Claim: Unprecedented, man-made trends in ocean’s acidity

“Anthropogenic CO2 emissions over the last 100 to 200 years have already raised ocean acidity far beyond the range of natural variations.”

The media release is below.


Unprecedented, man-made trends in ocean’s acidity

Nearly one-third of CO2 emissions due to human activities enters the world’s oceans. By reacting with seawater, CO2 increases the water’s acidity, which may significantly reduce the calcification rate of such marine organisms as corals and mollusks. The extent to which human activities have raised the surface level of acidity, however, has been difficult to detect on regional scales because it varies naturally from one season and one year to the next, and between regions, and direct observations go back only 30 years.

Combining computer modeling with observations, an international team of scientists concluded that anthropogenic CO2 emissions over the last 100 to 200 years have already raised ocean acidity far beyond the range of natural variations. The study is published in the January 22 online issue of Nature Climate Change.

The team of climate modelers, marine conservationists, ocean chemists, biologists and ecologists, led by Tobias Friedrich and Axel Timmermann at the International Pacific Research Center, University of Hawaii at Manoa, came to their conclusions by using Earth system models that simulate climate and ocean conditions 21,000 years back in time, to the Last Glacial Maximum, and forward in time to the end of the 21st century. They studied in their models changes in the saturation level of aragonite (a form of calcium carbonate) typically used to measure of ocean acidification. As acidity of seawater rises, the saturation level of aragonite drops. Their models captured well the current observed seasonal and annual variations in this quantity in several key coral reef regions.

Today’s levels of aragonite saturation in these locations have already dropped five times below the pre-industrial range of natural variability. For example, if the yearly cycle in aragonite saturation varied between 4.7 and 4.8, it varies now between 4.2 and 4.3, which – based on another recent study – may translate into a decrease in overall calcification rates of corals and other aragonite shell-forming organisms by 15%. Given the continued human use of fossil fuels, the saturation levels will drop further, potentially reducing calcification rates of some marine organisms by more than 40% of their pre-industrial values within the next 90 years.

“Any significant drop below the minimum level of aragonite to which the organisms have been exposed to for thousands of years and have successfully adapted will very likely stress them and their associated ecosystems,” says lead author Postdoctoral Fellow Tobias Friedrich.

“In some regions, the man-made rate of change in ocean acidity since the Industrial Revolution is hundred times greater than the natural rate of change between the Last Glacial Maximum and pre-industrial times,” emphasizes Friedrich. “When Earth started to warm 17,000 years ago, terminating the last glacial period, atmospheric CO2 levels rose from 190 parts per million (ppm) to 280 ppm over 6,000 years. Marine ecosystems had ample time to adjust. Now, for a similar rise in CO2 concentration to the present level of 392 ppm, the adjustment time is reduced to only 100 – 200 years.”

On a global scale, coral reefs are currently found in places where open-ocean aragonite saturation reaches levels of 3.5 or higher. Such conditions exist today in about 50% of the ocean – mostly in the tropics. By end of the 21st century this fraction is projected to be less than 5%. The Hawaiian Islands, which sit just on the northern edge of the tropics, will be one of the first to feel the impact.

The study suggests that some regions, such as the eastern tropical Pacific, will be less stressed than others because greater underlying natural variability of seawater acidity helps to buffer anthropogenic changes. The aragonite saturation in the Caribbean and the western Equatorial Pacific, both biodiversity hotspots, shows very little natural variability, making these regions particularly vulnerable to human-induced ocean acidification.

“Our results suggest that severe reductions are likely to occur in coral reef diversity, structural complexity and resilience by the middle of this century,” says co-author Professor Axel Timmermann.”

An animation showing the changes in aragonite surface saturation level from 1800 to 2100 is available at The animation is also playing at the Science on a Sphere in the Jhamandas Watumull Planetarium at the Bishop Museum in Honolulu.

