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by Lexi Krock From mid-February to late October 2000, one of the most severe fire seasons in United States history seared forests in more than 10 states. Though the 2000 fires in the U.S. were extraordinary in their scope and duration, they nonetheless fit a seasonal pattern of burning that is largely repeated in the U.S. and around the globe each year. On every continent except Antarctica, fires ebb and flow in response to cyclical weather conditions and regular human burning practices, consuming billions of acres in their wake. In the interactive portion of this feature, follow the progression of monthly global fire maps from January through December 2000 and explore some of the factors, continent by continent, that contributed to both regular and unusual fire situations during that year. To launch the maps, click on the map icon at right. For more general information on fire around the world, click on the continent links below. North America | South America | Europe | Africa | Asia | Oceania
 Forests are a chief feature of the North American landscape, blanketing one half and one third of Canada and the U.S., respectively. In both countries, periodic wildfires triggered by lightning can actually be beneficial to forest ecosystems. In Canada's dominant boreal-zone forests, trees have adapted readily to crown fires, releasing regenerative seeds soon after the fires have passed. In the U.S., scientists studying the species composition of forests recovering from fire have routinely observed that species diversity—both flora and fauna—is greatest in young forests that have replaced older forest burned only a few years earlier. Throughout North America and particularly in the U.S., wildfire management rests on a delicate balance. On the one hand, fire suppression is often necessary when blazes threaten life, property, or valuable natural resources. On the other, routine suppression of fires over long periods in ecosystems that would otherwise burn at regular intervals can lead to the buildup of abnormal amounts of fuel in the form of trees and shrubs; catastrophic fires often result when such vegetation eventually ignites. Both Canada and the U.S. have sophisticated fire management programs, which help maintain the balance between the health of the forests and the protection of human settlements. Lightning causes most wildfires on the continent, except in Mexico (and in Central America), where 97 percent of fires are intentionally set for agricultural purposes. North America's wide range of climate types allows wildfire to burn somewhere on the continent during almost every month of the year. This is particularly true in the southeastern U.S., where prescribed fires for land management account for 75 percent of all controlled burns in the country and are ignited year-round. Burning in North America begins in December and January with fires in Mexico, which burn through July but reach their peak during the dry months of March and April. The U.S. fire season lasts from early spring through October and peaks in July, August, and September. Forests in the higher latitudes of Canada and Alaska begin burning in April, and their fire seasons peak during the summer months. In general, the progression of fires in North America moves steadily north as temperatures increase through the spring and summer. To see these fire patterns in action, visit the interactive 2000 global fire maps.
 South American forests burn each year from both human-caused fires and natural wildfires. Throughout history, humans have practiced intentional burning in South America as a means of land conversion—to prepare land for crops or grazing and to clear large tracts of otherwise impenetrable forests for travel and hunting. Today, it is often difficult to discern which fires in South America are human-caused and which natural. Studies have shown that perhaps 50 to 90 percent of uncontrolled wildfires began as agricultural or land-conversion burns and then grew out of control. In general, as in Africa, the vast majority of forest fires in Brazil are begun intentionally. Many of the large-scale fires in South America are concentrated in Brazil, Argentina, Bolivia, and Venezuela, where farmers and cattle ranchers undertake prescribed burns. These burns are usually set in and around grassland and savanna environments during the dry season from May to October, which closely corresponds to southern Africa's dry season. An alarming proportion of South America's burning each year occurs in the Amazon rainforest region, often called the "lungs of the world." Though tropical thunderstorms in the rainforests preclude the ignition of fires by lightning almost 100 percent of the time, farmers converting large areas of Brazilian rainforest try year-round to start burns and keep them going wherever and whenever they can. Unfortunately, cleared rainforest land is rarely sustainable and reverts to non-arable land within a few growing seasons, causing farmers to undertake new burns every couple of years. To see these fire patterns in action, visit the interactive 2000 global fire maps.
 Fire ecologists often classify a broad region of the globe as "Europe" and divide it into two sub-regions: the Mediterranean, which encompasses all areas bordering the Mediterranean Sea, including northern Africa; and Western, Eastern, and Northern Europe. This European fire region extends from Iceland to Morocco and includes some 50 countries. The two European fire regions differ in their use of prescribed fire to thin potential wildfire fuels. In the Mediterranean region, particularly Italy, Portugal, Spain, Greece, and North African and Near Eastern countries almost never use prescribed burning, because it has proved less costly for these nations to fight fires as they arise. On average, some 50,000 fires burn annually in the Mediterranean basin, usually in the spring and summer months. Most of these fires result from human negligence and accidents. In Western, Eastern, and Northern Europe, by contrast, forest managers increasingly use prescribed fire as a means of both maintaining forest ecosystems for wildlife and preventing the encroachment of bush vegetation. Many of the fires that burn during the summer months in these regions are the result of such prescribed burning. The largest area of forests in the European region, spanning eleven time zones, is Russia. Approximately 95 percent of Russian forests lie in the boreal zone, as in Canada, and Russia's fire seasons closely resemble Canada's, with most burning occurring in late summer. A majority of Russia's boreal forests are remote and contain large amounts of accumulated fuel matter. Unmanaged fires burn freely during the fire season. Agricultural burning occurs in pockets of the Russian Federation, and many of these human-set fires quickly become uncontrolled wildfires. In recent years, fire-management teams in Russia have begun to assess ways to limit uncontrolled fires in the boreal forests, for they are a major source of carbon emissions; the carbon stored in these boreal forests accounts for approximately 37 percent of the total global carbon pool. To see these fire patterns in action, visit the interactive 2000 global fire maps.
