Thanks to a Senate hearing on global warming this week, Americans can expect a plateful of charges about dangers to our oceans and, in particular, coral reefs. They should take it all with a pinch of sea salt.
It's not that the objects of alarms -- particularly the condition of reefs in the Indian Ocean region, raised by such nongovernmental organizations as the World Wildlife Fund (WWF) and the Pew Charitable Trusts -- aren't of concern. Coral reefs are appropriately compared to the world's rain forests as habitats for wide varieties of life. They deserve protection.
But against what? Before we blame global warming, yet again, for a change in a species behavior or environment, we need to look closely at what is most likely to affect the reefs, and what is not.
The dying off of coral reefs is known as coral bleaching. This bleaching occurs when corals expel the symbiotic algae -- or Zooxanthellae -- that live in their tissues. This is usually in response to environmental stress, in particular high sea-temperatures, but also high solar radiation, fluctuating salinities, extremely low tides and often a combination of these factors. Then, of course, there are the several instances of pollution associated with several island locations -- mostly those with poor local sewage treatment and/or luxury liners dumping their sewage within close vicinity.
Global warming had nothing to do, for example, with elkhorn and staghorn corals becoming the first species to show rapid die-offs in the Florida Keys in the late 1970s and early 1980s. An extremely cold winter in 1977-78 wiped out large areas of cold-sensitive corals. By 1981, diseases had killed most of the remaining elkhorn and staghorn colonies. Three more cold winters ensued.
The environmental organizations' conjecture about global warming today killing the reefs is based on the belief that surface sea temperatures will increase about 2 degrees C (3.6 F) over the next 100 years, and that rising carbon dioxide levels are making the oceans more acidic.
The temperature increase, though, would fall within the range of temperatures along the reef today -- from 29-30 degrees Celsius (84-86 degrees Fahrenheit) in the north to around 23 degrees C (73 degrees F) in the south. And yet reefs exist nearly everywhere along this 6 to 7 degree C (11-13 F) gradient.
So all the corals aren't likely to die from their projected warming. But how likely is it that the sea surface temperatures will rise the 2 degrees C, 3.6 F, they claim.
The answer is: Not very.
The ocean's response to extensive heating is "ejection" of the major localized surface heat loads by way of Deep Convection -- intense expulsions of heat for the upper ocean wherever the sea surface temperatures exceed about 27.5 C. These expulsions create huge cloud towers up over 60,000 feet into the sky readily observed by satellite. The upper level Hadley Circulation carries this energy away from the equator, eastward and poleward. The associated surface winds also cause upper-ocean mixing that blends the cooler deep waters with the warmer surface, rarely allowing the surface to exceed 30degrees C for any significant length of time.
At the poles, heat is always lost, somewhat more in the dark winter months, but unceasingly. This cooling results in Polar Subsidence, with the cool air sinking, sending huge cool surface wind lenses eastward and equatorward along the surface. These lenses suck up heat as they flow along.
This circulation pattern is how the Earth maintains its relatively narrow temperature bounds, and it runs in cycles not of our choosing. It is extremely unusual for sea surface temperatures in the open ocean to exceed 30 degrees C, due to these and related processes.
Furthermore, the oceans are now heading into one of their periodic phases of cooling. Since the 1997-98 El Nino/Southern Oscillation, an enhanced pole-to-equator atmospheric motion due to enhanced Polar subsidence events has increased super-cooling events, in accordance with the typical 55 to 70 year dipolar Warm/Cool cycle. Of course, where it warms or cools depends on where you are standing within these large scale processes.
The trend is ongoing and will dominate the Global Circulation by 2008-2012, in accordance with its ~55 year periodicity. The Russian Arctic Institute is monitoring this transition, with their scientists' Atmospheric Circulation Index measuring the latitudinal versus meridional transport of energy by surface winds.
The effect of this cycle can be seen in this and last year's long, cold winters with extra near record low temperatures caused by extensive highly mobile polar cold fronts measured as cold high pressure regions in various places.
Now, if history and our experience can be trusted, we can expect an increase in seasonal cold outbursts along the western USA into the southeast, from Moscow south into Eastern Europe and the Middle East, as well as parts of lower South America and South Africa, and even south Australia, during their winter times. These will continue, per their usual time scales of about another 20-25 years, before we emerge from this cool phase and begin the transition into another epoch of generally warmer, remedial climate phases.
But what about the claims by Pew that CO2 produced from burning fossil fuels is "acidifying" the oceans?
The alarms raised are based on a finding this month in an National Oceanographic and Atmospheric Administration study that the average pH sampled in the oceans had declined from 8.2 to approximately 8.175 -- 0.025 units -- over the last 15 years. Scary? Hardly. Recent studies also show that the pH difference was 12 times that miniscule change at the time of the last glaciation, at 8.5 units -- and the reefs have thrived under that falling pH.
It would take pH a drop of 47 times that sampled by the NOAA to reach the 7 pH level when neutrality would occur. And that would require that the oceans not only absorb billions more tons of CO2 than mankind is going to emit, but that its buffering agents -- such as carbonate, nitrate and other radicals that minimize ocean acidity by accepting and expelling hydrogen ions -- disappear.
Fortunately for corals, as all marine species but unlike modern man, they have been through cycles such as this before, on all time and space scales. Modest changes in temperature are not about to wipe them out. Neither will increased carbon dioxide, which is a fundamental chemical building block that allows coral reefs to exist at all. It is their and our friend, generally, not the enemy.
What coral reefs have not had to deal with before -- 6-plus billion people, all leaving their fingerprints, or worse, behind -- very likely will continue to cause problems. And that is where the Congress, environmental organizations and world community should focus their concern -- against the real pollutants and real human damage caused to these rain forests of the sea. (That is, not global warming.)
Dr. Gary D. Sharp is the Scientific Director of the Center for Climate/Ocean Resources Study in Monterey Bay, California He was senior editor of the fourth Edition of the FAO Atlas on Living Resources of the Sea. http://sharpgary.org