“Rainfall in the Sahel has dropped 20-30 percent in the 20th century, the world’s most severe long-term drought since measurements from rainfall gauges began in the mid-1800s,” said study lead author Patrick Gonzalez, who conducted the study while he was a visiting scholar at UC Berkeley’s Center for Forestry. “Previous research already established climate change as the primary cause of the drought, which has overwhelmed the resilience of the trees.”
The study, which is scheduled for publication Friday, Dec. 16, in the Journal of Arid Environments, was based upon climate change records, aerial photos dating back to 1954, recent satellite images and old-fashioned footwork that included counting and measuring over 1,500 trees in the field. The researchers focused on six countries in the Sahel, from Senegal in West Africa to Chad in Central Africa, at sites where the average temperature warmed up by 0.8 degrees Celsius and rainfall fell as much as 48 percent.
They found that one in six trees died between 1954 and 2002. In addition, one in five tree species disappeared locally, and indigenous fruit and timber trees that require more moisture took the biggest hit. Hotter, drier conditions dominated population and soil factors in explaining tree mortality, the authors found. Their results indicate that climate change is shifting vegetation zones south toward moister areas.
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  IMAGE:Rainfall in the African Sahel declined more than anywhere else in the world in the period of recorded measurements, causing increased aridity, as evidenced by this dust storm in Senegal.Click here for more information. |
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“In the western U.S., climate change is leading to tree mortality by increasing the vulnerability of trees to bark beetles,” said Gonzalez, who is now the climate change scientist for the National Park Service. “In the Sahel, drying out of the soil directly kills trees. Tree dieback is occurring at the biome level. It’s not just one species that is dying; whole groups of species are dying out.”
The new findings put solid numbers behind the anecdotal observation of the decline of tree species in the Sahel.
“People in the Sahel depend upon trees for their survival,” said Gonzalez. “Trees provide people with food, firewood, building materials and medicine. We in the U.S. and other industrialized nations have it in our power, with current technologies and practices, to avert more drastic impacts around the world by reducing our greenhouse gas emissions. Our local actions can have global consequences.”
Other co-authors of the study are Compton J. Tucker, senior earth scientist at NASA’s Goddard Space Flight Center, and Hamady Sy, country representative for Mauritania at the Famine Early Warning Systems Network.
Funding from NASA and the U.S. Geological Survey helped support this research.
The Journal of Arid Environments had me laughing. When I was in college we had to give Grand Rounds presentations (although they called them something else). The idea was to hone our presentation skills so the professors always tried to trip up the presenters. There was one loathsome professor who read and would cite articles from the dullest, most obscure journals that none of us were even aware existed. I joked once about getting chewed out for missing a crucial article published in the “Scandinavian Journal of Ischemic Rats and Mice”. I wonder what the circulation of the Journal of Arid Environments is.
Patrick Gonzales has taken Trenberth’s advice and reversed the null hypothesis. The null hypothesis under this interpretation is that all climate change is human caused. Skeptics then have the burden of proof that something other than humans caused the change. This is perverse of course and is sufficiently outrageous in its perversity that it deserves to be a named fallacy.
I recommend “Trenberth’s Fallacy” or “The Fallacy of Human Driven Climate.”
There is a simpler description of this fallacy. This fallacy is committed when someone discovers some fact that conceivably could have been caused by AGW and concludes, on that basis alone, that it was caused by AGW.
Garrett,
More warming would be entirely beneficial for the biosphere. In a world where one-third of the population subsists on less than $2 a day, a few degrees more warming would open up millions of new acres to farming in areas like Siberia, Greenland, Mongolia, Canada, etc. The increased warmth would cause more ocean evaporation and thus more precipitation, providing water for crops.
And more CO2 would be even more beneficial, providing airborne fertilizer and making crops grow faster. Currently there is insufficient CO2 in the atmosphere. More is better.
