A gray whale surfaces off the coast of Point Loma near San Diego, Calif. Sonar from war-games exercises conducted by the US Navy has been found to cause severs harm to whales. (NEWSCOM)
CO2 could worsen whales’ sonar problems
By Eoin O'Carroll | 10.09.08
On Wednesday, the US Supreme Court heard a dispute between a group of conservationists and the Navy over sonar exercises that scientists say are killing and injuring whales. What isn’t often mentioned in the debate is how the burning of fossil fuels could be making the problem worse.
It’s not mentioned because the discovery of the connection was published only last week. Scientists have long known that increased carbon dioxide in the atmosphere causes ocean acidification, and they have also known that the amount of sound that can be absorbed by seawater partly depends on the water’s pH. But nobody thought to combine these two phenomena until ocean chemists Peter Brewer, Keith Hester, and their colleagues at the Monterey Bay Aquarium Research Institute came along.
Their paper, “Unanticipated consequences of ocean acidification: A noisier ocean at lower pH,” published last week in the journal Geophysical Research Letters, found that fossil fuels are turning up the ocean’s volume. Since the beginning of the Industrial Revolution, the overall pH of the world’s oceans has dropped by about 0.1 units, with more of the changes concentrated closer to the poles. The authors found that sound absorption has decreased by 15 percent in parts of the North Atlantic and by 10 percent throughout the Atlantic and Pacific
As Discovery News notes, these values are probably underestimated because they are based only on atmospheric CO2 absorbed into the ocean, and not on any other factors that could increase the acidity of the seawater.
And unless we curb our fossil fuel use, it’s only going to get louder down there. The Intergovernmental Panel on Climate Change concluded that unless carbon dioxide emissions are curbed, the ocean’s pH will drop about another 0.3 points by midcentury. This increase in acidity, say the authors, could decrease absorption by almost 40 percent, and sound could travel up to 70 percent farther.
In their abstract, the authors conclude: “Ambient noise levels in the ocean within the auditory range critical for environmental, military, and economic interests are set to increase significantly due to the combined effects of decreased absorption and increasing sources from mankind’s activities.”
Or, as a humpback whale might put it, “What? I can’t hear you!”
<< Whales, Navy clash at high court | MainComments
2. Jim Cummings | 10.09.08
The issue of ocean noise is much subtler than the debate over Navy sonar might suggest. Chronic moderate noise is likely causing far more impact than occasional loud noise such as sonar (e.g., drowning out faint vocalization or echoes used for communication and navigation, as well as causing elevated levels of stress hormones, which then make animals more susceptible to grosser impacts such as toxins). The increased propagation noted in this post will make concerns about shipping noise that much more pressing. Uncharacteristically, the US is currently leading the way in the international arena on this environmental issue: the US delegation to the IMO (International Maritime Organization) is pressing for formal consideration of the need to adopt ship-quieting technologies, and the United States Chamber of Shipping is participating actively in international scientific forums toward the same goal. See the Acoustic Ecology Institute website for more…
3. paul | 10.09.08
It’s all fun and games until we go to war and we lose because the law states we cannot use our technology the way we want to. Wake up people, the time for a WWIII is getting closer and we need all the tools we can to survive. Anyone who reads the news knows that the time is near. I appreciate all species of life and want to conserve them too, but to limit our capablities of defending our freedom over another species, well I would like to live. I agree that sonar should be limited to the captain of the boats discretion knowing that it MAY cause whales to die.
The world is a bigger place than just the ocean and whales. look at the bigger picture.
4. Mike Tweed | 10.09.08
To Andrew P,
I don’t doubt what you’re saying, but one cannot write off the importance of this problem just because of your counter-statement. There probably does need to be a significant change in order for any affect to be noticed, but you’re forgetting the nature of nature. Small and subtle changes over time can and do have huge effects on organisms due to the certain conditions of every countless variable involved with the life/fitness of an organism. Small and subtle things aren’t always small and subtle in every aspect, especially over a period of time.
