These days, the news is increasingly full of events linked to climate change: widespread forest fires, stronger hurricanes, droughts and floods. These represent calamities for the areas in which they occur; yet they could well be dwarfed by a much larger nightmare scenario that may well be a lot closer to reality than people realize.
On August 5, a study published in the prestigious journal Nature Climate Change made a few quiet waves in some elements of the media. Frankly, it should have been accorded banner headlines everywhere. The author, a German scientist named Niklas Boers, analyzed data from the North Atlantic Ocean over the past 150 years and concluded that what’s known as the Atlantic Meridional Overturning Circulation has shown “an almost complete loss of stability”, and could well be close to a collapse.
Also known as the “North Atlantic conveyer”, this major oceanographic feature is the pump that keeps Europe and other parts of the Northern Hemisphere warm. It takes warm, salty tropical water and circulates it via the Gulf Stream to higher latitudes, where the water cools and sinks — and the sinking drives the return circulation back south. To say that the conveyer moderates the climate is a huge understatement — it’s a significant reason behind why the world is no longer suffering through an ice age.
By the way, it’s worth noting that the period in which we live is one of several so-called “interglacials.” Our planet has alternated between long ice ages and shorter interglacial periods for the past 2.6 million years. These changes occur about every 100,000 years, with 90% of that time being an ice age rather than the much shorter and much more comfortable interglacials. They’re related to changes in the amount of heat the Earth receives because of fluctuations in its orbit, but the resulting climate shifts are significantly reinforced by other factors, including oceanic circulation patterns.
The problem is not just that the Atlantic is becoming warmer overall; it’s that the rising temperatures are melting glacial ice at a rate faster than was previously predicted by even the most pessimistic climate models. That melt — notably from the vast Greenland ice sheet — pumps huge quantities of fresh water into the ocean, lowering the salinity and density of the water. If this continues — and there is every indication that it will — then eventually the water that drives the southward circulation will fail to sink, and the conveyer will slow down or even turn off. The new study shows that the flow is already slowing down significantly.
You might have seen the 2004 movie The Day After Tomorrow, which had the Northern Hemisphere entering a new ice age because of exactly this scenario. In the movie, the change happened almost overnight, which is obviously not based on reality. However, ice cores from Greenland show that previous changes in the North Atlantic conveyer had massive climatic consequences over a period that in some cases may have been as short as a single decade.
So, ironically and paradoxically, global warming could actually catapult the Earth into a new ice age. At the very least, failure of the Atlantic conveyer would massively affect climate patterns from the Sahara to the Antarctic, from the Amazon to the Arctic. Northerly areas would become much colder, while those to the south would dry out.
Unfortunately, many of the often-vocal climate skeptics are political leaders who dictate policy, and they continue to promulgate doubts and misinformation about the reality of global warming, despite the fact that there is not a single bona fide climate scientist who denies it.
Inevitably, the politicians occasionally trot out someone with supposed “expertise” to support their position; but then you can always find some idiot with a Ph.D. who’s suitably deluded. I always give this analogy: if you took your car to 10,000 mechanics and all but one of them said your problem was X, and one said it wasn’t, who would you believe? That’s pretty much the situation with regard to the scientific consensus about climate change.
Our planet’s climate system is exceedingly complex, yet deniers always try to pretend it’s simple. Every time there’s a major winter cold snap, some conservative politician will inevitably sarcastically tweet “Gee, we could really do with some global warming now, huh?” They never bother to ask whether periods of intense cold could actually be caused by a warming climate; in actual fact, this is just what happens — warmer air changes Arctic circulation and often results in the frigid polar vortex being shifted farther south than it usually is.
A common retort from such people is that the warming trend is “just natural variation.” And indeed it’s true that past variations in climate, such as those causing previous ice ages, were entirely natural. But there is no doubt among scientists that the warming which the planet is currently experiencing is caused by the human-related release of greenhouse gases since the Industrial Revolution. Indeed, right after the paper on the Atlantic conveyer was published, the Intergovernmental Panel on Climate Change released a report which reaffirmed this fact, and gave dire warnings for the consequences of continuing to ignore a warming Earth.
Irrespective of whether people accept or deny the cause, climate change is real — and it doesn’t care what you or I think. Even without the shutdown on the Atlantic conveyer, increasing temperatures will eventually wreak such havoc on large areas of the planet that what we’re seeing today will seem trivial in comparison. Rising sea levels and desertification of agricultural areas have the potential to create refugee crises on a vast scale, and the damage caused by increasing wildfires, hurricanes and other local disasters will stress economies and stir additional social and political unrest. Unfortunately, autocrats thrive in conditions of such instability.
I’d trot out the usual mantra about the world needing to get together to take urgent action to reduce the impacts of global warming, but humanity won’t. Unfortunately, humans have a very long history of failing to take action about a problem — and indeed to deny its existence — until it’s staring them in the face. There will be attempts in some quarters to ameliorate the decline, but there are too many corporations and politicians who, for reasons of either ideology or profit, will continue to obstruct meaningful action. So our species is just going to have to deal with the consequences.
I don’t envy my four-year-old grandson as he grows up into that future. And if the North Atlantic conveyer does reach a tipping point, then he and everyone else will be fated to live through some truly dark and cataclysmic times.
Phil Clapham is a retired whale biologist who lives on Maury Island.