Increase in ocean acidity variability and extremes under increasing atmospheric CO2

Ocean acidity extreme events are short-term periods of extremely high [H+] concentrations. The uptake of anthropogenic CO2 emissions by the ocean is expected to lead to more frequent and intense ocean acidity extreme events, not only due to mean ocean acidification, but also due to increases in ocean acidity variability. Here, we use daily output from ensemble simulations of a comprehensive Earth system model under a low and high CO2 emission scenario to isolate and quantify the impact of changes in variability on changes in ocean acidity extremes. We show that the number of days with extreme [H+] conditions for surface waters is projected to increase by a factor of 14 by the end of the 21st century under a high CO2 emission scenario relative to preindustrial levels. The duration of individual events is projected to triple, and the maximal intensity and the volume extent in the upper 200 m to quintuple. Similar changes are projected in the thermocline. At surface, the changes are mainly driven by increases in [H+] seasonality, whereas changes in interannual variability are also important in the thermocline. Increases in [H+] variability and extremes arise predominantly from increases in the sensitivity of [H+] to variations in its drivers. In contrast to [H+] extremes, the occurrence of short-term extremes in low aragonite saturation state due to changes in variability is projected to decrease. An increase in [H+] variability and an associated increase in extreme events superimposed onto the long-term ocean acidification trend will enhance the risk of severe and detrimental impacts on marine organisms, especially for those that are adapted to a more stable environment.

Burger F. A., Frölicher T. L. & John J. G., 2020. Increase in ocean acidity variability and extremes under increasing atmospheric CO2. Biogeosciences Discussions. Article.

0 Responses to “Increase in ocean acidity variability and extremes under increasing atmospheric CO2”



  1. Leave a Comment

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.




Subscribe to the RSS feed

Powered by FeedBurner

Follow AnneMarin on Twitter

Blog Stats

  • 1,378,598 hits

OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book