Attempting to restrict the output of CO2 is tantamount to killing the world’s poorest. This is not speculation, it is a fact: when your income is $2 a day, you have to spend almost all of it on food. And that is the average income for a third of the global population. That means half of those earn less than $2 a day. They are on the edge of starvation.
Arguing that we must reduce “carbon” is no different than the Eugenicists of the 1930’s arguing that humans with medical or mental problems must be killed. They argued exactly that back then, and countries like Germany took that action. Today’s eco-fascists are arguing exactly the same thing, asserting that the planet has too many people. So some will have to be killed. Deliberate starvation seems to be their murder of choice. And they’re not kidding. The question is: Why would you allow yourself to be any part of their evil plan?
Is the Sahel greening?
Sorry,
http://www.thegwpf.org/images/stories/gwpf-reports/mueller-sahel.pdf
I seem to be having problems, try again,
http://www.thegwpf.org/images/stories/gwpf-reports/mueller-sahel.pdf
New headline: More Publications in a Warming World (and promotions)
Garrett says: (December 12, 2011 at 9:12 am)
I apologize if my referencing of a paper from an online journal that summarizes the subject from approximate 65 peer reviewed papers doesn’t meet your standards. Might I suggest that if you question the validity of the my reference, and consider it cherry-picking on my part, you might go read the 65 papers that it summarizes. You might also re-read the Olssen paper since it references conditions in the Sahel as far back the 1930s
The “deforestation” is probably a land use issue. Yes, the desert sands may be shifting (shocking!), and when dunes migrate they cover up the greenery, buildings, and even whole villages in their path. There may even be some (additional) aridity. But meanwhile…
Wildlife, Sheep, goats, cattle and camels make quick work of any grazeable food like grasses; at that point they and their herders turn to the trees. Was the tree above damaged by drought or by humans? I think the answer is: this is a tree that has been heavily lopped, top and bottom. (A browsing animal wouldn’t have been able to reach the top.) So humans have been lopping those branches, to the point where the existing folliage was insufficient to keep the tree alive. I would guess the harm was unintentional for the very reasons that Patrick Gonzalez mentions:
The tree in the picture above has been lopped. Compare to the pollarded tree in the photo here: http://en.wikipedia.org/wiki/File:Pollard_1.jpg
Prosopis africana is, according to one expert source, “a small to large tree (4-20 m), with an open canopy and drooping foliage, resembling Tamarindus indica…. (which is) highly valued as fuel and (for) charcoal making. Due to overexploitation P. africana has disappeared from large tracts of the South Sahel and North Sudanian savannas. Other uses : the bark contains some 18 % tannins, young leaves, shoots and pods are much sought after as fodder in the second part of the dry season, and branches are often broken down or lopped for the easy access of stock. Seeds are fermented and used as seasoning as those of Parkia biglobosa. Pounded dry fruits are a fish poison, again like those of Parkia. Virtually all parts of the tree are used for some medicinal care, as for Parkia.
If the existing trees are anywhere subject to migrating, nomadic people, their going to be used in the same way they’ve been used for millennia. They are a resource. Unless they become agrarian, settled people, and learn to plant and raise the trees for dune stabilization under orchard conditions, the trees will disappear.
University of Cal / Berkely seems to come up with a lot of this kind of stuff.
Are they measuring dryness of a century (20th) compared only to the previous 50 years (mid-1800s)? Huh? (Pardon the lay person response.) Could they be measuring the relative wetness of that first 50-year period instead?
Any commentary on environment anywhere in Africa which makes no mention of AFF (Anthropological Fire Fueling) or the the world’s number one desertifier, the goat, is not worth the time taken to read it. The people of the Sahel are basically nomadic or semi-nomadic and tree replanting is not one of their noted pastimes. The goats get taken with them on their travels to ensure that the next-door region has its annual grasses removed by the roots.
http://i446.photobucket.com/albums/qq187/bobclive/dustbowl.jpg
IMAGE:
Rainfall declined in the US in the period of recorded measurements, causing increased aridity.
