, a condition called acidosis. A study published in the journal Current Biology in July 2008 reported that the fertilisation of an Australian sea urchin (Heliocidaris erythrogramma) fell by 25 per cent in water at a pH of 7.7, which some models suggest will be common by 2100.
"A 25 per cent drop in fertility is the equivalent of a 25 per cent drop in the reproductive population," says Jon Havenhand, lead author behind the study, and a marine ecologist at the University of Gothenburg in Sweden. "It remains to be seen whether other species exhibit the same effect, but, translated to commercially and ecologically important species, such as lobsters, crabs, mussels and fish, acidification would have far-reaching consequences."
Though it's yet to hit the mainstream agenda in a similar way to climate change, ocean acidification could be damaging for our economies as well as our ecosystems.
Because of the size of the Australian coastline, 60 per cent of its territory is ocean. The CSIRO estimates that 10 per cent of the Australian economy is tied to the seas and in 2002/03 the maritime industry contributed about A$70 billion to the national economy. Oysters, mussels and abalone represent important fisheries to Australia (one quarter of the world's wild abalone is fished from Tasmanian waters) and all are shelled species that grow more slowly as pH drops.
Kleypas points to a 2006 report which predicts that a 10 to 25 per cent decline in the harvest of calcifying shellfish could create economic losses for the U.S. economy totalling up to U.S.$1.5 billion a year.
It's not just the impact on fisheries either. One study estimates that A$800 million out of A$900 million total tourism revenue in coastal regions of Far North Queensland in 1999 was related to the Great Barrier Reef – and tourism related to the reef is likely to take a nosedive if the reef deteriorates. "People probably will not pay to come and see weed-covered, rocky areas," says Tilbrook.
AS I SIT BAREFOOT, watching the Sun rise over Four Mile Beach on the last day of my trip, a couple with a child appear, along with other vacationers taking an early morning run along the tide. It's pretty evident how the entire local economy is tied up in tourism.
The quandary is, even with international agreement to drastically cut CO2 emissions – something that now, more than ever, I understand is desperately important – atmospheric levels of the greenhouse gas will still swell before they subside again, and there's not a lot we can do to stop it getting into the oceans.
Part of the reason ocean acidification threatens to be a bigger long-term problem than global warming is that marine life has so far shown little capacity to adapt to falling pH levels. "We know that, given enough time, many organisms can eventually adapt to climate change," laments Kleypas, "[but] it does not appear that many organisms can adapt to ocean acidification."
With action now, we can stop the worst-case scenarios from playing out. But I'm left wondering if we're already too late to do much to stop this disaster from happening. Looking out towards the Low Isles, I'm glad I came to see the reef myself before it was too late.
John Pickrell is the deputy editor of COSMOS and editor of Cosmos Online. The CSIRO provided food and accommodation during his stay aboard the Southern Surveyor.
