Confessions of a Greenpeace Dropout: The Making of a Sensible Environmentalist (70 page)

Climate science is a classic case of the necessity to distinguish between historical and present facts on the one hand, and predictions of the future on the other. There are a number of things we can say with relative certainty:

During the past 500 million years, since modern life forms emerged, the earth’s climate has been warmer than it is today most of the time. During these “Greenhouse Ages” the earth’s temperature averaged around 22 to 25 degrees Celsius (72 to 77 Fahrenheit).
[12]
All the land was either tropical or subtropical and the world was generally wetter. The sea level was much higher than today and life flourished on land and in the oceans. These warm periods were punctuated by three Ice Ages during which large ice sheets formed at the poles and in mountainous areas, effectively eliminating most plants and animals in those regions.

The two Ice Ages that preceded the current one occurred between 460 and 430 million years ago and between 360 and 260 million year ago. From 260 million years ago until quite recently, a Greenhouse Age existed for about 250 million years. Ice started to accumulate in Antarctica beginning 20 million years ago and eventually the current Ice Age, known as the Pleistocene, began in earnest about 2.5 million years ago.
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The Pleistocene, which we are still in today and during which our species evolved to its current state, accounts for only 0.07 percent of the history of life on earth.

During the coldest periods of the Pleistocene Ice Age the average temperature of the earth was around 12 degrees Celsius (54 degrees Fahrenheit) and there were large ice sheets on both poles. Before the recent retreat of the glaciers, beginning 18,000 years ago, the ice extended below the U.S./Canada border, over all of Scandinavia, much of northern Europe, and well into northern Russia. The sea was about 122 meters (400 feet) lower than it is today, having risen steadily since then and continuing to do so today.
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In recent times the sea has risen about 20 centimeters (8 inches) per century. The cause of sea level rise is a combination of melting glaciers (ice on land) and rising ocean temperature, as water expands when it gets warmer.

The earth’s climate underwent a general warming trend beginning with the end of the last major glaciation, about 18,000 years ago. This has not been an even warming, as there have been many fluctuations along the way. For example, during the Holocene Thermal Maximum between 9000 and 4000 years ago it was warmer than it is today by as much as 3 degrees Celsius (5.4 degrees Fahrenheit).
[15]
During this time the present-day Sahara Desert was covered with lakes and vegetation, clearly indicating there was much more rainfall there than today.
[16]
We know for a fact this was not caused by humans. Many scientists believe it was caused by variations in the earth’s orbit around the sun.

This historical record highlights the importance of analyzing the starting point and end point of temperature measurements when explaining trends, both up and down. It is warmer today than it was 18,000 years ago. But it is cooler today than it was 5,000 years ago during the Holocene Thermal Optimum. So it could be said we have been in a cooling trend for the past 5000 years even though it is warmer now than it was when the glaciation ended. I will try not to “trick” the reader by cherry-picking timelines that support a particular bias.

Today the average temperature of the earth is about 14.5 degrees Celsius (58 degrees Fahrenheit), decidedly closer to the Ice Age level than the Greenhouse Age level and only 2.5 degrees above the temperature at the height of the last major glaciation. The fact is we are still in the Pleistocene Ice Age and it is possible another major glaciation may occur sometime in the next 10,000 years, but that is a prediction, not a fact.

Carbon Dioxide (CO
₂
) is a greenhouse gas in that it tends to heat the atmosphere and thus raise the temperature of the earth. But water vapor is by far the most important greenhouse gas, contributing at least two thirds of the “greenhouse effect.” CO
₂
and other minor gases, such as methane and nitrous oxide, make up the other third of the greenhouse effect.
[17]
It is not possible to prove the exact ratios among the various greenhouse gases as they interact in complex ways. In particular, the balance between water vapor and clouds (made up of condensed water vapor) is impossible to predict accurately.
[18]

We know global levels of CO
₂
in the atmosphere have risen steadily from 315 parts per million (ppm) to nearly 390 ppm since scientists began taking regular measurements at Mauna Loa on the big island of Hawaii in 1958.
[19]
This is a very short time compared to the 3.5 billion years of life on earth. Many scientists assume that human emissions of CO
₂
from burning fossil fuels are the main cause of this increase. Some scientists question this assumption. It is a fact that CO
₂
levels were much higher than they are today during previous eras. This will be discussed in detail later.

The average temperature of the earth has fluctuated during the past 100 years, sometimes cooling, sometimes warming, and in balance has increased somewhat, especially during the periods from 1910 to 1940 and from 1980 to 1998. Since 1998 there has been no further warming and apparently a slight cooling. There is a lot of controversy around the accuracy of these trends. In particular there is a concern that many of the weather stations used to determine the global average were originally in the countryside but over the years have been swallowed up by expanding urban development. The “urban heat island effect” refers to the fact that concrete and heat from buildings results in an increase in temperature in urban areas compared to the surrounding countryside,
[20]
thus the possibility exists that the results have been skewed.

