As Hurricane Florence surges ashore in the Carolinas, it’s worth casting our minds back a dozen years to An Inconvenient Truth. Al Gore and his documentary crew attempted to mobilize the world around the imminent and pressing challenge of global warming then and since. His messages included the threat of increased severity and frequency of Atlantic hurricanes, something which is looking more and more prescient over the past few years of unusual storms.
Hurricane Florence is behaving in an unprecedented way. It started further north than average and then beelined almost straight west instead of curving further north. It’s predicted to stall on the coast and drift very slowly southward. Like Hurricane Harvey over Houston in 2017, it’s going to stay roughly in one place and drop enormous volumes of rain, amounts never experienced in the history of the region.
And Hurricane Florence is just the most impactful hurricane, so far, of an unusual season. It’s rare to have Atlantic and Pacific hurricanes churning simultaneously, yet that’s what we are seeing. Hawaii was threatened by Hurricane Lane, which is also rare. There are multiple tropical depressions and smaller hurricanes being tracked. This was supposed to be a lighter-than-usual season due to El Nino, but due to climate change, lighter doesn’t mean what it used to.
In context of this, it’s worth revisiting the predictions made in Al Gore’s film and assess their quality. And it’s worth going to the source and actually looking at what was actually said, not the straw men that have been erected since 2006 by skeptics.
Prediction: Could fuel worse and more Atlantic hurricanes. No specific timeframe was predicted.
Result: Worse already, but not more so far in the Atlantic. While Hurricane Florence following Irma and Harvey so closely feels significant, statistically it’s not yet possible to assert an increase in frequency.
Severity of hurricanes is another topic. Accumulated cyclonic energy (ACE) is a useful measure adopted by the USA and India. It measures the total wind energy of a cyclone and is updated every six hours to determine the total destructive energy in the system from beginning to end. This accommodates short and long durations as well as total wind speeds. While better than the current Saffir-Simpson scale, it’s still inadequate as it doesn’t measure the actual mass of air in motion which is correlated to size and storms appear to be getting larger in diameter as well. As an example, Superstorm Sandy wasn’t even a hurricane when it came ashore, but its huge size made it devastating.
The average accumulated cyclonic energy (ACE) of 1981 to 2010 was 63 to 103 units. As of September 12th, 2018, we’re already at 62 units and predictions are for an ACE total for the season above 103 units. 2017 was 225 ACE units with Irma alone having a cyclonic energy of 64.9 units by itself, the second highest hurricane on record. It’s worth pointing out that the trend line in the ACE graph of seasons from 1851 to 2017 is curving upwards. It’s not a linear advancement of energy, its an accelerating advancement of energy. Note that the graph and curve fitting are from public data and is not from a peer-reviewed report; it is indicative not definitive.
Asia, on the other hand, has seen both increased severity and frequency of typhoons making landfall over the past 40 years.
Ocean circulation: 80%
Prediction: Could shut down Gulf Stream conveyor belt bringing warm water to northern Europe. No specific timeframe predicted.
Result: Slowing, but not stopped. The scientific understanding of the Great Conveyor circulation model has been refined and is understand to be more complex. A study since has dropped tagged and trackable items into the conveyor and they have branched off in multiple unexpected directions. Once again, chaos rules in the details, which is not a reason to doubt the science over all. The documentary was accurate based on what was understood at the time but science has moved on. There is less likelihood of a significant icing for Europe with the new scientific understanding.
Prediction: Climate change would exacerbate drought contributing to regional conflict. No specific timeframe was predicted.
Result: Syrian conflict caused in part by climate change exacerbated drought. Studies looked at the underlying causes of drought in the region and found climate change had made it worse. That drought brought grazers and growers into conflict and caused migration to cities without resources to support the influx. Economic conflict and disruption contributed to the Syrian civil war. The war led to large-scale refugee flows, with millions flowing into neighboring regions and between 500,000 and a million entering Europe, leading to the rise of right-wing, anti-immigration parties.
