Shock Discovery: Warmer Climates Don’t Wreck the Ecosystem

Arctic Wolf Spider

Arctic Wolf Spider. By D. Sikes – originally posted to Flickr as 2008-06-03-5302a.jpg, CC BY-SA 2.0, Link

Guest essay by Eric Worrall

A climate scientist doing fieldwork has made the shocking discovery that, contrary to predictions, the Earth’s ecosystems might have some capacity for self regulation.



High temperatures make arctic wolf spiders ditch their favorite food, indirectly helping the environment.

THE ARCTIC TUNDRA is teeming with predators, just not the ones you might expect: By biomass, arctic wolf spiders outweigh arctic wolves by at least 80-to-1.

The eye-popping calculation, published today in PNAS by National Geographic explorer Amanda Koltz, could shape our understanding of how the Arctic will respond to future climate change.

Her study reveals that at increased temperatures and population densities, arctic wolf spiders change their eating habits, starting an ecosystem-wide cascade that could change how quickly melting permafrost decomposes.

In higher temperatures, decomposition occurs more quickly and wolf spiders are more active, so Koltz expected that when her mini-ecosystems got warmer, their wolf spiders would drastically reduce the springtail population. But Koltz found just the opposite.

In plots with more spiders, the spiders actually ate fewer springtails. These larger springtail populations then ate more fungus, which lowered the rate of decomposition. Among the hotter plots, the one with more spiders decomposed less than plots with almost no spiders. In a way, the spiders are helping to fight climate change in the arctic tundra.

The unexpected find has drawn praise from experts. “The novelty of Dr. Koltz’s paper is that it shows not only is [climate change] having direct impacts on these important ground dwelling animals but also on the complex ecological interactions between species on the tundra,” Joseph Bowden, an entomologist with the Canadian Forest Service who was not involved with Koltz’s research, says by email.

Read more:

The abstract of the paper;

Warming reverses top-down effects of predators on belowground ecosystem function in Arctic tundra

Amanda M. Koltz, Aimée T. Classen, and Justin P. Wright

PNAS July 23, 2018. 201808754; published ahead of print July 23, 2018.
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Edited by Alan Hastings, University of California, Davis, CA, and approved June 12, 2018 (received for review May 21, 2018)

Predators can disproportionately impact the structure and function of ecosystems relative to their biomass. These effects may be exacerbated under warming in ecosystems like the Arctic, where the number and diversity of predators are low and small shifts in community interactions can alter carbon cycle feedbacks. Here, we show that warming alters the effects of wolf spiders, a dominant tundra predator, on belowground litter decomposition. Specifically, while high densities of wolf spiders result in faster litter decomposition under ambient temperatures, they result, instead, in slower decomposition under warming. Higher spider densities are also associated with elevated levels of available soil nitrogen, potentially benefiting plant production. Changes in decomposition rates under increased wolf spider densities are accompanied by trends toward fewer fungivorous Collembola under ambient temperatures and more Collembola under warming, suggesting that Collembola mediate the indirect effects of wolf spiders on decomposition. The unexpected reversal of wolf spider effects on Collembola and decomposition suggest that in some cases, warming does not simply alter the strength of top-down effects but, instead, induces a different trophic cascade altogether. Our results indicate that climate change-induced effects on predators can cascade through other trophic levels, alter critical ecosystem functions, and potentially lead to climate feedbacks with important global implications. Moreover, given the expected increase in wolf spider densities with climate change, our findings suggest that the observed cascading effects of this common predator on detrital processes could potentially buffer concurrent changes in decomposition rates.

Read more (paywalled):

Some of the more amusingly simplistic climate predictions are claims that we’ll all be overrun with pest species like ticks and mosquitoes if the world warms.

Living on the edge of the tropics I’ve learned something that people who make such predictions obviously have not – warm climates also support an abundance of predators, which usually keep the pest species under control.

