Pine Beetles at it again - causing warming this time!

Yale Environment 360 tells us that Pine Beetle Attacks Cause Temperature Rise in Canadian Forests. Is it the beating of all those tiny wings creating heat? Their black carapaces (the shiny bits) absorbing more heat from the sun? No it's because trees naturally cool their environment. More beetles, fewer trees; fewer trees less cooling; less cooling, higher temperatures. Simple really, or so the researchers would have us believe. I just had to put down my dog-eared copy of "Only 100 days left to save the World - 101 things you didn't know about Global Warming" and read on.

The decimation of trees by mountain pine beetles in British Columbia has caused air temperatures in affected areas to climb by an average of 1 degree Celsius during the summer months, according to a new study. In an analysis of satellite and forest data collected between 1999 and 2010, scientists from the University of Toronto and University of California, Berkeley calculated that areas hit hardest by widespread pine beetle infestations have experienced even sharper temperature increases of several degrees Celsius, as regions are increasingly deprived of the natural cooling effect of trees. Since the evaporation of water through leaves prevents some of the sun’s radiation from heating the ground surface, the widespread loss of trees causes the temperature increases, said Holly Maness, a researcher at UC Berkeley and co-author of the study, published in the journal Nature Geoscience. And because warming temperatures and milder winters have helped pine beetles to flourish, these infestations are creating a feedback effect that is making the forests even more vulnerable. According to scientists, mountain beetles have affected 66,000 square miles in British Columbia, or 20 percent of the province’s total area.

That's pretty straightforward and convincing isn't it? What possible criticisms could I have? Well, for a start there's the chicken and egg business. (What's he talking about? - ed.). Did the pine beetles cause the warming or did the warming encourage the pine beetles to do what pine beetles do best (reproduce and eat, not necessarily in that order)? I ask only because "Global warming threatens pine forests, forcing federal officials to shift strategy" which I'd interpret as chicken -> egg whereas this paper seems to be claiming egg -> chicken -> bigger egg -> bigger chicken (feedback).

The thing that caught my eye was the apparently plausible warming mechanism outlined by Holly Maness - "Since the evaporation of water through leaves prevents some of the sun’s radiation from heating the ground surface, the widespread loss of trees causes the temperature increases". Now call me a sceptic, but I understood, as do many (most?) scientists and authors, that it was evapotranspiration wot dun it? Also, it's the leaves themselves which shade the ground below (simple really), and green chlorophyll absorbs sunlight, especially ultraviolet and infrared - the leaves are darker than grass, it's called the albedo effect. In a nutshell (how appropriate!)

Forests also influence local climate. Dependant on the latitude forest influences the temperature in a region: in the tropics forest have a net cooling effect through evapotranspiration while at higher altitudes, mainly boreal forests, there is a net warming effect because the relative dark colour of the canopies absorbs warmth from the sun (albedo effect).

When water evaporates through leaf pores, it absorbs heat (a lot of heat) thus cooling the leaves and the tree (and forest) canopy. Holly seems to think otherwise. It's true that the evaporated water vapour would absorb some short-wave infra-red from the Sun, but there's not a great deal of that radiation left by the time sunlight reaches the treetops; most is absorbed on its way through the atmosphere - by water vapour - lots more water vapour than the trees expire. Secondly, water vapour is the most abundant greenhouse gas (hasn't Holly heard that?), and absorption and emission of upward radiation from the forest canopy would certainly outweigh the small absorption of solar infra-red by the evaporated water vapour.

just a minute - surely the paper itself can't possibly say this can it?

The present mountain pine beetle infestation in forests in British Columbia ranks among the largest ecological disturbances recorded in Canada so far. These recent outbreaks are thought to have been favoured by large-scale climatic shifts, and may foreshadow outbreaks of a similar magnitude in North American forests over the coming decades. The associated forest dieback could result in substantial shifts in evapotranspiration and albedo, thereby altering the local surface energy balance, and in turn regional temperature and climate. Here we quantify the impact of the Canadian pine beetle disturbance on the local summertime surface energy budget, using measurements of evapotranspiration, albedo and surface temperature, obtained primarily through remote sensing. 

We show that over the 170,000 km² of affected forest, the typical decrease in summertime evapotranspiration is 19%. Changes to the absorbed short-wave flux are negligible, in comparison. As a result, outgoing sensible and radiative heat fluxes increased by 8% and 1%, respectively, corresponding to a typical increase in surface temperature of 1°C. These changes are comparable to those observed for other types of disturbance, such as wildfire, and may have secondary consequences for climate, including modifications to circulation, cloud cover and precipitation.

