afrol News, 12 June - Scientists observing the world's vegetation cover during the last two decades agree substantial changes are taking place due to the greenhouse effect. In Africa, the eastern parts are getting greener while other areas are becoming drier.

Our planet's climate is changing rapidly and has been doing so since at least the 1980s. While there still is a disagreement over the causes to these changes - most serious scientists however agree it is due to the so-called greenhouse gas emissions to the atmosphere - the warming up of earth is well documented and undisputed.

The effects of this greenhouse warming have been a major cause of concern. Expected dangers include a rising sea level due to the expected smelting of polar ice caps, more turbulent weather conditions and a drier world. This again could cause major migrations and a collapse of agricultural production.

So far, the effects on the cooler zones have been most studied, as these areas also experience the greatest temperature increases. Little has however been known about the consequences for the world's tropical climate zone, which some scientists claim will become drier, other claiming they will become moister.

Now, a US-Japanese scientists team of the University of Montana has studied the effects of global warming since 1982 and 1999 on the world's vegetation cover, using daily satellite photos from the period.

The conclusion is that global vegetation cover has increased by 6 percent during the studied period and that the regions mostly profiting from this are the tropical zones. The Amazon rain forests represented half of this global vegetation cover increase although these forests have been heavily exploited in the same period.

In the tropical forests region, it has actually been less rain that had produced this increased vegetation growth. Less clouds and more sun radiation had improved growing conditions, the scientists conclude in an article published in 'Science'.

In Africa, the picture is less clear than in the Amazon, however. Also here, the tropical forest region in the Congo Basin has experienced the clearest increase in vegetation growth. On the other hand, Western Africa's coastal tropical forests are growing at a slower paste, thus becoming less dense.

Many of Africa's semi-arid regions - mostly key agricultural regions - further seem to profit from global warming. Much of Eastern Africa and the Sudan belt in Western Africa are noting increased vegetation growth, the study shows.

Eastern Africa
The largest region experiencing positive changes is Eastern Africa and the Great Lakes region. A belt from the Red Sea to coastal Tanzania (excluding Somalia) has experienced a one percent increase in vegetation.

The Great Lakes region is included in this greening belt. Also the Congo River basin, including most of Congo Kinshasa, is becoming greener. In the rain forests surrounding Kisangani, vegetation cover has become over 1.5 percent denser.

The only area with less vegetation in the region includes the central Sudanese lowlands. Here, close to the Ethiopian border, important agricultural areas seem to become drier.

Southern Africa and Indian Ocean
In Southern Africa, the picture is less clear. A belt from the Angolan coast, through the Kalahari Desert of Botswana, to South Africa's Zululand is becoming markedly greener. Also northern Mozambique notes a small positive effect.

Other areas in Southern Africa have however seen a negative development, with less vegetation. Most of Namibia, South Africa's Cape provinces, southern Mozambique and the bulk of Zambia are noted by a less dense vegetation cover during the last decades.

Also the Indian Ocean islands of Madagascar, Seychelles and Comoros are experiencing a slight loss of vegetation cover. This is especially noted in southern Madagascar, were there are many signs of desertification.

West and Central Africa
In West and Central Africa, the differences between the moist coastal areas and the drier savannas in the hinterland seem to diminish.

The coastal forests, in particular a belt from Guinea-Bissau to Côte d'Ivoire, has lost around 1.5 percent of its vegetation cover during the last twenty years. A lesser but significant vegetation cover loss has also occurred in southern Cameroon and the entire Central African Republic.

The so-called Sudan belt of sparsely forested savannas, lying just north of the coast, however has experienced two decades of greening. In a belt from Guinea to northern Cameroon, vegetation cover has increased by around one percent.

The Sahel - the drier belt between the savannah and the Sahara desert - however has not experienced any significant change in its vegetation cover during these decades. The study thus doesn't support theories of a negative climatic change in this zone. Also the Sahara desert remains as it always has been - dry.

Northern Africa
In Northern Africa, the coastal zone from southern Morocco to northern Tunisia is experiencing a slow greening effect, corresponding with an increased vegetation cover all along the Mediterranean Sea.

Rest of the world
The tendencies in Africa correspond to the development of vegetation cover in the rest of the world. Especially the tropical forest regions - the Amazon, the Congo Basin, Central America, India and South East Asia - are experiencing the most noteworthy greening.

The semi-arid regions often are the losing zones, also beyond Africa. Thus, northern Mexico, central Brazil and the steppes of Russia are becoming less densely vegetated.

Most of the world's primary agricultural zones however seem to benefit from the climatic changes. Most of Europe, the US, Canada, Russia, India and China is becoming greener. Vegetation is also creeping towards the Arctic, thus increasing the arable lands of the globe.

By Rainer Chr. Hennig

© afrol News

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