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« Yeo fights for his right to trough | Main | A trickle of further information »
Saturday
Jul212012

Drought in the Horn of Africa

During our joint appearance on the Jeremy Vine show, George Monbiot said something that intrigued me, namely that there had been a decades long trend towards drought in the Horn of Africa.

This was interesting to me, as I'd heard this suggested before and had actually spent a short time trying to verify the claim about six months ago. However, I had been distracted by other things and had never bottomed it out.

After hearing George make the claim again, I decided it was worth digging a bit further and this post is the result. Although I can't say I have checked every available source, my researches have turned up very little to support the idea.

An IPCC report on the Regional Impacts of Climate Change produced this map of precipitation trends. It's rather old - dating from 1997 - but does seem to suggest a trend towards increasing rainfall in the area:

There have been two droughts in the area in recent years - 2006 and 2011 - but the map above does seem to preclude a "decades-long" trend towards drought.

I wonder what George's source is?

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Reader Comments (53)

The Team perhaps?

Mailman

Jul 22, 2012 at 2:16 PM | Unregistered CommenterMailman

All I've got so far is this sentence in a BBC piece

'Some say that climate change means that extremes of weather are becoming more common in the region.'

http://www.bbc.co.uk/news/world-africa-14249733

Jul 22, 2012 at 2:24 PM | Registered CommenterPharos

Maybe his source is Time Magazine.

In Africa, drought continues for the sixth consecutive year, adding terribly to the toll of famine victims.

http://www.freerepublic.com/focus/f-news/1663607/posts

:)

Jul 22, 2012 at 2:40 PM | Unregistered CommenterJohn M

http://www.oxfam.org/sites/www.oxfam.org/files/briefing-hornofafrica-drought-climatechange-foodsecurity-020811.pdf

and

http://na.unep.net/geas/getUNEPPageWithArticleIDScript.php?article_id=72

Jul 22, 2012 at 2:43 PM | Unregistered CommenterJeff Norris

His 'source' is more a case of reliance on the 'facts' being either obscure or plain fiction plus no-one to highlight his 'mistakes'. Thank heavens for the world of bloggers!

Jul 22, 2012 at 2:45 PM | Unregistered CommenterDave_G

Dart board?

Roll dice?

Just make shit up?

Jul 22, 2012 at 2:55 PM | Unregistered CommenterFred from Canuckistan

George's Source ?
Could it be the helpful pull-out supplement in to-day's Observer on 'Carbon Footprints'
'CO2 is a greenhouse gas. This means that once it's in the atmosphere, it traps the sun's heat, like a greenhouse, and keeps the earth warm. The more greenhouse gases in the air, the warmer the earth gets - too much of them causes ice to melt at the poles, sea levels to rise coral reefs to die AND FARMLAND TO TURN TO DESERT. This is Climate Change'.
Should you now be hooked, read on - 'Measuring how much CO2 our activities produce is a good way of calculating our impact on the planet. This measurement is called our 'carbon footprint'. The bigger our carbon footprint, the more we are affecting our planet'.
In case you think you are eternal damned,there is a way out -
'You can reduce your carbon footprint by adding more green to the world. Join a tree-planting scheme or just keeping a houseplant will help because plants take in CO2'.
So if you're going abroad this summer - remember to buy an aspidistra first !

Jul 22, 2012 at 3:05 PM | Unregistered Commentertoad

"Desertification, drought, and despair—that's what global warming has in store for much of Africa. Or so we hear.

Emerging evidence is painting a very different scenario, one in which rising temperatures could benefit millions of Africans in the driest parts of the continent.


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Ancient Cemetery Found; Brings "Green Sahara" to Life
Exodus From Drying Sahara Gave Rise to Pharaohs, Study Says

Scientists are now seeing signals that the Sahara desert and surrounding regions are greening due to increasing rainfall.

If sustained, these rains could revitalize drought-ravaged regions, reclaiming them for farming communities."

http://news.nationalgeographic.com/news/2009/07/090731-green-sahara.html

Jul 22, 2012 at 3:05 PM | Unregistered CommenterBruce

I apologize for the atrocious cut and paste of my previous post. :(

Jul 22, 2012 at 3:16 PM | Unregistered CommenterBruce

"I wonder what George's source is?"

