From Oregon State University College of Forestry some news that some people who want to blame pine beetle outbreaks on global warming won’t like. It seems there is a benefit.
“Albedo effect” in forests can cause added warming, bonus cooling
CORVALLIS, Ore. – Wildfire, insect outbreaks and hurricanes destroy huge amounts of forest every year and increase the amount of carbon dioxide entering the atmosphere, but scientists are now learning more about another force that can significantly affect their climate impact.
Researchers conclude in a new study that the albedo effect, which controls the amount of energy reflected back into space, is important in the climatic significance of several types of major forest disturbances.
In some cases – mostly in boreal forests with significant snow cover – increases in reflectivity can provide cooling. If the area disturbed by fire or insects is large, this cooling can substantially offset the increase in global warming that would otherwise be caused by these forest disturbances and the release of greenhouse gases. In other cases where the ground itself is unusually dark, albedo decreases can magnify concerns about warming.
Wildfires are not the only disturbance that significantly alters surface albedo, this study concluded. Insect outbreaks and defoliation by hurricanes can also change surface reflectivity, with effects on climate as great as those caused by carbon dioxide release from the disturbed area.
“On a global scale, warming caused by increased carbon dioxide still trumps everything else,” said Beverly Law, a professor in the Department of Forest Ecosystems and Society at Oregon State University. “On a smaller or local scale, however, changes in albedo can be fairly important, especially in areas with significant amounts of snow, such as high latitudes or higher elevations.”
Albedo is a measure of radiation reflected by a surface, in this case the surface of the planet. Lighter colors such as snow reflect more light and heat back into space than the dark colors of a full forest and tree canopy.
“This decreased absorption of heat by the land surface is a local atmospheric cooling effect,” said Tom O’Halloran, a recent postdoctoral research at OSU who is now with the Department of Environmental Studies at Sweet Briar College. “This was clear in one case we studied of trees killed by mountain pine beetles in British Columbia.
“In areas with substantial snow cover, we found that canopy removal due to either fire or insect attack increased reflected radiation and approximately offset the warming that would be caused by increased release of carbon dioxide,” O’Halloran said. “However, we haven’t been able to measure the full impact from the current beetle outbreak, which could take decades to complete.”
This complex phenomenon would be much less in lower latitudes or areas without snow for much of the year, the researchers said. It relates primarily to boreal or colder mid-latitude forests, such as the Canadian insect outbreak over 374,000 square kilometers of forest.
“The impacts of insects on forest carbon dynamics and resulting changes in albedo are generally ignored in large-scale modeling,” Law said.
The study also found that forest disturbance does not always cause an albedo increase. When Hurricane Wilma in 2005 partially defoliated more than 2,400 square kilometers of a mangrove forest in the Florida Everglades, it exposed an underlying land surface darker than the previous forest canopy. In that case, an albedo decrease effectively doubled the warming impact of released carbon dioxide.
All of the forces studied in this research – fire, insect attack and hurricanes – are expected to increase in severity, frequency or extent under climate change scenarios, the scientists said. In the United States alone, these events affect 20,000 to 40,000 square kilometers of forest a year. If Earth system models are to be accurate, this makes it important to more accurately incorporate changes in albedo.
Globally, forest disturbances are a major factor in the carbon cycle and greenhouse gas warming. They can instantly switch forests from carbon sinks into carbon sources for two decades or more. In cold regions where forest recovery is slower, albedo increases can persist for 100 years.
This research was published in Global Change Biology, a professional journal. It was supported by the U.S. Department of Energy, and used data from both the AmeriFlux Network and NASA MODIS sensor on the Terra satellite.
“largely offset warming that would otherwise result from increased release of carbon dioxide”
How about the warming released by the gigantic match that is Colorado, just waiting to be struck?
Shows you what happens when you pine for a certain interpretation.
“On a global scale, warming caused by increased carbon dioxide still trumps everything else,”
Or maybe, on a global scale, it’s albedo, especially of clouds and ice, that trumps everything else.
one of the things not mentioned is that lodgepole pine is kind of a weed in the forest. they grow in very thick stands and so if there is an infestation of some kind it spreads extremely rapidly. then the trees die and if they are not thinned or salvaged in a few years it turns into an extremely dangerous fire situation.
if there is a pronounced windstorm or intense earthquake in the area then the dead trees will fall to the ground and the resulting mess stops any movement through the area by land animals for a good many years.
C
The combination of last bitterly cold winter and the ensuing one should result in a natural and massive reduction in the pine bark pine beetle and spruce bud worm populations.
What remains is to manage (salvage logging) the fuel loading in the vast areas of dead and dying trees. I submit that the environmental impacts from damage to soils and watersheds done by extremely hot wildfires is far worse than the impacts from releasing the stored carbon in those trees into the atmosphere. There are always trade offs that must be evaluated in order to select the most favorable outcome.