More food more consumers, everything tends to balance.

Giant tropical spider

Nessie, the giant tropical spider which used to live on my porch. We had a deal – she ate lots of bugs, I didn’t spray her. Sadly she passed away on a cold winter night.


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Kristi Silber

“Earth’s ecosystems might have some capacity for self regulation.”‘

That’s not shocking at all – not to me, anyway. However, one must not assume from that the Earth’s ecosystems are immune to disruption.

Why would a climate scientist be studying spiders?

John M. Ware

“Why would a climate scientist be studying spiders?”

Whyever not? As the holder of an earned research Ph.D., I have spent much time my whole life studying matters outside my doctoral subject matter. As a musicologist (music historian), I studied such moderately related subjects as drama, literature, and history. But I also studied scientific literature* as I ran across it; visual arts, including painting and sculpture; and real estate law (I even wrote a book in that field) and horticulture (I now grow some 15,000 daylilies). While these outside studies did not impinge directly on historical musicology (concentrating on the Renaissance), they certainly gave me a broader understanding of the world in which the musicians about whom I studied wrote and performed. If the climate scientist chose to find out what changes that occurred in her chosen field (climate) actually did to the inhabitants of the world, including spiders, more power to her! I have yet to find an instance in which more knowledge proved harmful, either to the scientist or to others.

*For example, I found it very interesting, upon learning about the Medieval Warm Period and comparing its dates with the close of the Monophonic Era and the rise of polyphony, to note the degree of correspondence. Music history has often depended upon weather and climate, and knowing about that enriched my teaching.


“I grow some 15,000 daylillies” — please, please, what’s the secret in getting them to flower consistently throughout the summer? I’ve tried watering, not watering, full sun, partial sun and they only ever seem to flower once, though the plant doubles its size every year. (This is in a hot very sunny Seattle for the past few years)


They are limited by their genes!!! If you want reblooming daylillies then choose varieties that are reported to rebloom. If you want long blooming then choose varieties that are reported to long bloom, etc, etc.
It’s in their genes, whatever “it’s” is.

Johann Wundersamer

it’s always the known or unknown cause of the phenomenon.

for “it’s raining” it’s nature, clouds, whatever you guess, whatever you know.

Here “it’s” obviously the genes.

Kristi Silber

John, you sound like a Renaissance man. Very interesting. Do you also publish in fields unrelated to musicology? It’s uncommon for scientists to do work very far out of their field of expertise. I suppose “climate science” could be broadly interpreted to mean any science related to climate, but that’s not ordinarily what it means.

“Music history has often depended upon weather and climate” – that, too, is interesting. Do you have a theory to explain it?


“During Stradivari’s latter decades, he used spruce wood that was grown during the Maunder Minimum”.

Does the probability that instrument quality is affected by temperature and environment not establish a link between music historians and climate change? Ironically it appears that even the students of music history have a sound reason not to dispute the existence of the Little Ice Age and the Medieval Warm Period (pun intended). If one accepts that indeed there was a “Little Ice Age” (LIA); then one must also accept that the period preceding the LIA must have been warmer.

Mike Macray

John M. Ware:
…I have yet to find an instance in which more knowledge proved harmful, …

‘they’ say: “A little Knowledge is a dangerous thing!” Extrapolating therefrom: is more knowledge more dangerous? or less?… Depends I suppose on whether the relationship is direct or inverse… Like you I lean towards the former but have my doubts, there seems to be a Promethean message inherant in providing answers to those who lack the knowledge/understanding to ask the question….
Good luck with the daylilies!

Johann Wundersamer

“For example, I found it very interesting, upon learning about the Medieval Warm Period and comparing its dates with the close of the Monophonic Era and the rise of polyphony, to note the degree of correspondence. Music history has often depended upon weather and climate, and knowing about that enriched my teaching.”

Great ! Flutes of bones, drums of wood and however raw hide, guessing.