Perhaps we should follow the trail -

The Guardian of course -

"Prolonged drought in the Horn of Africa is the immediate cause of the severe food crisis already affecting around 10 million people in parts of Kenya, Ethiopia, Djibouti and Somalia.....How far the current conditions, classified by the UN as "pre-famine" – one step down from "catastrophe" – can be attributed to climate change is not clear. The last intergovernment panel on climate change report suggested that the Horn of Africa would get wetter with climate change, while more recent academic research has concluded that global warming will increase drought in the region..."

http://www.guardian.co.uk/world/2011/jul/04/drought-east-africa-climate-change


Shame that the link for the 'more recent academic research' appears to be broken -


"Global Network for the Study of Human Rights and the Environment Error

An error has occured which means Global Network for the Study of Human Rights and the Environment can not process that request.

We apologise for any inconvenience caused."

http://gnhre.uwe.ac.uk/RenderPages/RenderLearningObject.aspx?Context=47&Area=11&Room=99&Constellation=178&LearningObject=1091

So who is the GNHRE ?

"The GNHRE is an exciting international network of scholars, policy makers, lawyers and activists dedicated to re-imagining the interface between human rights and the environment."

http://www.waikato.ac.nz/law/research/global-network-for-the-study-of-human-right-and-the-environment

"On 16 May 1994, an international group of experts on human rights and environmental protection convened at the United Nations in Geneva and drafted the first-ever declaration of principles on human rights and the environment.

The Geneva group assembled at the invitation of the Sierra Club Legal Defense Fund--in cooperation with the Association mondiale pour l'école instrument de paix and the Société suisse pour la protection de l'environnement- -on behalf of Madame Fatma Zohra Ksentini, Special Rapporteur on Human Rights and the Environment for the United Nations Sub-Commission on Prevention of Discrimination and Protection of Minorities."

http://www1.umn.edu/humanrts/instree/1994-dec.htm

GNHRE - core team

"Radical lawyers include: Professor Conor Gearty; Professor Upendra Baxi (long time advocate for the ‘violated’ of Bhopal, India); Parvez Hassan (outstanding activist and lawyer honoured by UNEP and the IUCN); Polly Higgins (radical barrister and activist – campaigner for the crime of ‘ecocide’)...."

http://gnhre.org/profiles/

Oh yes.... THAT 'Polly Higgins' .............

"The proposal for the United Nations to accept “ecocide” as a fifth “crime against peace”, which could be tried at the International Criminal Court (ICC), is the brainchild of British lawyer-turned-campaigner Polly Higgins.

The radical idea would have a profound effect on industries blamed for widespread damage to the environment like fossil fuels, mining, agriculture, chemicals and forestry.

Supporters of a new ecocide law also believe it could be used to prosecute “climate deniers” who distort science and facts to discourage voters and politicians from taking action to tackle global warming and climate change.

“Ecocide is in essence the very antithesis of life,” says Higgins. “It leads to resource depletion, and where there is escalation of resource depletion, war comes chasing behind. Where such destruction arises out of the actions of mankind, ecocide can be regarded as a crime against peace.”

Higgins, formerly a barrister in London specialising in employment, has already had success at the UN with a Universal Declaration for Planetary Rights, modelled on the human rights declaration. “My starting point was ‘how do we create a duty of care to the planet, a pre-emptive obligation to not harm the planet?’”

After a successful launch at the UN in 2008, the idea has been adopted by the Bolivian government, who will propose a full members’ vote, and Higgins has taken up her campaign for ecocide.

See the Guardian article for the rest " "

http://wattsupwiththat.com/2010/04/11/climate-craziness-of-the-week-british-campaigner-urges-un-to-accept-ecocide-as-international-crime-proposal-to-declare-mass-destruction-of-ecosystems-a-crime-on-a-par-with-genocide/

Why am I not surprised ? -

but sorry Bish, failed to track down the actual 'science' but then again I suppose we can guess what it will be................and I really shouldn't keep getting side-tracked like this!!!!!!!!!!

Jul 22, 2012 at 3:34 PM | Unregistered CommenterMarion

"I wonder what George's source is?"

Posted not that long ago on someone's blog

"The truth, for the Left, is whatever they want it to be"

That's Monbiot's source.

Jul 22, 2012 at 3:36 PM | Unregistered CommenterJeremy Poynton

Was it the arch-environmentalists and eco-fanatics who started talking about "the globe" and "the planet" which must be saved from the depredations of the deniers? It always used to be called the world in my (earlier) day.

Jul 22, 2012 at 4:12 PM | Unregistered CommenterMessenger

A drought in one of the more arid areas on the planet, who would have thought it?

