Ocean Acidification and Northwest Shellfish: Did the Seattle Times Get the Story Right?

 Check my update on this: http://cliffmass.blogspot.com/2013/11/coastal-ocean-acidification-answering.html


Last month, the Seattle Times ran a glossy, three-part story called "Sea Change:  The Pacific's Perilous Turn" where it discussed the impacts of ocean acidification resulting from increasing CO2 in the atmosphere.  The article made some strong claims that increasing atmospheric CO2 and the resulting acidification of the oceans and coastal waters were causing acute problems today for the shellfish industry in the Northwest.  The third part of this series described how oyster larvae grown in Northwest shellfish farms had high mortality in 2005-2009, mortality that the ST blames on CO2-induced acidification of the coastal ocean by the atmosphere.

As I read the article I became increasingly concerned with contradictions within the story; furthermore, some conclusions did not appear to be supported by scientific evidence.  Since then I have read a number of relevant articles on the subject and have talked to some local experts.  My conclusion is that this series has some serious problems and draws several unwarranted conclusions.   Particularly that recent shellfish problems are the result of past or current CO2 levels in the atmosphere.

The Seattle Times Sea Change series can be found online, with loads of graphics and videos.

But before I go on, let me make clear that I believe ocean acidification IS a serious issue and that as the century unfolds, the lowering ph (a measure of the degree of acid or base) of the ocean will undoubtedly cause problems for a variety of sea life.   My biggest problem is with the Seattle Times claims that increasing CO2 in the atmosphere is doing damage now. 

Why am I concerned about this article?  Because I am troubled by the tendency of some media outlets and others to claim, without real evidence, that current problems (e.g., floods, hurricanes, tornadoes, snowstorms, etc.) are related to increasing atmospheric CO2.   Global warming is a serious issue but the major impacts are in the future, particularly for our area of the globe.  Trying to scare folks by blaming current problems on atmospheric CO2, without strong evidence, ruins the credibility of the scientific community.  And credibility is a precious thing.

Some Quotes

Let's begin by allowing the Seattle Times article to speak for itself though a few passages from the article.

In short, atmospheric CO2 is the problem.  And its impacts are coming faster than expected!

 

Apocalyptic.

Lethal, corrosive waters.  As we will see, this paragraph cannot be correct.

 

So, the Northwest acidification is the the canary in the coal mine.  The first in the world.  And has been "walloping" marine life and "hurting people." 

Pretty scary stuff.   The Seattle Times minces no words.  Damage to the shellfish industry during the last few years is the clear result of increasing CO2 in the atmosphere. 

This conclusion is probably not true, for reasons described below.

Some Background

    Those of you with a bit of chemistry know that a ph of 7 is neutral, above 7 is basic or alkaline, below 7 is acidic.   The world's oceans are alkaline, with typical values today of around 8.1.    The ph scale is logarithmic, so that an change of one unit is associated with a factor of ten change in acidity/akalinity. Carbon dioxide is increasing in the atmosphere, mainly due to burning of fossil fuels, and the oceans are also taking up a considerable amount (see figure).  The amount of a gas a liquid (such as sea water) can take up depends on temperature, with colder water being able to hold more CO2.  A measure of the amount of CO2 in the atmosphere and ocean is the partial pressure of CO2  (pCO2).

CO2 gas in solution can make sea water less alkaline or more acidic, and in fact this has happened, with increasing CO2 in the atmosphere leading to the world's oceans becoming less alkaline, specifically, a decrease of ph from about 8.2 before industrial society to around 8.1 today. To quote from the IPCC (Intergonvernmental Panel on Climate Change):

 " The pH of ocean surface water has decreased by 0.1 since the beginning of the industrial era (high confidence), corresponding to a 26% increase in hydrogen ion concentration"

The figure above shows the increase in atmospheric CO2 (red line), the increase in CO2 gas ofthe waters in the middle of the Pacific (dark blue), and the decline of ph from 8.11 to 8.07 since 1988 (24 years, light blue). 

