Skip to content

Study Claiming Insect Decline Due To Global Warming Is Based On Faulty Temperature Data.

January 20, 2019

By Paul Homewood


h/t Joe Public/Dave Ward


Many thanks to some real Sherlock Holmes work by Joe and Dave.




The article refers to this study by Brad Lister last year:




Arthropods, invertebrates including insects that have external skeletons, are declining at an alarming rate. While the tropics harbor the majority of arthropod species, little is known about trends in their abundance. We compared arthropod biomass in Puerto Rico’s Luquillo rainforest with data taken during the 1970s and found that biomass had fallen 10 to 60 times. Our analyses revealed synchronous declines in the lizards, frogs, and birds that eat arthropods. Over the past 30 years, forest temperatures have risen 2.0 °C, and our study indicates that climate warming is the driving force behind the collapse of the forest’s food web. If supported by further research, the impact of climate change on tropical ecosystems may be much greater than currently anticipated.


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.


Sounds like an open and shut case eh?

Lister even adds these temperature graphs to his paper:



Given that, as the paper itself admits, warming in the tropics in theory should be much less than elsewhere, claims of a 2C increase since the 1970s did not pass the sniff test. Fortunately Joe Public decided to go away and check the actual data used by Lister.

His findings should alarm anybody who believes in the integrity of science and peer review.

Let’s take a closer look at those graphs.

All the temperature data used comes from just two sites, El Verde and Bisley (not Bisely). But Bisley data only begins in 1993, so the comparisons with the 1970s rely solely on El Verde, the data for which is sourced from here.



And this is what the Station Metadata has to say:





In short, the data Lister uses prior to 1992 is worthless, and were substantially understated in comparison with those that followed.




If we begin the chart in 1997, we find that temperatures have actually been dropping, and not increasing (see below).



The metadata states that temperatures showed an abrupt increase in 1997, as the adjustments were ended. And this increase is clear on Lister’s chart (the above chart starts in 1997).

The metadata also links to the dataset:


And this provides some handy graphs.

Below is the chart of annual temperatures from 1993 to 2013. [The data only runs to Feb 2014]

This shows the same pattern of declining temperatures since 1992. We know that the data since 1997 is fully reliable, and this too shows a declining trend. Note too that Lister’s graph indicates temperatures since 2013 have been lower still for three of the last four years.

This still leaves us the problem of Bisley, where data starts in Feb 1993. CLIMDB only have data till Nov 2010, so full annuals are only available from 1994 to 2009:


For some reason, Bisley shows a rather different picture to El Verde, although there is no obvious warming trend. Given that El Verde and Bisley are only a few miles apart, it is obvious that the divergence between the two is due to dodgy data and not real.

To sum up, we have a paper which makes bold claims that arthropods have been declining at an alarming rate since the 1970s, and that the cause is climate warming.

Yet these claims are based on long term temperature data, which, according to the organisation that actually maintains the data, is not reliable and should not be used for long term trends.

The only reliable data covers the period since 1992, and this shows declining temperatures. Even this dataset is not consistent with the Bisley one.

Clearly the whole study is worthless, and the paper should be withdrawn.

There are some alarming facts about all of this:

1) Why did the researchers not suspect that the temperature data looked hopelessly wrong at the outset?

2) Why did peer review not do the basic checks that I did?

3) The study carries out some mindbendingly complex statistical analysis, linking arthropod decline to rising temperatures. But how can this analysis have been robust, when the temperature data was hopelessly wrong?

The conclusion is that the faulty temperature data matched the researchers’ expectations of climate warming, and consequently they never bothered to crosscheck. It would after all have been extremely simple to have asked the people who maintain the data.

Whether or not arthropods are in decline I have no idea. But by blaming non existent climate warming, there is a very real danger that the true cause is being missed. Indeed, looking at those graphs, it may well be climate cooling that is responsible.

I plan to contact PNAS, who published the paper, to request that it be withdrawn.




I have also crosschecked the temperature data from 1975 to 1991, available here. This correlates with Lister’s graph.

  1. A C Osborn permalink
    January 20, 2019 12:31 pm

    Science at it’s poorest, Bias Confirmation if ever we saw it.
    Great Analysis by you guys.

    • Adrian permalink
      January 20, 2019 1:01 pm

      Sadly it is science as it is now.

      Funding drives science. It is only been possible to get money from the likes of NERC if the ‘research’ is predicated on examining ‘impacts of climate change on……’ since the early 90’s. I expect US funding bodies have been similar over the past few years.

      Universities only employ those who get funding.

      ‘Science’ has nothing to do with it. It is about careers, salaries, security, all with a generous sauce of ego and arrogance poured over the top.

    • dave permalink
      January 20, 2019 1:24 pm

      You know that sinking feeling you get in the pit of your stomach, when an elderly relative in cognitive decline tells you that she has signed some papers, in her home, with an earnest young man who came to her with a ‘Government Approved Scheme?’

      The Western world is that elderly relative in cognitive decline. Why is ‘Modern Science’ so determined to help gull her? How did it come to this? Truly, I do not know.