Never mind investigating the weather, what about changes to the human footprint, just as in the UK where an increase in demand but not capacity has left the water suppliers with not enough spare when we have drirer periods has there been any population changes in Africa that could account for this shortage over the last 20 -30 years.

Jul 22, 2012 at 4:59 PM | Unregistered CommenterFrankSW

I wouldn't trust anything said by Mad Monbiot. A more classic example of the smug, opinionated, preachy type couldn't be found.

Jul 22, 2012 at 5:10 PM | Unregistered CommenterChris S

More people and their grazing animals means less ground cover and therefore more food shortages.

This gives the impression of increasing drought.

An "impression" is all that is needed to run another AGW "Extreme climate/weather" scenario,

Who needs facts?

Jul 22, 2012 at 5:44 PM | Unregistered CommenterDon Keiller

I covered this a while back Bish:

http://blackswhitewash.com/2011/07/05/drought-in-the-horn-of-africa-the-reality-is-nothing-to-do-with-climate-change/

Jul 22, 2012 at 5:52 PM | Unregistered Commenterblackswhitewash.com

Sadly though it's exactly these kinds of shenanigans that people have to be prepared to deal with. I'd bet that the sole reason moonbat even raised this is because he knew his references were so obscure that you wouldnt have been in a position to challenge him Bish, which is exactly what happened.

Mailman

Jul 22, 2012 at 5:59 PM | Unregistered CommenterMailman

Perhaps Monbiot's source can be found in an Oxfam briefing, link posted above by Jeff Norris:
"Rainfall trends are less clear: According to the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), there are no statistically significant trends in rainfall. However, more recent research suggests that rainfall decreased from 1980 to 2009 during the ‘long-rains’ (March to June)." The citation for the latter statement is Williams and Funk (2011) ‘A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa,’ J. Climate Dynamics online. http://sd-cite.iisd.org/cgi-bin/koha/opac-detail.pl?biblionumber=50611. This paper is available at the website of one of the authors.

Directly from that paper: "In recent decades (1980–2009), this response [in the Walker circulation] has suppressed convection over tropical eastern Africa, decreasing precipitation during the ‘long-rains’ season of March–June.This trend toward drought contrasts with projections of increased rainfall in eastern Africa and more ‘El Niño-like’ conditions globally by the Intergovernmental Panel on Climate Change." Figure 6c shows regional rainfall trends. For the Horn of Africa (region 5), there is a definite decrease since ~1995, but the historical variability is large -- e.g. recent precipitation matches the lows of the mid-1950s.

Moving off-topic from the question of Monbiot's source, I was intrigued by the contrast in these passages from the Oxfam report:
"Whether the drought in the Horn of Africa was made more likely by man-made climate change is as yet unclear due to the complexity of the local climate..." followed shortly by "Over the coming decades, unless urgent action is taken to slash greenhouse gas emissions, temperatures in the region will continue to rise and rainfall patterns will change. This will create major problems for food production and availability – one recent estimate published by The Royal Society suggests much of East Africa could suffer a decline in the length of the growing period for key crops of up to 20 per cent by the end of the century, with the productivity of beans falling by nearly 50 per cent."

This sort of speculation is exemplary of climate change discussion. Notice how calls for urgent action emerge full-grown from uncertainty, as Athena from the head of Zeus.

Jul 22, 2012 at 6:06 PM | Registered CommenterHaroldW

The Horn of Africa is a desert. It's a desert because it doesn't rain much there. When it doesn't rain it's called a drought. It's not rocket science.

Jul 22, 2012 at 6:44 PM | Unregistered CommenterJimmy Haigh.

[snip - O/T.]

Jul 22, 2012 at 7:11 PM | Unregistered Commenterspartacusisfree

The key idea, only 10 days old, is so obvious it's incredible it has remained undiscovered.

Jul 22, 2012 at 7:43 PM | Unregistered Commenterspartacusisfree

I've been hearing about drought and famine in the Horn of Africa since... I don't even know since any longer. Anyway it is a desert. You can tell that even from a satelite photo.

Jul 22, 2012 at 7:57 PM | Unregistered CommenterJosualdo

http://blackswhitewash.com/2011/07/05/drought-in-the-horn-of-africa-the-reality-is-nothing-to-do-with-climate-change/

Blackswhitewash has got it, the whole truth and nothing but the truth... it's worth a read. Thanks.

Jul 22, 2012 at 8:00 PM | Unregistered CommenterLucy Skywalker

spartacusisfree

You keep dangling bits of meat in front of our eyes re. this interesting radiative science bit - please, when's the article appearing? I'm all ears.

