An elder's guide to climate scepticism | Notes from the Panther Lounge | David Suzuki Foundation
Photo: An elder's guide to climate scepticism

By Stan Hirst

The other elders may drive me from the village with brooms and pitchforks when they read my confession. But the truth must out. I am, alas, a skeptic.

I am skeptical that my beloved Earth is going to self-destruct on 31 December 2012. I think it's more likely the Mayans ran out of the wild fig bark on which they were drawing their calendars. I am skeptical that I am by nature diplomatic, charming and easygoing because Jupiter was hanging out with Venus in the Fourth House of the night sky right about the time I came into the world 70-odd years ago. I am skeptical that the people responsible for the multi-billion dollar homeopathic remedy business have never learned to spell the words p-l-a-c-e-b-o and g-u-l-l-i-b-i-l-i-t-y. And all this scepticism flies in the teeth of the billions of people worldwide who buy into this stuff.

We sceptics are in good company. Albert Einstein was one. In 1933 he famously stated that black holes do not and cannot exist. He couldn't see one and couldn't find the rationale for them in his famous equations. Today, his successors have no such problems and not only think they have identified nearly 30 black hole candidates in the Milky Way galaxy but are now getting the proof that the holes behave in the relativistic way that Einstein's theories predict.

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But I'm concerned that we genuine skeptics are being given a bad name by all these so-called climate change and global warming skeptics out there.
We need to address a few issues to sort out these guys in the black hats. Firstly, what exactly is a skeptic? What is climate? And what is climate change and what does it entail?

The Oxford English Dictionary defines a skeptic as one who maintains a doubting attitude with reference to some particular question or statement. Michael Schermer, the entertaining editor of Skeptic magazine, enlarges the concept thus: "Modern skepticism is embodied in the scientific method that involves gathering data to formulate and test naturalistic explanations for natural phenomena. All facts in science are provisional and subject to challenge, and therefore skepticism is a method leading to provisional conclusions. The key to skepticism is to continuously and vigorously apply the methods of science to navigate the treacherous straits between 'know nothing' skepticism and 'anything goes' credulity."

And what is "climate" and how does it differ from "weather"?

Weather is the state of the atmosphere at any given moment to the extent that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. The way the concept is used in daily life refers to day-to-day temperature and precipitation activity. By contrast, climate is the term for the average atmospheric conditions over longer periods of time. The difference between the two creates major confusion for many. "How the heck can it be global warming when we're having record snowfalls in eastern Canada?"

Which leads us to the obvious next question: What is the evidence for climate change?

Lots of prestigious institutions keep honest meteorological data and report their findings. At the national level, Environment Canada? reports that the national average temperature for 2010 was 3°C above normal, which makes it the warmest year on record since nationwide records began in 1948. The previous warmest year was 1998, 2.5°C above normal. Four Canadian climate regions (Arctic Tundra, Arctic Mountains and Fiords, Northeastern Forest and Atlantic Canada) experienced their warmest year on record in 2010, and for six other climate regions the year was among the 10 warmest recorded. Southern Alberta and Saskatchewan were the only parts of the country with close to normal temperatures. Environment Canada's national temperature departures table shows that of the 10 warmest years, four have occurred within the past decade, and 13 of the past 20 years are listed among the 20 warmest.

At the international level, the Climatic Research Unit the University of East Anglia has global land and marine surface temperature data dating back to 1850. The Unit reports that the years 2003, 2005 and 2010 were the warmest on record. The mean global temperature has risen by 0.8°C over the past century. The World Meteorological Organization reports that the 10 warmest years on record have all occurred since 1998.

The U.S. Environmental Protection Agency has carefully summarized all the salient indicators of climate change occurring within the past century. These include:

  • Heat waves. The frequency of heat waves in the U.S. has risen steadily since 1970, and the area within the U.S. experiencing heat waves has increased.
  • Average precipitation has increased since 1901 at an average rate of more than six per cent per century in the U.S. and nearly two per cent per century worldwide.
  • Heavy precipitation. In recent years, a higher percentage of precipitation in the U.S. has come in the form of intense single-day events; eight of the top 10 years for extreme one-day precipitation events have occurred since 1990.
  • Tropical cyclone intensity in the Atlantic Ocean, Caribbean and Gulf of Mexico has risen noticeably over the past 20 years; six of the 10 most active hurricane seasons have occurred since the mid-1990s. This increase is closely related to variations in sea surface temperature in the tropical Atlantic.
  • Arctic sea ice. September 2007 had the lowest ice coverage of any year on record, followed by 2008 and 2009; the extent of Arctic sea ice in 2009 was 24 per cent below the 1979 to 2000 historical average.
  • Glaciers around the world have generally shrunk since the 1960s, and the rate at which glaciers are melting has accelerated over the past decade. Overall, glaciers worldwide have lost more than 8,000 km3 of water since 1960.
  • Lakes in the northern U.S. are freezing later and thawing earlier than they did in the 1800s and early 1900s; the length of time that lakes stay frozen has decreased at an average rate of one to two days per decade.
  • Snow cover over North America has generally decreased since 1972 (although there has been much year-to-year variability); snow covered an average of 8 million km2 of North America during the years 2000 to 2008, compared with 8.8 million km2 during the 1970s.

