Debate over climate change produces plenty of excess carbon dioxide, particularly in the United States, where acceptance of the scientific consensus on global warming has been slow in coming. Then again, this is a nation that still questions the scientific consensus on evolution by natural selection. The debate came to a head this year, with the near-simultaneous release of An Inconvenient Truth, former Vice President Al Gore’s new book on climate change, and the film of the same name, chronicling Gore’s quest to break through the wall of disinformation, cynical skepticism, and indifference surrounding the newly christened ‘climate crisis.’ Our unlikely hero is armed only with his trusty, scene-stealing Apple laptop and a level of animation not seen in Gore since his gently self-mocking cameo appearances in Futurama.

Six years ago, a major motion picture about Al Gore’s globe-trotting climate change slideshow would have been a tepid Saturday Night Live sketch, not the third-highest grossing US documentary of all time. But the Al Gore writing a lean and occasionally lyrical prose in An Inconvenient Truth—a prose eschewing the purple tendencies of his earlier book, Earth in the Balance, for compact efficiency—is not the Al Gore of the 2000 election, nor the bearded mountain-man of his post-2000 years in the wilderness. This is an Al Gore inspired, an Al Gore possessed, an Al Gore haunted by his disappointment in 2000; and one determined to prevent a partisan decision of the US Supreme Court from sealing the fate of our planet.

I began reading An Inconvenient Truth on the second day of a cross-continental drive in North America, starting in the Virginia foothills of the Appalachians and ending in the shadow of the Rockies in Calgary, Alberta. Although I had just returned from Oxford—not from Vietnam, as Gore had—I felt a certain symmetry in reading of Gore’s 1971 cross-country voyage, and how it alerted him to the natural splendour and epic scope of the North American countryside. This moment of empathy is representative of a particular charm of Gore’s book, a tactic carried over very effectively to the film: the interleaving of straightforward explanations of the science of climate change with a more personal journey on Gore’s part from cub journalist to passionate environmentalist and statesman.

Although there is plenty of science to be explained, Gore’s book is ultimately visual and visceral, drawing much of its impact from the juxtaposition of short text with striking images. This is unsurprising, since the book is in some sense a crystallisation of the slideshow presentation (and hence intimately related to the movie, in which a majority of the short 100 minutes are spent showing segments from Gore’s lectures around the world). The design of the book itself is superb, with two-page spreads of an anthill-like Tokyo suburb underwriting the fact that ‘most of the increase (in population) is in cities,’ and composite maps of a nocturnal earth covered by fireflies—each a bustling metropolis of millions—driving home the point that we are become ‘a force of nature.’ If the book drags at all, it is in the occasional sections dominated by text. Not because Gore’s writing is uninspired, but because the reader has become so addicted to the rich interplay of text and image, to the delight of folding over a page to discover just how high carbon dioxide levels will be in forty five years.

The evidence marshalled by Gore for the reality and the magnitude of the climate crisis is generally unimpeachable, and has received the imprimatur of the world’s top climate scientists. He thoroughly anatomises how we know that the average temperature is increasing (while cautioning that this is a global, not a local trend), from the mundane example of Antarctic ice cores to dramatic pictures of calving glaciers and collapsing ice shelves. The latter are arresting even as static images in the book; they are terrifying in real time, a set-piece of the film. The connection between rising temperatures and increased carbon dioxide in the atmosphere is presented in an especially charming way. Gore shows a graph of the carbon dioxide levels and a graph of the global average temperature over thousands of years. With a wink, he nudges the audience towards the obvious connection with the story of his schoolyard chum who ‘discovered plate tectonics’ by noting that Africa and South America looked like they once ‘fit together.’ Gore is perhaps too quick to brush over the distinction between correlation and causation on this matter (a favourite talking point of climate skeptics) and should have emphasised that climate models require anthropogenic carbon dioxide increases in order to reproduce current warming trends.

Gore makes an equally compelling case that climate change is climate crisis. Besides the now famous pictures of Florida and Manhattan drowned under higher sea-levels, he presents vignettes of human misery in every imaginable extreme condition, from the biblical 2005 floods in Shangdong province, China, to the simultaneous, earth-cracking drought in nearby Anhui province. And of course there is Katrina, immortalised in a wordless spread and epitomised by a wretched body floating in flood-water, a reminder that even mighty America can be brought low by natural disaster. Gore has been criticised by some for alarmism, for exaggerating the catastrophic consequences of climate change. While the amount of land he claims for the sea falls on the high end of estimates, and the connection between extreme weather and global warming is more tenuous than other pieces of Gore’s case, this cry of scare-mongering does not hold much water. This is because of the highly nonlinear nature of the climate.

Nonlinearity really demands its own article. As Gore says in the book and movie, nonlinear is just ‘a fancy way the scientists have of saying that ... changes are not all gradual.’ More concretely, it means that the input and the output of a nonlinear system are not directly proportional. Nonlinear systems are difficult to treat with the analytic techniques of classical physics and differential equations, and consequently much work in nonlinear systems is done numerically, by simulating the system under constraints provided by available data. Thus climate scientists use computer simulations to try to understand and predict the behaviour of the global climate. But nonlinear systems are often highly chaotic—sensitively dependent on initial conditions. Hence simulations must be done with exquisite care for their results to have anything but qualitative value.

