Worse things happen at sea

By Adam Smith

Climate scientists are in wide agreement that climate change is the most imminent and serious environmental problem we face today. The unrestricted emission of greenhouse gases into our atmosphere, from our cars, factories and power stations, is trapping heat from the Sun and warming our planet. It’s also driving more frequent extreme weather events, and greater unpredictability in the atmosphere.

However, climate change is not the only ill-effect caused by emitting greenhouse gases, a fact that is little-known or talked about when stacked up against the climate change agenda. Referred to as ‘the other CO2 problem’, or even ‘Climate Change’s distant cousin’ it’s a problem which will have devastating consequences on ocean ecosystems, economies and communities worldwide. Namely, the acidification of our oceans.

In 2012, over 34 billion tonnes of carbon dioxide were emitted into our atmosphere (that’s 93 million tonnes every day). This carbon dioxide had to go somewhere, and it did. Around half remained in the atmosphere, trapping heat from the Sun and driving global warming and climate change. A quarter was absorbed by land sinks, such as soils, or forests through photosynthesis.

The remaining quarter was absorbed by the oceans, reacting with sea water to form carbonic acid and other acidic molecules. As a result, the acidity of our seas is climbing. Since the Industrial Revolution, surface ocean pH levels have dropped by more than 0.1, and are expected to change by between 0.3 and 0.5 units by 2100. This might not sound like much, but will have serious negative consequences.

The main victims will be ‘calcifying’ organisms, which includes coral reefs. Laboratory tests have shown that increased ocean acidity inhibits their ability to grow and maintain shells. As a result, coral reefs will grow back more slowly, and be less robust and resistant to erosion. There are millions of marine species which depend on corals to reproduce, feed, and shelter larvae. Without coral reefs, these could be lost forever.

Further studies have shown the effects of increased ocean acidity on a host of other species. It has been shown to depress metabolic rates in jumbo squid, and inhibit immune response in shellfish. The knock-on effects this could have on the rest of the food chain are enormous.

Large organisations such as the Intergovernmental Panel on Climate Change are spelling out the potentially disastrous effects of climate change on society, so haven’t we got the message already?

In truth, our understanding of how a more acidic ocean could affect marine life is in its infancy, and more in-depth research is needed. Let’s hope that learning more about the potential threats to our oceans will provide ever more motivation to act now.



Image from Wikimedia Commons under creative commons license