Melting ice caps, potent carbon emissions, and changing forests – a new report suggests climate catastrophe is already here and ‘active’
We were told we had 12 years to avert climate catastrophe, but a new report from a team of international climate scientists suggests many of the pivotal tipping points may already be here.
A report in Nature, co-authored by seven climate scientists, suggests nine of the planet’s irreversible climate tipping points may be upon us already. These include the loss of rainforests, thawing of arctic ice, melting ice sheets and the destruction of coral reefs. With over half of the climate tipping points which were first identified a decade ago now “active”, according to researchers, these changes could collectively trigger a global tipping point that would spell an existential threat to humanity.
WHAT ACTUALLY IS A TIPPING POINT?
Tipping points are the moments where climate-change crosses the threshold of incremental change and triggers feedback loops that accelerate out of our control. Think of a chain of dominoes cascading in a hundred different directions. If you can stop the first domino falling, you might be able to stop them all. But once the reaction has started, you’re going to have a hard time controlling the mess on your floor.
Scientists believe the greatest threats to the climate are the current dangers posed to the Arctic sea-ice and the Greenland ice sheet, both of which may already be upon us. Ice sheets vary in size depending on the season, but for several decades now the size of ice sheets at their annual maximum has been decreasing. Parts of the West Antarctic ice-sheet appear to have already passed a ‘grounding line’, melting at an alarming and irreversible rate. If the rest of the ice-sheet follows suit we can expect sea-level rise on an unprecedented scale. Low-lying cities like Venice and Amsterdam will be permanently underwater, and a large numbers of cities including London and Shanghai will be at risk of annual flooding.
The human impact will be vast. Some predictions expect 200m climate refugees by 2050. But the economic impact will also be huge. The Thames Barrier cost £534m to construct and millions each year on top to keep the river at bay. Sheffield spent £21m on its flood defences, only for shoppers to be stranded in a Primark when the city was hit by “biblical” flooding last month.
200 species of plants and animals are already going extinct every single day. This number will only grow as tropical and boreal forests continue to be cut back. Forest fires and droughts have already doubled since 1980, turning carbon sinks (net absorbers atmospheric carbon) into carbon sources (the opposite). The Amazon rainforest, often called the world’s lungs, made news earlier this year after record-breaking forest fires. Along with the Amazon, the reduction of North American Boral forests is cited as a tipping point past which the climate may be irretrievable.
Permafrost is different to melting ice sheets. In Alaska, methane stored under permafrost beds has a potent effect on the atmosphere when released. Not dissimilar to the Amazon and Boreal forests, permafrost is what’s called a “carbon reservoir”, containing vital quantities of greenhouse gases from the atmosphere and regulating the planet’s temperature. When melted, the permafrost becomes a source of greenhouse gases.
Lenton and his co-authors warn that once Alaskan permafrost thaws beyond a certain level, there may be no coming back.
THE CORAL REEFS
The combination of warming, ocean acidification and pollution has destroyed vast ecosystems already. 99 percent of tropical coral reefs are expected to be lost if global warming reaches 2c above preindustrial levels. Some models predict at current rates that could be as soon as the middle of the century. Already coral reefs have died on a large scale. Along with the coral reefs, we can wave goodbye to entire ecosystems that depend on the corals for food and homes, and the people who depend on them for their livelihood.
The Atlantic Meridional Overtuning Circulation (AMOC) is the process by which ocean currents distribute global heat. Since the mid-twentieth century, the efficacy of this process has seen a 15 percent slowdown, thought to be related to Arctic sea-ice loss and Greenland melting.
This combination could destabilise monsoons in African and East Asia and trigger droughts in the Sahel and the Amazon.
SO WHAT ELSE?
None of the predicted tipping points exist in isolation. One of the biggest fears of passing a tipping point is climate-scientists predict one tipping point has a good chance of triggering several others, leading to a situation of chaotic unpredictability.
Atmospheric CO2 is already at levels last seen around four million years ago, and that record isn’t showing sign of slowing down yet.
Lenton and colleagues come to a simple conclusion:
“We argue that the intervention time left to prevent tipping could already have shrunk towards zero, whereas the reaction time to achieve net zero emissions is 30 years at best. Hence we might already have lost control of whether tipping happens. A saving grace is that the rate at which damage accumulates from tipping — and hence the risk posed — could still be under our control to some extent.”
“The stability and resilience of our planet is in peril. International action — not just words — must reflect this.”
So get out there and strike, engage with organisations and projects working for climate action, and rally your political representatives to send climate change to the top of their agenda.