· 6 min read
One would expect the two to tango in Belem!
There are some very compelling reasons to justify it a centre-stage.
The Atlantic Meridional Overturning Circulation (AMOC) is part of a single "conveyor belt" of continuous water exchange that transports water throughout the world’s oceans. It is the main ocean current in the Atlantic, including at the surface and at great depths, that is driven by changes in weather, temperature, and salinity. The AMOC transports a staggering amount of energy. Like a million nuclear power plants. Its collapse would radically alter regional weather patterns, the water cycle, and the ability of every country to provide food for its inhabitants.
Let's jump over to The Day After Tomorrow - a 2004 American science fiction disaster film based on the 1999 book The Coming Global Superstorm by Art Bell and Whitley Strieber. The movie depicts catastrophic climatic effects following the disruption of the North Atlantic Ocean circulation, in which a series of extreme weather events usher in climate change and lead to a new ice age. As SciFi now threatens us in real - let's connect the dots between planetary boundaries, earth systems, tipping points, and domino effects.
Theatre Amazon
• For host Brazil, an altered Intertropical Convergence Zone (ITCZ) triggered by AMOC could cause the wet and dry seasons to flip to the opposite times of year.
Such shifts would force plants, insects, fungi, mammals, and the trees themselves to rapidly adapt or face mass die-offs. Not to mention the trees themselves, which, in addition to supporting an intricate ecosystem, absorb tons of carbon from the atmosphere. And the logging leading to over-heating thereby the tipping point facilitating an AMOC.
Deforestation exacerbates this by changing local evaporation and rainfall patterns, further altering water availability.
• Deforestation and the water cycle: Approximately 20% of the Amazon has been deforested, with another significant portion degraded.
Trees recycle water via evapotranspiration, maintaining the region's rainfall. Losses from deforestation reduce local and downwind rainfall—a “domino effect” of forest degradation.
• Risk of tipping points: Beyond critical thresholds scientists warn of irreversible transition to a savanna-like ecosystem.
Combined effects of warming, drying, and deforestation could put 10–47% of Amazon forests at risk of structural collapse by 2050.
Local tipping points are already observed; regions with degraded soils or deforestation are losing resilience faster, reducing the forest’s ability to recover after droughts or fires.
• Loss of carbon sink function: Healthy Amazon forests sequester massive amounts of carbon (currently over 120 billion tonnes) and regulate climate.
Widespread tree mortality could convert the Amazon from a carbon sink into a net carbon source, accelerating global warming.
• Biodiversity loss: As a home to 10% of the world’s known species, the loss of canopy and understory habitat would lead to mass extinction risks
• Human populations relying on the Amazon for water, food, and livelihoods could face severe impacts from drought, crop failure, and disease outbreaks
• Drying trends, extended dry seasons, and reduced rainfall from deforestation and climate warming are early warning signals
• Southern and southeastern regions of the Amazon are most susceptible to local diebacks, risking a domino effect for neighboring forest areas
The rest of the world
The system slow down headed to a full stop. How long could that take? The IPCC came out with a report that the AMOC was “very unlikely” to shut down before 2100. A false sense of relief ensued. Sibling scientists Peter and Susanne Ditlevsen, after two years of refining their approach and a thousand runs, hit a middle point - 2057. In 95 percent of the model’s simulations, the AMOC tipped sometime between 2025 and 2095. Aren't we precariously close?
Dr. Stefan Rahmstorf, an oceanographer and climatologist at Potsdam University, is a foremost expert on the subject. His paper ‘Is The Atlantic Overturning Circulation Approaching A Tipping Point?’ is another piece of scientific work that no one should ignore.
• Below the surface of the ocean, the invisible waterfalls near Iceland and Greenland would stall. Widespread die-off of marine life in all likelihood. Shutting off the current would also cause the ocean’s surface to smooth out. The flattened water level will be higher than it is now, which will mean almost a meter of sea level rise along the US northeast coast - in addition to the sea level rise from melting glaciers.
• Without the big heat delivery that softens its winters, Europe would end up with much more intense seasons, according to a 2022 report. A lot more snow. Much less rain.
• In the post-tipping decades, many European cities might end up colder by 5 to 15 degrees Celsius. In Bergen, Norway, the temperatures could drop 35 degrees Celsius. Sea ice in winter might extend all the way down to the southern UK. The summers, meanwhile, get hotter and drier.
• An AMOC shutdown would clobber the food system. The fraction of land suitable for growing wheat and maize - staple crops worldwide - would drop by roughly half. In an analysis of how an AMOC collapse would affect agriculture in the UK, the authors wrote there would be “a nearly complete cessation” of arable farming. Goodbye oats, barley, wheat. A massive irrigation project could salvage the land at a cost of roughly $1 billion a year, more than 10 times the yearly profit from the crops. Food prices would spike.
• Further north, in places like Norway and Sweden, food production would also plummet. Those countries would have to rely heavily on imports. But perhaps not from the usual sources.
• Ukraine, Poland, and Bulgaria - Europe’s breadbaskets - would also be dealing with less rain, colder weather, and severe losses of income from the crash of their agricultural industry.
• Research on these projections is scant, but some studies say that if the rain band moves south, then India, East Asia, and West Africa would lose much or all of their monsoon seasons. Two-thirds of Earth’s population depends on monsoon rain, in large part to grow their crops. These changes would happen over only a few growing seasons rather than over generations, giving little time to adapt.
• In the precarious Sahel region in Africa, subsistence farmers might find that sorghum, an essential, nutrient-rich cereal, becomes nearly impossible to grow. Tens of millions of people might need to migrate to survive.
• Australia might enjoy a little more rain and crank out a few more loaves of bread per year.
Imagine all these forces unleashing around the same time. What mitigation or adaptation measures would be possible in such circumstances? If the triple planetary crises have to be addressed, isn't this the time? Are we opting to look the other way as a gray rhino darts towards us?
Now is our opportunity “to make the tipping points move the other way, from breakdown to breakthrough” - borrowing from Oliver Bolton.
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