Al Gore's An Inconvenient Truth movie review

By: Dr. Jeff Masters , 5:02 PM GMT on June 19, 2006

Al Gore's global warming movie, "An Inconvenient Truth," aims to call attention to the dangers society faces from climate change, and suggests urgent actions that need to be taken immediately. It is based on a slide show on climate Gore has presented to audiences worldwide over 1000 times in the past 15 years, but it is not purely a documentary. Gore's movie is an advocacy piece that is part documentary, part biography, and part campaign ad. I'll discuss all three of these aspects below. In brief, Al Gore has the right idea--climate change is an urgent issue that requires immediate action, and his thoughtful movie is a welcome addition to the usual array of mindless Hollywood summer fare. However, the movie has flaws. The presentation of the science is good, but not great--I rate it B minus. The excessive details on Al Gore's life make the movie too long, and his insistence on using the movie as something of a campaign ad detracts from its message.

An Inconvenient Truth as a biography of Al Gore
The creators of the movie presumably thought that simply presenting Gore's slide show would be too dull, so they decided to give the movie some human interest by interweaving a biography of Al Gore's life. Al Gore has led an interesting life, but "interesting" and "Al Gore" are not words one can often put together. As my daughter noted in her movie review yesterday, Al Gore is boring, and the 20 minutes or so of biography presented in An Inconvenient Truth is too much for a movie that is 1 hour and 36 minutes long. For example, I didn't really need to see the road where Al Gore totaled his car when he was 14 years old, or a replay of his loss in the 2000 election. On the other hand, some details of his past were interesting and relevant, such as the fact that he took college courses in the late 1960s from Harvard's Dr. Roger Revelle. Revelle and Dr. Charles Keeling were the pioneers in measurements of atmospheric CO2, and thus Gore got a very early exposure to the now infamous "Keeling Curve" (Figure 1), showing the build-up of atmospheric CO2. This early exposure to the significant impact humans were having on the atmosphere deeply affected Gore, and in the movie he details efforts he made to call attention to the issue long before most people had heard of it, back in the 1970s and 80s. Gore's slide show appropriately displays many graphs of the Keeling Curve, as it is probably the most important and most famous finding in climate change science.

Figure 1. The Keeling Curve is a record of CO2 measurements taken at he top of Mauna Loa volcano in Hawaii since 1958.

The science of An Inconvenient Truth
The science presented is mostly good, and at times compelling, but there are a few errors and one major distortion of the truth. Gore does an excellent job focusing on the most important issues, and usually presents them with a minimum of hype and distortion. The only exception to this comes in his treatment of global warming and extreme weather events such as hurricanes.

Basic global warming science
Gore begins the science part of his talk with a very easy to understand presentation on the basics of how the greenhouse effect works. His speech is clear, the graphics top notch, and he spices it up with a hilarious two-minute cartoon depicting roughneck global warming gases preventing poor Mr. Sunbeam from escaping Earth's atmosphere. Gore addresses the argument of skeptics who claim that the Earth is too big for humans to affect by showing Space Shuttle photos of how thin the atmosphere really is compared to the vast bulk of our planet. "The problem we now face is that this thin layer of atmosphere is being thickened by huge quantities of carbon dioxide," he asserts, which is not correct. The build-up of CO2 has virtually no effect on the density or thickness of Earth's atmosphere. The correct thing to say would have been, "The problem we now face is that this thin layer of atmosphere is being made more opaque to the transmission of infrared radiation (heat) by huge quantities of carbon dioxide."

Gore shows an impressive series of "then and now" images documenting the widespread retreat of many glaciers over the past century. Most dramatically, he shows Tanzania's Mt. Kilimanjaro, whose 11,000 year-old glaciers are almost gone. While not all the world's glaciers have retreated in the past century, Gore's presentation is an effective and reasonable way to show how global warming has affected the majority of the world's glaciers. Greenhouse skeptics, including Michael Crichton in his State of Fear book, are fond of bashing those who use Mt. Kilimanjaro as a poster child for demonstrating global warming. They cite scientific research showing that the glacial retreat on Mt. Kilimanjaro is due to drying of the atmosphere, not global warming. However, as discussed at great length in a post, the research which supposedly supports the skeptics' claims has been widely misquoted and misinterpreted, and much of Kilimanjaro's melting can indeed be ascribed to warming of the atmosphere since 1960.