  2. MrGrimNasty permalink
    January 20, 2019 12:35 pm

    It’s crazy to believe that such dramatic declines could be correct, short of an insecticide bombing campaign.

    There must be some obvious reason – methodology, seasonality, etc.

    Do they have those rampaging ants there that march and kill everything in sight in an area – it could just be unfortunate timing?

  3. Ian Magness permalink
    January 20, 2019 12:51 pm

    A really sad aspect of this outcome is that it diverts attention away from a very real problem in many parts of the world – including much of the UK – that hasn’t been studied correctly and the wrong, AGW-related conclusions drawn. I refer to depleted insect biomass, which has a profound impact on the overall natural food chain to the detriment of birdlife in particular. In Britain and much of Europe, the finger points strongly at the volumes of herbicide and pesticide used in many areas of farming – leaving countless acreage of fields ecologically dead for many months each year. Much more research, however, needs to be carried out to draw rational conclusions and come up with workable solutions. I have no idea whether these types of poison are affecting the tropics but one thing is for sure – manmade non-CO2 causes like deforestation are far more likely than CO2 rises which tend to enhance vegetation growth to the benefit of all.

  4. January 20, 2019 1:05 pm

    Peer review has never been about detailed checking, given that it is unpaid, usually anonymous, and the day job still has to be done. The real weapon for improving quality is reproducibility, all data and methods should be archived (routine in the real world of engineering) and made available to the public. The simple fact that someone (probably not a peer reviewer) might check what you have done should create what now appears to be out of fashion … the fear of making a mistake.

  5. January 20, 2019 1:09 pm

    Pardon my intrusion into the hand-wringing Chicken Little of the day, BUT……

    The Pleistocene glaciation which began some 2.58 million years ago is still ongoing with the ice advancing and retreating in approximately 100,000 year cycles. During that time there have been between 5-7 glacial episodes, depending upon which timeline you look at. The most recent Wisconsin Glacial Episode lasted from ca. 75,000-11,000 years ago. Currently, we are in an interglacial period with warming, melt and isostatic rebound of the crust.

    Our 2 major plant groups are the seed plants, Gymnosperms (pine, spruce, fir, etc.) arose during the Triassic Period between 245 and 202 mya. Then came the flowering plants or angiosperms in the Cretaceous 160 mya and became dominant by 120 mya. Insects evolved along with the flowering plants. So let’s just say, they have all be around for quite some time.

    Polar bears separated from the brown bear some 600,000 ya as a distinct species. Penguin fossils in New Zealand have now been found dating back to 61 mya.

    And I DO have a point with all of this. The plants, animals and insects have been around during all or most of this. Mass extinctions occurred prior to this period (Tertiary-Cretaceous Boundary, etc.).

    In botany, we said that the plants were “pre-disposed” meaning that if they survived one such episode, they had the genetic material to survive it again. This applies not only to plants, but to animals (even the cuddly polar bears and cute penguins) and the insects which depend upon the plants. They have made it when it was much cooler than today and they have made it when it was much warmer than today. They made it. They will make it.

  6. January 20, 2019 1:12 pm

    Some like it hot…

    In cold weather, insects slow down, and in hot weather, they become more active. During a warmer-than-normal winter, fewer insects die as a result of extreme cold. That means more insects are available come spring. In hot weather, insects’ reproduction rates increase and they grow faster.

  7. Brian Blagden permalink
    January 20, 2019 2:50 pm

    It is also suggested that the weather data at El Verde is obtained from ‘a tower above the forest canopy…’ – I’m not sure how the authors reconciled ‘above canopy’ temperatures from said mast with forest floor temperatures. After all the study was related to the ground fauna (albeit some of these may fly).

    @diphascon15 asks if reforestation and loss of pasture and pasture woodland adjacent to the research area in Puerto Rico could be a contributory factor and links to the following research

  8. January 20, 2019 3:37 pm

    Thanks for digging down on this one; the devil truly is in the details, and their supposition come up empty of support. Ironically, the alarmists/activists have argued both sides of this claim: That “good” insects like those in Puerto Rico will die from the heat, while “bad” insects will multiply and eat our food supplies. Sort of like, “Global Warming Favors Rats over Cute Animals.”
    I previously posted on why rising temperatures (even if they occur) are not the threat they claim, according to what is known about insects and heat stress.

    These scares always sound plausible, but on closer inspection are simplistic and unrealistic. The details show that each type of insect has a range of temperatures they can tolerate and allow them to develop. They are stressed and populations decrease when colder than the lower limit and also when hotter than the upper limit. Every species will adapt to changing conditions as they always have. Those at their upper limit will decline, not increase, and their place will be taken by others. Of course, if it gets colder, the opposite occurs. Don’t let them scare you that insects are taking over.

    • Joe Public permalink
      January 20, 2019 7:32 pm

      “Ironically, the alarmists/activists have argued both sides of this claim: That “good” insects like those in Puerto Rico will die from the heat, while “bad” insects will multiply ….”

