Deconstructing the “Truth”

Farther into the movie, Al explains the greenhouse gas effect. He presents a graphic that shows the sun’s rays heating the Earth’s surface resulting in infrared rays going from the Earth’s surface and back into space. His graphic suggests that some of the outgoing radiation is reflected from the top of the atmosphere and back to Earth. This idea is the basis of anthropogenic (man made) global warming theory. He fails to mention that this effect has never been measured, only calculated, and by scientists on one side of the debate. This is one of the most hotly debated issues in the global warming debate. Not only does this issue involve complicated theoretical quantum physics, but water vapor absorbs infrared radiation. As is often the case in global warming presentations, he forgets that water vapor is by far the most abundant greenhouse gas;3 to 4 percent of the atmosphere. And this is important because at most, man-made greenhouse gases are 1/ 10, 000 of Earth’s atmosphere.

With his description of greenhouse gases he presented a cartoon clip of the innocent sunrays being beaten up by the Greenhouse Gasses. But is water vapor really a bad thing?

Al also discusses the late Charles Keeling, a scientist who measured atmospheric carbon dioxide for many years. Al accurately describes how the amount of carbon dioxide in the atmosphere rises and falls with the seasons and why. He shows how Dr. Keeling measured a steady rise in carbon dioxide as the years went by, a trend often called the Keeling Curve. While some people still dispute the levels of man-made carbon dioxide in the atmosphere, I do not. For many years, carbon dioxide has been measured in many places and by many means;the results are almost identical in almost every instance.

Next, Al gets right to business showing some of the worlds receding glaciers. According to the national Snow and Ice Data Center, most glaciers around the world are receding. But when you look at scientific studies on individual glaciers you begin to understand that temperature is not always the cause and that all of the glaciers that Al mentions have been retreating for over 100 years.

Let’s start with Al’s first example, Mt. Kilimanjaro. Al might be benefited by the knowledge that Kilimanjaro began receding in 1880 before CO2 began increasing in the atmosphere (Molg et al. 2003a). Also, local temperature records show that there have not been increasing temperatures in the last 100 years (King’uyu et al., 2000;Molg et al 2003, Hay et al., 2002). Additionally, the temperature on the mountain near the glaciers never gets above the freezing point (Georges and Kaser (2002). The glaciers on Kilimanjaro and other mountains in the area are shrinking due to a change in local precipitation. In 1880 the climate in the area changed from a very humid to a very dry climate resulting in less clouds and more direct sunlight. (Kaser et al. 2004).

Al’s second example is Grinnell Glacier in Glacier National Park. In this case, when you look at the pictures of receding glaciers, it is easy to say that a warming climate is causing the glacier to disappear. But like Kilimanjaro, these glaciers started melting over 100 years ago.


Grinnel Glacier, Glacier National Park. Dates and arrows show melt since 1850

Himalayas – Glaciers have been found to be in a state of general retreat since 1850 (Mayewski & Jeschke 1979). In this section he also claims that 40% of the worlds population gets half of their water from streams and rivers that are fed by glaciers. This is an easily confused claim. Rivers that are fed by the Himalayas get most of their run-off from the spring snowmelt. They also have many dams that ensure that water will be available during dry months.


Italian Alps – Since the end of the Little Ice Age (about 1850), the hanging Glaciers and firn fields have retreated continuously.


Swiss Alps – Abstract. Since the culmination of the Little Ice Age, Alpine glaciers have been in a state of general retreat.


Peru ‚Äì The current warming that is melting the Quelccaya glacier in Peru began in 1830 according to Al Gore’s friend, Lonnie Thompson (Thompson 2006) * NOTE:The recent data from this ice core may be contaminated by rainwater that seeped into the top 20 meters of the ice.


And the same is true for all of the glaciers he mentioned. They all started retreating at the end of the Little Ice Age. Most glaciers around the world are retreating while some are not, mainly due to changes in storm tracks. Many of the glaciers around the world slowed or reversed their retreats during the cooling period between 1944 and 1976 and began retreating again after that. Many glacier retreats have accelerated in recent years.

Al then begins a presentation about how temperatures during the last thousand years were relatively stable until the last one hundred years using a graph that looked like the one below:


The data for this graph is from a 2003 study by Al Gore’s friend, Lonnie Thompson, a well-known scientist who studies glaciers. The graph itself has the look of what is known as a “hockey stick” graph. It usually demonstrates that temperatures were stable for the last 1, 000 years but suddenly rose in the last 100 years. While this particular graph is used by Al Gore to represent global temperature for the past 1, 000 years, the data is only taken from 7 locations in three mountain ranges. In fairness to Al, there have been several studies by scientists who used tree rings etc. from all over the world who have come up with the same general trend.

UPDATE: After this essay was published, a contributor to the blog “Climate Audit” discovered that the graph belongs to Michael Mann (MB98) and was presented in Lonnie Thompson’s study for comparison.

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