Wildfires
Uncontrolled blazes fueled by weather, wind, and dry underbrush, wildfires can burn acres of land—and consume everything in their paths—in mere minutes.
On average, more than 100,000 wildfires, also called wildland fires or forest fires, clear 4 million to 5 million acres (1.6 million to 2 million hectares) of land in the U.S. every year. In recent years, wildfires have burned up to 9 million acres (3.6 million hectares) of land. A wildfire moves at speeds of up to 14 miles an hour (23 kilometers an hour), consuming everything—trees, brush, homes, even humans—in its path.
There are three conditions that need to be present in order for a wildfire to burn, which firefighters refer to as the fire triangle: fuel, oxygen, and a heat source. Fuel is any flammable material surrounding a fire, including trees, grasses, brush, even homes. The greater an area's fuel load, the more intense the fire. Air supplies the oxygen a fire needs to burn. Heat sources help spark the wildfire and bring fuel to temperatures hot enough to ignite. Lightning, burning campfires or cigarettes, hot winds, and even the sun can all provide sufficient heat to spark a wildfire.
Although four out of five wildfires are started by people, nature is usually more than happy to help fan the flames. Dry weather and drought convert green vegetation into bone-dry, flammable fuel; strong winds spread fire quickly over land; and warm temperatures encourage combustion. When these factors come together all that's needed is a spark—in the form of lightning, arson, a downed power line, or a burning campfire or cigarette—to ignite a blaze that could last for weeks and consume tens of thousands of acres.
These violent infernos occur around the world and in most of the 50 states, but they are most common in the U.S. West, where heat, drought, and frequent thunderstorms create perfect wildfire conditions. Montana, Idaho, Wyoming, Washington, Colorado, Oregon, and California experience some of the worst conflagrations in the U.S. In California wildfires are often made worse by the hot, dry Santa Ana winds, which can carry a spark for miles.
Firefighters fight wildfires by depriving them of one or more of the fire triangle fundamentals. Traditional methods include water dousing and spraying fire retardants to extinguish existing fires. Clearing vegetation to create firebreaks starves a fire of fuel and can help slow or contain it. Firefighters also fight wildfires by deliberately starting fires in a process called controlled burning. These prescribed fires remove undergrowth, brush, and ground litter from a forest, depriving a wildfire of fuel.
Although often harmful and destructive to humans, naturally occurring wildfires play an integral role in nature. They return nutrients to the soil by burning dead or decaying matter. They also act as a disinfectant, removing disease-ridden plants and harmful insects from a forest ecosystem. And by burning through thick canopies and brushy undergrowth, wildfires allow sunlight to reach the forest floor, enabling a new generation of seedlings to grow.
Covering most of inland Alaska, Canada, Sweden, Finland, inland Norway, northern Kazakhstan and Russia (especially Siberia), as well as parts of the extreme northern continental United States, the taiga is the world's largest terrestrial biome.
In Canada, boreal forest is the term used to refer to the southern part of this biome, while "taiga" is used to describe the more barren northern areas south of the Arctic tree-line. Since North America and Eurasia were recently connected by the Bering land bridge, a number of animal and plant species (more animals than plants) were able to colonise both continents and are distributed throughout the taiga biome.
Others differ regionally, typically with each genus having several distinct species, each occupying different regions of the taiga.
Taigas also have some small-leaved deciduous trees like birch, alder, willow and aspen; mostly in areas escaping the most extreme winter cold.
However, the deciduous Larch is coping with the coldest winters on the northern hemisphere in eastern Siberia.
The southernmost part of the taiga also have trees like oak, maple and elm scattered among the conifers.
THE summer dry-season, now drawing to an end, is when the Amazon rainforest gets cut and burned. The smoke this causes can often be seen from space. But not this year. Brazil’s deforestation rate has dropped astoundingly fast. In 2004 some 2.8m hectares (10,700 square miles) of the Amazon were razed; last year only around 750,000 hectares were.
This progress is not isolated. Many of the world’s biggest clearers of trees have started to hug them. Over the past decade, the UN records, nearly 8m hectares of forest a year were allowed to re-grow or were planted anew. This was mostly in richer places, such as North America and in Europe, where dwindling rural populations have taken the pressure off forestland. But a couple of big poorer countries, notably China, have launched huge tree-planting schemes in a bid to prevent deforestation-related environmental disasters. Even in tropical countries, where most deforestation takes place, Brazil is not alone in becoming more reluctant to chop down trees.
