The Debate Over Global Warming

On pp. 84-85 of Business, 6th Canadian edition, the issue of air pollution and "greenhouse gases" is discussed. The top three largest greenhouse gas emitters per capita are Australia (7.3 percent of the world’s total), the United States (6.5 percent), and Canada (6.4 percent). Alberta is responsible for about 30 percent of Canada's total greenhouse gas emissions, and the oil sands development projects are a big reason.

In the 1990s, many scientists began to argue that air pollution and greenhouse gases were causing the temperature of the earth to rise (global warming), and that serious problems were going to be evident in the future unless something was done to reduce carbon dioxide emissions. Recently, a debate has arisen in the scientific community with respect to global warming. The two most extreme positions are held by "Malthusian pessimists" (those who think we are heading toward an inevitable crisis), and the "technological optimists" (those who think that advances in technology will be able to overcome any crises that might occur). Neither of these extreme views seems very useful. Instead, a careful analysis of empirical data about climate change is needed. This analysis needs to address two questions: (1) is the global average surface temperature of the earth really increasing, and (2) if it is, what is causing that to happen? We look at each of these questions in the following paragraphs.

Is Global Warming Occurring?

The majority of scientists think that global warming is real, and they point to data generated by the United Nations Intergovernmental Panel on Climate Change (IPCC), which shows that the average global temperature has risen about 0.6 degrees Celsius during the last century. Some places like Greenland have experienced significantly greater increases than that (1.7 degrees Celsius in the last 30 years).

Other scientists agree that warming is occurring, but they don't think the magnitude is as large as the IPCC claims. These dissenters include editors of scientific journals, directors of centers for climate research, and professors in many different scientific disciplines such as climatology, wildlife biology, marine geophysics, geology, mathematics, atmospheric science, computer modeling, physical geography, chemistry, and meteorology. Their main argument is that the IPCC data are contaminated and therefore exaggerate the amount of warming that has actually occurred. For example, taking temperatures in urban areas (so-called "heat islands") leads to overstatements about temperature levels. The skeptics argue that about half the warming that has been measured is caused by this type of data contamination. The IPCC says it has made an "urbanization adjustment" in its calculations so that temperature increases are not overstated. The skeptics respond by saying that the adjustments that have been made are insufficient, and that the IPCC continues to exaggerate the amount of warming that has actually occurred.

Measuring temperature is more complex than it appears at first glance. One problem is that the number and location of weather stations is constantly changing, so the comparability of weather data over time is not as good as we would like. For example, only one-third of the weather stations that were operating in the 1970s are still operating today. Other uncertainties arise because methods of measuring temperature may change over time. For example, many years ago, the temperature of sea water was measured by lifting a bucket of sea water into a ship and then measuring the temperature of the water. Now, water is taken into the engine room of a ship and then measured. But that might cause the reading to increase because of the warmer temperature in the engine room. Deciding where to measure temperature is another uncertainty. As we saw above, urban heating must be taken into account, but it is not clear what proportion of urban and rural sites should be included in temperature calculations. Scientists who are skeptical about global warming note that these uncertainties about how to measure temperature make it difficult to conclude with certainty that global warming is actually occurring. Is Global Warming Caused by Human Activity?

Let us assume for the moment that global average surface temperature is actually increasing, i.e., that global warming is a fact. The next question is "What is causing global warming?" When we consider this question, we also find debate among scientists, with some arguing that human activity is the culprit and others arguing that global warming (and global cooling) are natural occurrences.

Many scientists argue that the rapid increase in carbon dioxide emissions that has occurred during the last 200 years is the cause of global warming. These emissions—which are the result of human industrial activity—trap heat in the atmosphere (the "greenhouse effect") and cause the temperature of the earth to rise. The views of scientists who hold this view have been widely publicized, and many people accept them as fact. The IPCC has also concluded that greenhouse gases are the cause of global warming. Other scientists have expressed skepticism about human-caused global warming. They argue that climate variability is a natural phenomenon, and that it has impacted both plants and animals since the dawn of time. Consider some illustrative (and controversial) comments from the skeptics:

• Reid Bryson, emeritus professor of meteorology and the most-cited meteorologist in the world, says the idea that global warming idea is caused by the release of carbon dioxide into the atmosphere is absurd. He says that warming is occurring simply because we are still coming out of the "little ice age" of the early 1800’s.
• Robert Carter, a geologist and researcher at the James Cook University in Australia says that global warming is the result of natural climate change, the causes of which remain largely unknown.
• Don Easterbrook, a professor of geology at Western Washington University, says that global warming during the 20th century could well have occurred without any help from carbon dioxide.
• Tad Murty, a professor in the Departments of Civil Engineering and Earth Sciences at the University of Ottawa, says that global warming is the biggest hoax ever perpetrated on humanity. He notes that there have always been cycles of warming and cooling.
• Tim Patterson, a professor of geology at Carleton University points out that 450 million years ago carbon dioxide levels were ten times higher than they are now and yet the planet was in the depths of an ice age. He also points out that 10,000 years ago, when the earth was coming out of a particularly cold period, temperatures rose as much as 6 degrees Celsius in one decade. That is one hundred times more rapid than the current rise.
• A survey of 530 climate scientists from 27 different countries found that 53 percent of them thought that the current state of scientific knowledge did not allow for a reasonable assessment of the impact of greenhouse gases on climate.