Kip Hansen

Kristi ==> Amanda Koltzis “a postdoc in the Dept. of Biology at Washington University in St. Louis, and I’m interested in the cascading effects of climate change on communities and ecosystem functioning.”
Writing a climate change hook into a story or designing it into a study is what gets the grant money.
I have more comments on this study to follow further on.

Kristi Silber

“Writing a climate change hook into a story or designing it into a study is what gets the grant money.”

That may be true, but it could also be true that people are simply genuinely interested in the effects of climate change.

Kristi Silber

7 down votes for suggesting people are interested in studying the effects of climate change. That and countless comments say a lot about the way some people view scientists. It’s one of the most insidious, unreasonable, harmful and successful effects of climate change “skeptic” propaganda. The fully indoctrinated would sooner trust the half-baked “science” of an arrogant layman who doesn’t know the difference between a correlation and regression than those who have spent years training to become scientists and decades developing their expertise. It’s like trusting me to design a skyscraper because I’ve read a few books about architecture and engineering claiming you could build Trump Tower with saltines and ketchup.


I’ve got news to you. Nothing is immune to change.

The climates been changing for millions of years. Most of those changes are a lot larger than the small changes seen in the last few hundred years.
And life not only survived, it thrived.

Percy Jackson

The simple answer is that Eric does not know the difference between a climate scientist and a biologist. The only place where Dr. Koltzis is described as a climate scientist is in Eric’s blog. Elsewhere she is described as an ecologist or an national geographic explorer and she is a member of the biology department.


According to the trolls, a climate scientist is anyone who agrees that CO2 is the master molecule.

Richard G.

Climate study has resided in the realm of biology since it was described by Wladimir Köppen. Climate is described and mapped in terms of biomes. The advent of non-biologist climate scientists is a recent phenomenon that has emerged from the invention of modern analytical instruments. We tend to overlook the fact that the earth’s system is always in disequilibrium as it chases it’s tail from day to night while spinning through the seasons. Enjoy the ride.

Walter Sobchak

Follow the money.



“why would a climate scientist be studying spiders?”

How else do you get published?


Who’d a thought that ecosystems can adapt to change?
Just like they have for the last 3 billion years.

old construction worker

“Why would a climate scientist be studying spiders?” Why you say? There is government money to be had.


I call BS….
how do they know spiders ate less springtails….caught them and pumped their stomachs?
..or did what they could try….count spiders and try to count springtails

Springtails lay huge masses of eggs, almost daily….and mature in a week…

….Springtail populations just out competed the spiders….which is the obvious reason


I think this was a models all the way down sort of study from the write-up. They basically ran a predator-prey model with different assumptions baked in. Naturally assuming an RCP 8.5 scenario with the hottest arctic climate model they could find..

Percy Jackson

That is nonsense from start to finish. You need to read the paper. There are no models in it – it is carefully controlled experiments and observations from beginning to end. This is how they describe what they did:

We explored the effects of wolf spider density and warming on community composition, litter decomposition, litter N loss, and available soil nutrients through a fully factorial field experiment. Mesocosms were circular, 1.5 m in diameter, and enclosed with aluminum flashing that was buried 20 cm belowground and stood 20 cm above the soil surface to contain the belowground community and wolf spiders, who are not skilled climbers. Plots were distributed across five blocks and randomly assigned to one of the six spider density/warming treatments. For the warming treat- ment, we placed ITEX OTCs over half of the plots during the summer seasons only. The ITEX method typically increases mean air temperature within the OTCs by 1–2 °C.
Wolf spider density treatments included the following: (i ) low, (ii ) control, and (iii) high density. At the beginning of each summer, we removed all possible wolf spiders from low-density plots and added spiders to high- density plots such that they would have approximately twice the early sea- son average density of control plots, which was 1.1 wolf spiders per square
meter. We continued to check and remove individuals from the removal plots throughout each summer. Visual inspection and live pitfall trapping at the end of the summer seasons verified that we successfully manipulated wolf spider densities during both summers of the experiment.

