Al Gore’s climate documentary “An Inconvenient Truth” arrived in theaters 20 years ago, in May 2006. The film had a profound effect on the public’s awareness and understanding of climate change, a number of surveys found.
I count myself among those who were dramatically influenced by “An Inconvenient Truth.”
In 2006, the topic of climate change had not yet significantly breached the public consciousness. Despite having just embarked on a career as an environmental scientist and having recently completed my graduate studies with degrees in astrophysics and physics, I had only a vague notion about the problem of climate change before seeing the documentary.
I remember thinking as I left the theater, “If the science in this film is right, how is it possible that we’re not doing anything to stop climate change?” Answering this question put me on a path to becoming a climate journalist and educator.
The film was a watershed moment for me and countless others. It also retains cultural significance to this day. In an October 2025 episode of his podcast centered on climate change contrarianism, which has over 1 million views on YouTube, Joe Rogan and his guests mentioned Al Gore and his film a dozen times. That included Rogan’s claim that “What Al Gore predicted in this stupid movie, which is so far off. He thought we were all going to be dead today, right?”
Spoiler alert: That’s not right. Gore never said we would all be dead by now; Rogan made that up.
Read: Five ways Joe Rogan misleads listeners about climate change
For its 20th anniversary, I revisited the film. I found that its scientific overview was imperfect but predominantly accurate, and that despite worsening impacts, the world has made significant progress in addressing climate change over the ensuing two decades.
‘An Inconvenient Truth’ was right on the basic science
Many climate science experts have reviewed “An Inconvenient Truth,” including University of Washington climate scientist Eric Steig, who in a 2008 paper wrote that although the film included some oversimplifications, “The portrayal of the science of climate change in ‘An Inconvenient Truth’ is largely correct.”
Gore outlined the basic science underpinning climate change the same way I explain it to college students today: By burning vast amounts of fossil fuels, humans have increased the amount of heat-trapping carbon dioxide in the atmosphere. That pollution traps more heat in Earth’s thin lower atmosphere, warming the planet’s surface.
When the film was released, the atmospheric concentration of carbon dioxide had surpassed 380 parts per million, a level 36% higher than at any time in the prior 650,000 years.
To emphasize how high carbon dioxide levels could rise if fossil fuel consumption continued unabated, Gore climbed aboard a scissor lift.
“Within less than 50 years, it will be here,” he said, pointing to the top of a graph where projected concentrations reached around 500 parts per million.
Now 20 years later, carbon dioxide levels are approaching 430 parts per million, and as Gore suggested, remain on pace to reach 500 parts per million by 2056, barring successful efforts to slow their rise.
Because carbon dioxide is the principal control knob governing Earth’s temperature, as a team of NASA climate scientists documented in a 2010 study, the carbon dioxide levels and temperature have hewed closely throughout the planet’s history. As Gore accurately explained, abrupt and dramatic spikes in carbon dioxide invariably cause global warming by trapping more heat.
Shrinking glaciers
In perhaps the most oversimplified section of the documentary, Gore reviewed the declines of various glaciers around the world.
One of the most common critiques of the film lies in Gore’s discussion of the glaciers of Mount Kilimanjaro. It only lasted for 30 seconds, but Gore implied that global warming was to blame for their decline, asserting that “within the decade, there will be no more snows of Mount Kilimanjaro.”
In fact, several studies, including this 2004 paper, have found that a decline in local precipitation tied to changes in the Indian Ocean is the major cause of the mountain’s shrinking glaciers – of which some remnants remain today – although global warming is also a contributing factor.
Next, Gore claimed that within 15 years, Glacier National Park would become “the park formerly known as Glacier.”
One 2003 study did suggest that many of the glaciers in Glacier National Park could disappear by 2030 due to global warming, but fortunately, that has not quite borne out. Although the glaciers in the park continue to decline due to rising temperatures, a 2019 study estimated that it might take until 2100 for Glacier National Park to become glacierless.
But Gore was correct that global warming is causing the accelerating decline of many glaciers around the world, and that this shrinkage poses water security threats to the 2 billion people who rely on mountain glaciers for their water supply.
Worsening extreme weather
Gore also explored the links between climate change and extreme weather, describing a deadly 2003 European heat wave. A 2016 study estimated that global warming was responsible for about half the deaths in London and Paris caused by that heat wave. He also reviewed the devastating impacts of Hurricane Katrina, whose damages an analysis last year estimated climate change worsened by 25% or more.
