Guest Post by Bob Tisdale
UPDATE: Repaired a few typos.
How often do we see this happen—a press release about a scientific study states or suggests that global warming was the cause of a factor being studied, when the paper itself doesn’t come to that conclusion…and/or the data contradict it?
An example crossed my desk yesterday. (Thanks, Anthony.)
The closing paragraph of the press release Why are seabirds abandoning their ancestral nesting grounds in the Gulf of California? from the University of California, Riverside reads(my boldface):
Increased frequencies of abnormally warm waters in the Gulf of California, possibly as a result of globally warming oceans, coupled with extremely high fishing pressure, are delivering a combined blow to the legendary productivity of the Gulf of California, forcing seabirds to fly away in search for more suitable environments, even if that means abandoning their ancestral nesting grounds and moving into highly transformed industrial landscapes such as the San Diego Saltworks or the LA Harbor Container Terminal.
That’s odd. The paper that’s the subject of the press release doesn’t come to the conclusion that global warming is causing the migratory practices of the studied sea birds.
The press release is about the Velarde et al. (2015) paper Warm oceanographic anomalies and fishing pressure drive seabird nesting north. The abstract reads:
Parallel studies of nesting colonies in Mexico and the United States show that Elegant Terns (Thalasseus elegans) have expanded from the Gulf of California Midriff Island Region into Southern California, but the expansion fluctuates from year to year. A strong inverse relationship between nesting pairs in three Southern California nesting areas [San Diego saltworks, Bolsa Chica Ecological Reserve, and Los Angeles Harbor (1991 to 2014)] and Isla Rasa in the Midriff (1980 to 2014) shows that terns migrate northward when confronting warm oceanographic anomalies (>1.0°C), which may decrease fish availability and hamper nesting success. Migration pulses are triggered by sea surface temperature anomalies localized in the Midriff and, secondarily, by reductions in the sardine population as a result of intensive fishing. This behavior is new; before year 2000, the terns stayed in the Midriff even when oceanographic conditions were adverse. Our results show that terns are responding dynamically to rapidly changing oceanographic conditions and fish availability by migrating 600 km northwest in search of more productive waters.
The conclusions of Velarde et al. (2015) are (my boldface):
In conclusion, three factors seem to be playing a role in the range changes of nesting Elegant Terns. (i) The success of conservation measures in the tern’s nesting grounds both in Mexico and California has allowed an increased population growth of the species, and the exponential increase in the Isla Rasa colony in particular seems to be pushing reproductive pairs onto new nesting grounds in California. (ii) Superimposed on this systematic and continuous expansion, there is a pulse-like variation in local SST conditions in the Midriff, which seems to drive nesting pairs to emigrate toward California when surface seawater in the Midriff is too warm, the thermocline is too deep, and fish availability is poor. (iii) The decision by seabirds to abandon their traditional nesting grounds in the Midriff is compounded by the fishing effort during the previous season, which further increases the proportion of Elegant Terns migrating away from the Gulf of California.
Besides an overall growth of nesting Elegant Terns in Isla Rasa and southern California colonies as a result of successful conservation efforts, since year 2000 whenever Elegant Terns have confronted poor oceanographic conditions, indicated by high SST (>1.0°C) anomalies in the Midriff, breeding pairs have abandoned Rasa, a behavior that is further augmented by high sardine fishing effort and landings in the Midriff. This oscillatory migration dynamics between distant nesting sites suggests that Elegant Terns can make fast decisions and dynamically adapt to rapid changes in the global environment. The adequate maintenance of a healthy fish community in both the Gulf of California and the Pacific is an important priority that will help support healthy seabird communities, as well as healthy marine ecosystems in general and sustainable fisheries.
“[P]ulse-like variation in local SST conditions” and “high SST (>1.0°C) anomalies in the Midriff” do not equate to global warming. In fact, the data provided by Velarde et al. contradict the press release.
The January to April sea surface temperature anomaly data for the years of 1983 to 2014 are provided in the Supplementary Material for Velarde et al. (2015). See their Table S3 Oceanographic data. I’ve plotted their data for the Midriff of the Gulf of California and Baja California’s Pacific coast at the same latitude. See Figures 1 and 2. Both show cooling since 1983, based on the linear trends.
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Note: as far as I can tell from the paper, the data for the Midriff of the Gulf of California is for the 1 deg latitude by 1 deg longitude grid of 29N-30N, 114W-113W.
It’s sad when claims made in a press release are not supported by the conclusions of the paper its advertising, even sadder when data supplied as part of a scientific study contradict that press release.
Shouldn’t truth-in-advertising laws also apply to press releases for scientific studies?
As a result of the false claims made in the press release, it has been picked up by alarmist mainstream media outlets. Examples:
ScienceWorldReport—Climate Change: Seabirds are Abandoning Ancestral Nesting Grounds in California.
The findings reveal that warm waters may be the cause behind these shifts. This, in turn, could be a result of globally warming oceans.
The reason for the migration is to be found in global warming.