Kristi Silber

(And this gets down-voted!!! Mind-boggling.)

Percy Jackson

You need to read the actual paper not the related popular press article. They carefully
measured the population of both species and also intermediate predators and noted that increased wolf-spider size corresponded to fewer intermediate predators and more Collembola leading to them “suggesting that under warming, wolf spiders may have prefer- entially preyed upon intermediate predators, effectively releasing Collembola from predation by both groups.” Note that it is a suggestion in the paper not a claim.


So the wolf spiders aren’t eating the springtails, but then to what have they shifted their diets? Surely they aren’t on hunger strike in protest. Perhaps the diets of the springtails changed to make them less palatable to the spiders?
At least they honestly conducted a survey and reported the results, and drew the wrong conclusions from it.


Being cold blooded, their appetites should increase as temperatures increase.

Kristi Silber

Rocketscientist – what are the right conclusions?

Kristi Silber

(A QUESTION gets down-voted???)

Percy Jackson

Read the paper – there are three possible suggestions in it.
1) “In plots with high wolf spider densities, intensified predation on preferred Collembola species may have released less palatable species (65) from competition and enabled them to reach higher abundances under warming. ”
2) “Alternatively, under elevated wolf spider densities, warming-associated increases in spider activity could result in more frequent antagonistic inter- actions with other predators ”
3) “Under warming, we observed that numbers of intermediate predators declined as wolf spider densities increased (Fig. 1B). The reduction in intermediate predators corresponds to a progressive increase in Collembola, suggesting that under warming, wolf spiders may have prefer- entially preyed upon intermediate predators, effectively releasing Collembola from predation by both groups.”


There you go then.
Nature has it all planned out.


There you go then….
The deity , In it way , knew we would find it was all ordained.
The veil is so slowly withdrawn.
Gor! blimey Guv. You is clever.
Way to go . Yet? 😉


There is no such thing as THE ecosystem, there is only AN ecosystem. It has been ever thus.

Bruce Cobb

Sounds like the makings of a movie: you’ve got; climate change (of course), some scientists way up in the Arctic god-knows-where, and wolf spiders. Big ones. Man-eating ones. And they’re on the move, looking for food!

Neil Jordan

Hollywood beat you to it:
But you will have to settle for desert tarantulas. They get as big as a small hand and at dusk might travel in herds in mating ceremonies.

Komrade Kuma

OMG!!! Climate change has lured SPIDERS FROM MARS TO INVADE EARTH!!!! Why didn’t the CAGWarmistas see that one coming??!! WTF do we pay them all that money for???

Kip Hansen

Oh my . . . the field work for this “study” took place “Our study took place from early June 2011 through late July 2012 near Toolik Field Station (68°38′N and 149°43′W, elevation = 760 m), a well-studied area of moist acidic tundra (74) on the North Slope of Alaska.”

SIX years ago….what do you suppose has been happening during all those six long years?

I’ve emailed Amanda Kotlz and asked her . . . .I’ll post the answer as a reply to this comment.

Percy Jackson

There is probably any number of reasons why this took a while to published. Almost every academic has a draw full of results they mean to write up when they get a chance. Off hand I can think of any number of reasons from moving jobs, materity leave, taking time off, finishing your PhD, fighting to get it into a different journal, the student/researcher who did the work leaving and or a combination of any number of these.

Is there any reason why a researcher should publish fast and often rather than taking their time and doing a thorough job?


I have a smaller spider that lives behind the light bulb on my porch. She catches a ton of bugs. We leave her web unless she expands her terrritory too far and then I pull down only what is in the way of my coming and going.

Pop Piasa

Jumping spiders don’t need webs and keep the mites off plants. They also won’t crawl on people and stay out of sight. I never kill them if they come indoors.