Nonetheless, one thing climate simulations do reveal is the ability of the earth’s delicate balance of ecosystem, weather, ocean currents, and so forth to lurch violently and rapidly from one apparently stable state to another. As skeptics are quick to point out, there are many feedback systems in the climate. Some are positive, and drive the system out of equilibrium. The tendency of sea-ice melt to encourage further melting is a pertinent examble; ocean water stores more heat than the highly reflective sea ice, and hence acts as a ‘heater’, helping to melt the remaining ice. Other feedback systems are negative, and tend to restore the system to an equilibrium condition. Many skeptics are essentially betting that unknown feedback mechanisms are negative, and will miraculously conspire to drive our perturbed climate back into equilibrium, rather than conspiring to drive it into some new equilibrium that is perhaps not so hospitable to our current way of life. This is an incredibly irresponsible assertion. These skeptics may be ignorant of the subtleties of nonlinear systems, as in the case of many so-called ‘experts’ lacking advanced degrees in climatology or allied quantitative disciplines. Or perhaps their expertise is clouded by bravely wishful thinking and the support of those shortsighted corporations that still view the science of climate change as a danger rather than an opportunity. Gore does a real service to the public in clarifying this subtle technical point.

Having read An Inconvenient Truth before seeing the film, I was given an opportunity to pay careful attention to the movie's subplot, which has less to do with the rise of earth’s temperatures than with the rise of Al Gore as a new hero of America’s anaemic left. As a performer and a teacher myself, I can only commend and envy Gore’s newfound ease in front of an audience: without seeming glib (he is terribly but not wearisomely earnest) Gore exudes enthusiasm for his topic, wearing the manner and the chic black suit of your favourite college professor like a second skin. Your favourite college professor is not necessarily your hippest, and Gore isn’t above the hammy joke (‘I used to be the next President of the United States’) or the academic equivalent of a Jackass stunt (launching himself into the air on a Genie lift to illustrate just how high carbon dioxide levels will be in 2050). But these quirks make Gore more rather than less endearing, and effectively prime us for sympathy when director Davis Guggenheim cuts to scenes of a determined Gore passing through airport security, or a troubled Gore painstakingly assembling Keynote slides for his next talk. In the latter shots Gore’s professorial intensity is exchanged for an almost prophetic air of burden. Miraculously, this creates actual dramatic tension in a documentary, tension that for this viewer boiled over into seething resentment during the bitter minute devoted to the 2000 election.

Viewers of An Inconvenient Truth cannot help but indulge in a game of ‘what if', perhaps unfairly pitting the born-again Gore of 2006 against the tremendously unpopular and beleagured President of the same year. The movie only gestures indirectly at such speculations, and Gore is generally delicate in his book regarding the current administration. He does not, however, spare the brimstone in indicting the White House’s contemtible and contemptuous attitude towards the truths of science (for example, the hiring of oil-company stooge Philip Cooney as chief of staff for the White House environment office). More cutting is Gore’s evisceration of the cynical campaign to sow doubt in the minds of voters regarding climate change. To illustrate the perfidy of these latter-day sophists, Gore points to an internal memo from a coalition of special interest groups pushing global warming skepticism. This memo states as the coalition’s objective to ‘reposition global warming as theory, rather than fact.’ The crass stink of Madison Avenue wafting off the memo recalls other famously malodourous public disinformation campaigns: the sulphrous reek of Big Tobacco’s timeless cancer coverup, and the barnyard tang of the more recent Intelligent Design circus. Gore has the anger of a zealot for the charlatan science of global warming skeptics. Indeed, one of Gore’s most endearing traits, apparent in the book but obvious in the film, is his tremendous respect for scientific truth. For every moment of Gore playing the professor is a moment where he becomes a boundlessly enthusiastic prize pupil. This is in sharp, tragic contrast to the hedging of President Bush, who is happy to be undecided about evolution in the face of all those facts as long as it is politically expedient to do so.

If An Inconvenient Truth stopped here—if it were satisfied with a relentless exposition of the science of global warming and a brutally frank dissection of the flimsy political manoeuvring intended to hide this threat from the public—it would be a timely, and necessary book. But it would be a book for our time, and Gore a man of this moment, not the figure of historical import many already conjure him to be. Indeed, the book probably would not have topped the New York Times best-seller list, nor would the film have broken box office records. In fact, it all might have been rather depressing.

What elevates the book, and the movie, is the way that Gore’s personal story and the story of climate change move in carefully orchestrated counterpoint to articulate a vision of hope and a challenge for the future. If Gore indulges in fear-mongering, it is not the cheap partisan tactic that promises a war that will not end against an enemy that cannot be defined. Gore defines the enemy—and it is us. He promises a war, but it is a war against the darker aspects of human nature, the selfish, shortsighted worldview that drives us to plunder now at the expense of our neighbors and our children. Gore’s battle will be fought in the halls of Congress, and in corporate boardrooms; but also in our voting booths, at our dinner tables, on our electricity bills. An Inconvenient Truth provides the explicit marching orders in great detail, particularly the book (the final seventeen ‘green pages’ of tips justify the purchase entirely). But it is the film that calls out most clearly the moral challenge—and offers up Gore as an example.

Gore is fond of pointing out that the Chinese logogram for ‘crisis’ consists of the characters for ‘danger’ and ‘opportunity.’ Gore has certainly lived this wisdom. With An Inconvenient Truth, he has taken the danger of the climate crisis and made it an opportunity to reinvent himself as the unshakable moral center of the Democratic Party. Let us hope that we heed Al Gore on climate change: ‘This is a moral issue.’ And let us hope that we can follow his example in making an opportunity of the climate crisis: an opportunity to reinvigorate the pragmatic and democratic traditions in both America and the wider world; an opportunity to recognise that ours is a small, fragile ark in the inky vastness of space. We have every obligation to defend it. Perhaps, as I did, you will begin by reading this book, seeing this movie; then replacing an incandescent bulb with a compact fluorescent light. Perhaps we will end, together, by saving the world.

Jacob Foster is a DPhil student in mathematical physics at Balliol College, Oxford, and a PhD student in complexity science at the University of Calgary. His current interests range from the mathematical properties of complex networks to the geometry of the Big Bang.