Gore does an excellent job discussing the ice caps of Greenland and Antarctica. Again, Gore's graphics are superb, and he does a nice job narrating. He shows animations of what a 20-foot rise in sea level would do to Manhattan, Florida, India, and China. A 20-foot sea level rise is what we expect if all of Greenland or all of the West Antarctic Ice Sheet were to melt. Such a 20-foot rise is not expected by 2100, and it would have been appropriate for Gore to acknowledge that the consensus of climate scientists--as published in the most recent report by the United Nations' Intergovernmental Panel on Climate Change (IPCC)--is that sea level is likely to rise between 4 and 35 inches, with a central value of 19 inches, by 2100. He should have also mentioned that temperatures in Greenland in the 1930s were about as warm as today's temperatures, so the current melting of Greenland's glaciers does have historical precedent. Nevertheless, the risk of a catastrophic melting and break-up of the Greenland or West Antarctic ice sheets is very real, when we consider that sea level before the most recent ice age was 15 feet higher than it is now. Gore is right to draw attention to what might happen if sea level rose 20 feet.

Drought and heat waves
An excellent discussion of the most serious climate change issue our generation is likely to face, the threat of increased drought and reduced water supplies, is presented. Gore makes reference to the extreme heat wave that affected Europe during the summer of 2004, and I was glad to see that he didn't blame the heat wave on global warming--he merely said that more events of this nature will be likely in the future.

Hurricanes and severe weather
The biggest failure in the movie's presentation of science comes in the discussion hurricanes and severe weather events. The devastation wrought by Katrina is used to very dramatic effect to warn of the dangers climate change presents. We are told that Katrina grew "stronger and stronger and stronger" as it passed over the warm waters of the Gulf of Mexico that were heated up by global warming. We are told that global warming is increasing the intensity of hurricanes, but not provided information on the great amount of uncertainty and vigorous scientific debate on this issue. Graphs showing recent record insurance losses from natural disasters are presented, but no mention is made of how increasing population and insistence on building in vulnerable areas are the predominant factors causing recent high insurance claims from disasters such as Katrina. Gore points to some unprecedented events in 2004 as evidence of increasing severe weather events worldwide--the record 10 typhoons in Japan, the most tornadoes ever in the U.S., and the appearance of Brazil's first hurricane ever. However, examples of this kind are meaningless. No single weather event, or unconnected series of severe weather events such as Gore presents, are indicative of climate change. In particular, the IPCC has not found any evidence that climate change has increased tornado frequency, or is likely to. Gore doesn't mention the unusually quiet tornado season of 2005, when for the first time ever, no tornadoes were reported in Oklahoma in the month of May.

Other science
Gore presents many other important aspects of climate change, including the threat of abrupt climate change leading to a shut-off of the Gulf Stream current, the increase in damaging insect infestations and tropical diseases, loss of coral reefs, loss of ice in the polar ice cap, and melting of permafrost in the Arctic. With the possible exception of his treatment of the spread of tropical diseases, all of these issues were presented with sound science.

An Inconvenient Truth as a campaign ad
Gore has repeatedly said that he has no intention of running for president again, and that this movie was created as part of his life-long passion to protect the environment. Gore undoubtedly does care very deeply about the planet, but this movie very much looks like a campaign ad. We are shown many scenes of Gore being applauded, Gore traveling the globe to present his slide show, and Gore working to uncover evidence of Republican shenanigans to alter or suppress climate change science. Gore is portrayed as a humble and tireless crusader for good, and if the movie is not intended to promote his political ambitions, it is certainly intended to benefit the Democratic Party. All this gets in the way of the movie's central message.

At the end of the movie, we are presented with the same image that Gore started the movie with, that of a beautiful river in the wilderness. Throughout the movie, Gore emphasizes how beautiful and special our planet is, and he does an effective job conveying this. He also makes a powerful case that something can and should be done to protect the planet, and it is worth hearing his message, even if the science is flawed and the messenger does get in the way of the message. Overall, the movie rates 2.5 stars--worth seeing, but you might want to wait until the DVD comes out.