In November 2009 the release of thousands of emails, leaked or hacked, from the Climatic Research Unit of the University of East Anglia in the U.K. shocked the climate change community. It was quite clear from a number of email exchanges that the scientists with this most important source of information had been manipulating data, withholding data, and conspiring to discredit other scientists who did not share their certainty that humans were the main cause of climate change. These revelations were quickly dubbed “Climategate” and have since been hotly debated in climate change circles.
[21]
[22]
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It is very difficult to find a balanced account of this scandal. Commentary is divided sharply, with believers claiming that while the scientists involved behaved badly, this does not change the fact that the science is clear that humans are causing warming, while skeptics claim the revelations demonstrate the books have been cooked, placing the entire hypothesis of global warming in doubt.

In December 2009, after months of promotion and hype, the Copenhagen conference on climate change ended in disaster for the true believers. The delegates at the largest international meeting in history failed to reach a single binding decision to control CO
₂
emissions. There does not seem to be any conceivable strategy to achieve international agreement on this subject. The United States will not sign a deal that does not include China, India, Brazil, and the other developing countries. The developing countries will not agree to reduce or restrict their CO
₂
emissions so long as the U.S. and other industrialized countries have far higher emissions on a per capita basis. Whereas the U.S. emits nearly 20 tonnes (22 tons) of CO
₂
per person, China emits 4.6 tonnes (5.1 tons) and India emits 1.2 tonnes (1.3 tons). There is no possibility this impasse will be resolved in the near future. The U.S. will not agree to reduce its emissions to a lower level while the developing countries increase theirs. The developing countries will not agree to a system in which the U.S. and other industrialized countries are allowed even higher per capita emissions. Despite this obvious impasse, the delegates continue to meet regularly, thousands of people jetting to desirable locations like Bali, Montreal, and Rio de Janeiro at public expense, with no possibility of ever reaching agreement.

We can be fairly certain of the facts listed above, with the qualifications given. While this is very interesting, it is not the known facts but rather the unanswered questions that are most intriguing. Climate change cannot be defined by a single question. It is much like peeling back the layers of an onion, beginning with the science, leading to possible environmental impacts, followed by potential economic and social impacts, and concluding with policy options. Among these questions are:

Is CO
₂
, the main cause of global warming, either natural or human-caused?

Are human-caused CO
₂
emissions the principle cause of recent global warming?

Is the recent warming trend fundamentally different from previous warming and cooling trends?

If warming continues at the rate experienced in the 20
^th
century into the 21
^st
century will this be positive or negative for human civilization and the environment?

Is the melting of glaciers and polar ice really a threat to the future of human civilization?

Will increased CO
₂
result in “acidification” of the oceans and kill all the coral reefs and shellfish?

Is it possible for humans to halt global warming and to control the earth’s climate?

Which would cost more to the economy, an 80 percent reduction in fossil fuel use or adaptation to a warmer world?

Could the United States and China ever agree to a common policy on reducing CO
₂
emissions?

* Is the effort to conclude a binding agreement to control CO
₂
emissions among all nations futile?

These are just some of the many questions we must answer if we are to make intelligent choices about the direction public policy should take on the subject of climate change.

Before going into more detail I will clarify two key points. First, the fact that both CO
₂
and temperature are increasing at the same time does not prove one is causing the other. It may be that increased CO
₂
is causing some or most of the increased temperature. It may also be that increased temperature causes an increase in atmospheric CO
₂
. Or it may be they are both caused by some other common factor, or it may be just coincidental they are both rising together and they have nothing to do with one another. Correlation does not prove causation. In order to demonstrate one thing causes another, we need among other things, to be able to replicate the same cause-effect sequence over and over again. This is not possible with the earth’s climate as we are not in control of all (or any of) the factors that might influence climate. Now, if we had a record of CO
₂
and temperature going back many millions of years and it showed that increased temperature always followed increased CO
₂
, we would be a long way toward proving the point. As we shall see later, the historical record is not so clear on the relationship between CO
₂
and temperature.

Second, it is often assumed that the interests of humans and the interests of the environment are one and the same. This may be the case for some factors, such as rainfall, but for others it simply does not apply. Take sea level rise, for example. If the sea level rises relatively rapidly, it will damage a great deal of human infrastructure and a great deal of work and expense will be required either to protect or to replace farms, buildings, wharfs, roadways,
etc.
But fish and other marine creatures will be perfectly happy with the rising sea level and most land animals will not find it difficult to move a few feet higher. A 1.5 meter (5-foot rise) in sea level may inundate Bangladesh, turning much of it into a salt marsh and displacing millions of people. This would be devastating for humans, but from an environmental perspective there is nothing wrong with a salt marsh. From an ecological point of view, a natural salt marsh represents an improvement over intensive agriculture with monocultures of nonnative food crops. Fortunately, no credible scientist believes the sea level will rise anywhere near 1.5 meters in the next century.