Wednesday, February 23, 2011

Pascal Oettli et al., Environ. Res. Lett. 6 (January-March 2011), Are regional climate models relevant for crop yield prediction in West Africa?

Environ. Res. Lett6 (January-March 2011) 014008; doi: 10.1088/1748-9326/6/1/014008


Are regional climate models relevant for crop yield 
prediction in West Africa?

Pascal Oettli1,2, Benjamin Sultan1,5, Christian Baron3 and Mathieu Vrac4

1 IPSL—LOCEAN, Paris, France
2 University of Tokyo, Tokyo, Japan
3 CIRAD UPR AIVA, Montpellier, France
4 IPSL—LSCE, Gif-sur-Yvette, France
5 Address for correspondence: LOCEAN, Boite 100, T45/55, 4 Place Jussieu, 75252 Paris 
cedex 05, France

Received 18 October 2010; Accepted 17 January 2011; Published 1 February 2011
Abstract. This study assesses the accuracy of state-of-the-art regional climate models
for agriculture applications in West Africa. A set of nine regional configurations with eight
regional models from the ENSEMBLES project is evaluated. Although they are all based
on similar large-scale conditions, the performances of regional models in reproducing the
most crucial variables for crop production are extremely variable. This therefore leads to
a large dispersion in crop yield prediction when using regional models in a climate/crop
modelling system. This dispersion comes from the different physics in each regional model
and also the choice of parametrizations for a single regional model. Indeed, two configurations of the same regional model are sometimes more distinct than two different regional models. Promising
results are obtained when applying a bias correction technique to climate model outputs.
Simulated yields with bias corrected climate variables show much more realistic means and
standard deviations. However, such a bias correction technique is not able to improve the
reproduction of the year-to-year variations of simulated yields.
This study confirms the importance of the multi-model approach for quantifying uncer-
tainties for impact studies and also stresses the benefits of combining both regional and 
statistical downscaling techniques. Finally, it indicates the urgent need to address the main 
uncertainties in atmospheric processes controlling the monsoon system and to contribute 
to the evaluation and improvement of climate and weather forecasting models in that respect.

Wednesday, February 16, 2011

Zambia is burning: Insights From a Honeymoon in Zambia

Insights From a Honeymoon in Zambia


Zambia is burning.
Its fires are not of the ethnic conflict-civil war variety we are used to seeing in the occasional reports on Africa that surface in western media. Its flames do not stir the imaginations or pull at the heartstrings of western readers like child soldiering or Janjaweed militias.
No, this burning is of fire and ash. Its cause, while less dramatic than ethnic conflict, is devastating in its longterm effects.
A roadside vendor in Zambia, where drought and desertification is a constant threat.Daniel WeeksA roadside vendor in Zambia, where drought and desertification is a constant threat.
Tucked in the middle of southern Africa, Zambia is burning because life south of the equator is becoming dangerously hot and dry. That is in large part because since the Second Industrial Revolution of the middle 19th century, the West has been pumping billions of tons of climate-changing carbon into the atmosphere with impunity, leaving Africa hotter and drier than at any time since our earliest ancestors found their feet and began to walk away.
We walk away still. At least that’s what the two of us newlyweds were doing when we drove the main road that connects Livingstone in the southwest with the capitol Lusaka in the middle at the end of our honeymoon, and discovered the otherwise pitch-black and pot-holed central artery lit up by incessant bush fires along the way.
We didn’t mean to drive the road at night, but car troubles at the Zimbabwean border put us back five hours on the eve of our departing flight (it takes a village to fix a car: a mechanic, an electrician, and a dozen or so of their helpers to be precise). By the time we hit the bumpy road, we were admittedly fairly desperate to reach the airport the following morning and be gone.
Zambia is a peculiar honeymoon destination, as not a few friends observed. For us, it was firstly a welcome escape from the flurry of planning three weddings in three cities on two continents: a nod to Sindiso’s Swati culture in Johannesburg, our shared Christian identity in Cape Town, and Dan’s Waspy heritage in northern New Hampshire.
We came to Zambia hoping for cheap prices, the wild bush, and a bit more exposure to the everyday realities of life in the Global South than one gets at a Cancun resort (In our more aspirational moments, we think that being challenged by more than each other is good for marital bliss and a sense of purpose longterm).
We didn’t find much in the way of cheap prices, a hardship we genuinely lamented until we considered the missing zeros between our incomes and those of the people around us. As for the wild bush and human suffering, those we found in abundance. Only the bush was brown and burning, which made the human suffering–in what is already the world’s twelfth-poorest country–all the more extreme.
But we digress. Back to our nighttime drive, what surprised us even more than the burning itself was the fact that we were alone in our surprise. Locals lugging heavy loads of coal or corn as much as thirty miles to the nearest town (sometimes aided by a bicycle, cart or donkey, sometimes not) breathed in the heavy smoke unfazed. Mothers and children would cross the street if the heat on one side got too bad, but otherwise continue their pre-dawn chores without a thought.
There wasn’t a fire truck or helicopter in sight…small wonder in a country where the average individual earns $850 per year and it costs nearly $100 to fill up a tank of gas. Even if Zambians could afford the trucks and choppers to fight the fires, where would they find enough water to fill the other tank? Victoria Falls is a majestic fount indeed, but that water feeds Lake Kariba and the mighty Kariba Dam. The dam, in turn, was built to light the cities of Zambia and neighboring Zimbabwe, such as they are.
When Zambia burns by fire it burns by poverty too. And one cause, at least, is shared by both. The rise in concentration of atmospheric carbon from 284 parts per million by volume (ppmv) 150 years ago to nearly 400 ppmv today is hastening drought and desertification in sub-Saharan Africa to a shocking degree. It’s a cause which cannot be addressed by improving governments or building schools or staffing clinics on the ground, desirable as those things might be. Rather, it’s a cause for which we in the industrialized West must take a large share of the blame.
As we were pained to see, global climate change is turning once-fertile fields from green to brown, turning soil into dust, turning water into a gold that cannot be extracted from even the richest African mine. It is undermining economic growth and foreign exchange, and denying some one billion of the world’s poorest citizens even a toehold on the ladder of industrialization and wealth.
No, we did not meet happy Africans on our honeymoon. Kind and courteous, yes, but also hot and thirsty and mostly poor, and having not much reason to hope that things will change before they die. At the end of the week, we boarded our plane and walked away. God willing, not for good.
Daniel Weeks is the president of Americans for Campaign Reform, and Dr. Sindiso Mnisi Weeks serves on the Law Faculty of the University of Cape Town (specializing in women’s rights and customary law). They divide their time between Concord, NH and Cape Town. They met in 2007 while studying at Oxford as Marshall and Rhodes Scholars, respectively.

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