To those of us living in Boulder and surrounding communities, it may come as a surprise that many people remain unconvinced that the use of fossil fuels is the main contributor to current climate change.
But before diving into the discussion of the consequences of climate change it’s worth identifying some misconceptions first. The terms “weather,” “climate change,” “the greenhouse effect” and “global warming” are often confused for one another and are sometimes simply misunderstood. These terms mean very different things.
“Weather” is what happens tomorrow or next week. Climate is the average of what happens over years. That’s important to remember because one particularly hot or cool week or month does not mean that climate is changing. Only by averaging over years do climate trends become observable.
“Climate change” is a measure of the long-term differences of weather patterns across the world over periods of decades to millions of years. Long-term increases or decreases in ocean temperature or acidity, glacier and ice cap coverage, trends in the amount of snow and rain, and the frequency of severe storms like hurricanes are all examples of climate change. Earth’s climate has changed countless times throughout its 4.5 billion-year history, but this change is often very slow, with long periods of relative stability. Records indicate that the Earth may have once, or even multiple times, been almost entirely covered in snow and ice over its history; there is also evidence that suggests that at other times in the past the Earth has been exceptionally hot. Think of Earth’s climate as a pendulum swinging back and forth from hot to cold roughly every 10,000 to 100,000 years. Climate change is a natural phenomenon, and our actions are accelerating this process.
“The greenhouse effect” is often the most misunderstood of these terms. The greenhouse effect is essential to the survival of life on this planet. Just as a greenhouse provides warm and moist conditions in which we grow plants, our planetary greenhouse effect is responsible for the same warmth and moisture, but on a much larger, planetary scale.
Almost all of us have experienced getting into our cars on a warm summer day and realizing that the car’s interior is much warmer than the outside. This is the greenhouse effect in action. Visible light from the Sun goes through your car windows and is absorbed in the interior causing an increase in temperature. The seats then radiate energy, but in the form of infrared rather than visible light. Even though we can’t see infrared light without specialized equipment, it can be felt in the form of heat.
There is an infrared camera in the lobby of Fiske Planetarium that visitors can use for free. Visible light escapes through the windows while the infrared light remains trapped, resulting in an increase in temperature.
Earth’s atmosphere behaves just like our car windows. Some of the gases in our atmosphere, such as carbon dioxide, methane and even water have the ability to trap and/or block the transmission of infrared light.
Without the greenhouse effect, infrared light leaving the Earth’s surface would escape into space, leaving the Earth much cooler than it is, particularly at night. The gases in our atmosphere prevent that from happening and trap the heat. Earth’s average temperature is roughly 15 degrees C (59 degrees Fahrenheit), whereas its temperature without the greenhouse effect might be -16 degrees C (3 F). The greenhouse effect is not, in itself, a problem; rather, it is having concentrations of greenhouse gases that are too high that is of great concern.
An example of what happens when such concentrations are too high can be seen by looking at our planetary neighbor, Venus: the Venusian atmosphere is more than 96 percent carbon dioxide (compared to 0.038 percent on Earth), and the temperature can reach 460 C, which is hotter than your oven can get. On the other hand, the planet Mars has a very thin atmosphere is quite cold at -63 degrees C (-81 F). Venus, Earth and Mars are often referred to as the “Goldilocks” planets. Venus is the porridge that is too hot, Mars is porridge that is too cold and Earth is just right.
Finally, the term “global warming” is often used when referring to anthropogenic (human-caused) climate change. Since the end of the industrial revolution in the late 1800s, the temperature of the Earth has rapidly increased, and this trend has been seen in temperatures recorded in many locations around the globe.
But an average warming of the climate is not the only result of climate change. Climate models also predict more extreme weather episodes such as hurricanes and heavy precipitation, including snow in some places, and the climate history of Earth shows that many periods of rapid climate change were accompanied by episodes of extreme weather. Towards the end of 2010 and into the beginning of 2011 we have seen a lot of extreme weather across the world, from massive winter storms bringing snow to Atlanta, Ga., to unprecedented flooding in Australia, to a devastating heat wave in Russia. For us in Colorado we are still seeing a wetter-than-normal winter season in the mountains, and at the start of the new year, the average snowpack across the state was 140 percent of normal. This is only a year, so it should be described as weather, but it is the trend that “global warming” is predicted to cause. If you hear the media or politicians claim that a recent stint of cold-weather events is proof that global warming is a myth or made up, they are simply wrong.
Unfortunately, deliberate misinformation also clouds the climate debate. In the media you can find claims of a “climate conspiracy” among scientists (often on sites paid for by those who don’t want to face climate change.) But weather and earth scientists don’t hold secret meetings; they are open to anyone who wants to attend. At the American Geophysical Union meeting in San Francisco 15,000 to 20,000 participate. Scientists from all over the world report on what is happening to air and ocean temperatures, glaciers, volcanoes — you name it. Not all, but an overwhelming majority find evidence that demonstrates increasing climate change. The scientists aren’t hiding anything. In fact, most are happy to talk about their work if you ask. The evidence of climate change has increased over the last several decades, and that is what scientists are reporting.
Now that we have clarified these sometimes confusing terms, we can focus on what we can do to change things, and what happens if we do nothing. First, many kinds of data clearly show climate change in the form of a trend toward warmer temperatures. Scientists agree that the Earth’s climate is warming. The real question facing us is how much of this warming is “anthropogenic” (caused by the actions of mankind). For instance, is all of the warming caused by humans, or is most of it natural, with our actions accounting for a small fraction? If our impact on global climate is large enough, the planet’s natural regulatory mechanisms may become overwhelmed and lead to further, even more dramatic increases in both temperature and extreme weather events in the future.
The two main sources of anthropogenic global warming on Earth appear to be the release of greenhouse gases as a result of the burning of fossil fuels, and global deforestation. While the burning of fossil fuels is the most obvious culprit in global warming, the role of trees and vegetation in providing a natural defense against concentrations of greenhouse gases is often overlooked. Forests pull carbon dioxide out of the atmosphere during photosynthesis, and emit breathable oxygen as a byproduct. Widespread deforestation due to human activity is seriously crippling one of our planet’s climate regulation mechanisms: according to an Environmental Protection Agency study from 2005, a one-acre forest can sequester two metric tons of carbon dioxide (CO2) in one year. Two metric tons of CO2 is the same amount of CO2 released when using 227 gallons of gasoline. A Department of Transportation study states that each driver in the U.S. uses about 730 gallons of gas per year. When we put it all together, this means it takes roughly three acres of forest to offset your yearly carbon emission from driving you car.
Do we need to stop burning fossil fuels entirely? Some might say yes, but most agree that this is unlikely to happen as long as such fuels remain available. What actions can we take? As consumers, we have a great deal more power to effect change than we might suppose, and our actions don’t rely on government action to impact the global climate. Even small steps toward making clean energy cost-effective and improving efficiency in our appliances, homes and vehicles can have a real-world impact. Agricultural changes that enable more efficient use of land can help to reduce deforestation, as can minimizing the use of plant products that are not derived from renewable sources. There is no single, magical solution to global warming and climate change, but the vast majority of the evidence tells us that we can no longer wait to take action.
For more on this article please go to http://fiske.colorado.edu/sciencecolumns.php
