Summit County Citizens Voice

A sea ice map of the North Pole region showing the current extent of the ice compared to historic average, from the National Snow and Ice Data Center.

Global climate tipping points could come without warning; ocean acidification and impacts to marine life clearly tied to human carbon footprint

Compiled from press releases from the University of Alabama and UC Davis

SUMMIT COUNTY — A recent study by scientists at the University of California, Davis, suggests that some large-scale climate change impacts won’t be noticed until the effects are dramatic — and when it’s too late to do anything about them.

That could make it more challenging for researchers who are looking for early warning signs of major changes like shifting ocean current shifts, said award-winning theoretical ecologist Alan Hastings.

“Our new study found, unfortunately, that regime shifts with potentially large consequences can happen without warning — systems can tip precipitously. This means that some effects of global climate change on ecosystems can be seen only once the effects are dramatic. By that point returning the system to a desirable state will be difficult, if not impossible,” Hastings said.

Hastings is one of the world’s top experts in using mathematical models to understand natural systems. Scientists widely agree that global climate change is already causing major environmental effects, such as changes in the frequency and intensity of precipitation, droughts, heat waves and wildfires; rising sea level; water shortages in arid regions; new and larger pest outbreaks afflicting crops and forests; and expanding ranges for tropical pathogens that cause human illness.

Top scientists and policy advisers are trying to anticipate climate changes that could cause major impacts to humans in order to prepare emergency plans and figure out ways to adapt. But the results from the UC Davis study suggest that ocean currents — for example the warm Gulf Stream — could drastically shift with almost no advance warning.

“Climate scientists worry about tipping points … Thresholds beyond which a small additional increase in average temperature or some associated climate variable results in major changes to the affected system,” presidential science adviser John Holdren said in a press release about the new UC Davis study.

Ocean acidification

Such major changes could play out in the world’s oceans, where marine biologists are monitoring increased acidity and the resulting impacts on marine life.

“The oceans are a sink for the carbon dioxide that is released into the atmosphere,” said Antarctic marine biologist Jim McClintock, who has spent more than two decades researching marine species off the coast of Antarctica.

“Carbon dioxide is absorbed by oceans, and through a chemical process hydrogen ions are released to make seawater more acidic. “Existing data points to consistently increasing oceanic acidity, and that is a direct result of increasing carbon dioxide levels in the atmosphere; it is incontrovertible,” McClintock said.

“The ramifications for many of the organisms that call the water home are profound. “There is no existing data that I am aware of that can be used to debate the trend of increasing ocean acidification,” he said.

McClintock and three co-authors collected and reviewed the most recent data on ocean acidification at high latitudes for an article in the December 2009 issue of Oceanography magazine, a special issue that focuses on ocean acidification worldwide. McClintock also recently published research that revealed barnacles grown under acidified seawater conditions produce weaker adult shells.

When the oceans reach a certain level of acidity, it could rob many marine organisms of their ability to produce protective shells – and tip the balance of marine food chains, according to McClintock.

” … (O)cean acidification is simply happening too quickly for many species to survive unless we reverse the trend of increasing anthropogenically generated carbon dioxide that is in large part driving climate change,” he said. “Evolution simply may be unable to keep up, because it typically takes marine organisms longer periods, hundreds or even thousands of years to naturally adapt.

“In addition, the increased acidity of the seawater itself can literally begin to eat away at the outer surfaces of shells of existing clams, snails and other calcified organisms, which could cause species to die outright or become vulnerable to new predators.”

McClintock said the delicate balance of life in the waters that surround the frozen continent of Antarctica is especially susceptible to the effects of acidification. The impact on the marine life in that region will serve as a bellwether for global climate-change effects, he says.

“The Southern Ocean is a major global sink for carbon dioxide. Moreover, there are a number of unique factors that threaten to reduce the availability of abundant minerals dissolved in polar seawater that are used by marine invertebrates to make their protective shells,” he said.

Acidification also could exert a toll on the world’s fisheries, including mollusks and crustaceans. The loss of such marine populations could greatly alter the oceans’ long-standing food chains and produce negative ripple effects on human industries or food supplies over time, he said.

McClintock has logged more than two dozen trips to Antarctica, with ongoing research that explores the chemical defenses of polar marine organisms and impacts of ocean acidification on marine invertebrates. McClintock Point, located at the entrance of a three-mile stretch of land known as Explorers Cove in Antarctica, was named for the biologist in 1998.

Follow McClintock, his fellow University of Alabama research biologist Charles Amsler, Ph.D., and their research team’s upcoming visit to Antarctica from February through May at www.antarctica.uab.edu. Later in 2010 McClintock will lead his third Climate Challenge Education Mission cruise to Antarctica.

Filed under: Environment, global warming Tagged: | Bob Berwyn, climate change, climate tipping points, conservation, Environment, global warming, ocean acidification, Summit County Colorado, UC Davis, University of Alabama