 Fire ecologists have dubbed Africa a "continent of fire" because of its widespread annual patterns of burning. In the southern, western, and eastern regions of Africa, the trees and grass of the savannah biome—the most extensive area of savannah in the world—become extremely flammable during the dry season, which lasts from May to October in southern Africa and January to April in west and east Africa. About 90 percent of fires in Africa are human-caused. Set during the dry seasons to remove dead vegetation that accumulates after harvesting, the fires promote new, high-quality growth. People also set fires in order to control undesirable plants in crop areas and to drive grazing animals to less-preferred growing areas. The practice of intentional burning in Africa has a long tradition among settled farmers and nomadic peoples, and while it was widely discouraged during the colonial period, since the 1950s, governments have promoted the regulated use of fire as an important tool for grazing management and agriculture. Most countries have laws regarding burning, which are enforced to varying degrees. Lightning is the second major source of fire on the African continent. Africa is highly prone to lightning storms, which generally occur during the wet seasons. In the early part of the wet seasons, when the fuel is still dry enough to ignite and sustain burning, the African climate is highly conducive to lightning fires, which have their own fire season during this time. Unlike human-caused burning in regions of the world that are not naturally given to a fire ecology, such as the South American tropical rainforest, fire is an integral component of the African ecosystem that scientists believe has an extensive and important evolutionary history on the continent. Many African plant species and animals, for example, have growth and reproduction cycles so linked to Africa's fire seasons that they would likely become locally extinct without fire. (For more on this phenomenon, see How Plants Use Fire.) To see these fire patterns in action, visit the interactive 2000 global fire maps.
 Incidences of fires in Southeast Asia are particularly affected by the El Niño weather phenomenon, which occurs every few years and can produce either prolonged dry or wet seasons. If sustained drought occurs, many of the forest vegetation types in Southeast Asia become vulnerable to forest fires. The year 2000 was not an El Niño year, and many of the fires burning in 2000 in Southeast Asia are the result of agricultural burning, often in rice paddies, rather than drought-induced wildfires. El Niño was responsible for the most dramatic Southeast Asian fire situation of the past decade, which occurred in Kalimantan, Indonesia in 1997 and 1998. Almost a year of drought in this region produced many months of severe fires, which were initially set by people to clear forest. The fires blanketed Southeast Asia in a dense haze, caused widespread respiratory health problems, and produced transportation delays and accidents on land, at sea, and even in the air. Economic losses were estimated at over $9.3 billion. Many fires burn in China each year, even though forests account for only 16.5 percent of the country's landmass. More than 95 percent of fires can be attributed to farmers or human carelessness, though in northwest China, the most abundant forest region in the country, lightning can account for more than 30 percent of fires. Fire seasons peak in May and October in the northeast and from January to April in the southwest. To see these fire patterns in action, visit the interactive 2000 global fire maps.
 Australia, the major landmass in the Oceania region, is a fire-prone continent with a diverse range of vegetation types, many of which are unique to the continent. Fires burn readily and naturally in Australia's predominantly flat, dry, and warm landscape at all times of the year, beginning in Most fires in Australia begin naturally, though Australian farmers and aboriginal tribes practice some controlled agricultural burning. Fire-management authorities regularly ignite prescribed burns to remove potential fuels for the protection of human lives and property, often in woodlands abutting major cities in the southeast and southwest. In Fiji, large areas of grassland burn naturally each year, but most burning is the result of torching by sugarcane farmers during harvest season. New Zealand experiences relatively few fires each year (approximately 3,000 annually), most of which humans generate in order to improve pastures for animals and encourage new growth. To see these fire patterns in action, visit the interactive 2000 global fire maps. Lexi Krock is editorial assistant of NOVA Online. Sources and photo credits
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This false-color infrared image shows wildfire damage in Bitterroot National Forest, Montana on August 14, 2000. Dull red areas show recently burned areas while bright red areas depict live flames (especially beneath the blue smoke cloud). The green areas denote unburned vegetation. More than 300 square miles of Bitterroot burned during the summer of 2000.
Biomass burning in South America produces extremely high carbon monoxide levels in the atmosphere. This NASA image shows a massive carbon monoxide cloud over South America on March 3, 2000. Blue denotes the lowest levels of carbon emission, yellow denotes intermediate levels, and red to pink to white coloration denotes progressively higher concentrations.
On July 13, 2000, a plume of smoke from a wildfire in Greece interrupts an otherwise clear sky. Hot, dry weather contributed to a string of fires in Greece and Italy during the summer of 2000.
The southern Africa fire season in 2000 peaked in early September. The heaviest burning occurred in western Zambia, southern Angola, northern Namibia, and northern Botswana. Some of the blazes were over 20 miles long.
Agricultural fires in April 2000 speckle the landscape of southern Cambodia, northern Thailand, and northern Laos, and produce a thick gray haze overhead.
Roughly a dozen wildfires burn between Western Australia (left) and into Queensland (right) in October 2000. In this image, clouds appear bright white and smoke plumes appear darker and grayish. The pixels containing the wildfires appear red (hot) and yellow (hotter). The large dark splotches appearing here are burn scars from previous wildfires.
