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Last week, an extremely sensitive instrument located in a metal hut at the top of Mauna Loa, a volcano in Hawaii, 21,000 meters high – recorded a terrifying human feat: thanks our growing dependence on the burning of carbon dioxide in the Earth's atmosphere has risen to 415 parts per million. This is the highest level since humans have lived on Earth. And this is further evidence (as if new evidence was needed) of our heart's determination to cook the planet we live on.
For the planet itself, 415 ppm is not a BFD. Over the past 4 billion years, it has been much higher. But for us humans, 415 is a very dangerous number. The last time the CO2 levels were at 415 ppm, about 3 million years ago, during the Pliocene period, there was a lot of life on Earth, but the Earth itself was a place radically different. Beech trees grew near the South Pole. There was no layer of Greenland ice and probably not any layer of ice from West Antarctica. The sea level was 50 or 60 feet (or more) higher.
This is the world we are creating for ourselves by pushing carbon dioxide levels to 415 ppm. At present, the oceans absorb a lot of atmospheric warming. But these oceans are like a big steering wheel and the heat will be radiated. This means, among other things, good bye the ice floe, hello diving in a condo in Miami.
One way to think about the levels of carbon dioxide in the atmosphere is to use a thermostat for the planet. As you will remember in the third year science class, carbon dioxide is exhaled by animals, including humans, and inhaled by plants. It is also released when plants and animals break down, during the eruption of volcanoes and, more importantly, when we burn fossil fuels. Last year, we released about 37 billion tons of carbon dioxide into the atmosphere by burning fossil fuels. The more coal, oil and gas we burn, the higher the number. Before the industrial revolution, the level of carbon dioxide in the atmosphere was 280 ppm. Sixty years ago, it was 315 ppm. In recent years, it is increasing by about 2 or 3 ppm per year.
This might not seem like a lot. However, carbon dioxide molecules are very effective at trapping heat in the atmosphere. Scientists have understood it very well since the 19th century. Carbon dioxide molecules are like prison guards in the Earth's atmosphere: they let in sunlight, but they do not let out the heat. Scientists discuss the effectiveness of carbon dioxide for global warming, but it is generally accepted that a doubling of 280 ppm carbon dioxide levels will warm the Earth's atmosphere. 2 to 3 degrees Celsius.
At present, at 415 ppm, the climate has already warmed by about one degree. And you do not have to be a scientist to see the impacts: glaciers are melting, sea levels are rising, forest fires are increasing, hurricanes and typhoons are intensifying. The changes are so fast and so profound that a recent United Kingdom report has suggested that more than a million species of animals and plants are in danger of extinction.
Measuring the level of carbon dioxide in the atmosphere is one of the most important and least valued scientific achievements of our time. Charles Keeling, a discrete geochemist from Scranton, Pennsylvania, wondered in the 1950s whether it would be useful to have a baseline measurement of carbon dioxide levels in the Earth's atmosphere. In the 1950s, the heat-trapping properties of CO2 were well understood, but the link between fossil fuel combustion and climate change was still tenuous. And measuring levels of carbon dioxide in the atmosphere was more complex than it seemed, largely because carbon dioxide is a trace gas, measured in parts per million, and that carbon dioxide levels vary with local conditions, depending on plant life and emissions. nearby power plants and other fossil fuel appliances.
In 1955, Keeling camped at Big Sur State Park in California, collecting air samples from flasks to measure their carbon dioxide content. Three years later, seeking even more clean air, he dragged his instruments to Mauna Loa in Hawaii and began taking action there.
Keeling quickly made two important discoveries. The first was that the Earth breathed. As the seasons change, the levels of carbon dioxide in the atmosphere oscillate slightly. He immediately realized that this was due to the seasonal growth of plants, especially trees. As trees grew and grew in the spring and summer, carbon dioxide levels decreased slightly. When trees lost their leaves in autumn and winter and the leaves began to decompose, carbon dioxide levels increased.
His second, more disturbing and consistent conclusion was that each year, the maximum level of carbon dioxide in the atmosphere was a little higher than the year before. And this increase, it was clear, was due to the burning of fossil fuels.
"It quickly became clear that its measured CO2 increase was proportional to fossil fuel emissions and that humans were at the origin of the change," said James E. Hansen, director of the Goddard Institute for the New York Times. Space Studies of NASA. "It has changed our outlook on the extent to which the Earth can absorb the human assault."
Sixty-one years have passed since Keeling took his first step on Mauna Loa (who died in 2005, his son, Ralph Keeling, a professor at the Scripps Institution of Oceanography, who operates the Mauna Loa Observatory, now taken over.), and data for these years can be mapped into what is now called the Keeling curve, which measures the annual growth of carbon dioxide levels in the atmosphere.
When you look at this curve, two things are obvious. First, it is a smooth ascending curve, without cuts, hollows or trays. Despite the decline in the cost of solar energy, despite all the climate change on the streets, despite forest fires, melting glaciers and increasing summer heat, it is clear that, by the only measure that really matters, we did less than zero. reduce levels of carbon dioxide in the atmosphere.
The second thing you notice is that not only does the curve continue to rise, but it increases faster than ever before.
Among other things, the Keeling Curve is a perfect record of the self-destructive impulse of Homosapiens. We have known for exactly 61 years that the burning of fossil fuels warms the Earth's atmosphere and instills the stability of our climate Goldilocks – the world neither too hot nor too cold that allowed humans to flourish in the 10,000 last years. – at risk. And we have not done anything about it. In this sense, the Keeling Curve can prove to be a film of civilization, a horrible story, told in scientific terms, of our destruction of life as we know it on Earth.
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