Posts Tagged ‘Sharma S et al’

Nonsense speculation posing as science

August 17, 2011

Another example of nonsense speculation which gets published and then drives headlines only because they invoke the magic words “climate change”. A case of speculative IPCC model results being used as inputs for another speculative model about fish extermination and coming to a mildly alarmist conclusion.

Not a measurement in sight. But many pages, lots of statistics, 4 tables, 2 figures and 66 references to come to the amazing conclusion and state the obvious that cold water fish may die out if they are forced to live in warm water. 

As my son would put it “Duh”!!

A new paper in PLOS One.

Comparing Climate Change and Species Invasions as Drivers of Coldwater Fish Population Extirpations

 Sharma S, Vander Zanden MJ, Magnuson JJ, Lyons J (2011), PLoS ONE 6(8): e22906. doi:10.1371/journal.pone.0022906

The “researchers” actually measured nothing. They took a data-base of the conditions in which populations of a particular kind of fish (the cisco) existed. These parameters include air temperature among many others. They then did a statistical regression to infer how the populations might depend upon air temperature. They then took temperature increase assumptions from the climate change scenarios of the IPCC and applied them to the data base to speculate what that might do to the fish populations. They then reach their conclusions that climate change would extirpate a large section of the fish population and that this would be worse than the impact of invasive species.

And this is considered peer-reviewed science!!!!

They write in their paper:

Coldwater fishes, such as cisco [Corgeonus artedii] require cold water temperatures, high dissolved oxygen concentrations, and oligotrophic conditions, and thereby are sensitive indicators of environmental change. In Wisconsin, cisco are close to the southern edge of their range and are listed as a species of special concern. Cisco live in larger and deeper inland lakes with cold, well-oxygenated deep waters. Under climate change scenarios, as air temperatures increase, epilimnion and hypolimnion water temperatures are expected to increase. As water temperatures increase, the duration of the lake stratification period is expected to increase, isolating the deep waters from exchanges with the atmosphere, making it more likely that metabolic activity will reduce dissolved oxygen concentrations in the hypolimnion to stressful or lethal levels. The combination of warmer water temperatures and lower dissolved oxygen concentrations under climate change scenarios in larger, deeper lakes typically suitable for coldwater fishes could result in their extirpation.

Cisco are sensitive to the introduction of non-native rainbow smelt (Osmerus mordax). Rainbow smelt is native to the northeastern coast of North America and was introduced to the Laurentian Great Lakes in the 1920s. In Wisconsin, rainbow smelt have been introduced into lakes deliberately by anglers for sport fishing purposes. Furthermore, fertilized eggs of rainbow smelt may have been unintentionally introduced into lakes by residents cleaning smelt on their piers. When rainbow smelt invade a system, they negatively interact with native species through predation and competition. Invasion of rainbow smelt has been linked directly to changes in zooplankton community composition, decline in recruitment of walleye (Sander vitreus), and extirpation of cisco and yellow perch (Perca flavescens) . For example in Sparkling Lake, Wisconsin, the cisco population was extirpated through predation-induced recruitment within eight years of detection of rainbow smelt. …… 

Geo-referenced lake-specific data were collected for 13,052 lakes in Wisconsin from a variety of sources including the North Temperate Lakes Long Term Ecological Research (NTL-LTER) program, Wisconsin GAP (Geographic Approach to Planning for Biological Diversity) database, Wisconsin Department of Natural Resources databases, refereed publications, government reports, and dissertations. From the aforementioned databases, a suite of variables describing lake morphology, water chemistry, physical habitat, and fish species occurrence were compiled. Environmental variables retained in the final dataset were: surface area (hectares), maximum depth (metres), perimeter (kilometres), Secchi depth (metres), pH, conductivity (µS/cm), and mean annual air temperatures (°C). For water chemistry variables, annual averages were used in the dataset. 

Current air temperatures and scenarios of future mean annual air temperatures were obtained from the Wisconsin Initiative on Climate Change Impacts (WICCI) Climate Working Group. Mean annual air temperatures were statistically downscaled for Wisconsin on a 0.1° latitude ×0.1° longitude grid. Climate data were summarised for three time periods: 1961–2000, 2046–2065, and 2081–2100 and averaged over these three sets of years as suggested by the Intergovernmental Panel on Climate Change (IPCC) to reduce temporal variation in climate. Then, projected air temperatures from 15 general circulation models and the IPCCs A1, A2 and B1 scenarios (although not all general circulation models incorporated all three scenarios) totalling 78 climate change scenarios were used to develop future projections of cisco occurrence. The A1, A2 and B1 scenarios incorporate a range of variation in greenhouse gas emissions inferred for various time periods in the 21st century. The A1 scenario is the most extreme and assumes the highest greenhouse gas concentrations, followed by the A2 and B1 scenarios. …….

Our results highlight the threats to coldwater fish species. The probability of cisco extirpations could be reduced in Wisconsin through three interventions. First, the mitigation of climate change through the reduction of greenhouse gas emissions could significantly reduce the worst case losses of cisco. ….

Oh dear!!

Needless to say this non-science – since it uses the magic phrase “climate change” and has an alarmist theme – has no difficulty in being published and generating nonsense headlines in Science Daily:

Climate Change Could Drive Native Fish out of Wisconsin Waters 

ScienceDaily (Aug. 16, 2011) — The cisco, a key forage fish found in Wisconsin’s deepest and coldest bodies of water, could become a climate change casualty and disappear from most of the Wisconsin lakes it now inhabits by the year 2100, according to a new study. In a report published online in the journal Public Library of Science One, researchers from the University of Wisconsin-Madison and the Wisconsin Department of Natural Resources project a gloomy fate for the fish — an important food for many of Wisconsin’s iconic game species — as climate warms and pressure from invasive species grows. ………

In addition to the ecological change that would be prompted by a warmer Wisconsin climate, Sharma notes, the impoverishment of aquatic ecosystems will have potential socio-economic implications, especially in a setting like Wisconsin where recreational fishing is an iconic pastime, not to mention an important industry.

“This could very well impact the fishing experiences we have,” avers the Wisconsin researcher.

But rather than make me concerned about climate change this nonsense report based on idle – but fashionable – speculation makes me much more concerned about the predominance of modelling over measurement and what passes in some quarters for for science.

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