Global Warming
Global Warming And Its Effects
After much debate, it appears as if there is finally some consensus among the world’s scientists: global warming (or as some prefer to call it, climate change) is a definite fact, not just a theory.
The Intergovernmental Panel on Climate Change (IPCC) is a group that was established in 1988 by the World Meteorological Organization and the United Nations Environment Program. According to the IPCC, Earth is warmer today than it has been at any time over the past 1,000 years. Also, over just the last 100 years, the overall surface temperature of the planet has risen by approximately 0.6° C (± 0.2°). Although this may appear to be a very small rise in temperature, overall global temperatures have remained stable over thousands of years. As a matter of fact, the average global temperature today, 15° C, is only 5° C warmer than the average global temperature during the planet’s last Ice Age.
Also, during the past 100 years, human activities—the burning of fossil fuels, like coal and petroleum, in particular, in cars, trucks, power plants and other industrial applications--have significantly increased the greenhouse gas content of the earth’s atmosphere. Greenhouse gases are so named because they act like the glass walls of a greenhouse, which keep the temperature inside the greenhouse higher than the temperature outside. Greenhouse gases, like water vapor and carbon dioxide (CO²), trap heat near the planet’s surface, which in turn are causing the earth’s temperature to rise. The last 10 years have been the warmest of the last century.
Of course, without the greenhouse effect, the earth’s temperature would drop to a chilly 18° below zero C, and most life on the planet would cease to exist. As it stands, more than 95% of our atmosphere is made up of oxygen and nitrogen, which are not greenhouse gases. But the continuing increase in greenhouse gases due to future human activities could present a danger to most, if not all, life on the planet.
The vast majority of the world’s climate experts agree with the fact that the temperature is rising. Remaining arguments deal with the specific effects that the planet will experience, as well as what measures we should take.
The IPCC has estimated increases in average global temperatures as ranging anywhere from 1.4° to 5.8° C by the year 2100. Two factors will influence the range of possible futures: 1) The many different types of weather patterns that exist around the world, from the mountains to the deserts and from the Arctic to the tropics, and 2) the unpredictability of human behavior.
Many different possibilities have been imagined of what might occur as global temperatures rise, depending on a variety of factors, both natural and man-made.
Precipitation levels might change, with some areas getting more rain than ever, and others less, which would affect farming and agriculture. Storm systems could increase in both frequency and strength, bringing more hurricanes and flooding.
Higher temperatures might also lead to higher ozone levels, greatly increasing smog levels in major cities and industrialized areas. Even a small rise in atmospheric temperatures might change cloud patterns. Warm air near the ground might cause lower clouds (which reflect sunlight back into space) to evaporate, thus allowing heat to rise farther into the atmosphere. As it rises and cools, it forms higher clouds, which absorb more heat. More high clouds would cause more heat to be trapped at the surface, and over time the atmosphere will end up holding more and more heat.
The oceans play one of the most important parts in climate change. Because water is 1000 times more dense than air and can hold four times more heat, ocean currents transport heat around the world. Changes in temperature might slow or even stop some ocean currents, leading to significant cooling in those areas. Higher temperatures will also cause some of the planet’s polar and sea ice, glaciers, and permanent snow cover to melt, which may make both the level and the temperature of the seas rise, which could change the course and speed of ocean currents and alter the habitats of sea plants and animals.
Researchers have found that, over the past 100 years, sea levels have already risen by 10 to 15 cm. The IPCC predicts that sea levels may rise anywhere from .09 to .88 meters over the next 100 years. This would have an adverse effect on places like islands and other low-lying areas which would be devastated by a rise in sea levels.
Yet another effect of global warming is the changing of the earth’s albedo, which is the amount of energy reflected back into space. Albedo is measured in a range between 0 (no reflection whatsoever) and 1 (complete reflection, almost like a mirror). Our planet’s average albedo is .31, meaning that Earth reflects back about 31% of incoming solar radiation. But different environments have different albedos, with forests ranging from between .07 and .15, oceans averaging about .10, deserts about .3 and snow, ice and clouds ranging between 0.6 and 0.9. As the snow and ice melt, they expose a much darker surface, which has a much lower albedo. Therefore, a relatively small amount of melting might lead to a warmer surface, which would melt even more ice, causing a “runaway” warming trend. This may have happened before—scientists have discovered evidence from the Cretaceous Period (120–65 million years ago) which reveals that there was little or no snow and ice cover at that time, causing the earth’s albedo to be significantly lower, and average temperatures were some 8°-10° C higher then than they are now.
In some places around the world, meteorologists find it nearly impossible to predict tomorrow’s weather; naturally, supposition and speculation about the future of our planet run rampant. But one thing is absolutely true: global warming is a fact. Whether or not it will continue, and to what degree it will further affect life on this planet, remains to be seen.