Arctic ice: 100%
Prediction: The Arctic could see its first sea ice–free summers in the next 50 to 70 years.
Result: Massive ice loss in summer in Arctic has been observed. This summer has seen ice breaking up in areas where it hasn’t broken up since at least the 1970s when satellite studies began, and presumably much earlier. There is a very high probability of 100% summer ice loss by 2052 according to the latest studies, well within Gore’s timeframe.
Antarctic ice: 90%
Prediction: Warming waters will be melting the Antarctic ice sheet (ice on both land and floating on ocean). No specific timeframe predicted.
Result: Mixed in the short term. Major ice sheets have broken off Antarctica. The large majority of studies show reduced Antarctic ice mass, but one major and credibly structured study shows increased ice at present albeit with predictions of future loss by authors. There is serious cause for concern due to ocean-side ice dams holding back land glaciers. There is also some good news, in that the Antarctic bedrock, compressed by the ice cap, is rebounding much faster than expected which will reduce some of the undercutting effects. However, melting due to warming is still happening much faster than rebounding, so this is only somewhat dampening the impacts.
Sea level rise: 100%
Prediction: Melting ice and expanding seawater are raising global sea levels.
Result: Melting ice and expanding seawater are raising global sea levels and it’s accelerating. At the time of the documentary, sea level rise had been linear. As of IPCC 5, the extent of Greenland ice sheets melting was only beginning to be understood. The science has improved since 2006 and 2014 and it’s commonly understood that the curve of melting will be steeper than previously understood and and the degree of melting by 2100 will be higher. What’s poorly understood is that the median of 0.6 meters in IPCC 6 was the global average and that places closer to the equator will see — once again on average — higher degrees of sea level rise due to centripetal force from rotation of the Earth, a loss of gravitational pull due to polar ice caps and thermal expansion.
Extreme temperatures: 100%
Prediction: Warming temperatures will cause more frequent and more deadly heat waves.
Result: Warming temperatures have caused more frequent and more deadly heat waves in multiple parts of the world. And it’s not just direct heat. The threshold for deadly heat waves is based on temperature and humidity. The global warming kicker is that with every degree Fahrenheit in increased heat, there’s 4% more water vapor in the air. For every degree Celsius, it’s 7%. Wet bulb temperature, the point at which humans can’t shed heat due to a combination of temperature and humidity, is being reached more and more often globally, with threats to all outside work forces. It’s very difficult to grow crops if you can only tend them after dark.
An Inconvenient Truth was an A+ paper at the time, with the worst potential impacts both supported by the understood science and not ascribed to specific timeframes. It’s held up well and even with the advances in science, it’s still an A-quality product. If Gore were to release a V2.0, it would undoubtedly correct the places where the science has advanced, but it wouldn’t require much change.
Gore made some more specific statements about possible timeframes for Arctic ice-free summers in the years after the documentary was released, but not in the documentary itself. Most of the points that ‘skeptics’ attribute to Gore are not accurate attributions, but conflated or cherry-picked. As one example, in an interview he was pressed for an answer about a scenario with 1,000 ppm CO2 in the atmosphere and pointed out the window at a nearby highway, saying it would be under water. This was plucked from the interview as if it were a prediction about current conditions and timeframes and turned into an anti-Gore, anti-warming talking point. Always check the sources.
- Changing climate: 10 years after An Inconvenient Truth
- Hurricanes had already become worse due to global warming before 2017
- Hurricane Florence, Like Harvey & Sandy Before Her, Will Test Hurricane Wind Scale Accuracy
- The ‘extremely active’ 2017 hurricane season is finally over — here are the insane records it set
- Chaos theory does not invalidate or explain global warming
- After 10 Years, ‘An Inconvenient Truth’ Is Still Inconvenient
- An Inconvenient Truth Then and Now: What’s Changed for Our Climate Since 2006?
- Accumulated cyclone energy
- Is the ice sheet covering Antarctica shrinking or growing?
- Ice-sheet mass balance and climate change
- Greenland and Antarctic ice sheets, European Environmental Agency