Hmm, wonder what the role of Samory might have been – he waged a scorched earth campaign against French invaders of West Africa in the late 1800s.
Before AGW became popular, the desertification of the Sahel was studied intensively and found to be caused by deforestation due to use of trees for firewood and overgrazing with sheep, goats and cattle, which killed the trees, leading to less rainfall, leading to less trees, etc.
The reforestation of the Sahel has lead to moderate to great success in restoring shrub land and improving rainfall and crops. Lots of links to Reforestation Sahel.
The clearest illustration of very long term drying in the Sahel is the extent of Lake Chad. Hint: once upon a time, long long ago, it was much bigger than it is now. This has nothing to do with anything done by man. This is bit like the Kilimanjaro snow fiasco. People who know nothing about Africa visit for just long enough to collect some superficial talking points to support the conclusions that they formed before they began. They might as well be arguing for the Ptolemaic planetary system.
Poor chap, he was probably hoping to make quite an impact after the planet-saving results of a highly successful Durban conference, when he would be sure of admiration for his sagacity and the usual uncritical recitation of the gospel of The Cause. I wonder if he reads this blog? I do hope so.
I’ve got a different idea about the bark beetles in this part of the US. As “scientists” always say, the hypothesis certainly “requires more research”, but it’s at least a tantalizing correlation.
http://www.polistrasmill.blogspot.com/2011/12/kudos-to-spokesman-review.html
I am not surprised. As I have said many times before, the winter jetstreams and their associated low pressures have moved south by about 500km, into the Med, fornthe last 3 years. This gives cold anticyclonic winters for N Europe, and wet cyclones for the Med area. (Which is why the UK was without any wind power for the 2009 and 2010 winters.)
So the question should really be – if trees are dying south of the Sahara (because the Sahara is slowly ‘moving’ south), then how many new trees are growing in Tunisia and Algeria because the north is wetter? (Can someone confirm rainfall trends in N Africa? )
Remember that North Africa was the breadbasket of Ancient Rome, and so it is likely that the area was rather wetter than we see today.
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Anyone who has even the most rudimentary paleo climate knowledge knows that movement of the Sahara toward the equator (and hence Sahel drying) is typical during a cold period.
“As this conspicuous pattern is linked to the Sun’s activity, which again is based on the Sun’s dynamics, an explanation of the phase reversal, too, should be found in the Sun’s dynamics. I have shown that there are torque cycles in the Sun’s oscillation about the center of mass of the solar system which are associated with solar activity (Landscheidt, 1986 a, b, 1999 b ) and climate change (Landscheidt, 1983, 1987, 1988, 1990, 1995, 1998 a,b, 2000 c ).
On this basis, I correctly predicted energetic solar eruptions, strong geomagnetic storms, weaker solar activity past 1990, the end of the Sahelian drought, extrema in global temperature anomalies, drought conditions in the United States, and the last two El Niños 1 to 4 years before the events. The forecast of solar eruptions and geomagnetic storms, checked by astronomers and the Space Environment Center, Boulder, covered six years and achieved a hit rate of 90 %. ”
http://www.john-daly.com/theodor/solarnao.htm
Here is some data from Carthage – Tunis in N Africa
http://www.tutiempo.net/en/Climate/Tunis-Carthage/03-2011/607150.htm
Rainfall for Jan, Feb, Mar (rainy season) total for 3 months in mm
1995 100
2000 169
2001 134
2002 037
2003 236
2004 093
2005 196
2006 181
2007 145
2008 089
2009 268
2010 168
2011 265
So in Tunis, the winters (rainy season) have been rather wetter recently. It would be interesting if someone could do a better analysis of rainfalls in N Africa to see if this is consistent across the region.
And if the Sahara High has moved south for 3 years, it is not surprising that flora to the south of the Sahara has suffered. I don’t know the depth of the root structures and the water table in southern Saharan regions, but three years without rain will put a strain on any biosphere.
