South Asia: Climate and Vegetation

A HUMAN PERSPECTIVE Every April and May, much of South Asia bakes in the heat. People endure temperatures that regularly top 100°F. Dust fills the air, and streams dry up. People walk for miles looking for water. Then—when it seems that no one can survive another day—the clouds roll in. The skies open up, and the rains come. People celebrate when the land turns green.

But their celebration is short-lived, as the downpour continues. Soon, the ground can hold no more water. Rivers overflow their banks. Families are forced from their homes as towns and cities are flooded. Thousands may die before the waters eventually recede, and the land dries out. South Asians see this cycle repeat itself each year.

Climate—Wet and Dry, Hot and Cold

Half of the climate zones that exist on Earth can be found in South Asia. This means that South Asians must adapt to widely varying conditions.

CLIMATE ZONES

South Asia has six main climate zones, as you can see on the map on page 557. The highland zone has the coldest climate. This is the area of the Himalayas and other northern mountains, where snow exists year-round. The lower elevations, which include the lush foothills and valleys of Nepal, Bhutan, and northern India, are much warmer. They are in the humid subtropical zone that stretches across South Asia. The Indo-Gangetic Plain also occupies much of this region.

The semiarid zone—a region of high temperatures and light rainfall—is found at the western end of the Plain and in parts of the Deccan Plateau. The desert zone covers much of the lower Indus Valley, in the borderlands of western India and southern Pakistan. The driest part of this area, the Thar Desert, gets very little rain—averaging 10 inches a year. The tropical wet zone is found along the western and eastern coasts of India and in Bangladesh. Temperatures are high, and rainfall is heavy. In fact, Cherrapunji in northeastern India holds the world's record for rainfall in a month—366 inches. Southern Sri Lanka also has a tropical wet climate, while the north is tropical wet and dry.

MONSOONS AND CYCLONES

Although climate varies in South Asia, the region as a whole is greatly affected by monsoons, or seasonal winds. Each year, from October through February, dry winds blow across South Asia from the northeast. From June through September, the winds blow in from the southwest, bringing moist ocean air. Heavy rains fall, especially in the southwestern and Ganges Delta portions of South Asia.

This rainfall is crucial to life on the subcontinent. Yet, the monsoons can cause severe hardship for millions, especially those living in the lowlands of India and Bangladesh. The monsoons also are highly unpredictable. Some areas may get too little rain, while others get too much. The monsoons are a sometimes beneficial, sometimes difficult feature of life in South Asia.

The most extreme weather pattern of South Asia is the cyclone, a violent storm with fierce winds and heavy rain. Cyclones are most destructive in Bangladesh, a low-lying coastal region where high waves can swamp large parts of the country. A severe cyclone can cause widespread damage and kill thousands of people.

Vegetation: Desert to Rain Forest

Plant life in South Asia varies according to climate and altitude. As you can see on the map on page 557, vegetation ranges from desert shrub and temperate grasslands to dense forests in the wettest areas.

VEGETATION ZONES

The most forested parts of South Asia lie within the tropical wet zone, particularly the western coast of India and southern Bangladesh. Lush rain forests of teak, ebony, and bamboo are found there, along with mangroves in the delta areas. In the highland zone, which includes northern India, Nepal, and Bhutan, there are forests of pine, fir, and other evergreens. The river valleys and foothills of the humid subtropical zone have forests of sal, oak, chestnut, and various palms. But deforestation is a problem everywhere. For example, less than one-fifth of India's original forests remain. Cutting down forests has caused soil erosion, flooding, climate changes, and lost wildlife habitats.

In the semiarid areas of South Asia, such as the Deccan Plateau and the Pakistan-India border, there is less vegetation. The main plant life is desert shrubs and grasses. The driest areas, like the Thar Desert, have little plant life, and as a result, few people live there. The tropical wet and dry climate of northern Sri Lanka produces both grasses and trees. How South Asians interact with their environment will be discussed in the next section.