If this year’s La Nina is intense, and winter temperatures in the affected forests are very low for a few days, that will kill off lots of beetle larvae.
“On a global scale, warming caused by increased carbon dioxide still trumps everything else,”
And her study of forest albedo provides what evidence for this sweeping statement? Perhaps it is her qualifications in “Forest Ecosystems and Society” which provide her with the expertise to pronounce so authoritatively on this most complex issue.
By extension, this research shows that as the sub-Arctic warms, trees will grow taller and delay the snow-reflection effect. That will promote local warming, extending the growing season to make trees taller (etc). For any given insolation, the warming-cooling cycles are self-accelerating within whatever limits there are in the climate system.
As the CO2 heating effect is probably taken from the IPCC documents, we understand that the cooling effect is actually twice what he stated. Apply a similar correction to the case in Florida.
“On a global scale, warming caused by increased carbon dioxide still trumps everything else,”.
Keep believing. It’s essential for the funding.
They are just looking for an excuse for the lack of warming over the past decade.
The boreal forest in Canada gets very little insolation when the snow is on the ground!
at lattitude 55N for Canadian boreal forest:
June 20 MJ per Meter squared.
December 3 MJ per Meter squared.
A slight change in albedo in a tiny part of the forest when there is no radiation adds up to a whole lot of nothing! (347,000 hectares are affected from a total size of Canadian boreal forest of 290 million hectares)
…but what would I know, I’ve only worked in the forest my whole life?
correction bc forestry says 16 million Ha affected not 340,000! My point is the same though
While I’m clarifying, for anyone who thinks its not a “slight” albedo change, remember that snow and frost change the forest albedo to nearly 60% so the difference between a forest covered in snow and a field covered in snow is almost nothing. Perhaps if you never go outside these things are less clear!
(sorry Mods for the multiple posts!)
“Albedo is a measure of radiation reflected by a surface, in this case the surface of the planet. Lighter colors such as snow reflect more light and heat back into space than the dark colors of a full forest and tree canopy.”
“The study also found that forest disturbance does not always cause an albedo increase. When Hurricane Wilma in 2005 partially defoliated more than 2,400 square kilometers of a mangrove forest in the Florida Everglades, it exposed an underlying land surface darker than the previous forest canopy. In that case, an albedo decrease effectively doubled the warming impact of released carbon dioxide.”
The whole arguments around albedo are too simplistic and in almost every case like this omit any other characteristics that influence the absorption of solar radiation. Although forests are ‘dark’ they are generally cooler than ‘lighter’ features. So the rain forests that girdle the earth around the equator are relatively cooler than treeless places like deserts that have a higher albedo, especially those with white salt flats. Where are the hottest surface temperatures in the world? OK, so it is assumed here that this phenomena only applies to boreal forests, but just one moment. Are we to assume that the snow just disappears when it falls over forest, because if it doesn’t reach the ground then it’s in the canopy.
But then of course we have this sentence:
“However, we haven’t been able to measure the full impact from the current beetle outbreak, which could take decades to complete.”
“The study also found that forest disturbance does not always cause an albedo increase. When Hurricane Wilma in 2005 partially defoliated more than 2,400 square kilometers of a mangrove forest in the Florida Everglades, it exposed an underlying land surface darker than the previous forest canopy. In that case, an albedo decrease effectively doubled the warming impact of released carbon dioxide.”
I forgot to comment on this. Bare earth will absorb heat not because of it’s albedo but because it is exposed. It is lazy analysis to think the difference between mangrove forest and land surface is just a matter of albedo. And wait one minute again. Mangrove forest will be in water, because thats where mangroves grow. So the hurricane not only removed the mangroves but the water as well!
I have a hard time believing any of this. I will consult some experts at The Western Institute for Study of the Environment–http:// westinstenv.org to get their feelings and thoughts about this.
pk says:
“… if there is a pronounced windstorm or intense earthquake in the area then the dead trees will fall to the ground and the resulting mess stops any movement through the area by land animals for a good many years.”
We’ll have to destroy nature in order to save it!
And a purely empirical “self-organizing model” found that CO2 had no linkage, cause or effect, with global climate, warming or temperature:
http://www.climateprediction.eu/cc/Main/Entries/2011/9/13_What_Drives_Global_Warming.html
So “double” isn’t a large enough multiplier for ground albedo changes vs. CO2. You need something that approximates infinity.
This kind of forest burns every 50 years anyway.
The mid-to-high-latitude forests are 25% to 50% fire scarred which has a higher Albedo than the forest which hasn’t been burned recently. Certainly not enough of a change to show up in the Albedo calculations (we can’t actually measure any changes in Albedo anyway or at least nobody seems to be doing it).