5. Hank | 10.09.08
How do you acidify salt water? You can reduce alkalinity, and if more alkalinity is needed, humans can take “on shore” resources and spread them, “off shore”, can they not?
6. Eoin | 10.09.08
Hank, you’re right in pointing out that seawater has a higher pH than pure distilled water, so and even the most dire predictions of ocean acidification would still leave the ocean’s pH greater than 7. So I guess that “ocean acidification” is a somewhat misleading term. Maybe it should be “ocean alkalinity reduction.”
As for taking “on shore” resources and spreading them “off shore” to increase the alkalinity of the ocean, I guess we do that every time we pour Drano down the sink. But I doubt that does much good for the whales, or any other marine creatures for that matter.
7. David Thomson | 10.09.08
“As Discovery News notes, these values are probably underestimated because they are based only on atmospheric CO2 absorbed into the ocean, and not on any other factors that could increase the acidity of the seawater.”
The values are “underestimated.” That means they have not measured the actual values of ocean pH. How do they know that other factors aren’t working to normalize the pH? This sounds like a case of theory being accepted as fact before the facts are presented to prove the theory. And now they have this theory as fact being presented as evidence supporting an IPCC political agenda. Whatever happened to the solid science of the 1800s, where theories were inferred directly from data and were not used as the sources of data?
8. Fubar4Fun | 10.09.08
First off…you don’t argue a case about sonar in court by blaming CO2 levels in the atmosphere. The sheer stupidity that human kind are affecting the global changes as imagined by the ‘Chicken Little’s’ of the science world is preposterous. This coupled with the FACT that we are at the end of a rather dramatic solar cycle which undoutedly raised solar temperatures a slight over the 22 years of its cycle. Now that the sun has ended its active cycle, this year, the year that hasnt been entered into the record books yet because it is still 2008, has been the coolest summer around the world on record. How can you explain Global Warming and CO2 with that evidence alone? Just wait….you haven’t seen the mini ice age yet that will take place this winter when all the melt water which is not salt impregnated evaporates and becomes cloud mass delivering snow and ice across the Northern Hemisphere for the next 22 years. Look at the geological record if you wish to refute this. It gets hot then it gets cold then it gets hot then it gets…all throughout Earths history.
As far as SONAR disturbing the whales…If the manuevers are done per the way the Navy wants, the whales will not be in the area when the testing takes place. Nobody has asked about the testing criteria, the the general cause and effect if the testing were done a week from the second Tuesday of any month. These frivilous efforts to raise a complaint are being wasted in this case and equate to $$$ and extreme stress levels for all involved. Be better to just pack a lunch and go fishing.
9. Geoff | 10.09.08
And, it should be noted that we don’t know very much about aquatic mammals hearing. Just because a 6 db change equals a doubling of loudness, doesn’t mean that a 15 to 40 percent increase in sound transmissibility is negligible. For example, small increases in ambient noise can create significant changes in speech interference in humans. What effect does it have on cetaceans? Increases in ambient noise can produce significant stress level changes in humans. What effect does it have on cetaceans? Increases in transmissibility increases the range where harmful db levels can hurt cetaceans, thus, making the oceans that much smaller, acoustically.
10. Geoff | 10.09.08
So what if the alkalinity of sea water is higher than fresh water. That’s not the point. The point is that the sea water alkalinity is changing faster than aquatic life can adapt to it. In the case of cetaceans, the key issue my be acoustic. In the case of corals, it is bleaching or, for that matter, life itself. We have inadvertently tampered with the chemistry of the oceans by dumping our waste (solid, liquid and gaseous) into the seas at a faster rate than the seas can process it and faster than life can adapt to it.
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1. Andrew P. | 10.09.08
This is all a smokescreen. Mammalian hearing response is logarithmic: To perceive a sound as being twice as loud, the power level needs to go up TENFOLD. A 10 to 15 percent increase in background noise would hardly be noticed by the whales, or any other marine life. Brewer and Hester may know chemistry, but they’re obviously ignorant in other areas. To quote humorist Will Rogers, “Everybody is ignorant, only on different subjects.”