This study was funded by The Nature Conservancy (, the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) through its sponsorship of the International Pacific Research Center, and National Science Foundation grant #0902551.

Citation: T. Friedrich, A. Timmermann, A. Abe-Ouchi, N. R. Bates, M. O. Chikamoto, M. J. Church, J. E. Dore, D. K. Gledhill, M. González-Dávila, M. Heinemann, T. Ilyina, J. H. Jungclaus, E. McLeod, A. Mouchet, and J. M. Santana-Casiano: Detecting regional anthropogenic trends in ocean acidification against natural variability. Nature Climate Change – DOI: 10.1038/NCLIMATE1372.

10 thoughts on “Claim: Unprecedented, man-made trends in ocean’s acidity”

  1. Funny how they don’t mention pH measurements at all. Isn’t that the way acidity versus alkalinity is usually measured? Aragonite? WTF?

  2. “The extent to which human activities have raised the surface level of acidity”

    This is a lie. No sea is acidic. None. Anywhere.

  3. Last numbers I saw a couple of years ago . . . they were saying the oceans went from 8.7 to 8.5 . . . . disaster looms . . . this is a non issue in my swimming pool as it is in the ocean. Whenever I see “Computer Modellers” . . . the red flag goes up . . . these are not scientists they are frauds!!!

  4. How do I know? The model tells me so. More pseudo science libsqueeze from punch drunk libtards. As noted by Dale, the oceans are alkaline, not acidic. PH is in the normal range of variability @ 8.1 mas o menos. The last time it dropped below 8 (less than 7 is acid) was 1930 @ 7.9. Using the word ‘acidification’ when less alkaline is correct, gets folks who don’t check the real data all fired up.

    To keep the grant $ flowing, the alarm has to go out. There is no $ saying not to worry, all is okay.

  5. I find all of this ocean acidification crap very funny. I inject CO2 into several of my fish tanks in order to promote plant growth. I inject enough CO2 to lower the pH from 7.1 to 6.3 every day during the time the lights are on in the fish tanks. This happens every day. The shrimp, snails and other shellfish are doing very well. The plants in these tanks also are growing very well and I have to remove on average two pounds of plant material every week from my 125 gallon tank. As far as my fresh water tanks and a friends salt water tanks are concerned CO2 is a wonderful addition promoting health and beauty in our aquariums.


  6. “direct observations go back only 30 years” & “beyond the range of natural variations” tell me they really don’t know what the ‘normal’ range of sea surface acidity is, or “should be”. In point of fact, the pH of most of the sea surface waters is weakly alkaline — non-acidic.
    At best they can declare an *average* over 30 years, and ESTIMATE a variability based solely on recent conditions. There is not enough data even to venture a “trend” forecast.

  7. Lookig at the models and time frames, kind of hoping the warmists jump all over this too soon. Then again, the papers print the scandal and no one notices the retraction. 17,000 – 20,000 years is long-term model for unpecedented? I thought we’d had climate and CO2 for a while longer than that. I thought we were in a 150,000 year repetitve cycle of sorts. 30-year spot check unprecedented against our models. Well, congratulations on nothing.

    This is a study. Studies always have an “on the other hand” because they aren’t proof. The other hand must be huge.

  8. “Nearly one-third of CO2 emissions due to human activities enters the world’s oceans.”

    Probably the majority of this carbon dioxide is assimilated in the process of nourishing the ocean plankton. Also, for the purposes of this “study” we will ignore the hot battery acid flowing from the mid-ocean ridge black smokers on a 24/7 basis. Funny how the mollosks down there seem to be “happy as clams.”

  9. “Combining computer modeling with observations …”

    As usual, all they have are computer models.

    Ocean acidification is only happening in their Tron or Matrix world.

  10. Acidity is do to excess hydrogen ions. Exactly how does CO2 create excessive hydrogen atoms?
    I did not see one word on the chemistry behind this jump to conclusions.

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