At the end of the movie, Gore presents some tips on how everyone can contribute, and points people to his web site, However, I would recommend that people who want to get educated about climate change get their information from web sites not associated with a politician; perhaps the least politicized source of information is the latest scientific summary of the Intergovernmental Panel on Climate Change(IPCC), a group of over 2000 scientists from 100 countries working under a mandate from the United Nations in the largest peer-reviewed scientific collaboration in history.

Jeff Masters

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78. thelmores
7:29 PM GMT on June 19, 2006
"hey, the methane comes out of the cow's mouth, as a belch, not out the other end as a fart! really."

i stand corrected! :)

i'm much better at eating cattle, than discussing it! ;)
Member Since: September 8, 2005 Posts: 0 Comments: 3833
76. NAtlanticCyclone
7:28 PM GMT on June 19, 2006
I always thought that the upper atmosphere was cooler and if it got warmer then it would become more unstable because warm air is unstable with humidity and dew points rising.
75. tworiversnj
7:23 PM GMT on June 19, 2006
When it's once again time to turn to excitement in the tropics, please move this review to your education links page. It would be great to have access to it as we do the "Day After Tomorrow" essay. Thank you.
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74. rwdobson
7:26 PM GMT on June 19, 2006
hey, the methane comes out of the cow's mouth, as a belch, not out the other end as a fart! really.

seriously, the #1 source of methane is landfills, not cows, and both are pretty small compared to fossil fuels.

and it is true that much of the CO2 in the atmosphere is naturally produced. definitely. what is a concern is the increase above the natural baseline.
Member Since: June 12, 2002 Posts: 0 Comments: 1694
72. rwdobson
7:25 PM GMT on June 19, 2006
"as the upper layer of the atmosphere warms and then becomes unstable and creating a large twist in the lower atmospheres. Any possiblities with this."

No. As the upper layers of the atmosphere warm, the atmosphere becomes more stable, not unstable.
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71. Cregnebaa
2:17 PM EST on June 19, 2006
The interest in when CO2 levels were high historically in the past before man, I assume due to volcanic eruptions, for me is how the earth recovered the equillibrium.
Wether through increase in plant life, that died and ended up as fossil fuels, absorption in the oceans etc.
If it is the former then deforestation, increase of city areas, with an ever increasing population is going to hinder that avenue again.
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70. NAtlanticCyclone
7:23 PM GMT on June 19, 2006
I believe with my instincts that this is possibly a global warming period that our earth goes through just before an ICe Age and then cools and then warms again. This part I agree is natural, but this process could be put into a quicker pace by human increased activity effecting the earth.
68. thelmores
7:03 PM GMT on June 19, 2006
you can't just take into account co2 emission..... what about all the methane gas emitted by cow farts! maybe we should look to see if we have more cattle now than in the past! LOL

i know we have more pigs than we used too! ROFL

Sorry, just trying to lighten things up a little.... some people in here just seem a little too uptight! :)
Member Since: September 8, 2005 Posts: 0 Comments: 3833
67. ExecPro
7:21 PM GMT on June 19, 2006
I once read that most of the CO2 in the atmosphere is actually from natural events. I read some comments about Vocanoes, which is one that I knew about. Another is Forest fires - so I ask the question, do we now do a better job of preventing and stopping forest fires or do we cause more of them then would naturally occur. If we didn't make such advances in controling and stopping forest fires would there be even more C02 in the air?
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65. rwdobson
7:18 PM GMT on June 19, 2006
Gulf Scotsman, try looking up this info on Google if you want to support your point. The info is out there and not that hard to find.