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And they’ll watch if you wave to them, and wave back until they get bored and/or hungry.

Pop Piasa

Almost makes one think that climate changes somewhat quickly, doesn’t it. Only thing is, this study looks to be too short-termed to encompass anything but changing weather.

Gary Pearse

Daily we are reminded that Trump has taken down the clime syndicate as if it was made of tissue paper. The number of papers damping and dampening control knob political science is now outnumbering the once epidemic of terminal climatosis that was so rife that Cook was able to consult 12,000 clisci papers published in a mere decade! That’s 7.5 papers published every day of the academic calendar! Thats a paper published every hour of each day of the academic year. I believe I was the only person in the world to have been so gobsmacked by the inconceivable fecundity of these climateers. All using one linear equation! At a cost of several billion a year. Trillions if you count the response of governments to the invisible crisis. Hey the actual study itself which got so much attention from everyone else couldnt compete in my mind with the mountain of waste paper.

After Trumps win and quick reversal of the neomarxbrothers campaign to impoverish us all, sceptic papers, formerly resisted and scuttled and delayed, gushed forth. EU chopped its climate budgets, the Goon Energy fund had to stop its work and its honcho resigned. Coal came back in days. Why was the cat away so long.

Kristi Silber

“Living on the edge of the tropics I’ve learned something that people who make such predictions obviously have not – warm climates also support an abundance of predators, which usually keep the pest species under control.”

That explains why insect vector-borne disease is so much more common in the temperate zone. Who needs DDT or mosquito nets when there are so many natural predators?


Mosquitos are much worse in the boreal taiga zone than anywhere else. And malaria was a major problem there (as well as in the US) until wiped out, mostly through better housing (malaria is almost always transmitted indoors and at night).

And at the present time insect vector-borne disease is certainly much worse in the tropics than in the temperate zone, though this may partly reflect differences in the quality of housing and sanitation (remember the big yellow-fever epidemics in e. g. Philadelphia in the eighteenth century?).


Yes indeed.
I remember.
I was infected by the last global immortality epidemic.
I am dying to forget!!

Diseases that can be Transmitted by Mosquitoes (in the Northern USA and Canada, as described by the Minnesota Dept. of Health) – This treatise describes six different mosquito-borne diseases that occur in the northern forest areas of North America. Mosquito populations there are huge but incidence of these diseases is generally rare.

My questions are NOT related to climate change. Malaria was once prevalent in Northern countries, including the USA, Canada and Russia and has since been eradicated there.

Here are my questions, with some initial research. More expert opinions are requested – thank you in advance for your comments..
1. When and how was malaria eradicated in Northern countries?
It was reportedly accomplished in the USA mostly in just a few years during and after WW2, primarily using DDT. Prior to that time, the areas where malaria was endemic had greatly reduced, apparently due to causes other than DDT.
2. What is to stop malaria from recurring in these countries?
About 1700 cases of malaria are diagnosed in the USA each year, primarily travelers returning from Africa and SE Asia. The Centre for Disease Control monitors cases and reacts as necessary.

DDT has also reportedly been used in the USA to control bubonic plague vectors.

Regards, Allan


Allan, One of, if not the last malaria epidemic in the USA was in Perry, Florida in 1949. The epidemic was stopped by putting screens and screen doors on everyones houses. Mosquitoes were already showing resistance to DDT. While it still certainly helped screens are what did the trick. The last malaria cases I am aware, contracted in the USA, were also in Florida during the late 1980s and early 1990s, just outside Tallahassee and in Palm Beach County. Both were traced very quietly back to migrant worker camps, a significant problem seldom if ever discussed in the illegal immigration debate. Most of the dengue cases in Texas are from a similar case “zero.”

Thank you Edwin.