Some in the media have talked about seawater becoming more corrosive due to the impacts of increasing CO2, but this is clearly not true.  Both an alkaline and acidic ph can be corrosive; being at 7 is least corrosive (neutral).  Sea water is getting closer to seven and thus is becoming less corrosive.  Shellfish larvae and juveniles are sensitive to ph, particularly when the ph drops below roughly 7.5, with an inability to form shells. I guess that is their definition of corrosive.

So while the global ocean ph has dropped by .1 over the past hundred years or so, and roughly .05 during the past quarter century, what has happened in the coastal and inland waters of the Pacific Northwest?   As we shall see, the local variations here have dwarfed those found in Hawaii or in most of the world's oceans.  For example, the next plot shows  the ph at Bay Center on Willapa Bay (southern WA coast) for the second half of this summer (data from the very nice UW NANOOS web site).  You will note the water is a bit more acidic (about 7.5) than the ocean average, with daily large swings of .6 and even larger weekly declines by over 1 (to a ph of 6.6). 

Similar variations are noted at Nahcotta, on the other side of the Bay, with ph swings of .6 or more, far more than the long-term trend due to global increases in CO2.

A longer-term measurement program at Tatoosh Island (published in Wooton and Phister 2012) showed a substantial decline of ph from an average of around 8.2 in 2000-2004 to roughly 7.7 in 2010.   And also note the large variability each year around one ph unit.

So we have learned a few key pieces of information from these and other data.  First, that the variability of coastal ph in the Northwest during the each year (.6 to 1)  is far larger than global changes in ph due to increases in CO2 in the atmosphere (around .1).   Second, that the ph of our coastal waters have declined during the last decade far more quickly than the global average, with the global declines clearly tied to increases in atmospheric CO2.

To put it another way, it seems highly unlikely that changes in atmospheric CO2 are driving the large observed changes of ph of our local waters.  The clear implication: the Seattle Times has gotten this story fundamentally wrong.

What could explain these large changes in ph of our coastal waters?  One possibility, mentioned in the Seattle Times article, is increased upwelling (upward motion of water)  along the Northwest coast.  Upwelling tends to occur around here in the summer as northerly winds develop.  The deep water is less alkaline than the surface waters because it is colder, the lack of photosynthesis in the darkness below, and because of the decay of organic matter dropping in from above.  Thus, upwelling can bring up more acidic water.  Here is what the Seattle Times article said:

Now there are a lot of problems with this theory about "corrosive" waters, surfacing under upwelling conditions, causing the recent problems for the NW shellfish industry.  First, there is no evidence that upwelling variations explain the problems in 2005-2009.   Here is the summer coastal upwelling index for 45N that I secured on the NOAA web site that discusses acidification. 

 You will notice that upwelling actually WEAKENED during 2007-2011 and the upwelling before was not extraordinarily large.   And there is another flaw in the upwelling argument, and particularly the connection with atmospheric CO2: as noted in the Blue Ribbon Panel on Washington State ocean acidification, the sub-surface waters along the coast that are being upwelled are relatively old waters that were not in contact with the atmosphere for decades...that means they would have the characteristics of the atmosphere decades ago when CO2 was far less.  But the Seattle Times has an ominous spin on even this point:

The ST is determined to connect the upwelling impacts on increasing atmospheric CO2.  Coastal upwelling along our coast has a large amount of variability and does produce large and significant modulations of coastal ph.  But upwelling's past variations have little to do with increased CO2 in the atmosphere.  (As an aside, some climate models suggest that by the end of the century a warming earth might increase the strength of high pressure over the northeast Pacific and thus upwelling, but not now).

The problems for Northwest oysters described in the article and elsewhere are not for adult oysters in the wild, but for larvae ground in commercial hatcheries.  Some analysts (like here) suggest that the real problem is poor hatchery management, such as taking in cold (and thereby more acidic water), heating it up quickly, and thus exposing the larvae to less alkaline conditions.  Or the hatcheries used surface water during upwelling periods, when the conditions are less alkaline.  The ST article does not examine hatchery practices.   In fact, it appears that local hatcheries have generally solved the problem by providing more attention to the quality of their intake waters.