The guys running the satellites need precise Albedo numbers (because it can affect satellite tracks) and I believe they are still using the numbers developed more than a decade ago.
I disagree with a couple comments. I have worked in lodgepole forests as a forester.
Cold winters only kill significant numbers of bark beetles if there is very little snow. Snow covering the lower part of the tree insulates it and the beetles.
I wouldn’t call lodgepole a “weed tree”. It may be the only tree that can grow on a particular site or it may moderate site conditions to allow other species to become established. Lodgepole stands may or may not be very dense–it depends on site history and conditions.
It would take one hell of an earthquake to down many more trees that a routine blow. Any that would fall from a quake were ready to fall anyway.
The story claims beetle damage on 374,000 square kilometers of forest, not hectares. That works out to 92,000,000 acres, or about as large an area as Montana, the 4th largest state. And that’s just in Canada. The beetle has ravaged large areas of the western US, too.
what a classic reality check on the warmistas. The more that is revealed over time the more you realise that their climate model is about as sophisticated as if the medicos understood the human muscular-skeletal system as a stick man. just child like.
WTF ? You mean there are negative climate forcings? Duhhh! Yuh don’t saay?!
“Scheme” may be accepted in the UK as “program”, but from where I come from it has decidedly negative connotations.
Ponzi Scheme, etc…
The opening phrase that sarcastically says “It seems there is a benefit” is a bizarre way to lead off on this. So, one local environmental damage leads to a negative feedback that might possibly give a miniscule offset to another global environmental problems … a bit like spitting into the wind I would think.
‘How about the warming released by the gigantic match that is Colorado, just waiting to be struck?’
If the Sun had not sent that energy down to the trees which absorbed it, there would be no forest there in the first place. Photosynthesis eventually gives back what it took in, whether in the life-cycle of the forest or the fossil fuels buried by geology. No photosynthesis, no fauna, no man.
ModernMan is just smart enough to realize that the energy is going to depart for colder regions of space eventually. Ingrates don’t want anybody to have use of it…unless thier cause is Nobel enough.
Back to the forest. If it cooked off in a wildfire in summer, it would still not do anything for the cold of the following winter. The heat escapes to space.
And lowered evapotranspiration will reduce precipitation levels as well.
Still, a colder winter and a few wildfires will sort the beetle problem.
“On a global scale, warming caused by increased carbon dioxide still trumps everything else,”
Excellent. Sounds like we can safely ignore everything else as well.
I saw the word ALBEDO and thought great an article that is examining what I consider a poorly researched subject which I believe could have significant implications to discredit CAGW to be let down by a group of tree doctors who have no idea what they are talking about except that it will take them years before they can confirm it. Did you get the hint, more time needs more money, hint hint hint.
The key words in this very limited study are those that describe impacts as being important in only a very small area. In reality pine beetles are devastating huge areas of the boreal forests in the entire Northern Hemisphere. As a consequence, vast amounts of stored up CO2 are being released into the atmosphere and this release will continue as rotting of the tree persists, and in the event of wildfire, will accelerate further.None of these are trivial events.
It’s interesting that nobody here has commented on the fact that the pine beetle problem itself is an indication of higher winter temperatures. I have read that the massive outbreak is due in large part to the fact that the beetle population is no longer kept in check by sharp winter freezes.
Had a nice trip to Western Canada in June this year and asked a ranger why so many trees were brown. His answer was that the pine beetle was at work and that was the result of a lack of forest fires. Indians burned down selective parts of forests until the 1800’s, mainly to attract game into the cleared land, where fresh herbs, grass and trees were growing. That renewed the forests all around. The pine beetle mainly attacks mature overaged trees and not the young trees. This is nowadays a huge problem in national parks, where no clearing is done…
These infestations are a result of two things. One issue is the fact that many forests are not managed and are too dense. Too many genetically marginal trees are there. Secondly, fire suppression has resulted in way too much deadfall – classic beetle hatching conditions.
RE: thedudeabides says:
October 20, 2011 at 9:40 am
It’s interesting that nobody here has commented on the fact that the pine beetle problem itself is an indication of higher winter temperatures. I have read that the massive outbreak is due in large part to the fact that the beetle population is no longer kept in check by sharp winter freezes.
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That’s an urban legend. Look at the life cycle of a beetle. Beetles are not even in adult form during winter, in any four season climate!
Pine Beetle cycles occur every 30 to 40 years. This is nothing new. It happens with regularity.
To connect the forrests ravaged by PB cycles to global warming is a useless exercise.
USFS was fighting spruce bud worm in the early sixties. they were hand spraying with a mixture of diesel fuel and DDT. this was applied by several crews of 30-40 men in the courdelane forest.
didn’t seem to help much.
C