Jul 22, 2012 at 8:04 PM | Unregistered CommenterLucy Skywalker

Aw, Bish, you're a Drought Denialist!

Jul 22, 2012 at 8:33 PM | Unregistered Commenterdearieme

"Could give it an airing on Tallbloke: looks like I've found the mechanism behind Miskolczi...." ---spartacusisfree

Please do. If it works, it's science. If it doesn't work, we'll have learned that it doesn't, which is also science.

Jul 22, 2012 at 8:46 PM | Unregistered Commenterjorgekafkazar

Re: Jul 22, 2012 at 2:43 PM | Jeff Norris


http://na.unep.net/geas/getUNEPPageWithArticleIDScript.php?article_id=72


Thanks for the link, Jeff

From the article by the United Nations Environment Programme (November 2011)

"Food Security in the Horn of Africa: The Implications of a Drier, Hotter and More Crowded Future

Nearly 44 per cent of the population in the Horn of Africa is already subject to extreme food shortages. What will happen if the population continues to grow and climate change exacerbates the harsh conditions? "

But it was the UN via the IPCC who persuaded the world that CO2 caused Climate Change problems were potentially catastrophic and required immediate action and that one of the 'solutions' was biofuels

"The gradual move away from oil has begun. Over the next 15 to 20 years we may see biofuels providing a full 25 percent of the world's energy needs"
-Alexander M Iler, Assistand Director-General for the Sustainable Development Department, FAO

... Recent oil price increases have had devastating effects on many of the world's poor countries, some of which now spend as much as six times as much on fuel as they do on health...In such national settings the macroeconomic benefits of channelling fuel revenues into poor rural economies could be substantial ..."

United Nations "Sustainable Bioenergy: A Framework for Decision Makers"

http://www.un-energy.org/sites/default/files/share/une/susdev.biofuels.fao_.pdf


Get that

"In such national settings the macroeconomic benefits of channelling fuel revenues into poor rural economies could be substantial"

So governments put in place anti-carbon policies that distorted the market and encouraged the production of bio-fuels.

Lots of 'fuel revenues being channelled into rural economies' in Africa, the African governments are initially delighted. A land grab in Africa to grow biofuel crops - they welcome the extra investment

http://www.guardian.co.uk/environment/2011/may/31/biofuel-plantations-africa-british-firms


But Africa is already struggling simply to feed its ever-growing population - the biofuels are a complete disaster

http://www.africanbiodiversity.org/sites/default/files/PDFs/Biofuels%20-%20A%20Failure%20for%20Africa%20(ABN,%20Dec%202010).pdf

And there are at least some attendees at the UN conference in Cancun to point out the hypocrisy

"Biofuelling the COP Hypocrisy


"Chiapas Ecobus 100% Biodiesel!" scream the sides of the shuttle buses that endlessly transport delegates between Cancun Messe and Moon Palace. They seem to be saying it like it's something to be proud of. As if biofuels were actually a real climate-friendly alternative to fossil fuels, instead of a social, ecological and climate disaster.

Do COP organisers really not know that the science shows that the land clearances, production and processing of biofuels produce much more CO2 emissions per gallon than fossil fuels? Did they not notice the devastating 2008 global food crisis, caused in large part by biofuel production displacing and using food crops?

In Africa, we've seen how biofuel plantations displace farmers and indigenous peoples, cut down rainforests, and drive corporate grabbing of our most fertile and agricultural land. Land that we urgently need to grow food. And yet the buses state proudly that "100 thousand hectares of Jatropha in Chiapas" were used to grow the oilseeds.

It seems that we've all been brought here by a big and unwieldy vehicle that promotes false solutions with disastrous social and environmental impacts, and is failing to address climate change. Hmmm. Sound familiar?

Anne Maina & Teresa Anderson, African Biodiversity Network."

http://www.gaiafoundation.org/blog/biofuelling-cop-hypocrisy


So.....

"It seems that we've all been brought here by a big and unwieldy vehicle that promotes false solutions with disastrous social and environmental impacts, and is failing to address climate change. Hmmm. Sound familiar?"

Absolutely couldn't have put it any better myself.....