      Yes – the likes of mosquitoes must be super intelligent & adaptable, whilst cuddly things like polar bears are supposed to simply stay put & perish.

      “Climate change promotes the spread of mosquito and tick-borne viruses.

      Spurred on by climate change, international travel and international trade, disease-bearing insects are spreading to ever-wider parts of the world.”

  9. Broadlands permalink
    January 20, 2019 4:07 pm

    “I plan to contact PNAS, who published the paper, to request that it be withdrawn.”

    Please let everyone know what their response is to this absurd peer-reviewed? paper trying to put the blame on “global warming”… another “me-too” publication.

  10. alexei permalink
    January 20, 2019 5:10 pm

    Arthropods include many species such as ants and cockroaches, whose survivability has been predicted to outlast Man’s, even in the event of nuclear devastation. One wonders why that didn’t occur to Messrs. Lister and Garcia.

  11. Leslie Johnson permalink
    January 20, 2019 5:59 pm

    I had commented on this study in Dec 2018, but using NOAA gridded data. Same result. Very little warming over the study period, and actually a cooling since 1998.

  12. Phoenix44 permalink
    January 20, 2019 6:00 pm

    The claim that 98% of the insect mass had gone does not pass the smell taste. That is literally unbelievable, and any peer review should have questioned very sceptically that claim – the idea that even the change in climate they claim would have caused an almost total loss of insect life is extraordinary in itself

    • Hivemind permalink
      January 21, 2019 12:51 am

      Publish-or-perish. They have to publish papers to meet their performance agreements. There is nothing to describe the quality the papers need to meet. And let’s face it – the peer reviewers will give a it quick pass if it puts everything down to global warming.

  13. Athelstan permalink
    January 20, 2019 6:41 pm

    Proceedings of the National Academy of Sciences of the United States of America (PNAS) is the official scientific journal of the National Academy of Sciences, published since 1915.

    With broad coverage, spanning the biological, physical, and social sciences, the journal publishes original research alongside scientific reviews, commentaries, and letters.

    From 1999–2009, the last period for which data are available, PNAS was the second most cited journal across all fields of science.[1] PNAS is published weekly in print, and daily online in PNAS Early Edition. /quote.

    How could they (PNAS) publish this article without even the scantest of scrutiny? Ah but then, it’s all about the ‘meme’ and the political chimera of man made Armageddon ain’t it, soooooooooooooooo bugger the science………….”hey men whatever you guys say!”

    Now listen UP PNAS, unless you delete this atrocious bit of mythologizing green agenda rot by Lister and Garcia, the tattered banner, of reputation which your desperately prejudiced organization still clings to, will be rent to shreds – your justification, your reason to be – gone.

    Finally and we ask, when you do rightly disappear up your own crassly biased fundament: who the hell would miss you?

    A. nobody, no one at all, the same with; ‘nature’, RI, AGU et al.

  14. Jack Broughton permalink
    January 20, 2019 7:55 pm

    Great expose and illustration of the low standard of both scientific research and peer reviewing that is applied in “climate science”. The use without question of dubious temperatures are clearly disgraceful, however as a school-child error the abuse of regression is also clear: plotting the best straight line through a very small amount of data is bad enough, but then to quote a regression coefficient that show that the correlation is of poor quality without any comment, demonstrates real ignorance. A line with a negative slope would have only a slightly worse correlation. The most valid statistic for this spread is clearly the mean: but that is steady temperature, so cannot be.

    I’ve often commented about how tools like excel in the hands of idiots is very dangerous as they think that the lines automatically fitted by the software are significant even when they are not.

  15. January 20, 2019 10:49 pm

    Reblogged this on Climate Collections.

  16. richard permalink
    January 21, 2019 12:46 pm

    Wow weird-

    “Global warming could increase both the number and appetite of insect pests, new research finds, which could pose a serious threat to global crop production”

    Good old alarmists every angle covered.

  17. January 21, 2019 5:18 pm

    It’s known as CONFIRMATION BIAS. Very simple.

  18. Bob Vislocky permalink
    January 22, 2019 12:58 am

    Paul, I posted an article on WUWT last month about this same faulty insect article:

    If you’re serious about contacting PNAS to have the paper withdrawn, feel free to use any of my charts, text or analyses.

    • January 22, 2019 10:47 am

      Thanks Bob. I’m doing a joint letter with GWPF, so these will be useful

  19. January 23, 2019 10:34 pm

    I am quite skeptical about the conclusions of the study as well. However, this critique does not address the main contention of the study, which is that the insect decline is caused primarily by a higher incidence of extremely hot days, and not necessarily by a rise in average temperatures. Does your analysis of the raw data affect this hypothesis as well?

    • January 24, 2019 10:42 am

      After the new thermometer was introduced in 1992 “recorded max temps increased substantially”. This not only increased the averages, it also increased the number of days above 29C

  20. Joe Public permalink
    January 25, 2019 2:33 pm

    The Harrabin has now started … “Insectageddon”


  1. Saved By Pseudo-Renewable Energy? - Capitol Hill Outsider

Comments are closed.

%d bloggers like this: