Only the complete cessation of all human carbon emissions within this decade and removing carbon from the atmosphere will save us from immolation.
Fifty-five million years ago, the earth suffered a fever. Somehow, 12,000 billion tonnes of carbon escaped into the atmosphere — and global temperatures soared by 5-8 degrees Celsius over the next few thousand years. What caused this event is subject to debate by scientists, but a vast release of methane from the deep oceans or burning peat swamps and jungles in the tropics are favoured theories.
The key lesson is that it takes only a relatively small push for the earth to generate catastrophic shifts in heating or cooling on its own.
Underlying all the rhetoric and posturing, the genuine promises and the veiled insincerities at COP26 in Glasgow lies one enormous and utterly risky assumption: that humans can stop the climate machine from cooking the planet. Growing evidence suggests we may no longer be in control of our own fate.
Most people by now have heard of “tipping points” — where the earth system flips rapidly from one state to another, without the possibility of a return; where a small change in a system makes a big difference. In the end, humanity’s fate will most probably depend not on our own actions but on what happens with these nine key tipping points:
- West Antarctic ice sheet: this is currently melting three times faster than it was in the 1990s. If the sheet goes, it will lift the oceans by 3.3 metres and add to global warming through the loss of ice that reflects the earth’s excess heat into space.
- Greenland ice sheet: this is now on track to disintegrate completely, raising sea levels by 7.7 metres and adding to global warming by the loss of its reflectance.
- Amazon dieback: the world’s largest rainforest is shrinking rapidly through human destruction and fire. Scientists believe that once 25 per cent is lost, the rest will rapidly convert to dry savannah and desert, changing the climate both locally and globally. From soaking up carbon, the Amazon has now begun pouring out a billion tonnes a year, adding to human-caused global warming.
- Boreal forest dieback: the northern forests hold one third of all terrestrial carbon, but they are now shrinking rapidly due to logging, fire and climate change, removing one of the key “brakes” on global warming. Like the Amazon, they will begin to emit billions of tonnes of carbon instead of absorbing it.
- Melting tundra: frozen methane in tundra and on the seabed is one of the largest carbon banks on the planet, totalling an estimated 3-5 trillion tonnes. The melting of the tundra could yield 240 billion tonnes of carbon, and the seabed far more. Peat fires in former tundra will add to the carbon emitted. Neither process can be halted by human action.
- Monsoon shifts: these are expected to result in increasingly erratic weather with sharper droughts and larger and more frequent floods in India, south-east Asia, China and western Africa. So far flood intensity has increased by about a third since the mid-1990s.
- Ocean circulation changes: ocean currents are the earth’s main heat distribution system and their changes presage major climatic disruption over land. The Atlantic Gulf Stream is already showing signs of breaking down, with serious consequences for western Europe and eastern North America in the form of harsher winters and stronger storms. Similar concerns apply to the Southern Ocean current, the largest natural influence on global warming.
- Global wildfires: the number and intensity of fires in forests, tundra, peat swamps, grasslands and semi-arid regions is climbing rapidly. On any day there are between 10,000 and 30,000 blazes raging globally. As fire intensity grows, it will release vast amounts of new carbon into the atmosphere, accelerating global warming, and destroy the very systems that lock it up.
- Cloud changes: anxiety is growing over how the earth’s cloud cover will respond to global heating. As the planet warms, more water vapour enters the atmosphere and clouds form. In theory this should have a cooling effect. However, recent research indicates that in a hotter world clouds may actually thin out or disperse — admitting more heat.
There are numerous other tipping points and feedbacks, including the loss of the world’s corals, the destabilisation of the El Nino/Southern Oscillation, the spread of deserts and the loss of sea ice, which all add to the impacts of the major tipping points.
These tipping points reinforce one another, forming what scientists call a “cascade”, which will add another 1.5C or more to the 3-4C already unleashed by human activity. This will lead to the condition known as Hothouse Earth, in which much of the planet becomes basically unliveable for humans and large animals. Summer heatwave temperatures of 50, 60 and even 70 degrees will become common in the world’s hot regions such as the Middle East, sub-Saharan Africa, Australia, south-western US, the Gobi Desert in East Asia and Andean South America.
The reason for the urgency at COP26 is that this cascade of self-reinforcing, irreversible changes was once thought to set in once the earth warmed by plus 2 degrees. However, new observational science tells us that most of these effects are already under way at plus 1.2 and 1.5 degrees and are proceeding faster — some much faster — than expected. And there is little we can do about any of them. The earth is now warming itself.
Humans lit the match. Our home is afire. The dwindling possibility of saving ourselves from immolation requires not only a complete cessation of all human carbon emissions within the current decade, but also heroic measures to remove carbon from the atmosphere, such as replanting half the world with trees. Even then there must be serious doubt on whether tinkering with the intricate machinery of climate will yield anything other than fresh, unanticipated disasters.
It is time to put aside the juvenile nationalistic chest-thumping and disputation, and for all peoples to throw all their energies into a human survival strategy — recognising even then that only some of us may be saved.