    So we honest skeptics have no issue with the evidence for global warming. It's incontrovertible. Not even Sarah Palin could refudiate it.

What about the evidence for anthropogenic inputs to global climate change? In other words, to what extent are human activities — specifically the emission of carbon dioxide, methane and other greenhouse gases — responsible for the global warming observed to date?

Total global greenhouse gas emissions (expressed as carbon dioxide equivalents) are nearing 30 billion metric tonnes per year. As a result, mean global atmospheric carbon dioxide concentration has gone from about 280 parts per million during pre-industrial times to more than 380 parts per million today. Earlier CO2 data were collected from ice cores in eastern Antarctica and have been the subject of dispute by so-called climate skeptics, but the modern-day data come from state-of-the-art instrumentation on Mauna Loa in Hawaii and are incontestable. From 1990 to 2008 the radiative forcing of all greenhouse gases in the Earth's atmosphere increased by about 26 per cent, the rise in carbon dioxide concentrations accounting for approximately 80 per cent of this increase.

It turns out that atmospheric CO2 is not homogeneous. Some of it contains carbon-12, the rest carbon-13 (one more neutron per atom than carbon-12). Green plants prefer carbon-12 in their photosynthetic reactions. When fossil fuels, which are derived from ancient plants, are burned, the carbon-12 is release into the atmosphere. Over time, the continuous carbon-12 emissions change the atmospheric proportion of carbon-13 to carbon-12, and this proportion can be measured in corals and sea sponges. So not only have background levels of CO2 increased over the past century, they are directly linked to fossil fuel burning. And we honest skeptics are still cool with the concept.

Next question: Is the extra anthropogenically derived CO2 responsible for the observed warming trend? The so-called "greenhouse" effect of CO2 is well-known and can be measured easily in a laboratory. But it has also been measured globally over the past 30 years by satellite-mounted infrared sensors and found to be significant. Moreover, the amounts of global atmospheric downward long-wave radiation over land surfaces measured from 1973 to 2008 have been examined and found to be significant in contributing to the global greenhouse effect.

The U.S. Environmental Protection Agency's summary includes some biological indicators of long-term climate change in the U.S.:

  • The average length of the growing season in the lower 48 states has increased by about two weeks since the beginning of the 20th century, a particularly large and steady increase having occurred over the past 30 years. The observed changes reflect earlier spring warming as well as later arrival of fall frosts, and the length of the growing season has increased more rapidly in the west than in the east.
  • Plant hardiness zones have shifted northward since 1990, reflecting higher winter temperatures in most parts of the country; large portions of several states have warmed by at least one hardiness zone.
  • Leaf and bloom dates of lilacs and honeysuckles in the lower 48 states are now a few days earlier than in 1900s.
  • Bird wintering ranges have shifted northward by an average of 56 kilometres since 1966, with a few species shifting by several hundred kilometres; many bird species have moved their wintering grounds farther from the coast, consistent with rising inland temperatures.

So there you have it. Take all the scientific evidence available and it would be difficult not to concur with the 97 out of 100 climate experts who think that humans are causing global warming.

So, if the evidence satisfies the honest skeptic amongst us — i.e., those who take the time to seek out and evaluate the evidence and try their level best to come to an honest and defensible conclusions — why then is there a substantial body of opinion that holds countervailing views; i.e., that there is no warming or climate change (it's all just natural variation), or that there is change but we ain't responsible (it's Mother Nature's fault)?

That would be the subject of future postings from the Elders. It opens up the opportunity for some innovative taxonomy of climate change personalities, but I'll leave the naming to others!

February 14, 2011
http://www.davidsuzuki.org/blogs/panther-lounge/2011/02/an-elders-guide-to-climate-scepticism/

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