Wednesday, January 2, 2008

More controversy

"For years, many scientists have been making dire predictions of widespread irreversible ‘desertification’ in the African Sahel. But recent findings have proven them wrong.

Satellite images consistently show an increase in ‘greenness’ since the 1980s over large areas, confirming evidence on the ground indicating that the Sahel has recovered from the great droughts of the 1980s, and that human factors have played a large role in reclaiming the desert.

Although variable rainfall and droughts are seen as normal in arid and semiarid climates, the droughts that struck the Sahel in the late 1960s through to the 1980s were unprecedented in length and severity. Land degradation and famine during the droughts, exacerbated by political instability and unrest, prompted the UN to hold a conference on desertification in 1977. This initiated a debate, still ongoing, on the causes and effects of drought, land degradation and desertification." (...and Rania is back, with thanks!)

I don't know how many of you have been following the very interesting blog comments exchange in the "Senate Skeptics" post, and if you haven't, take a look, believe me, it is worth it. Here's another controversial issue: is the UNCCD all wrong?


Steve Bloom said...

That's interesting about the Sahel. I hadn't been following trends there other than the occasional mention in the general media, but a few months ago there was a progress article (full text here, title and abstract pasted below) on the poleward shift of the sub-tropics that made me wonder if indeed we should not be seeing a reversal of the Sahel drying as the tropics move north (all else being equal, and understanding that land use practices have been important there).

"Widening of the tropical belt in a changing climate

"Some of the earliest unequivocal signs of climate change have been the warming of the air and ocean,
thawing of land and melting of ice in the Arctic. But recent studies are showing that the tropics are also changing. Several lines of evidence show that over the past few decades the tropical belt has expanded. This expansion has potentially important implications for subtropical societies and may lead to profound changes in the global climate system. Most importantly, poleward movement of large-scale atmospheric circulation systems, such as jet streams and storm tracks, could result in shifts in precipitation patterns affecting natural ecosystems, agriculture, and water resources. The implications of the expansion for stratospheric circulation and the distribution of ozone in the atmosphere are as yet poorly understood. The observed recent rate of expansion is greater than climate model projections of expansion over the twenty-first century, which suggests that there is still much to be learned about this aspect of global climate change."

dimitrios KERTIS said...