Tony Figueira presents POLARITY
August 12, 2013Ongula Village Homestead Lodge – new manager
August 12, 2013Text by Hu Berry
The Desert is both fascinating and terrifying It is the great, lonely void, And humans instinctively dread being brought face-to-face with themselves. For you, the Desert is not a setting, It is a state of soul. The Desert turns you inward.(from the writings of a Tibetan Monk)
Deserts are very special places. They embrace all continents – the Equator, the Poles, and the open sea. They can be hot or cold, on the highest mountain peaks or, as at the Dead Sea, where the salinity is seven times that of the oceans, nearly 400 metres below sea level.
Namib desert. Photo ©Paul van Schalkwyk
At least 10 discernible deserts are named in the New World and 27 are recognised in the Old World. Add to this the frozen realms of the Arctic and Antarctic Circles, because their minimal precipitation qualifies them as arid regions. Names like Death Valley, Baja, Mojave, Arabian, Gobi, Kalahari, Namib and Sahara conjure up visions of barren isolation. If the oceans cover 71% of the Earth’s surface, then deserts vie for second place, with 61 million square kilometres or 35% of Earth’s land surface classified as ‘desert’. Definitions of a desert are not as simplistic as they sound.
The Latin word desertus means abandoned, while the English dictionary describes a desert as ‘an uninhabited, desolate, uncultivated, barren treeless and waterless region’. This is misleading because deserts are, in parts, inhabited, cultivated, and not necessarily without trees and water. It took years of debate between climatologists, geologists, geographers and biologists to produce an acceptable definition. Today a desert is defined as a geographical area where life processes are regulated by infrequent, isolated and unpredictable inputs of water.
Dunes and water. Photo ©Ron Swilling
Our Cradle of Civilisation arose in the aridity of the Middle East, between the confluence of two rivers, the Tigris and the Euphrates. Three great religions, Judaism, Christianity and Islam, were founded in this region, all monotheistic, worshipping one God only. The barren wildernesses of the Earth inspire poets, artists, writers, scientists, philosophers and the military.
The brilliance of generals such as Germany’s Rommel (dubbed the Desert Fox) and Britain’s Montgomery of El Alamein was displayed in the Sahara. Later, we entered the nuclear age in the desert of New Mexico. Now our civilisations threaten the fragile ecosystems of many deserts. Eventually, according to biblical prophesy, we may face our demise in the desert at Armageddon where the armed forces of this world will engage in the final, supreme conflict of nations.
Absence of moisture means that desert surfaces receive more than twice the amount of the Sun’s radiation (achieving a temperature of 580C in the Sahara) than humid regions. Similarly, deserts lose twice as much heat at night, sometimes dropping to minus 180C. Most deserts are located around the 30-degreelatitude in both hemispheres – a result of global air circulation, which forms vast cells of descending, dry, hot air in these regions.
Moreover, especially in the southern hemisphere, Antarctic currents sweep northwards along the western sides of continents, giving rise to the relatively cool, coastal Atacaman, Peruvian and Namib deserts. By comparison, the continental inland deserts of Asia and Australia are far from the sea, thereby greatly reducing the possibility of moisture reaching them. South America’s Andes, North America’s Rocky Mountains and India’s Himalayas craft the third type of desert.
Ostriches roaming the Namib desert. Photo ©Ron Swilling
They create ‘rain-shadow barriers’ that harvest the rain-bearing winds blowing in from the ocean, leaving dry air in their wake. Even the North and South Poles cannot escape the freezing dehydration and are referred to as ice deserts. Closer to home, Namibia’s Etosha Pan extending over 5 000 square kilometre is classified as ‘saline desert with dwarf shrub savanna fringe’.
Far from being lifeless, deserts harbour many forms of life, some with extreme adaptations. An ancient creosote bush found in North America’s Mojave Desert was recently described by scientists. At 11 000 years it may represent the oldest form of plant life. This is 6 000 years older than the Great Pyramid of Cheops in Egypt’s Sahara. Arizona’s giant saguaro cactus contradicts the popular notion of a lack of water in the desert. Weighing nine tons and with a height of 15 metres, its fleshy stem contains 75% to 95% moisture. What’s more, its longevity and prolific nature produces 40 million seeds in 200 years. Nevertheless, the desert decrees that only one of these will reach full maturity every two centuries, a prime example of population control.
Aerial of the Namib desert by ©Paul van Schalkwyk at http://www.paulvans.com/
The world’s fastest land animal, the cheetah, courses across Old World deserts at 110 kilometres an hour. The speediest rodent in existence, the Mara or Patagonian ‘hare’ is a swift sprinter. While not a true hare, it has long, rabbit-like ears and is capable of reaching 45 kilometres an hour (about the same speed as the fastest human). As for the Namib Wheel Spider, when danger threatens, this eight-legged wonder forms a wheel, using its legs as spokes, to make a hasty escape. The 33-degree angle of a dune’s slope enables it to revolve 20 times (or one metre) per second to send it hurtling down the slip-face.
When it comes to resilience to dryness, few animals can match the Australian desert frog, which remains in a dormant torpor for five years. Who can equal the animal that survives the smallest geographic range known for any vertebrate? The Mojave Desert pupfish triumphs by having a geographic distribution of only 20 square metres. And Namibia’s desert-adapted elephants (that slide down sand dunes), its rhinos (that chomp and relish the deadly-to-humans milkweed Euphorbia virosa) and its beach-combing desert lions (that hunt fur seals), create a kaleidoscope of desert life that is unique on our planet.
Dunes and sea. Sperrgebiet National Park. Photo ©Trygve Cooper
The Arabic word sahra, meaning wilderness, refers to the Sahara. It is the biggest desert on Earth, being more than seven million square kilometres in area and covering 25% of Africa. In terms of biodiversity, however, it cannot compete with the Namib. Although 50 times smaller, the Namib owes it success as the desert with the greatest diversity of life forms to the rich supplies of fog moisture generated by the cold Benguela Current flowing northwards up the Namibian coast.
Yet most deserts are threatened by human activities. Let us remember the words of a person who loved the desert: “First came the forests, then came civilisation, then came the deserts…”
This article was originally published in the January 2007 Flamingo magazine.
Hu Berry was a scientist, conservationist and specialist tour guide. He was one of Venture Publications' most valued authors. Sadly he passed away in July 2011. To read more about him click here.