Jul 22, 2012 at 9:12 PM | Unregistered CommenterMarion

May I suggest his Grace the following read:
"The Meteorology and Climate of Tropical Africa" by Marcel Leroux, Springer/Praxis 2001

Jul 22, 2012 at 10:18 PM | Unregistered CommenterTomRude

It's all pretty academic though isn't it. Unless the claimant can be brought to account 'immediately' the message is made and the masses are convinced. Knowing what a radio show guest is going to say can't be predicted therefore the advantage is theirs - and they know it. If only radio show HOSTS had the balls to say "well, that's what YOU claim but since we have no evidence to hand we must take your assertions with some caution" then live media is a godsend to the alarmists. Occasionally the counterpart to the proponent is on the ball and 'could' shoot them down in flames but that's only if familiarity with the exact situation is known else the counterpart is seen to be 'flustering' thereby bolstering the alarmists claims!
No wonder alarmists are keen for radio/TV coverage - unless, of course, the subject matter is strictly contained at which time the alarmist usually loses - and spectacularly so!

Jul 22, 2012 at 11:34 PM | Unregistered CommenterDave_G

I hope our host mentioned MWP so many times "The Moonbat" started to cry.

Jul 23, 2012 at 12:17 AM | Unregistered CommenterAC1

Marion

Higgins, formerly a barrister in London specialising in employment, has already had success at the UN with a Universal Declaration for Planetary Rights, modelled on the human rights declaration. “My starting point was ‘how do we create a duty of care to the planet, a pre-emptive obligation to not harm the planet?’”

Man has so far not figured out a way to harm the planet so Higgins is getting ahead of the game. However maybe she intends actions like removing resources to be a crime.
I hope the new law is even handed and that the planet will be severely punished for petulant acts of self harm such as volcanic eruptions and earthquakes.

Jul 23, 2012 at 12:31 AM | Registered CommenterDung

Is it just me ? Does climate change really cause itself ?

"The climate is different now and the reason is because of climate change". This is like saying that rain is caused by drops of water falling from the sky.

Jul 23, 2012 at 12:58 AM | Unregistered CommenterJack Hughes

George Monbiot is a gullible fool, who thinks that a run of mild winters and an early spring is evidence of climate change. In the same article he also states that "our summers will be long and warm" and that "most sceptics" are in the pay of Exon Mobil. I am sure he means well but given his track record very little of what he says or writes deserves to be taken seriously. If he says there is a trend towards drought in Horn of Africa then the chances are the region will experience average or above average rainfall for the foreseeable future. If you read this George, please browse some climate history, and you will find that nothing we have experienced in the British Isles in the last 30 years is unusual or unprecedented. Same with the Arctic.

Jul 23, 2012 at 1:31 AM | Registered Commenterlapogus

Shouldn't really have to do B Hill's work for him but one of your gang has passed:

http://newsbusters.org/blogs/pj-gladnick/2012/07/21/rip-alexander-cockburn-leftist-global-warming-heretic

Jul 23, 2012 at 1:40 AM | Unregistered Commenterbigcitylib

I have a lot of respect for George Monbiot. He is rather to the left of me on politics, but his stance on nuclear power and his willingness to go against the entrenched positions of the left (etc) marks him as an honest commentator. He also published a list of his assets and interests which make his pronouncements believable as being aired in his own interests and nobody else's. Agree with him or not, that is your prerogative, but his good faith should not be in doubt.

Dung, your statement that, "Man has so far not figured out a way to harm the planet...", is true only if you consider all of nature as a resource to be harvested for human benefit. I didn't think you believed that (but maybe I'm confusing you with other correspondents). If on the other hand one thinks that all species are part of the planet, that the planet and its ecosystem are inter-linked are are the only thing that keep us alive, and that these things have intrinsic 'value', over and above their utility to humans, then the loss of species and damage to the environment are surely causes of 'harm' the planet.

Jul 23, 2012 at 1:52 AM | Unregistered CommenterBitBucket

George Monbiot is raising alarm over the very climate change that has driven human evolution for the past 7 million years (at least). As north Africa gradually dried out, the jungles where our primate ancestors lived gave way to savannah and then semi arid desert. Is Monbiot ignorant of this, or just relying on the ignorance of others to get away with his outrageous B.S.? I'm guessing the latter.

Even if Monbiot's claim is true (which I doubt), we are a product of this kind of climate change. And it has nothing to do with us or the CO2 we release to the atmosphere. If anything, the increasing CO2 is helping to green the Sahel by giving vegetation a worldwide boost.

Jul 23, 2012 at 2:46 AM | Unregistered CommenterLouis Hooffstetter

All this being said, there are still real human beings involved in this saga. Graphs and forecasts and math only go so far. Ultimately, this may just be part of what happens in the world. People die every day for all sorts of reasons. We just shouldn't lose our humanity when arguing about what science tells us about any given situation.