Scientists like those noted above have concluded that human activity is not the cause of global warming, and each one gives a specific reason for his view. More generally, global warming skeptics make several main arguments in support of their position. First, there is overwhelming evidence that variations in the earth’s temperature have occurred in the distant past, and these variations couldn't possibly have been caused by human industrial activity because there weren't any humans. There is also evidence from the relatively recent past (500-800 years ago) about temperature variations, and these are from a time when human industrial activity was at a very low level compared to the 21st century. For example, Norse colonies that were established in Greenland in the 10th century collapsed by the 14th century, partly because the climate turned colder. Ice cores tell us the climate in Greenland was relatively mild from 800 AD to 1300 AD, but then the climate got colder. Temperatures in Greenland have increased 2.7 degrees Fahrenheit over the last 30 years, and this shows—so the dissenters argue—that the natural cycle of warming and cooling is continuing, but it has nothing to do with human activity.

Second, since the thermometer wasn't invented until 1602, we don't have a very long time period of accurate temperature records to examine as we look for warming trends. Records going back thousands of years are needed before we can say with any confidence that a warming (or cooling) trend is actually occurring. Using temperature records from a decade or two is simply not adequate.

Third, research shows that changes in the earth's climate correlate well with fluctuations in the brightness of the sun. In fact, this correlation is much better than that between earth's climate and carbon dioxide levels. Analysis of core samples from the sediment in British Columbia fjords showed a consistent 11-year cycle in marine productivity which correlates closely with the known 11-year cycle of sunspots. Scientists predict that by the year 2020 the sun will be entering a phase of weaker output, and they conclude that a period of unusually cool temperatures is likely. They think that global cooling, not global warming, is the biggest threat. Several other research studies of tree rings and freshwater river levels also strongly suggest that the sun drives climate change.

What Does All This Mean?

If the scientists who say that global warming is being caused by human activity are right, initiatives to stop climate change by reducing carbon dioxide emissions is well-advised. But if the scientists who say that global warming is not caused by human activity are right, there isn't much that we can do about climate change. We will somehow have to cope, but we should not spend large amounts of money trying to stop climate change because we have no control over it.

Regardless of whether global warming is human-caused or is a natural occurrence, there are some likely outcomes that will occur because of it. In other words, there will be both winners and losers if the average global temperature goes up. Consider some winners:

• In Greenland, rising temperatures mean that more pasture area can be grazed by sheep and cows, and a greater variety of vegetables can be grown than was formerly the case; this will improve Greenland's economic performance
• In B.C., for every 1.8 degree Celsius rise in average temperature, wine-growing can expand 200 kilometres to the north
• In the Peruvian Andes, potato farmers now cultivate crops at the 5,000 metre level; previously potatoes could not be grown above 4,500 metres

Questions For Discussion

1. Given the information presented above, as well as other information you have discovered, do you think the evidence supports the argument that global warming is occurring?
2. Given the information presented here, as well as other information you have discovered, do you think the evidence supports the argument that global warming is caused by human activity?
3. List some additional winners and losers that are likely as a result of global warming.
4. "While there are some uncertainties about global warming, the problem is significant enough that we need to take immediate action to reduce carbon dioxide emissions. If we don't, in 40 or 50 years it will be too late." Do you agree or disagree with this statement? Defend your answer.

Sources: Ross McKitrick, "Contaminated Data," The National Post, December 5, 2007; Lawrence Solomon, "Open Mind Sees Climate Clearly," The National Post, June 29, 2007, p. FP15; www.en.wikipedia.org/wiki/List_of_Scientists_opposing_global_warming_consensus, accessed on June 28, 2007; Christopher Essex, "There is No Global Temperature," The National Post, June 23, 2007, p. FP15; Timothy Patterson, "Read the Sunspots," The National Post, June 20, 2007, p. FP17; David Ebner, "The Greening of the Oil Sands," The Globe and Mail, January 6, 2007, p. B4; Lauren Etter, "For Icy Greenland, Global Warming Has A Bright Side," The Wall Street Journal, July 18, 2006, pp. A1, A12; Patrick Brethour, "Canada's Big Emitters Brace For Investment Climate Change," The Globe and Mail, February 19, 2005, p. B4; Jared Diamond, Collapse. Penguin Books, 2005, pp. 493-494; Robert Park, Voodoo Science. Oxford University Press, 2000, pp. 31-34, 43-45; James Trefil, 101 Things you Don't Know About Science and No One Else Does Either. Boston: Houghton Mifflin, 1996, pp. 124-126, 142.