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Is It Climate Change or Global Warming?

The term climate change and global warming are often used interchangeably as they refer to the same environmental problem. Some people prefer to use climate change as climate is more evident to us and climate change is not as controversial as global warming. It is probably okay to use either term, but for those who like precision in language, we will take a tour through climate science to sort out the difference.

Climate and Weather: It is said that no one can predict the weather and that is true as no one can predict very far in advance whether it will rain or storm or how cold or hot it will be. However, if we observe the weather of a region over a long period of time, a pattern emerges. That pattern is the climate and, though we cannot predict the weather accurately, we have a much better chance of predicting climate. If we observe such things as the high and low temperatures, the amount of rain, when the first frost and the last freeze usually occurs, a pattern emerges. The climate is quite important to us as it determines the crops we grow, the types of house we build, and the clothing we wear. Climate determines the plants, animals, and insects that live in our region and even the types of health problems and diseases. The factors that determine climate have been observed to vary slowly with time and we expect the climate in a region to remain relatively stable over long periods.

Climate Change: In the last century, and particularly in the last three decades, we have noticed that climates in many regions of the Earth are changing. The daytime high temperatures are higher, the nighttime lows are warmer, the patterns of drought and rainfall have changed, and storms seemed to have become stronger. Frost occurs later in the year and the last freeze occurs earlier, which has caused gardening zones to move. The ranges of many species of plants, animals, insects and bacteria have shifted, and there has been invasions of non-native, sometimes invasive, species into new areas. Our observations have shown that the climate is definitely changing, and those changes are sure to have consequences for us.

Global Warming: Since the early 1800’s, scientists have been concerned with whether our use of fossil fuels has affected the temperature of the Earth. With an increasing understanding of the role greenhouse gases play in stabilizing the temperature of the Earth, scientist wondered whether burning fossil fuels might affect the energy balance of the Earth. Burning carbon fuels releases carbon dioxide, CO2, which they knew to be an important greenhouse gas and there was speculation about whether an increase of CO2 in the air could actually cause the Earth to warm. Critics of the idea argued that water was a much more important, that the relatively small amount of CO2 in the air would not make a difference, and that the amount of CO2 man produced was minuscule compared to what was already there.

The Role of CO2: With a better understanding of the atmosphere and the advent of computers, G. N. Plass in 1956 was able to calculate the climate sensitivity of the Earth to CO2. He found that doubling the concentration of CO2 in the air would cause a 3 to 4 °C increase in the Earth’s temperature. A number of more recent studies have confirmed his work and have shown that, though the concentration of CO2 in the air is small, it accounts for about 25% of the greenhouse effect. Certainly, increasing the amount of CO2 in the air should cause the Earth to warm. In the last century, our emission of CO2 has increased from a minuscule amount to over 50 billion tons annually and the concentration of CO2 in the air has risen from 280 parts per million (ppm) to 385 ppm. But, has that caused global warming?

The Temperature Scorecard: The temperatures over the Earth vary widely from place to place with the weather and the season. However, the temperature of a particular place measured over a long period of time has a pattern and we can use the pattern as a scorecard. There are temperature records that go back to about 1850 and these have given us a way to keep track of whether the Earth is warming. By using ships logs, weather stations, and satellite measurements, NASA has compiled the Earth’s annual mean temperature from 1880 to the present. Though it varies widely from year to year, the Earth’s annual mean temperature shows an upward trend and the Earth is definitely getting warmer.The scorecard shows that over the last century the Earth has warmed about 1.3°F, which does not sound like much. However, since that is the average over the whole Earth, it represents a tremendous amount of energy and it is the energy in the atmosphere that drives our weather and determines our climate.

So there we have it, a cause and effect relationship. Climate change is caused by global warming, which in turn is caused by the increasing CO2 in the atmosphere, and the CO2 is increasing because of our use of fossil fuels. Though it is probably irrelevant whether we call it climate change or global warming, it is very relevant that we understand the relationships and think about our role. The way we use fossil fuels has consequences for us and for the rest of the species on the planet.

(c) 2010 J.C. Moore

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