The progress made in recent years shows that mankind is not doomed to strip the planet of its forest cover. But the transition from tree-chopper to tree-hugger is not happening fast enough. Over the past decade, according to UN figures, around 13m hectares of forestland—an area the size of England—was converted each year to other uses, mostly agriculture. If the world is to keep the protective covering that helps it breathe, waters its crops, keeps it cool and nurtures its biodiversity, it is going to have to move fast (see our special report this week).
A bad old habit
For at least 10,000 years, since the ice last retreated and forests took back the earth, people have destroyed them. In medieval Europe an exploding population and hard-working monks put paid to perhaps half its temperate oak and beech woods—mostly, as is usually the case, to clear space for crops. Some 100m hectares of America’s forests went in the 19th century, in an arboreal slaughter similarly reinforced by a belief in the godliness of thus “improving” the land. That spirit survives. It is no coincidence that George Bush junior, one of America’s more god-fearing presidents, relaxed by clearing brush.
In most rich countries the pressure on forests has eased; but in many tropical ones—home to around half the remaining forest, including the planet’s green rainforest girdle—the demand for land is increasing as populations rise. In Congo, which has more rainforest than any country except Brazil, the clearance is mostly driven by smallholders, whose number is about to double. Rising global demand for food and biofuels adds even more to the heat. So will climate change. That may already be happening in Canada, where recent warm winters have unleashed a plague of bark beetles, and in Australia, whose forests have been devastated by drought and forest fires.
Clearing forests may enrich those who are doing it, but over the long run it impoverishes the planet as a whole. Rainforests are an important prop to continental water-cycles. Losing the Amazon rainforest could reduce rainfall across the Americas, with potentially dire consequences for farmers as far away as Texas. By regulating run-off, trees help guarantee water-supplies and prevent natural disasters, like landslides and floods. Losing the rainforest would mean losing millions of species; forests contain 80% of terrestrial biodiversity. And for those concerned about the probable effects of climate change, forests contain twice as much carbon as the atmosphere, in plant-matter and the soils they cover, and when they are razed and their soils disturbed most is emitted. If the Amazon went up in smoke—a scenario which a bit more clearance and a bit more warming makes conceivable—it would spew out more than a decade’s worth of fossil-fuel emissions.
REDDy, steady, grow
Economic development both causes deforestation and slows it. In the early stages of development people destroy forests for a meagre living. Globalisation is speeding up the process by boosting the demand for agricultural goods produced in tropical countries. At the same time, as people in emerging countries become more prosperous, they start thinking about issues beyond their family’s welfare; their governments begin to pass and slowly enforce laws to conserve the environment. Trade can also allow the greener concerns of rich-world consumers to influence developing-world producers.
The transition from clearing to protecting, however, is occurring too slowly. The main international effort to speed it up is an idea known as REDD (Reducing Emissions from Deforestation and Forest Degradation), which pays people in developing countries to leave trees standing. This is not an outlandish concept. It is increasingly common for governments and companies to pay for forest and other ecosystem services. To protect its watershed, New York pays farmers in the Catskills not to develop their land. REDD schemes aspire to do this on a much larger scale. The only notable success of the Copenhagen climate-change conference last year was a commitment to pursue them. Half a dozen rich countries, including Norway, America and Britain, have promised $4.5 billion for starters.
The difficulties are immense. REDD projects will be effective only in places where the government sort-of works, and the tropical countries with the most important forests include some of the world’s worst-run places. Even in countries with functioning states, some of the money is bound to be stolen. Yet with sufficient attention to monitoring, verification and, crucially, making sure the cash goes to the people who can actually protect the forest, REDD could work. That will cost much more than has so far been pledged. The most obvious source of extra cash is the carbon market, or preferably a carbon tax. Since saving forests is often the cheapest way to tackle carbon emissions, funding it this way makes sense.
With global climate-change negotiations foundering, the prospects of raising cash for REDD that way look poor. But the money must be found from somewhere. Without a serious effort to solve this problem, the risk from climate change will be vastly increased and the planet will lose one of its most valuable, and most beautiful, assets. That would be a tragedy.