Confessions of a Greenpeace Dropout: The Making of a Sensible Environmentalist (71 page)

A Longer View

Our lifetimes are so short compared to the billions of years of life’s history on earth that we tend to dwell on the very recent past when considering historical information. Nearly all the discussion of climate change is in the context of the past 100 years, or occasionally the past 1000 years, even though the earth’s climate has changed constantly for billions of years. Let’s take a look at the history of climate change in this larger context, in particular the past 500 million years since modern life forms evolved.

Temperature

The earth’s average temperature has fluctuated widely over the past one billion years (see Figure 1). It is interesting to note that during the Cambrian Period, when most of the modern life forms emerged, the climate was much warmer than it is today, averaging 25 degrees Celsius (77 degrees Fahrenheit). Only at three other times during the past billion years has the temperature been as cold as or colder than it is today. The age of the dinosaurs, the Jurassic and Cretaceous Periods, experienced a warm climate with a moderate cooling spell in the late Jurassic. Following the dinosaur extinction the climate remained warm for 10 million years, spiking to 27 degrees Celsius (80 degrees Fahrenheit), followed by a gradual decline that eventually led to the Pleistocene Ice Age. As the graph below indicates, it is colder today than it has been throughout most of the past billion years.

Humans generally prefer warmer climates to colder ones. When I mention that the global climate was much warmer before this present Ice Age, people often say something like, “But humans were not even around five million years ago, certainly not 50 or 500 million years ago. We have not evolved in a warmer world and will not be able to cope with global warming.” The fact is we did evolve in a “warmer world.” The human species originated in the tropical regions of Africa, where it was warm even during past glaciations nearer the poles. Humans are a tropical species that has adapted to colder climates as a result of harnessing fire, making clothing, and building shelters. Before these advances occurred, humans could not live outside the tropics. It may come as a surprise to most that a naked human in the outdoors with no fire will die of hypothermia if the temperature goes below 21 degrees Celsius (70 degrees Fahrenheit). Yet as long as we have food, water, and shade we can survive in the hottest climates on earth without fire, clothing, or shelter.
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The Australian Aborigines survived in temperatures of over 45 degrees Celsius (113 degrees Fahrenheit) without air conditioning for 50,000 years.

The fact that humans are essentially a tropical species explains why even today there are no permanent residents of Antarctica and only four million people living in the Arctic (0.06 percent of the global population). Most of the Arctic population is engaged in resource extraction and would not choose to live there otherwise. Historically, the very small populations of indigenous people in the Arctic managed to eke out a living by inhabiting ice-shelters, getting food from marine mammals and oil from marine mammals for heating and light. They used sled dogs for transport and protection from polar bears. There is a good reason why there are more than 18 million people in Sao Paulo, Brazil, only 4,429 residents in Barrow, Alaska,
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and 3,451 inhabitants of Inuvik, Northwest Territory.
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Why are there 300 million people in the United States and only 30 million in Canada, which is larger geographically? One word answers this question: cold. About 80 percent of Canadians live within 100 miles of the U.S. border, as it is warmer there (although not by much in many regions) than it is in 90 percent of the country, which is frozen solid for six or more months of the year.

Figure 1. Graph showing global average temperature during the past billion years.
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So clearly, on the basis of temperature alone, it would be fine for humans if the entire earth were tropical and subtropical as it was for millions of years during the Greenhouse Ages. It would also be fine for the vast majority of species in the world today, most of which live in tropical and subtropical regions. But this would not be the case for some other species that have evolved specifically to be able to survive in cold climates.

The polar bear did not exist until the Pleistocene Ice Age froze the Arctic and created the conditions for adaptation to a world of ice. Polar bears are not really a distinct species; they are a variety of the European brown bear, known as the grizzly bear in North America. They are so closely related genetically that brown bears and polar bears can mate successfully and produce fertile offspring.
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The white variety of the brown bear evolved as the ice advanced, the white color providing a good camouflage in the snow. Once bears could walk out to sea on the ice floes, it became feasible to hunt seals. It is possible that if the world warmed substantially over the next hundreds of years that the white variety of the brown bear would become reduced in numbers or even die out. This would simply be the reverse of what happened when the world became colder. Some varieties of life that exist today are only here because the world turned colder a few million years ago, following a warmer period that lasted for over 200 million years. If the climate were to return to a Greenhouse Age those varieties might not survive. Many more species would benefit from a warmer world, the human species among them.

The polar bear did not evolve as a separate variety of brown bear until about 150,000 years ago, during the glaciation previous to the most recent one.
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This is a very recent adaptation to an extreme climatic condition that caused much of the Arctic Ocean to freeze over for most of the past 2.5 million years. The polar bear did manage to survive through the interglacial period that preceded the one we are in now even though the earth’s average temperature was higher during that interglacial than it is today.
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So as long as the temperature does not rise more than about 5 degrees Celsius (9 degrees Fahrenheit) above the present level, polar bears will likely survive. But that is a prediction, not a fact.

