Климат и почвы Северной Австралии

Northern regions of Australia
the former administrative subdivision

The above generalisations, however, mask the immense variability of the climate throughout the whole region. With the exception of the extreme north of the Northern Territory, rainfall variability throughout Northern Australia is quite markedly higher than most comparable climates in other continents. For example, at Charters Towers, the rainfall over the wet season can vary from less than in 1901/1902 to over in 1973/1974. The chief cause of this very high variability is erratic tropical cyclones, which occur from December to April and in many places can deliver as much as of rain over a day or two, causing extremely large floods in the region's rivers. For example, in April 1898, a tropical cyclone gave in one day at Whim Creek in the Pilbara, but for the whole of 1924 that same station recorded only for the whole year. Tropical cyclones may cross the coast anywhere in Northern Australia but are most frequent between Derby and Onslow on the west side and between Cooktown and Rockhampton on the east. Inland, variability of rainfall is related to the penetration of the summer monsoon, with high rainfall in seasons like 1973/1974, 1975/1976 and from 1998 to 2001 when the monsoon is most powerful. Climate change has seen increases of up to fifty percent in annual rainfall since 1967 over the western half of Australia's tropics, but has not seen any increase over the east. The increase over the west is sometimes attributed to aerosol pollution over industrialising areas of China and India, but may be related to global warming. Frosts are common in the southern inland during the winter, but in some years, such as 1998, they are much less frequent due to the recent incidence of warm pools in the Indian Ocean.

Except in the Lake Eyre Basin and adjacent areas to the east, the soils of Northern Australia are quite remarkable in global terms for their low fertility and difficulty of working. Most of them consist chiefly of hard laterite developed during period of climate much more humid than even that of Darwin today. Since there has been no mountain building in the region since the Precambrian and no glaciation since the Carboniferous, the region's soils have generally been under continuous weathering without renewal for over 250 million years, as against less than ten thousand for most soils in Europe, Asia, North America and New Zealand which have been formed from recent mountain building or glacial scouring of the land. This immensely long weathering time means that nutrient levels in Northern Australian soils are exceptionally low because practically all soluble minerals have long been weathered out. The major constituents of most soils in Northern Australia are iron and aluminium oxides, both of which are not only very insoluble but also serve to reduce the soil pH and remove phosphorus from the soil as insoluble iron and aluminium phosphates. The insolubility of these metal oxides also serves, under the extremely harsh conditions during the dry season in the north and generally in the south, to create massive sheets which are impossible to plough. In the Lake Eyre Basin, deposition from volcanic regions to the east has produce cracking clay soils of quite high fertility which are still often fairly low in phosphorus but have very good levels of potassium, calcium and sulfur. These soils provide the best grassland for grazing in the region. The youthful, volcanic Wet Tropics has a number of areas of fertile alluvial soils that support intensive horticulture.

The extreme soil poverty of most of Northern Australia has the effect of confining large herbivores such as the kangaroo to the better soil in the dry grasslands since they cannot digest the extreme poor fodder from the northern monsoonal regions. However, the frequency of fires during the desiccating dry season from May to September means that forests cannot establish themselves except in sheltered places. This has created a unique type of tropical savanna environment in which fires play a crucial role in elevating the extremely low nutrient levels and aiding growth during the wet season. The many large rivers of the region such as the Mitchell, Gilbert Einasleigh, South and East Alligator, Daly, Ord and Fitzroy support populations of the saltwater and freshwater crocodiles, which are by far the best known animals of the region. There are also a number of species of python. Further south, where rivers are not adequate to support crocodiles, there exist a number of quite unique lizard species. The Wet Tropics, like all tropical rainforests, is very rich in unique species, and importantly contains some of the most primitive flowering plants in the world.

Northern Australia faces major challenges to economic growth. Although the climate and soil poverty have defied all attempts to develop large scale agriculture in large parts of Northern Australia, some agricultural and horticultural industries have seen strong growth. For example, in the Wet Tropics, mango, sugar cane and banana growing are major industries. Notable failures in ventures into attempting rice cultivation have occurred in both the Ord River area in the Kimberley region of Western Australia, and the Humpty Doo Rice Project in the Northern Territory. Northern Australia produces more than 93% of Australia’s mangoes, more than 94% of Australia’s bananas, and more than 95% of Australia’s sugar. Sheep and beef cattle are also raised successfully across Northern Australia, usually on extremely large properties. Northern Australia accounts for 64% of Australia’s national beef cattle herd. The geological factors that make Northern Australia's soils so unsuited to traditional agriculture, however, make it extremely rich in ores of abundant, insoluble lithophile metals such as aluminium, iron and uranium. It has the world's largest deposits of all these metals, and as less reactive chalcophile metals have been depleted Northern Australia has become very important to the economies of mineral poor Asian nations. It was Northern Australian iron ore that fed the Japanese post war economic miracle and the Four Tigers of South Korea, Taiwan, Hong Kong and Singapore. At 2015, Northern Australia accounted for over 70% of Australia’s known resources of iron ore, lead, and zinc. During the 1950s and 1960s, the government of Robert Menzies attempted to develop farming in Northern Australia, but pests made this impossible even when varieties of rice suited to the soils were developed. Today, however, sugar cane growing has expanded into the Ord River basin without surpassing cattle and tourism as the main industries of the region.