A little later in the film, Gore outlined the threat that the Atlantic Meridional Overturning Circulation could collapse. This ocean conveyor belt transports warm and cool water through the Atlantic, Indian, and Southern Oceans. By moving warm water from near the equator to the North Atlantic, this ocean circulation helps keep northern Europe significantly warmer than it would otherwise be.
Gore explained that the last time this circulation collapsed, about 12,000 years ago – as a result of a flood of melting ice water at the end of the last ice age – temperatures in Europe plummeted. A study published last month found that the climate models that best match observational data are those that are the most pessimistic, suggesting that the circulation may seriously weaken this century to the point of potential collapse.
The film also included an overview of threats that sea level rise poses to coastal cities around the world. Ice melt from land-based glaciers and the polar ice sheets has increased over the ensuing two decades, causing the rate of sea level rise to accelerate since the documentary was filmed.
Gore also covered numerous other dangerous climate impacts, including the expanding range of infectious disease vectors like mosquitoes, the impact on species of shifting ecosystem ranges and the altered timing of seasons, and the bleaching of coral reefs and the threat it poses to marine ecosystems. All of these problems continue to worsen to this day.
More than 97% of studies agree: modern climate change is human-caused
The film described a memo from strategist Frank Luntz that had advised Republican politicians, “You need to continue to make the lack of scientific certainty a primary issue in the debate.”
In fact, by 2006, there was a strong scientific consensus that modern climate change was human-caused. In 2004, science historian Naomi Oreskes had published the first survey of the published climate science literature. Gore pointed out that in her sample of 928 peer-reviewed study abstracts, none disagreed with the consensus position that humans are causing global warming.
In a 2013 paper, my colleagues and I updated and expanded upon Oreskes’ 2004 study. We examined nearly 12,000 abstracts of peer-reviewed climate studies and invited the authors to categorize their own papers. In both cases, we found that among peer-reviewed studies that took a position on the question, over 97% agreed that humans are responsible.
Then, in 2016, we published another paper in collaboration with Oreskes and other authors of climate consensus studies, concluding that “the finding of 97% consensus in published climate research is robust and consistent with other surveys of climate scientists and peer-reviewed studies.”
More recent studies have found that the expert consensus likely exceeds 99% today, despite a few prominent figures still proclaiming it a hoax.
Progress in climate policies and solutions
At times, Gore seemed discouraged by the lack of progress in addressing climate change.
“I look around and look for really meaningful signs that we’re about to really change; I don’t see it right now,” he said. But he also expressed hope, saying, “I have faith that pretty soon, enough minds are changed that we cross a threshold.”
About a decade later, 175 countries signed the Paris climate agreement. Today, every nation in the world has ratified the agreement except Yemen, Iran, and Libya – and President Donald Trump recently withdrew the United States for the second time.
The International Energy Agency estimates that since 2015, climate and clean energy policies around the world have erased a full degree from Earth’s global warming trajectory. Before the Paris agreement, countries were on a path to release enough climate pollution to cause a catastrophic 3.5-4°C global warming by 2100; today, we’re on a path toward 2.5-3°C.
Read: New report has terrific news for the climate
It’s not yet enough to meet the Paris agreement’s target of limiting global warming to “well below 2°C,” but we still have the opportunity to further reduce emissions and future warming.
In the film, Gore visited China and described the country’s coal power plant growth as “enormous.” Today, that descriptor best fits the country’s clean energy deployment. As a result, China’s climate pollution has now been flat or falling for about two years, and its clean technology exports to countries around the world are surging. In its new Global Energy Review, the International Energy Agency said that “the world has entered the Age of Electricity,” with virtually all of electricity demand growth being met by clean sources.
In short, despite a few oversimplifications, the scientific descriptions in “An Inconvenient Truth” have largely withstood the test of time, and the climate impacts outlined in the film have continued to worsen in tandem with rising global temperatures. But international agreements, domestic climate policies, and accelerating deployments of ever-cheaper clean technologies have started to bend the emissions curve downward.
I think that if Al Gore’s 2006 self were to visit 2026, although more action is still needed to meet the Paris targets, he would be encouraged by the progress humanity has made in addressing the climate crisis.
Republish our articles for free, online or in print, under a Creative Commons license.