To listen to climate activists and the media, you would think the polar bear population is already in a steep decline. A little investigation reveals there are actually more polar bears today than there were just 30 years ago. Most subpopulations are either stable or growing. And the main cause of polar bear deaths today is legally sanctioned trophy hunting, not climate change. Of an estimated population of 20,000 to 25,000 bears, more than 700 are shot every year by trophy hunters and native Inuit. One hundred and nine are killed in the Baffin Bay region of Canada alone. And yet activist groups like the World Wildlife Fund use the polar bear as a poster child for global warming, incorrectly alleging that they are being wiped out by climate change.

The population of polar bears was estimated at 6000 in 1960. In 1973 an International Agreement between Canada, the United States, Norway, Russia, and Greenland ended unrestricted hunting and introduced quotas. Since then only native people have been allowed to hunt polar bears, although in Canada the native Inuit often act as guides for nonnative hunters. As a result of this restriction on hunting, the population has rebounded to its present level of 20,000 to 25,000. The International Union for the Conservation of Natural Resources Polar Bear Specialist Group reports that of 18 subpopulations of bears, two are increasing, five are stable, five are declining, while for six subpopulations, mainly those in Russia, there is insufficient data.
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There is no reliable evidence that any bear populations are declining due to climate change and all such claims rely on speculation; they are predictions based on conjecture rather than actual scientific studies.

At the other end of the world in Antarctica, numerous species of penguins have evolved over the past 20 million years so that they can live in ice-bound environments. There are also many species of penguins that live in places where there is no ice, such as in Australia, South Africa, Tierra del Fuego, and the Galapagos Islands. It took 20 million years for the Antarctic ice sheet to grow to the extent it has been for the past 2.5 million years, during the Pleistocene Age. Antarctica differs significantly from the Arctic in that most of the ice is on land and at higher elevation. It is very unlikely Antarctica will become ice-free in the near future. It took millions of years for the present ice sheet to develop. In all likelihood the penguins will be able to breathe easily for thousands, possibly millions of years.

Coming closer to the present day, there is good historical evidence that it was warmer than it is today during the days of the Roman Empire 2000 years ago and during the Medieval Warming Period 1,000 years ago.
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We know that during the Medieval Warming Period, the Norse (Vikings) colonized Iceland, Greenland, and Newfoundland. The settlements in Newfoundland and Greenland were then abandoned during the Little Ice Age that lasted from about 1500 to the early 1800s.
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The Thames River in England froze over regularly during the cold winters of the Little Ice Age. The Thames last froze over in 1814.
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Since then the climate has been in a gradual warming trend. Given that there were very low levels of CO
₂
emissions from human activity in those times, it is not possible that humans caused the Medieval Warming Period or the Little Ice Age. Natural factors had to be instrumental in those changes in climate.

Speaking of natural factors, it is clear the climate changes over the past billions of years were not caused by our activities. So how credible is it to claim we have just recently become the main cause of climate change? It’s not as if the natural factors that have been causing the climate to change over the millennia have suddenly disappeared and now we are the only significant agent of change. Clearly the natural factors are still at work, even if our population explosion and increasing CO
₂
emissions now play a role in climate change. So the real question is, are human impacts overwhelming the natural factors or are they only a minor player in the big picture? We do not know the definitive answer to that question.

Let’s go back to the IPCC’s
Fourth Assessment Report
in 2007, which stated: “
Most
of the observed increase in global average temperatures
since the mid-20th century
is
very likely
due to the observed increase in anthropogenic (human-caused) greenhouse gas concentrations”[my emphasis]. The first word,
most
, in common usage means more than 50 percent and less than 100 percent, i.e., more than half but not all. That’s a pretty big spread, so clearly IPCC members don’t have a very precise estimate of how much of the warming they think we are causing. If they are that uncertain, how do they know it’s not 25 percent, or 5 percent? They restrict the human influence to “since the mid-20th century,” implying humans were not responsible for climate change until about 60 years ago. So the logical question is, What was responsible for the significant climate changes before 60 years ago, the warming between 1910 and 1940, for example? The most problematic term in their statement is “very likely,” which certainly provides no indication of scientific proof., The IPCC claims that “very likely” means “greater than 90 percent probability.”
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But the figure 90 is not the result of any calculation or statistical analysis. The footnote entry for the term “very likely” explains, “in this Summary for Policymakers, the following terms have been used to indicate the assessed likelihood, using expert judgement, [my emphasis] of an outcome or a result: Virtually certain > 99% probability of occurrence, Extremely likely > 95%, Very likely > 90%, Likely > 66%, More likely than not > 50%, Unlikely < 33%, Very unlikely < 10%, Extremely unlikely < 5%.”
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One expects “judgments” from judges and opinionated journalists. Scientists are expected to provide calculations and observable evidence. I’m not convinced by this loose use of words and numbers.