But this is what climatic regions do – they shift occasionally. As I said before, Mauritania (Algeria, Libya, Tunisia and Egypt) were the bread basket of the Roman and Byzantine Empires, which suggests they were rather wetter.
And it was not simply the climate that changed. Algeria, Libya, Tunisia and Egypt were all 100% Byzantine Christian, until they were put under pressure by a drying climate. This, together with the aggressive armies of Islam, ensured the whole region was subdued and taken over by the sword and forceably converted. Perhaps a wetter N Africa may seed some new shoots…..
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“Alexander Feht says:
December 12, 2011 at 8:14 am
Just a few thousand years ago the whole of Sahara, where wind now blows about sand dunes for hundreds of miles, has been covered with grass and trees, supporting innumerable herds of grazing animals, giraffes, elephants, monkeys, and predators.”
And several thousand years before that, during the last ice age the Sahara expanded south, almost to the coast of Guinea, and rainforests were reduced to a few small coastal and montane refugia. The sand dunes are still there, under the woodland and forest. Because Sahara grows when the climate is cold and shrinks when it is warm. During the previous (warmer) interglacial it disappeared almost completely.
This particular area has seen great changes in climate over the years as has much of Africa. The climate has varied between rain forest and savannah as the tropical weather patterns move. The Sahel is an area the the ITCZ migrates across. During warm periods, the ITCZ tends to migrate farther from the equator and during cooler periods in migrates closer. This particular portion of the planet experiences quite dramatic changes in rainfall due to variations in the path of the ITCZ.
During the LIA there is evidence that the ITCZ migrated closer to the equator or, more accurately, didn’t migrate as far away from the equator when the Earth is cooler.
Here is a view of the current ITCZ which is the primary overall rainmaker in that part of the world:
http://www.cpc.ncep.noaa.gov/products/fews/ITCZ/itcz.shtml
It would be no surprise that the Sahel would have dried during the modern warming. But also, places South of it would have received more rain than they had in the 1970’s. We will soon see a return of the droughts that we saw during that period if we are in a new period of cooling. Ethiopia will again dry out as it did in the 70’s. During the LIA, the Sahel probably got a lot more rain than it does now because the ITCZ probably landed right on top of it. It probably dried out until about 1950 in the early 20th century warming, then maybe got a little wetter until 1975 or so and then got dryer still during the late 20th century warming.
The key thing here is that climate in that region IS NOT STABLE! It is right on the edge of the Sahara. It’s rains can vary considerably from year to year or decade to decade due to the positioning of the ITCZ.
What we have here is another case of Berkeley again attempting to create the illusion that climate would be stable and perfect for everyone in all locations and they any change in it is A: bad and B caused by humans. It is pretty much a zero sum game in this case with the Sahel. If you want that place to get more rain, someplace else has to get less.
We have studies that show the ITCZ has made very long term changes over time. About 9000 years ago to about 5000 years ago it was slowly drifting toward the equator in response to a decline in summer insolation. During this period places changed from rainforest to savannah and vice versa as the precipitation changed. Monsoons in India became shorter. The Levant dried out. About 3000 things changed quickly for some reason and by 2000 years ago were pretty close to the present regime of temperature and precipitation though we have been gradually cooling even more over the past 2000 years. From 5000 ya to 2000ya the Dead Sea lost about 50 meters of water. The flows of the Jordan River would have greatly diminished and an area that had been green became desert and that desertification continues even today with some decadal variation but generally drier weather over the past 2000 years.
What the Sahel is seeing is normal variation that has been common during the past 200 years. It will have wet times, it will have dry times.
That would coincide in timing with a great change in weather patterns that would have started at about 2kya. The entire region would have experienced a great drying out. That same period is even seen in the Western US where the Great Basin saw a dramatic reduction in moisture about 2kya. It causes hardship. It causes upheaval.. When things get dry or cold and food gets scarce, traditionally people go on the march.
With what? The Chevy Volt? (I doubt he’s speaking of nuclear.)
I trust there’ll be some letters in the next issue that get the author’s goat.