“That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. This distant image of our tiny world underscores our responsibility to deal more kindly with one another, and to preserve and cherish the only home we’ve ever known.” – Carl Sagan. Image@freepik
How climate works
A ball in space
Our planet is a tiny ball flying around the sun at 67,000 mph and spinning at 1,000 mph. Its atmosphere is a mixture of gases that enable life to exist. The earth is roughly 8,000 miles in diameter, but from the surface to outer space is only around 60 miles, so the atmosphere is as thin as the skin on our bodies.
How atmosphere began
In Earth’s early days primitive bacteria emitted gases that enriched the atmosphere enabling more complex bacteria to evolve. The earliest bacteria did not even breathe oxygen. Later in evolution, two bacteria cooperated to create a way to process oxygen, and they are still active today in the mitochondria of human cells.
One gas after another
As plankton, plants and animals evolved, they kept adding gases that enabled new species to live, including the gas which causes water vapour to form into clouds, leading to rain and paving the way for life on land. The delicate balance of gases in our atmosphere is maintained by an extremely sophisticated web of life.
Keeping cool
As with all stars, our Sun’s heat has increased by 25% over the last four billion years, yet Earth has maintained a steady temperature suitable for life. In this way it is similar way to the human body. The body contains around a trillion non-human bacteria that make up 99% of our cells, and the whole system works together to maintain a steady temperature whether in the tropics or the arctic, at plus or minus 40 degrees celsius. An increase of more than two degrees is a fever and can be life-threatening. In a similar way, Earth is made up of trillions of life-forms that operate together as a one large self-regulating system that maintains a steady temperature. When the sun was cooler life on Earth was kept warm by a blanket of CO2 in the atmosphere, but as the sun warmed the primary activity of Earth’s systems has been reducing atmospheric CO2 in order to keep cool. An increase of two degrees threatens the whole system.
How high is too high?
Over the last million years, atmospheric CO2 varied between 100 and 300 parts per million. High levels of CO2 corresponded with heat ages and low levels with ice ages. But since the industrial revolution CO2 levels have risen far higher, reaching 420 parts per million in 2023. In the same year, Earth’s average temperature reached 1.46 degrees above pre-industrial levels. Climate scientists say we need to stay below 1.5 degrees of global heating to avoid catastrophic climate change.
Tipping points and feedback loops
As temperatures go up we reach tipping points where the increases accelerate due to feedback loops. One of these is at the North Pole. White ice reflects the sun’s heat straight back into space but as the ice melts more incoming sunlight is absorbed by the dark ocean, warming the sea and melting the ice faster. Another example is the Arctic ‘permafrost’ that covers many millions of square miles. As temperatures go up this frost is starting to melt. Below it are peaty soils containing masses of organic matter which releases CO2 when it comes into contact with the air. As it decomposes it also produces methane, a powerful greenhouse gas.
Playing our part
The scientist James Lovelock described this as the Earth going into a morbid fever. To re-stabilise the climate we need to halve CO2 emissions by 2030, and reduce them to net zero by 2050. We also need to regenerate our soils, forests, and ecosystems so they can absorb approximately one trillion tonnes of excess CO2 that is already in the atmosphere. These might sound like huge tasks beyond our reach as individuals, but happily this is not the case. The activities that generate CO2 emissions are all done to produce the products and services we use in our daily lives. There are low-carbon alternatives for all of these products, which gives us the power of choice. This means that every one of us can play our part, indeed has to play our part, to achieve climate stability.
So, here’s to restoring the life support systems on Planet Earth, and to having a more enjoyable life at the same time.
Written by Mukti Mitchell