REUTERS/Bjorn Sigurdson/Scanpix

Former U.S. Vice President Al Gore delivers his acceptance speech for the Nobel Peace Prize during a ceremony in the City Hall in Oslo December 10, 2007.

Dec. 10, 2007 | Your Majesties, Your Royal Highnesses, honorable members of the Norwegian Nobel Committee, Excellencies, ladies and gentlemen, I have a purpose here today. It is a purpose I have tried to serve for many years. I have prayed that God would show me a way to accomplish it. Sometimes without warning the future knocks on our door with a precious and painful vision of what might be. One hundred and 19 years ago, a wealthy inventor read his own obituary, mistakenly published years before his death. Wrongly believing the inventor had just died, a newspaper printed a harsh judgment of his life's work, unfairly labeling him the merchant of death because of his invention, dynamite. Shaken by this condemnation, the inventor made a fateful choice to serve the cause of peace. Seven years later, Alfred Nobel created this prize and the others that bear his name. Seven years ago tomorrow, I read my own political obituary in a judgment that seemed to me harsh and mistaken, if not premature. But that unwelcome verdict also brought a precious, if painful gift: an opportunity to search for fresh, new ways to serve my purpose. Unexpectedly, that quest has brought me here. Even though I fear my words cannot match this moment, I pray that what I'm feeling in my heart will be communicated clearly enough that those who hear me will say, "We must act." The distinguished scientists with whom it is the greatest honor of my life to share this award have laid before us a choice between two different futures, a choice that to my ears echoes the words of an ancient prophet: Life or death, blessings or curses, therefore choose life, that both thou and thy seed may live. We, the human species, are confronting a planetary emergency, a threat to the survival of our civilization that is gathering ominous and destructive potential, even as we gather here. But there is hopeful news, as well. We have the ability to solve this crisis and avoid the worst, though not all, of its consequences, if we act boldly, decisively and quickly.

However, despite a growing number of honorable exceptions, too many of the world's leaders are still best described in the words Winston Churchill applied to those who ignored Adolf Hitler's threat, and I quote: "They go on in strange paradox, decided only to be undecided, resolved to be irresolute, adamant for drift, solid for fluidity, all powerful to be impotent." So today we dumped another 70 million tons of global warming pollution into the thin shell of atmosphere surrounding our planet, as if it were an open sewer. And tomorrow we will dump a slightly larger amount, with the cumulative concentrations now trapping more and more heat from the sun. As a result, the Earth has a fever, and the fever is rising. The experts have told us it is not a passing affliction that will heal by itself. We asked for a second opinion -- and a third -- and a fourth -- and the consistent conclusion, restated with increasing distress, is that something basic is wrong. We are what is wrong, and we must make it right.

Last September 21st, as the Northern Hemisphere tilted away from the sun, scientists reported with unprecedented alarm that the north polar icecap is, in their words, falling off a cliff. One study estimated that it could be completely gone during summer in less than 22 years. Another new study, to be presented by U.S. Navy researchers later this week, warns it could happen in as little as seven years -- seven years from now. In the last few months, it has been harder and harder to misinterpret the signs that our world is spinning out of kilter. Major cities in North and South America, Asia and Australia are nearly out of water due to massive droughts and melting glaciers. Desperate farmers are losing their livelihoods. Peoples in the frozen Arctic and on low-lying Pacific islands are planning evacuations of places they have long called home. Unprecedented wildfires have forced a half a million people from their homes in one country and caused a national emergency that almost brought down the government in another.

Climate refugees have migrated into areas already inhabited by people with different cultures, religions and traditions, increasing the potential for conflict. Stronger storms in the Atlantic and the Pacific have threatened whole cities. Millions have been displaced by massive flooding in South Asia, Mexico and 18 countries in Africa. As temperature extremes have increased, tens of thousands have lost their lives. We are recklessly burning and clearing our forest and driving more and more species into extinction; the very web of life on which we depend is being ripped and frayed. We never intended to cause all this destruction, just as Alfred Nobel never intended that dynamite be used for waging war. He had hoped his invention would promote human progress. We shared that same worthy goal when we began burning massive quantities of coal, then oil and natural gas. Even in Nobel's time, there were a few warnings of the likely consequences. One of the very first winners of the prize in chemistry worried that, in his words, "We are evaporating our coal mines into the air." After performing 10,000 equations by hand, Svante Arrhenius calculated that the Earth's average temperature would increase by many degrees if we doubled the amount of CO2 in the atmosphere.

Seventy years later, my teacher, Roger Revelle and his colleague Dave Keeling began to precisely document the increasing CO2 levels day by day. But unlike most other forms of pollution, CO2 is invisible, tasteless and odorless, which has helped to keep the truth about what it is doing to our climate out of sight and out of mind. Moreover the catastrophe now threatening us is unprecedented, and we often confuse the unprecedented with the improbable.

We also find it hard to imagine making the massive changes that are now necessary to solve the crisis. And when large truths are genuinely inconvenient, whole society can, at least for a time, ignore them. Yet as George Orwell reminds us, sooner or later, a false belief bumps up against a solid reality, usually on a battlefield. In the years since this prize was first awarded, the entire relationship between human kind and the Earth has been radically transformed. And still we have remained largely oblivious to the impact of our cumulative actions. Indeed without realizing it, we have begun to wage war on the Earth itself. Now we and the Earth's climate are locked in a relationship familiar to war planners: mutually assured destruction.

More that two decades ago, scientists calculated that nuclear war could throw much debris and smoke into the air, it would block life- giving sunlight from our atmosphere, causing a nuclear winter. Their eloquent warnings here in Oslo helped to galvanize the world's resolve to halt the nuclear arms race.

Now science is warning us that if we do not quickly reduce the global warming pollution that is trapping so much of the heat our planet normally radiates back out of the atmosphere, we're in danger of creating a permanent carbon summer.As the American poet Robert Frost wrote, "Some say the world will end in fire, some say in ice. Either," he notes, "would suffice." But neither need be our fate. It is time to make peace with the planet.

We must quickly mobilize our civilization with the urgency and resolve that has previously been see only when nations mobilized for war. These prior struggles for survival were won when leaders found words at the 11th hour that released a mighty surge of courage, hope and readiness to sacrifice for a protracted and mortal struggle. These were not comforting and misleading assurances that the threat was not real, not imminent, that it would afflict others but not ourselves, that ordinary lives might be lived even in the presence of extraordinary threat, that providence could be trusted to do for us what we would not do for ourselves. No, these were calls to come to the defense of the common future. They were calls upon the courage, generosity and strength of entire peoples, citizens of every class and condition, who were ready to stand against the threat, once asked to do so. Our enemies in those times calculated that free people would not rise to the challenge. They were, of course, catastrophically wrong.