Bringing it all together

The essential point I am trying to make here is that major drops in ph along the Washington coast are predominantly NOT due to increases of CO2 in the atmosphere.  Sure, there is a modest increase in ph due to atmospheric CO2, but this is small compared to variations from other causes.

Let me give you an analogous situation.   A large tsunami struck Japan last year and did terrible damage along their coast.  Global warming due to anthropogenic CO2 has caused sea level to rise several inches during the past decades. Yes, CO2-related increases made things slightly worse, but the disaster would have happened anyway.   I believe this is a close analogy for the acidification problems we have seen in our region...they would have happened anyway.

And there are many other possibilities for the rapid acidification during the past decade, and the Blue Ribbon panel notes several of them:

"Other regional factors affecting ocean acidification in Washington include runoff of
nutrients and organic carbon (such as plants and freshwater algae) from land, and local
emissions of carbon dioxide, nitrogen oxides, and sulfur oxides, which are absorbed by
seawater from the atmosphere. The relative importance of these local drivers varies by
location. For example, acidification along the outer coast of Washington and Puget Sound
is strongly influenced by coastal upwelling while acidification in shallow estuaries,
including those in Puget Sound, may be particularly influenced by inflows of fresh water
(which is naturally lower in pH than seawater) carrying nutrients and organic carbon
from human and natural sources. The added organic carbon, as well as nutrients that
stimulate excessive algal growth, can make seawater more acidic when algae and other
organic matter decompose."

So coastal ph can influenced by a number of factors other than increased atmosphericCO2, including variations in upwelling, influxes of fresh water, chemical and run-off pollution, among many others.  Might a combination of them explain what has happened?  Regarding fresh-water run-off, I was surprised that none of the acidification documents I reviewed noted the huge coastal precipitation/flooding events of 2006 and 2007;  could they be important?

Native and Foreign Shellfish in the Northwest

It is very interesting to note that dying baby Pacific oysters headlined in the Seattle Times piece are not natives.  They were imported during the early 20th century from Japan, a location without the large upwelling variations prevalent along the western side of the Pacific.   My research so far suggests that our native shellfish species are doing fine....happy as a clam, so to speak.  You might even have noticed the headlines of the record razor clam season we are having:

Could it be that our native species are far more accustomed to the naturally varying ph of our region and that the imports are not?

More research, not media hype, is needed

Considering the considerable uncertainty about what is going on, including weaknesses in the atmospheric CO2 explanation for our recent problems, one can be glad that Governor Inslee has found funds for an ocean acidification center at the UW.  This center, located in the UW College of the Environment, can bring together UW experts  and others (such as coastal ocean experts at NOAA) to figure out the origins of the Northwest acidification and problems with young oysters noted in Blue Ribbon panel and the ST article.  As CO2 increases in the atmosphere, its impacts will undoubtedly grow larger in time. According to the IPCC:

"Earth System Models project a global increase in ocean acidification for all RCP scenarios. The corresponding decrease in surface ocean pH by the end of 21st century is in the range of 0.06 to 0.07 for RCP2.6, 0.14 to 0.15 for RCP4.5, 0.20 to 0.21 for RCP6.0 and 0.30 to 0.32 for RCP8." 

 Still smaller than the interannual and intraannual variations we have seen on our coast, but getting large enough to potentially have impacts.

But the fact that atmospheric CO2 is probably not the main cause of recent problems is reason for hope:  perhaps the origins are from mechanisms we can control (like poor sewer treatment, excessive far or forest run-off, poor practices at oyster hatcheries).   A series, like the one found in the Seattle Times, may get people's attention, but without good science behind it and overhyping mistaken ideas, it can lead to undermining the credibility of the environmental sciences that society must depend on to make the right decisions. 

Bellingham Talk on October 15th
I will be giving a public talk on "The Future of Weather Forecasting" in Bellingham on October 15th.    In this talk, I will discuss the development of weather prediction from folk sayings to numerical weather prediction, and will describe what I think will happen over the next decades.  For more information, go here.