Reforestation is good for fighting change because trees absorb CO2, above and beyond the other environmental goodness they produce, but … (there’s always a “but” ) … new work from Elizabeth Burakowski, a postdoctoral research associate at UNH, shows one potential drawback: New forests decrease the albedo, or reflectiveness, of land compared to fields and scrubland.
Decreasing the albedo of land is associated with increased global warming – it’s one of the scary positive-feedback loops resulting from the loss of snow cover and permanent glaciers. So does that mean regrowing forests can increase global warming?
The researchers say that it is important to note that this study focused on albedo and that other surface properties related to land cover can also affect surface climate, such as how much water is moved from the vegetation to the atmosphere and how rough a canopy is, which can affect the redistribution of energy at the surface. While reforestation is a likely contributor to historical warming trends in the New England region, the researchers say more studies are needed to determine how much of the warming from that time to the present is due to land cover change and how much is due to other factors like greenhouse gas emissions and natural climate change.
That’s from the press release (here). As is often the case in science, as in life, answering one question raises two more.
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So deforestation and barren wastelands increase albedo which is a negative feedback?
Perhaps here is a happy potential confluence here between floating white trash bags and terrestrial albedo. A lot of discarded shopping bags are white and make their way to the oceans. I understand there are vast islands of floating plastic right now. Of course we would have to reclaim the non-white pieces and dispose of them otherwise. And perhaps we could provide styrofoam supports inside the white bags to assure they float while exposing the maximum area to the sun.
This could be a good project for a modern CCC and all those able-bodied people who are not working but are being tabulated as employed and allowing the admin’s specious claim of un-employment below six percent.
This is absolutely the first time I’ve said or possted this any where!
When the Pilgrims landed in Plymouth and the Jamestown Colony was formed, there was a single forest that covered much of the northern half of the United States from the Atlantic to the Mississippi River. So by the logic here, the climate should have been warmer. It wasn’t. This one points out one of the bigger problems with members of the man-made climate change or global warming crowd; the belief everything that there is today was that way in the past.
albedo should not be a problem, just plant grass at the same time you plant trees.
Why do people ignore the benefits of grass? Not the kind on your lawn but the grass that occupied the plains when the buffalo roamed? Grass that grows 3 to 5 feet tall. It has the reflective qualities that trees don’t, and an acre of grass that is in full growth has MORE square footage of surface area (CO2 absorbing area) than the same acreage of trees. Another advantage of grass is that if there is a fire, the grass will grow back to full growth in a couple years, whereas trees take a couple decades or more to achieve growth to maturity. Grass also requires less water, keeps the ground from erosion better than a tree, and a strong wind doesn’t blow down and uproot grass.
Trees are more symbolic of ‘green’, but much less functional.
I think that is a thousand times better reforest, to follow all scratching their bellies, as today they do, and doing nothing. We want to start excellent initiatives, such as massive reforestation of large forests, and stop listening to silly things like you write here, paid by oil corporations.
This discussion misses the forest for the trees. Reforestation is primarily done to enable sustainable forestry. Harvest 5% annually and reforest before moving on to the next 5% next year and you never run out of forest, it becomes a sustainable, like a crop, and you return to the same lot every 20 years. The albedo of different lots will be different depending on how long ago they were harvested. But the AVERAGE ALBEDO over all those forest is the same year, after year, after year.
Question: In climate change, reforestation has a … (what’s the opposite of “silver lining”?)
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Answer: A dark black cloud
Forest cover lowers the albedo, yet is associated with a decrease in local air temperature – http://onlinelibrary.wiley.com/doi/10.1029/2010JG001486/full
Apparently the cooling from increased transpiration more than offsets the increased absorption of solar heat. The moisture pumped into the atmosphere also generates clouds, which have a higher albedo – it’s not clear what the net affect on albedo is.
Note that the cooling affect is less in areas with moist Summers. Where I live, in the Pacific Northwest, Summer humidity is low and the cooling affect is very strong – no doubt it’s less in New England.
A recent article from Europe said a problem with reforestation is the replanting with different types of trees. Different trees have different reflectivity but replanting with similar local trees can be more expensive. Another issue I found while looking into the Plague in Europe is how the post plague lower population, and subsequent reforestation, may have lead to the mini-ice age. The timing of the cold onset and natural reforestation seemed to align. I believe that was from a Dutch Professor but I don’t have his name right now. Has anyone looked into the increased heat retention of modern mega-cities? Decades of pouring concrete and asphalt are much more reflective and harder to undo than returning fields to forest.
geez louise….first trees keep us cooler and absorb co2. Now they are not reflective and could keep us warm…nature! but yet in urban areas there are movements to green the roof to help with water run off and keep the roofs cooler, there by reducing the heat bubble affect.
so which is it…trees good? trees bad?
and science wonders why they are treated with skepticism.
Interesting article.
I assume (know what they say about assume) that forest cover converts more solar energy to organic matter then grassland. So even if the albedo is lower I wonder if the next result is higher temperature?
So Humans are damned if they do and damned if they do not? No wonder climate change is received in so tepid a manner by society.
The net effect may be a slightly higher average temperature but thanks to all the evapotranspiration associated with a forested area diminishes the extremes. So high temps would not be as high and low temps would not be as low. So you’re trading a warmer average for less extremes.