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Climate change

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Human activities are profoundly affecting the world’s climate, and mountains are a sensitive indicator of that effect. Each day, the burning of fossil fuels produces greenhouse gases that enhance the heat-trapping capability of the earth’s atmosphere, gradually raising the planet’s temperature – already by an average of 0.6° in the 20th century alone. Because of their altitude, slope and orientation to the sun, mountain ecosystems are easily disrupted by variations in climate. Mountains are particularly sensitive to climate change, and a wide variety of factors (temperature, precipitation) determine the distribution of species in these regions. Extremes of climate are becoming more and more common in mountain areas. As the world heats up, mountain glaciers are melting at unprecedented rates, while rare plants and animals struggle to survive over ever diminishing areas, and mountain people, already among the world’s poorest citizens, face greater hardships. Understanding how climate change affects mountains is vital as governments and international organizations develop strategies to reverse current global warming trends, elaborating treaties such as the Kyoto Protocol and the United Nations Framework Convention on Climate Change.

The roots of climate change

Many things we do contribute to world climate change. Industrial processes and farming activities, poorly insulated homes as well as an unfettered enthusiasm for cars all generate gases that trap the sun’s rays in the atmosphere. These gases, which include carbon dioxide, methane and nitrous oxide, enhance the “greenhouse” effect that naturally takes place in the environment.

As the sun heats the earth’s surface with short-wave radiation, the earth radiates energy back into space. Some of this outgoing long-wave energy is naturally trapped and absorbed by atmospheric greenhouse gases such as water vapour and carbon dioxide. Without this natural greenhouse effect, average temperatures would be much lower (around -19° C) and life as we know it would not exist. Problems arise when atmospheric concentrations of greenhouse emissions increase and more energy is trapped, keeping the earth’s surface hotter than it would otherwise be.

Some climate models predict that average global temperatures will rise between 1.4 and 5.8°C by the year 2100 and temperature increases will be greater close to the Poles (in Sweden, for example, the temperature is expected to rise by around 10°C). Although a few degrees might appear insignificant, an increase of this kind is far greater than any climate change experienced since the last ice age, 10 000 years ago. Among the consequences imagined, fierce storms will become more frequent and sea levels are expected to rise by 9 to 98 cm, causing flooding and untold damage to island nations and low-lying coastal communities. Already, the inhabitants of Kiribatu in the South Pacific are being forced to abandon their island because of the rising sea level. Meanwhile, New Zealand has promised asylum to the 11 000 residents of the island of Tuvalu, which looks likely to sink beneath the sea before long. The effects of melting polar ice caps releasing vast volumes of water would be still more devastating in terms of altering sea levels.

Mountain glaciers are melting

Mountain glaciers are melting at unprecedented rates. Over the last century, glaciers in the European Alps and the Caucasus Mountains have shrunk to half their size, while in Africa only 8 percent of Mount Kenya’s largest glacier remains. If current trends continue, by the end of this century many of the world’s mountain glaciers, including all those in Glacier National Park in the United States, will have vanished entirely.

Changes in the depth of mountain glaciers and in their seasonal melting patterns will have an enormous impact on water resources in many parts of the world.

In Peru, approximately 10 million residents of Lima depend on freshwater from the Quelcaya Glacier. In other parts of the world, rapid glacial melting is expected to disrupt agriculture and cause flooding. In Nepal, a glacial lake burst its banks in 1985, sending a 15 m wall of water rushing downhill, drowning people and destroying homes. Many climatologists believe that the decline in mountain glaciers is one of the first observable signs of human-induced global warming.

The rarest species are most at risk

Because of their shape and size, mountains support a wide range of climatic condition. Climbing just 100 m up a mountain slope can offer as much climatic variety as travelling 100 km across flat terrain.

Mountain climates are like narrow bands, each stacked on top of the other. Every rise in altitude generates different conditions, supporting unique and often isolated ecosystems with some of the world’s greatest variety of plant and animal life.

As the world heats up, however, conditions within each of these narrow bands is changing. Already scientists have witnessed examples of species moving uphill in search of more suitable habitat. The upward advance of tree lines in response to rising temperatures has been documented in mountainous regions all over the world in recent decades.

Climatologists know that a predicted rise in global temperatures of 3.15C would be equivalent to an ecological shift upwards of about 500 m in altitude. The changes that are likely to take place are predicted to be too rapid for entire ecosystems to keep pace with them. At present there is evidence that plant and animal species are being crowded out by a series of temperature-driven forces as species nudge higher up mountain-sides: bringing invasions of trees, lower elevation plants and predators. Not all species are able to move. Those confined to the tops of mountains or below impassable barriers –from delicate flowers to small mammals – face extinction as their habitat shrinks.

The rarest species are most at risk of extinction. The first danger signs have come from plants but animals and insects are also under threat. Among these are mountain pygmy possum in Australia, ptarmigan and snow bunting in the United Kingdom, marmots and pikas in the US, Gelada baboons in Ethiopia and monarch butterflies in Mexico.

Increased moisture, as well as temperature, have complex effects on delicate mountain ecosystems. As glaciers melt and retreat, life forms are also profoundly affected. Less visibly, contaminants are released into the atmosphere and spread over a broad area, with negative effects on plants, wildlife and humans too.

Climate change and mountain people

For mountain people, each day atop the world’s most extreme landscapes is a test of survival. Now, however, as global climate change threatens to disrupt mountain environments, life for most mountain people will only get harder. For example, just as warming trends are forcing many species to migrate uphill in search of habitat, mountain people too will have to adapt to changes – or leave their homes as traditional sources of food and fuel grow scarce. At the same time, mountains will become more dangerous as melted permafrost and glacial run-off accelerate soil erosion as well as the likelihood of falling rocks, landslides, floods and avalanches. Extreme events and catastrophes are predicted to become more and more common. Many mountain peoples depend upon agriculture for their livelihoods, but climate change could have a significant adverse impact on farming. Irrigation will be affected, first by floods and then by drought, making survival harder for subsistence farmers as well as those who grow cash crops. Nearly all economic activities, such as logging and tourism, are likely to decline as mountain ecosystems are changed irrevocably.

One of the indirect consequences of global warming in mountain regions is increasing risk of infectious diseases. Scientists have reported that the mosquitoes that carry malaria, dengue and yellow fever are spreading to higher altitudes as temperatures warm. Ticks are proliferating northwards and to higher altitudes, causing disease, and insect pests are predicted to spread causing damage to crops. Mountain people are among the world’s poorest citizens. With few resources to ward off infectious diseases, they are likely to be among global warming’s greatest victims if human activities that contribute to climate change are not soon reversed.

Monitoring mountains

Mountains are an indicator of global climate change. These fragile ecosystems are highly sensitive to changes in temperature, and they are found on every continent. Indeed, many climatologists believe that the changes occurring in mountain ecosystems provide an early glimpse of what may come to pass in lowland environments. For this reason, it is vital that the biological and physical components of mountains are strictly monitored and studied. Information on the health of mountain environments will undoubtedly assist governments and international organizations as they develop management strategies and mount strong campaigns to reverse current global warming trends.

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