Fragwürdige Temperaturdaten stellen Ergebnisse einer Insektenalarmstudie in Frage

Eine typische Alarmgeschichte: Die Insekten sterben, weil es immer heißer wird! Lister & Garcia 2018 in PNAS:

Climate-driven declines in arthropod abundance restructure a rainforest food web
A number of studies indicate that tropical arthropods should be particularly vulnerable to climate warming. If these predictions are realized, climate warming may have a more profound impact on the functioning and diversity of tropical forests than currently anticipated. Although arthropods comprise over two-thirds of terrestrial species, information on their abundance and extinction rates in tropical habitats is severely limited. Here we analyze data on arthropod and insectivore abundances taken between 1976 and 2012 at two midelevation habitats in Puerto Rico’s Luquillo rainforest. During this time, mean maximum temperatures have risen by 2.0 °C. Using the same study area and methods employed by Lister in the 1970s, we discovered that the dry weight biomass of arthropods captured in sweep samples had declined 4 to 8 times, and 30 to 60 times in sticky traps. Analysis of long-term data on canopy arthropods and walking sticks taken as part of the Luquillo Long-Term Ecological Research program revealed sustained declines in abundance over two decades, as well as negative regressions of abundance on mean maximum temperatures. We also document parallel decreases in Luquillo’s insectivorous lizards, frogs, and birds. While El Niño/Southern Oscillation influences the abundance of forest arthropods, climate warming is the major driver of reductions in arthropod abundance, indirectly precipitating a bottom-up trophic cascade and consequent collapse of the forest food web.

Siehe auch Bericht in der Washington Post. Passt alles bestens ins klimaalarmistische Konzept. Leider scheint die Studie komplett danebenzuliegen. Auf WUWT zeigte Bob Vislocky, dass die maximalen Temperaturen im puertoricanischen Studiengebiet wohl gar nicht angestiegen sind:

The problem is that the data from those two stations should never have ever been used in this research study. For example, Bisley only started reporting in 1994, which means that the temperature record only covered the second half of the 38-year time period used to study the insects. Unless the authors had temperature data going back to the start of their study period in 1976 how in the world can they claim that the insect decline from their first expedition in 1976-77 to the second one in 2012-13 was due to climate change?

The situation for the observing station in El Verde is outright comical. This station has had a checkered history beginning with its odd choice of thermometer location (on top of a concrete roof). Roughly 25% of the data between 1976 and 2013 is reported as missing with no values provided. From 1976-1978 and 1987-1989 the daily observations were not real, but rather long-term average values were substituted. Moreover, prior to 1992 many of the max temperature observations were extrapolated from surrounding locations. Additionally, from 1989-1992 the temperatures reported were often that of the current reading at observation time instead of the maximum temperature, so adjustments had to be applied to correct those values. To top all of that there were instrument issues cited in the early 1990s that prompted replacement of the thermometer in September of 1992. The amount of corrupt data was so extensive prior to 1992 that the caretakers of the data set specifically state that this data is suspect and not valuable for interpreting long-term trends as it would pollute the later data record after 1992. Here are the links to the historical El Verde max temperature spreadsheets and more importantly the description of the data where the issues regarding the data sets are exposed.

But wait, there’s more! After the instrument change in September 1992, recorded maximum temperatures increased substantially at the station! As a result, a correction factor was applied to the data beginning in September of 1992 to make it compatible to previous data record; however the exact nature of the correction was not documented. Unfortunately, the correction factor ceased to be applied starting in 1997, so who knows what impact this had on the temperature trend. Lastly, even after the instrument change in 1992, over 35% of the daily readings are still reported as missing.

Ganzen Beitrag auf WUWT lesen