February 18, 2011

Coral Reefs Expand As the Oceans Warm

Filed under: Adaptation, Animals, Plants

Hold onto your hats, this will come as quite a shock.

Well, not really—unless you count yourself among that pessimistic bunch who sport blinders that only allow you to see bad things from global warming. And if you are one of those poor souls, you better stop reading now, because we wouldn’t want reality to impinge on your guarded (and distorted) view of the world.

But for the rest of us, the following news will fit nicely into the world view that the earth’s ecosystems and are robust, adaptable and opportunistic, as opposed to being fragile, readily broken, and soon to face extinction at the hand of anthropogenic climate change.

A hot-off-the-presses paper in the peer-reviewed journal Geophysical Research Letters by a team of Japanese scientists finds that warming oceans expand the range of tropical corals northward along the coast of Japan. At the same time, the corals are remaining stable at the southern end of their ranges.

That’s right. Corals are adapting to climate change and expanding, not contracting.

But, you don’t have to take our word for it. Here is the news, straight from the authors:

We show the first large-scale evidence of the poleward range expansion of modern corals, based on 80 years of national records from the temperate areas of Japan, where century-long measurements of in situ sea-surface temperatures have shown statistically significant rises. Four major coral species categories, including two key species for reef formation in tropical areas, showed poleward range expansions since the 1930s, whereas no species demonstrated southward range shrinkage or local extinction. The speed of these expansions reached up to 14 km/year, which is far greater than that for other species. Our results, in combination with recent findings suggesting range expansions of tropical coral-reef associated organisms, strongly suggest that rapid, fundamental modifications of temperate coastal ecosystems could be in progress.

This certainly throws buckets of cold water on all the overly heated talk about how the decline in coral reefs as a result of anthropogenic global warming is going to decimate fisheries and tourism the world over. Perhaps it actually will have a negative impact in some locales, but in others, it seems that it could have quite the opposite effect.

And it is this opposite effect—a positive impact of coral reef communities and their dependents—that is routinely left out of climate change impact assessments.

For instance, when the infamous first draft of the still infamous Global Climate Change Impacts in the United States report from the U.S. Global Change Research Program was released for public comments, it included this bit of text from the “Society” chapter (page 47 of the report):

“A changing climate will mean reduced opportunities for many of the activities that Americans hold dear. For example, coldwater fish species such as salmon and trout that are popular with fishermen will have reduced habitat in a warmer world, and coral reefs are already severely compromised. Hunting opportunities will change as animals’ habitats shift and as relationships among species in natural communities are disrupted by their different responses to rapid climate change.”

We submitted the following two comments (from among our 75+ pages of comments that we submitted) in regards to that rather bit of gloomy text:

Specific comment 78. Chapter Society, page 47, Second paragraph, first sentence

Comment: Enough with the pessimism.

Recommendation: Change the sentence to read “A changing climate may mean reduced opportunities for some activities and increased opportunities for many other of the activities that Americans hold dear.”

Specific comment 79. Chapter Society, page 47, Second paragraph, second sentence, “…coral reefs are already severely compromised.”

Comment: Warming SSTs along the U.S. Gulf and Atlantic shores should encourage coral reefs to expand northward. In fact, evidence of northerly range expansion of elkhorn and staghorn has recently been reported (Precht, W.F., and R.B. Aronson, 2004. Climate flickers and range shifts of reef corals. Frontiers in Ecology and the Environment, 2, 307-314). Currently, the southern portions of Florida define climatologically the northernmost portion of the coral habitat in the western Atlantic, a warming climate presents the opportunity for a habitat expansion that could bring corals further northward and closer to the U.S. mainland. Since coral reefs represent a major tourist destination, not only would a northward range expansion be a benefit to the corals themselves, but may well also represent enhanced economic opportunities along the southeastern U.S. coast.

Recommendation: Update the paragraph on the changing patterns of recreational activities to include the likelihood that coral reefs will expand northward into U.S. coastal waters and increase recreational opportunities associated with them. As it now stands, the statement fails to meet the authors’ claim of providing the “best available science” and of conveying “the most relevant and up-to-date information possible” and otherwise violates applicable objectivity requirements.

Apparently our comments had some impact, but not to the full extent that we intended.

Indeed, in the final version of the USGCRP report, the first sentence of the quoted passage above was changed to “A changing climate will mean reduced opportunities for some activities and locations and expanded opportunities for others.” So far so good.

The next sentence in the final report is “Hunting and fishing will change as animals’ habitats shift and as relationships among species in natural communities are disrupted by their different responses to rapid climate change.”

In other words, the powers that be at the USGCRP decided to drop the whole part about coral reefs, rather than having to include a discussion about the potential benefits of climate change (but don’t be so naïve to think that they dropped the potential negative impacts on coral reefs from the entire report—oh no, they have a section dedicated to those in the “Coral reefs” portion of the “Ecosystems” chapter—with nary a mention of possible (probable) range expansion and concomitant expanded economic possibilities).

Such is the nature of the vast majority of climate change assessment reports—emphasize the negatives and downplay or completely ignore the positives.

But this shouldn’t come as much of a surprise to the dedicated readers of World Climate Report.

Nor should the realization that the expansion of coral reefs in Japan is but a single example of organisms responding positively to the benefits and opportunities presented by a changing climate.

We have covered many other examples in the past, and we promise even more examples in the days, months, years to come.

Reference:

Yamano, H., et al., 2011. Rapid poleward range expansion of tropical reef corals in response to rising sea surface temperatures. Geophysical Research Letters, 38, L04601, doi:10.1029/2010GL04674.




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