Lee Riffee

I can’t for the life of me understand where this phobia of a warmer planet comes from…..assuming those who beat the climate change drum incessantly actually believe that a little warming is a problem! But I do know one thing – some of the largest and most impressive looking creatures that ever walked this earth did so at a time when it was so warm that the poles were ice free, even in winter. Obviously dinosaurs (and many marine and flying reptiles) prospered on a tropical planet, and even early mammals managed to survive torrid temperatures that could only be imagined by the most extreme warmists today.
Some creatures do better on a cold planet and others do best in warmth, but there will always be living things on this earth that will be able to handle temps that are warmer (and even much warmer) than now as well as much colder than now.

Tom in Florida

This is nothing to do with a warmer planet. This phobia has been created to fool the ignorant masses of people into submission to an all governing world body whose only intention is to live high off the hog and control everyone else. Perhaps now you can better understand the emotional and fear mongering approach.



You wouldn’t say that if you lived in Australia.


I don’t understand where this hysterical phobia about spiders in Australia comes from. Australia has two dangerous spider species, which is one more than North America.

If one of them didn’t happen to be endemic to the Sydney area, you would never hear about venomous Australian spiders. I suppose it would be the same if the Black Widow only occurred in or around New York City.

Tom in Florida

The blame falls squarely on the shoulders of Paul Hogan.

Smart Rock

tty – I’ve always understood that there are two dangerous spiders in North America – the Black Widow and the Brown Recluse.

Geoff Sherrington

Well, I live in Melbourne Australia that does not have the Sydney funnel web spider problem. Other spiders, no problems, not even red backs under the dunny seat.
I will start to worry when peer reviewed papers show drop bears in the bush growing larger. They have the scientific certainty of global warming, therefore, you must feel FEAR. Geoff.


Drop bears target tourists ONLY according to a “peer reviewed article”
The science is settled. Being a Victorian and therefore possibly a faux Australian; you should perhaps not be too complacent, Geoff.


Koalas can be scary, oddly enough. I remember the first time I heard one, during my first visit to Oz nearly 40 years ago. I was camping in the Brisbane Ranges when I heard this frightful roar in the middle of the night. I noted the direction and in the morning walked out along the bearing to look for tracks, and what did I find? A koala peacefully munching leaves in a tree a hundred yards away.


They don’t have to be venomous to be scary.

Same goes for sharks, crocodiles, and drop bears.


Shocking! I believed that every form of life dies and a starts anew each time there is climate change, that is: always.

The novelty of Theresa Machiemer’s research is that it breaks with dogma that research on climate change has to show greater eco-instability and great environmental harm, particularly in its threat to humans.

In his farewell address to the nation, Eisenhower warned that federal funding for science would be scientific distorts to get more grants. That’s what we’ve been seeing with climate research.

Linda Goodman

Didn’t the Medieval Warm Period already establish that warmer is better overall? Or am I missing something?

Smart Rock

That’s why they needed to make it disappear, Linda

Greg Strebel

The use of the term ‘cascade’ is too connected to the term “tipping point’. The rather obvious situation is that annual temperature changes, not necessarily ‘climate change’ will result in short term, localized ecosystem effects. Isn’t this totally analogous to numerous cycles we observe at the macro level, with, for example, weather affecting berry fecundity affecting the population of berry eating creatures, affecting the population of carnivores of those creatures? Hare and lemming population fluctuations affect fox, wolf and raptor populations. All just cycling along in one big ever-changing panorama.
That localized short term changes in weather produce a chain of events in no way binds the future to some sort of death spiral, as implied by the concept of tipping points. Areas of permafrost shrink and grow at the fringes and ‘islands’ defined by latitude, elevation and exposure. The shrinking is not historically associated with massive releases of methane as speculated by the fearmongers to start a cascade of melting, as this would have been observed already with the general retreat since the depths of the Little Ice Age.

Johann Wundersamer

I would like to have cobwebs in the apartment – that would limit the fly and mosquitoes problem.

Women do not tolerate this, they go with vacuum cleaners on cobwebs.

A rational discussion of this topic is not possible.