Climate change means one world’s death and another’s birth

A few years ago in a lab in Panama, Klaus Winter tried to conjure the future. A plant physiologist at the Smithsonian Tropical Research Institute, he planted seedlings of 10 tropical tree species in small, geodesic greenhouses. Some he allowed to grow in the kind of environment they were used to out in the forest, around 79 degrees Fahrenheit. Others, he subjected to uncomfortably high temperatures. Still others, unbearably high temperatures—up to a daily average temperature of 95 F and a peak of 102 F. That’s about as hot as Earth has ever been.

It’s also the kind of environment tropical trees have a good chance of living in by the end of this century, thanks to climate change. Winter wanted to see how they would do.

An acidic ocean

Disturbingly, scientists have observed something similar happening in the ocean. Much of the carbon dioxide humans release into the atmosphere is eventually absorbed by the sea, gradually making the water more and more acidic. This process of ocean acidification can wreak havoc on marine invertebrates, dissolving their shells and then their fragile bodies.

But just like in the tropical forest, “there are always the winners as well as the losers of climate change,” says Ivan Nagelkerken, a marine ecologist at the University of Adelaide in Australia. To get an idea of which species might thrive under ocean acidification, he headed to two places where underwater vents already spew carbon dioxide into the sea: Vulcano Island in Italy and White Island in New Zealand. “These CO2 vents are natural laboratories where you can get a peek into the future,” Nagelkerken explains.

As in Winter’s experiment, that future was far from lifeless. But the kind of life it supports has Nagelkerken worried. Carbon dioxide vents can occur in any marine ecosystem, from coral reefs to kelp forests to seagrass plains. But no matter where you are, life in the most acidic pockets looks strikingly similar. Immediately around a vent, all ecosystems “transform into systems that are dominated by turf algae—very short, fleshy algae with very little structural complexity,” Naglekerken explains. What’s more, “we did not observe a single predator on those vents.”

As a result, the food web is dramatically simplified, the number of fish species drops, and the ecosystem becomes “much less valuable and productive.” Small grazing fish that love turf algae will probably excel in the acidic oceans of the future. But as they take over, “everywhere will start to look like everywhere else,” Nagelkerken says.

The new, homogenous ocean won’t be good for humans. The fish that are likely to thrive in the oceans of the future—small, adaptable species such as gobies and blennies—are, simply, not fish people like to eat. And even if human tastes evolved, those fish wouldn’t fill us up; most gobies clock in at fewer than 4 inches long. Humans like to eat big predators, like tuna and marlin—exactly the kind of species that had disappeared from the CO2 vents Nagelkerken studied. As ocean acidification restructures marine ecosystems, the first to go will be the fish that people rely on for money and food.

Lizzie Wade, Wired, 1 September 2015. Full article.

 

 

1 Response to “Climate change means one world’s death and another’s birth”


  1. 1 olgaanghelici 3 September 2015 at 10:55

    It is unfortunate that the terminology used in the title and content of this article is misleading. The definition of “acidic” in the Oxford English dictionary is “having the properties of an acid; having a pH of less than 7″. Despite the process of ocean acidification (the acidity of seawater has increased 26% since preindustrial time), the oceans are alkaline (pH higher than 7) and will not become acidic in the foreseeable future. Hence, while it is accurate to refer to the increase in acidity, the “acid” or “acidic” should not be used when referring to seawater. Note that there are few exceptions, seawater can be acidic in the immediate vicinity of CO2 vents or in purposeful perturbation experiments.


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