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64. NAtlanticCyclone
7:18 PM GMT on June 19, 2006
Would a F6 tornado convince of Global Warming as the upper layer of the atmosphere warms and then becomes unstable and creating a large twist in the lower atmospheres. Any possiblities with this.
63. AZ
12:21 PM PDT on June 19, 2006
Don't want to step on your toes. That is your forte.
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60. AZ
12:05 PM PDT on June 19, 2006
Silly Houstonian.
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58. djshay
7:10 PM GMT on June 19, 2006
No matter if you agree or disagree with the movie's science, I think we all need to be made more aware of the effect that we humans have on the earth. Anything that shines a spotlight on preserving the planet is ok by me. Even if todays warming isn't caused by human activity, if we continue to spew pollutants into the atmosphere and pollute our seas, rivers and streams, it will eventually have an adverse effect. It might be 20 years from now or 200, but we all need to start being more aware.
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57. DenverMark
7:06 PM GMT on June 19, 2006
That's the conclusion I come to. The bottom line is total CO2 in the atmosphere has increased significantly since 1959. I think prior to the mid-70s, the aerosols we were also putting into the atmosphere were cancelling the effect of the CO2. Once power plants, industry, and vehicles were made cleaner and above-ground nuclear testing stopped, the warming began to show up in the '80s.
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56. franck
7:01 PM GMT on June 19, 2006
The nomenclature for what is tropical, extra tropical, semi-tropical, cold core, warm core, etc. are now distorted. Physical circumstances are changing. For example, from personal experience alone it is clear to me that the zonal climate of the US has moved north at least 200 miles in the forty years, and that is no exaggeration. If anything it is an undertatement.
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55. JeffMasters (Admin)
7:04 PM GMT on June 19, 2006
According to this article posted at by Dr. Gavin Schmidt, the ratio of human to volcano-produced CO2 is about 50 to 1:

"One point that is also worth making is that although volcanoes release some CO2 into the atmosphere, this is completely negligable compared to anthropogenic emissions (about 0.15 Gt/year of carbon, compared to about 7 Gt/year of human related sources) . However, over very long times scales (millions of years), variations in vulcanism are important for the eventual balance of the carbon cycle, and may have helped kick the planet out of a 'Snowball Earth' state in the Neo-proterozoic 750 million years ago."

Jeff Masters
53. rwdobson
6:54 PM GMT on June 19, 2006
Gulf, the fact is, CO2 concentrations are increasing. We can measure that. These concentrations increased at the same time as human-caused CO2 emissions increased dramatically. We can measure thos emissions as well.

Volcanos, as far as we know, are not increasing their emissions of CO2, so they are pretty much irrelevant to the question of increasing CO2 concentrations in the atmosphere.
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52. JeffMasters (Admin)
6:38 PM GMT on June 19, 2006
"AS you well know, Jeff Masters, Tonado frequency HAS increased in the US, dramatically since the 1950's If you look at the curve, it is very similar to every other indicator of global warming:"

This increase in tornadoes is due in part or entirely due to increases in the U.S. population and in better tornado observation networks, which let far fewer tornadoes go unreported now than in the past. I listened to several talks at the 2006 American Meteorological Society meeting by our leading tornado experts who all agreed that the short length of the tornado record and it's relatively poor quality make it impossible at this time to detect if there are long-term changes in tornado activity as a result of human-caused climate change. This is the conclusion of the IPCC as well.

Jeff Masters
51. Mysticdog
6:45 PM GMT on June 19, 2006
"However, you're excactly right that small scale eruptions do not throw as much particles into the atmosphere to block sunlight, but still pumps tons of C02, making the question very relavent."

"I would still like to see the science compared side by side of the TOTAL volume of green house gases from human activity as a comparison against the volume of gases caused by volcanic activity planet wide. Say over the past 2 decades when this has become such a political issue. I am interested to see the breakdown and comparison if anyone could find such data. And where on earth does the greatest amount of human green house gas emissions actually come from."

Go to the DOE site. In 2003, 25 Trillion tons of CO2 was pumped out in the pursuit of energy.

Between 1980 and 2003, 511 TRILLION tons of CO2 was pumped out in pursuit of energy production. The US was responsible for 123 TRILLION tons of that.

"The researchers note that Mt. Etna, a volcano which produces 35,000 tons of carbon dioxide per day and is the largest single source of natural carbon dioxide in the world"

So lets see... thats about 13 million tons a year. 13 million tons out of 25 trillion tons... carry the two... yes, that in fact comes out to SQUAT.

Seriously, you guys could do this yourselves. I mean, if you were interested in actually learning instead of flinging as much mud at the problem as possible.
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49. DenverMark
6:56 PM GMT on June 19, 2006
Thanks, Michael for answering one of my questions. It seems CO2 stayed fairly steady during warmer and cooler periods in the last 1000 years until the Industrial Revolution. I guess other factors were at work to cause climate variations before.
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46. DenverMark
6:45 PM GMT on June 19, 2006
Some other questions I have:

Are we having more volcanic eruptions now than in centuries past?

