Lush vegetation and barren landscapes, incredible rainfall and desert-like environments, frosty and tropical temperatures: some countries offer climatic extremes in a comparatively small area. But which is the most diverse? Jürgen Böhner, Professor of Physical Geography at the University of Hamburg, has an answer that is only surprising at first glance. He says the country with the greatest climatic diversity is Nepal. "It has these extreme differences in altitude that no other country can match, from 8848 metres on Mount Everest to less than 200 metres in the Indus-Gangetic plain," says Boehner.
In the high Himalayas at more than 7000 metres, permafrost prevails. Here, even in the warmest month of the year, temperatures barely exceed 0°C. In the lowlands, on the other hand, there are partly tropical conditions. The weather can be dramatically different in the country over short distances, for example in the Kali Gandaki Valley, the deepest valley in the world. Here it changes from semi-desert to very humid environment over only 50 kilometres. "In my opinion, this is the most spectacular diversity you can imagine within one country," says Böhner.
Some other countries have a wide range of climatic conditions, too. Bolivia is one such case. Tropical rainforests in the lowlands are only a few hundred kilometres away from the extremely dry plateaus in the Andes. And in southern Chile, the western slope of the Andes is very humid, whereas in the north, the Atacama Desert, there is sometimes not a drop of rain for decades.
In Austria, on the western side of the Southern Alps, up to 6,000 litres of rain per square metre falls annually on average, while only 330 litres fall on the eastern side of the mountains.
Norway can also be very dry. According to Böhner, the eastern side of the Jotunheimen mountains experienced practically sub-Saharan conditions, with average annual precipitation of less than 300 litres per square metre. "But the nation is better known for its very humid west coast with many fjords."
Countries such as Russia, Canada and the USA have a great variety of climatic conditions simply because of their north-south expansion. "It can be observed in terms of the diversity of vegetation zones," says Böhner. This in turn depends on how their boundaries are defined. Böhner distinguishes between hygric – that is, vegetation zones that depend on the amount of precipitation, such as the transition from tropical rainforest to desert climates – and the so-called heat deficiency boundaries, where temperature conditions are decisive for vegetation differentiation. This can be seen, for example, in high mountains such as the Alps, where the vegetation changes considerably from the valleys to the mountain peaks.
In Germany, according to Boehner, the Harz mountains offer great climatic diversity. On the Brocken which, at 1141 metres above sea level, already reaches the timberline, it is very rainy, while further east – in the lowlands of the Saale – there is sometimes only as much rainfall as in the southern Sahel in Africa. "And you don't have to travel that far to experience climatic diversity," says Böhner.
