Ocean Acidification

What is ocean acidification?

For millions of years, the exchange of CO2 between the surface of the ocean and the atmosphere remained constant.In the past 150 years, humans have greatly increased the amount of CO2 in the atmosphere by burning fossil fuels and changing land-usepractices.As a result, the ocean has absorbed about 29 percent of this additional carbon.This added CO2 has had significant effects on the ocean.

Surface waters are now 30 percent more acidic than they were atthe start of the industrial era.Ocean acidification is now happening at a faster rate than at any point in the last 66 million years, and possibly in the last 300 millionyears.And projections show that by the end of this century, ocean surface waters could be more than twice as acidic as they were at the end of last century if we do not reduce our carbon emissions.

Ocean acidification affects marine life 

Coastal and marine ecosystems are under tremendous stress from climate change.

Ocean acidification, paired up with other climate impacts like warming waters, deoxygenation, melting ice, and coastal erosion, pose real threats to the survival of many marine species.

Ocean acidification is particularly detrimental to species that build their skeletons and shells from calcium carbonate (like clams, mussels,crabs, phytoplankton, and corals), and that constitute the bottom of the food chain.

Acidification reduces the availability of carbonate ions in ocean water, which provide the building blocks these organisms need tomake their shells and skeletons, significantly reducing the chances for their offspring to survive.

In the presence of other climate stressors, ocean acidification makes it harder for species to bounce back.

Take the problem of coral bleaching, for example. Corals maintain materialistic relationship with photosynthetic algae living in their tissue:corals provide shelter for the algae and each provide the other with nutrients necessary for their survival.

But when water temperatures get too high, corals expel these algae,leaving them more vulnerable to disease and less able to maintain and build their skeletal structure.

Ocean acidification hinders the ability of corals to recover from these bleaching events because it reduces the amount of calcium carbonate available that corals need to grow back to health.

A report by the Intergovernmental Panel on Climate Change finds that 99 percent of the world’s warm-water coral reefs could disappear if global average temperatures rise 2°C or more above pre-industriallevels.

Why should we all care, and what can you do?

If you live in Kansas or Oklahoma, you may think that ocean acidification doesn’t affect you.

Ocean acidification impacts important sectors of the US economy, like fisheries and tourism, it affects food supply, and makes global warming worse by hindering the oceans’ ability to absorb CO2.

For communities that depend on coastal resources, their way of life and cultural identity are on the line.

The most effective way to limit ocean acidification is to act on climate change, implementing solutions to dramatically reduce the use of fossil fuels. If we dramatically cut our global warming emissions, and we limit future warming, we can significantly reduce the harm to marine ecosystems.

• The most recent National Climate Assessment projects that by taking action now we could avoid steep declines in fish catch potential, thus reducing harm to fisheries.

•The IPCC report highlights that with significant emissions reductions,30% of coral reefs would be spared from extinction.