What 'An Inconvenient Truth' Got Right (And Wrong) About Climate Change

The 2006 documentary 'An Inconvenient Truth' showcased environmental advocate and former vice president Al Gore's mission to raise awareness about climate change and its perils. Despite its somber theme and unconventional storytelling—built around a slideshow presentation Gore took on tour—the film, directed by Davis Guggenheim, became both a commercial and critical hit. It garnered Academy Awards for Best Documentary and Best Original Song, and grossed nearly $50 million worldwide.

'The film was one of those rare cultural moments that shifted how people worldwide perceived their surroundings,' says Ken Berlin, president and CEO of the Climate Reality Project, an activist organization founded by Gore, via email. 'It motivated millions to start conversations about the climate crisis and personally engage in efforts to solve it, sparking an entirely new generation of activists.'

Eleven years later, the sequel 'An Inconvenient Sequel: Truth to Power' — directed by Bonni Cohen and Jon Shenk — debuted at the Sundance Film Festival on Thursday, January 19, before receiving a broader release in July. This provides an opportune moment to revisit the original 'An Inconvenient Truth' and evaluate how accurate Gore's warnings and calls to action have proven to be. What elements of the film held up, and what aspects might require revision in light of new developments regarding climate change?

When 'An Inconvenient Truth' was first released, it received generally positive feedback from climate researchers. In a 2006 interview, National Snow and Ice Data Center scientists Walt Meier and Ted Scambos, for instance, confirmed that Gore's message was largely accurate, with only a few minor scientific discrepancies. Scambos reiterated this assessment in a recent email, maintaining that his perspective has not changed much.

'The fundamental truth, and its inconvenience, still stands,' writes Scambos, a senior research scientist. 'In fact, it is more evident than ever that greenhouse gases are a primary driver of the climate warming we are observing.'

When the film debuted, there were discussions about a supposed hiatus in global warming, which a recent study has determined was due to measurement errors. However, Scambos emphasizes that the planet's warming trend persists. 'The year 2016, for instance, will have a global average temperature nearly 1 full degree C (just under 2 degrees F) higher than the period from 1951-1980. This is half of the temperature rise target established by the Paris Agreement on climate change.'

As Gore's film predicted, carbon dioxide levels have continued to climb. 'Carbon dioxide has now surpassed the 400 parts-per-million threshold,' Scambos notes. 'For the 6,000 years leading up to around 1900, the concentration rarely exceeded 280 ppm.'

Since 2006, Scambos says, our understanding of climate change has advanced, but the new data doesn't invalidate the core message of the film. 'What we've learned are finer details—such as how warm ocean water is influencing the retreat of sea ice and ice sheets, how the flow speeds and thicknesses of glaciers and ice sheets are changing, and the historical context of the ice ages, including the causes and timing of abrupt climate shifts.'

He also points out that 'Arctic sea ice continues to shrink in both extent and thickness, breaking new summer minimum records in 2007 and 2012, and showing a significant reduction this fall compared to the expected growth rate. Greenland is losing mass at a rate of 200 billion tons per year, Antarctica is shedding mass at half that rate, and the world's mountain glaciers are shrinking.'

That isn't to say 'An Inconvenient Truth' got everything correct. Scambos notes that, in an attempt to spur public action, the film did amplify some alarming scenarios. For instance, portraying much of Florida sinking beneath rising seas was 'a bit over-the-top.' 'This will take centuries, and once again, the model used was the most pessimistic,' he explains.

A recent article from Science News points out some other aspects of the film that may be subject to revision by scientists today. For example, the film used disturbing footage from Hurricane Katrina in 2005 and implied that climate change was directly responsible for the increasing frequency and severity of hurricanes. However, since then, hurricane frequency has declined, and the intensity of storms hasn't increased significantly.

Gore also predicted in the film that 'within a decade, there will be no more snows of Kilimanjaro.' University of Massachusetts scientist Doug Hardy, a co-author of a 2002 Science article that formed the basis of Gore's statement, points out that Gore was stretching the truth a bit. Research shows that snow cover on the mountain has come and gone seasonally for over a century and a half. Nevertheless, the broader point—that the mountain's glaciers are disappearing rapidly—is mostly accurate.

'Based on my observations from 19 ascents of the mountain, I believe that some major glaciers will indeed be gone by 2020,' Hardy writes in an email. 'These include the Furtwängler Glacier, the only one entirely within the crater, and most of the glaciers on the mountain's south side, which are the primary ones visible to climbers on the trail.'

'No, all the ice on Kilimanjaro won't vanish by then,' Hardy says. 'Some areas of the Northern Icefield could still be more than 40 meters [131.2 feet] thick in 2020, and ice may remain for 3-4 more decades. Nonetheless, all glaciers on the mountain continue to shrink—reducing in size and thinning. Aesthetically, the mountain will be quite different without the glaciers.'