Slow acidification of the winter mixed layer in the subarctic western North Pacific

We used carbon dioxide (CO2) system data collected during 1999–2015 to investigate ocean acidification at time-series sites in the western subarctic region of the North Pacific Ocean. The annual mean pH at station K2 decreased at a rate of 0.0025 ± 0.0010 yr−1 mostly in response to oceanic uptake of anthropogenic CO2. The Revelle factor increased rapidly (0.046 ± 0.022 yr−1), an indication that the buffering capacity of this region of the ocean has declined faster than at other time-series sites. During the winter in the western subarctic region, the pH declined at a slower rate of 0.0008 ± 0.0004 yr−1. This was attributed to a reduced rate of increase of dissolved inorganic carbon (DIC) and an increase of total alkalinity (TA). The reduction of DIC increase was caused by the decline of surface water density associated with the pycnocline depression and the reduction of vertical diffusion flux from the upper pycnocline. These physical changes were probably caused by northward shrinkage of the western subarctic gyre and global warming. Meanwhile, the contribution of the density decline to the TA increase is canceled out by that of the reduced vertical diffusive flux. We speculated that the winter TA increase is caused mainly by the accumulation of TA due to the weakened calcification by organisms during the winter.

Wakita M., Nagano A., Fujiki T. & Watanabe S., in press. Slow acidification of the winter mixed layer in the subarctic western North Pacific. Journal of Geophysical Research: Oceans. Article (subscription required).

0 Responses to “Slow acidification of the winter mixed layer in the subarctic western North Pacific”



  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 )

Twitter picture

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

Facebook photo

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

Google+ photo

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

Connecting to %s




Subscribe to the RSS feed

Powered by FeedBurner

Follow AnneMarin on Twitter

Blog Stats

  • 1,040,447 hits

OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book