That would seem to set the record straight. Perhaps the article's author and one of the co-authors should have read the paper, or at least the abstract.

Global warming threatens pine forests, forcing federal officials to shift strategy

Really? It's global warming threatening pine forests? The ever-balanced and conclusive report in the Washington Times has all the facts:

A bag, a beetle and a warming threat to trees: A plastic bag that fights a beetle infestation on a western conifer is an emblem of how federal researchers are working to steel high-elevation pine forests in the West against the onslaught of climate change.

A beetle? A beetle is climate change? Seems the "federal researchers" are working to "steel high-elevation pine forests" against a beetle, not climate change. Are the beetles caused by climate change? There are plenty of links in the second paragraph to seemingly provide additional information from the WP archives of truth and light for those who bother to click on them. Most people don't of course, I do, I'm an inveterate link-clicker.

The conifer, with its accoutrements, represents a small salvo in the battle against a beetle infestation, fueled partly by warmer temperatures. But it is also a larger symbol of how researchers from the Forest Service — in concert with National Park Service officials and other scientists — are working to steel high-elevation pine forests in the West against the onslaught of climate change.

Let's take them in order, first the "beetle infestation".

The death rates of trees in Western U.S. forests have doubled over the past two to three decades, according to a new study spearheaded by the U.S. Geological Survey, driven in large part by higher temperatures and water scarcity linked to climate change.

Beetles feature in that report, but the emphasis is on other factors, the "driven in large part" factors, the immediate threat being from beetles, as one might expect.

What about the "Forest Service" - lots of information about that august body, their policies and their strategy? No, it's titled "Obama administration issues major rewrite of national forest rules", and it's about how the Forest Service will respond to that "rewrite". Two down two to go, so how about the "high-elevation pine forests" link? All about pine forests? No, it's about bark beetles, and there's a lot more about beetles in this article, supposed to tell us about forests, than on their "beetle infestation" link. Confused yet? Here's what it says about the main reason for the beetle-fest

In a natural forest, wildfires keep the percentage of prime beetle fodder at around 25 percent, says Allan Carroll, one of Canada’s foremost insect ecologists at the University of British Columbia in Vancouver. But thanks to dedicated firefighting and other factors, aging pines made up more than half of some forests by 1990. In other words, human management of the forests has turned them into an incredible smorgasbord for beetles.

That's the main reason for forest fires also, the increase in older, diseased and dead trees, which the "join the dots" brigade ignore totally in blaming an increase in fires on "climate change". Try lighting a fire with green twigs.

The best is to come, the "climate change" link surely must do better, and explain climate change and what's causing it, and what the terrible outcomes will be? No, it's about the threat of rising sea level on Louisiana's Highway 1. Wait, what? The report blames climate change for the apparently imminent demise of one of the world's iconic species, a strip of concrete and tarmac. What does it have to say about the real reason for Highway 1's fate?

The land is sinking, in part because engineers have redirected sediment flowing from the Mississippi River more directly into the Gulf of Mexico, improving navigation but no longer shoring up the wetlands.

Score for this link: climate change 0, facts 1

That's the "informative" links done and dusted, ridiculed and debunked, so back to the reason for this post. The beetle infestation is "fueled partly by warmer temperatures":

Scientists know that global warming will reshape these forests, which provide crucial habitat and food for key species, curb soil erosion and slow melting snow destined for local water supplies. What they don’t yet understand is which trees are best poised to survive under these changed conditions and how they can help them adapt in the decades to come.

If they don't know which trees are "best poised to survive", then they clearly don't know which trees are "least poised to survive" either (if you know one, you must know the other), and by extension what the effects of "climate change" will be on pine trees in general (but they know a lot about beetles, so that's alright).

Now, some regions of the Northern Rockies have experienced an 80 percent die-off of whitebark pines, and the Natural Resource Defense Council projects that between 80 and 100 percent of remaining trees in some areas will be killed by mountain pine beetles, whitepine blister rust or a combination of the two.

Not "global warming", not "climate change"?

“It’s not as if after these threats come through and climate change continues that these ecosystems will return to what they were,” Schoettle said, “but they will persist and will continue to function.”

So it's not "global warming" that's the real threat, it's pine beetles and bark rust(aided by people nailing plastic bags to thousands of trees maybe?). From that last comment, the imminent demise of North America's pine forests has been greatly exaggerated. When has the Washington Post ever printed any good news? (It's a rhetorical question btw, but if you know of any, the comment box is below.)

For a factual and detailed of the mountain pine beetle, check out this on the Colorado State University site (beware, the linked pdf is 10mb, and takes an age to download)