Cutting CO2 emissions vital to keep oceans alive

The oceans have absorbed about 40% of the carbon dioxide (CO2) emitted by humans over the past two centuries. This equates to roughly 500 billion metric tons of carbon dioxide, equivalent in weight to about 28 inches / 70 cm of water across the whole US State of Texas.

Slowing global warming
This has slowed global warming, but at a serious cost: the extra carbon dioxide has caused the ocean’s average surface pH (a measure of water’s acidity) to decline by about 0.1 unit from pre-industrial levels – a 25% increase in hydrogen-ion concentration. Small changes in the Ph value can make a big difference because pH is measured on a logarithmic scale – analogous to the Richter scale, which measures the strength of Earthquakes. For example, a drop by one pH unit means a ten-fold increase in acidity.

Corals in danger
Experiments have shown that just small changes can damage marine life such as corals. Large areas of the ocean are in danger of exceeding these levels of pH change by mid-century, including reef habitats such as Australia’s Great Barrier Reef and the Hawaiian Islands Coral Reef Reserve.

Drastic cuts neccessary
- Putting carbon dioxide int the atmosphere at a scale and pace at which we do, it not only has substantial consequences for climate but also for ocean chemistry and we need to consider this when talking about reducing emissions. Drastic emission cuts at some point in the future might be an option in terms of climate change but it could blate for coral reefs and other marine organisms, says Richard Zeebe from the School of Ocean and Earth Science and Technology at the University of Hawaii at Manoa.