Projects : Ocean Acidification

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PacIOOS has partnered with NOAA Pacific Marine Environmental Laboratory (PMEL) to provide real-time data from thirteen buoys across the Pacific Ocean. These buoys measure the carbon dioxide content in the atmosphere and ocean which in turn provides valuable information to monitor ocean acidification.

On the map below, click on a buoy for further details of that particular buoy and carbon dioxide measurements. There are five buoys located in and around the Hawaiian Islands, therefore, zooming into this location would be beneficial for better investigation.


What is Ocean Acidification?

Ocean acidification is the progressive increase of acidity in the ocean. The increase in carbon dioxide, or CO2, in the atmosphere from anthropogenic sources has subsequently led to the increase of carbon dioxide absorbed in the ocean. Dissolving carbon dioxide in the ocean results in a chemical reaction releasing hydrogen ions (H+). Therefore, the increase in hydrogen ions is analogous to the increase in acidity in the ocean. Acidity is measured with the pH scale.

The figure below shows the time series of atmospheric and ocean carbon dioxide concentrations in the Hawaiian region. The increase of CO2 in both air and sea corresponds to a decrease in ocean pH over a long period of time. Real-time data merged through time creates time series useful for identifying these types of major trends. Note that carbon dioxide naturally varies on daily and seasonal timescales due to changes in the daily and seasonal vegetation cycle.

HI time series

NOAA PMEL, R.A. Feely, BAMS, 2008.

This time series shows the increase in the amount of carbon dioxide in air and seawater corresponding with the decrease in ocean pH over a couple decades. Carbon dioxide in the air is measured in parts per million volume (ppmv), and the partial pressure of carbon dioxide in seawater is measured in relation to the standard atmosphere (µatm). Seawater data is collected from the Hawaii Ocean Time-series (HOT) cruises, and the atmospheric data is from the Mauna Loa Observatory.

Why does it matter?

There are many ocean processes sensitive to the amount of carbon dioxide dissolved in the ocean. One major process that is affected by the increase of acidity is calcification. Decreased calcification rates in calcifying species, such as stony corals and shelled organisms, could weaken their skeletons. As a consequence, the survival of these species may be lowered, affecting the overall ecosystem and food chain.