Jul 23, 2012 at 2:55 AM | Unregistered CommenterRufus

bcl: Fan of Plum, too. Two out of infinity ain't bad. Rest in Peace Alexander Cockburn, Brave Skeptic.
===============

Jul 23, 2012 at 4:35 AM | Unregistered Commenterkim

LH, were it not for changing ecological niches, we would still be trying to crawl out of the sea. This latest mass human madness is so rigid as to be very brittle.
==================

Jul 23, 2012 at 4:43 AM | Unregistered Commenterkim

Marion: "...and I really shouldn't keep getting side-tracked like this!!!!!!!!!!"

For the sake of one's mental health you should not Marion; however, unless people such as you do get so side-tracked such obscene tripe as this may be missed and allowed to grow with no scrutiny -- so, thanks for noting it.

Jul 23, 2012 at 6:10 AM | Unregistered CommenterRoger Carr

Jul 23, 2012 at 2:46 AM | Louis Hooffstetter
---------------------------------------------

When I was a schoolboy in the 60s and 70s, I was taught that the Sahara was expanding at roughly a mile a year ... now it is 2012 and I read that the Sahara is greening again and shrinking. 'Terrible' thing this man-made drought that it causes the Sahara to go green. Monbiot, therefore, must be a fact-free zone.

Jul 23, 2012 at 7:49 AM | Unregistered CommenterStreetcred

Thanks to BigCityLib for reporting the sad death of Alexander Cockburn. He had a famous spat with Monbiot over global warming, as they called it back in 2007. Monbiot won on points when he revealed that some of Cockburn’s information came from a magazine published by Lyndon LaRouche. That’s how they do science round Moonbat way. “Never mind the facts. Show me the politics of your editor”.
Perhaps, as a mark of respect, Jeremy Poynton would like to retract his accusation that all leftists are inveterate liars. it’s extremely tiresome.

Jul 23, 2012 at 7:56 AM | Registered Commentergeoffchambers

[Snip - manners]

Jul 23, 2012 at 8:19 AM | Unregistered Commenterconfused

Ecotretas wrote a blog titled Horngate about the fact that the IPCC models predicted greater rainfall in the Horn of Africa. Of course this has not stopped anyone ascribing last year's drought in this area to global warming / climate change.

http://ecotretas.blogspot.com/2011/09/horngate.html

Jul 23, 2012 at 9:08 AM | Unregistered CommenterKeith

IPCC AR4 2007, Chapter 11, page 850:
"There is likely to be an increase in annual mean rainfall in East Africa."
See the ecotretas link for more detail.

Jul 23, 2012 at 12:17 PM | Registered CommenterPaul Matthews

Paul Matthews

Yes, I saw that. I'm trying to get to the bottom of the trend in recent decades.

Jul 23, 2012 at 12:19 PM | Registered CommenterBishop Hill

Only slighty OT - I find this very interesting, especially the microclimate doughnut effect around the outside of the glasshouses.

http://www.youtube.com/watch?v=WtcHEbxfGTk&feature=g-user-u

Jul 23, 2012 at 1:35 PM | Unregistered CommenterFilbert Cobb

There is a similar graph in a the book the film "An Inconvenient Truth" by Al Gore. Same big green blob over Mogadishu, where the worst of last years drought was centered. Globally Gore stated that rainfall increased by around 20% in the C20th. Did not draw any inferences of the implied increase on cloud cover on global average temperatures though.

Jul 25, 2012 at 11:23 PM | Unregistered CommenterManicBeancounter

Jul 23, 2012 at 12:19 PM | Bishop Hill

This question may depend on whether you are defining drought as just rainfall, or the net availability of water in the soil (or rivers) as determined by the difference between rainfall and evaporation.

I think the AR4 WG1 observations chapter says either no discernible trend in precip in the Horn of Africa, or not enough data to be sure.

It does suggest an increase in drought as defined with the Palmer Drought Severity Index (PDSI), as a consequence of increased temperature which drives evaporation. However the use of PDSI for long-term climate change is a bit controversial. Sheffield and Wood show it diverges from more physically-based modelling estimates of soil moisture drought at high temperatures. Unfortunately I don't know what Sheffield and Wood themselves suggest for soil moisture drought (as opposed to precipitation drought) for the Horn of Africa.

The IPCC SREX report was slightly less confident than AR4 on whether widespread increases in drought are being seen worldwide. This is going to be an extremely interesting aspect of AR5.

Jul 26, 2012 at 12:30 AM | Registered CommenterRichard Betts

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