What data do we have on CO2 concentrations in centuries past? How did it vary between the warm period about 1000 AD vs. the Little Ice Age from 1500 to the mid-1800s?

With the cooling that occurs after major volcanic eruptions (in the early 1800s that caused the cold summer in 1816 or Pinatubo and the cool summer of 1992), don't the effects of aerosols injected into the atmosphere cancel the effects of the greenhouse gases?
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43. jeffB
6:11 PM GMT on June 19, 2006
GulfScotsman wrote:

What is the science of the TOTAL amount of green house GASES from volcanic activity. Relative to the amount of green house GASES from human activity? Putting aside particulate matter that eventually settles out.

It's apparently difficult to get a precise measurement of annual volcanic CO2 production. It might be 150 times less than anthropogenic emissions:

Or maybe only 30 times less:

Or maybe 50 times less, according to this site cited by the "global warming is a myth" advocates at

None of this is definitive, but it ought to be enough to quash the "volcanoes put out more CO2 than humans" meme once and for all. Ought to be, but I know it won't. Too "inconvenient". :-)
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41. Mysticdog
6:40 PM GMT on June 19, 2006
Carbon emission responsibility chart:
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36. Mysticdog
6:36 PM GMT on June 19, 2006
" I remember in the 70's everyone was panicking about the coming ice age."

You remember incorrectly. Very few scientists were "panicked". In fact it got almost no media play at all - a couple of magazine covers.

Now, we know that the measurements that were of slight concern were infact caused by the "global dimming" phenomenae that has been well explained and demonstrated, due to the high amount of particulates that fossil fuel burning industries were putting out.
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35. DenverMark
6:26 PM GMT on June 19, 2006
My question is, while volcanoes produce much more greenhouse gases than human activities do, wouldn't that be part of the Earth's natural balance? Would the relatively small, but growing amounts of greenhouse gases produced by human activity be tipping the balance in favor of warming?
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34. Mysticdog
6:14 PM GMT on June 19, 2006
"However, he should have balanced his discussion of the high loss of life such heat waves cause with the expected reduction in loss of life from fewer severe cold waves."

Why? There is no reason to expect there to be fewer cold waves, or less intense cold wave. I'd expect there to be more extreme cold snaps in a world of increased global warming.

The artic gets no sunlight in the winter. It is always going to be damn cold there, unless there is a total venusian-like climate change. The question is how far that cold air penetrates south, catching people by surprise.

More energy in teh atmosphere will great greater differences between high and low pressure systems. The greater the difference, the greater the winds. The greater the winds, the greater distance cold air from the artic is going to penetrate south (even as warm air fills in behind it).

There were record cold snaps last year, places that never see snow got it. Why? Because of what I just described.

In fact, we can almost certainly expect greater losses of life from heat AND cold as the average temperature heats up.

"We are shown many scenes of Gore being applauded, Gore traveling the globe to present his slide show, and Gore working to uncover evidence of Republican shenanigans to alter or suppress climate change science. Gore is portrayed as a humble and tireless crusader for good, and if the movie is not intended to promote his political ambitions, it is certainly intended to benefit the Democratic Party."

Why shouldn't those things be highlighted? Is there any doubt republican leadership and its industrial base work tirelessly to decieve people about climate science? Is there any doubt Gore has worked to expose those things? Is there some reason people shouldn't know that?

Gore is no longer a politician.

"Gore points to some unprecedented events in 2004 as evidence of increasing severe weather events worldwide--the record 10 typhoons in Japan, the most tornadoes ever in the U.S., and the appearance of Brazil's first hurricane ever. However, examples of this kind are meaningless. "

But trends are not, and showing how those trends result in real meaningful increases is perfectly sensible.

AS you well know, Jeff Masters, Tonado frequency HAS increased in the US, dramatically since the 1950's If you look at the curve, it is very similar to every other indicator of global warming:

As you also well know, Jeff Masters, tornadic activity is fully expected to increase in a world of stronger weather fronts causing stronger storms, all caused by the greater differentials between highs and lows one would expect on an Earth affected by global warming.

As always, I recognize the importance some people place on appearing jaded and unimpressed. I think you should take your role here more seriously than that.
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