Could the Earth undergo sudden, rather than gradual, climate change? A recent report in a prestigious science journal assesses the likelihood and concludes: yes, it could.

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In my last post, I discussed my increasing conviction that we’re heading for a sudden, catastrophic climatic event. By “sudden”, I mean just that: not a gradual change over centuries or decades — something to which we might, if we’re lucky, be able to adapt — but an event that will overwhelm us over a matter of a few years or even a single year or season. This is not something that’s often discussed (unless you’re a follower of Whitley Strieber’s Superstorm theory); climate change, while generally accepted these days as being real and clearly very dangerous, is usually discussed in terms of it being a gradual process.

Now a research paper published in the Proceedings of the National Academy of Sciences journal suggests that many of Earth’s climate systems will undergo a series of sudden shifts this century as a result of human-induced climate change.

While not specifically mentioning superstorms, the report’s authors highlight several areas of concern, some of which are linked to the conditions required to set off a chain of events that could lead to a superstorm. Professor Tim Lenton from the University of East Anglia, the lead researcher on the study, told the BBC: “Our findings suggest that a variety of tipping elements could reach their critical point within this century under human-induced climate change. The greatest threats are tipping of the Arctic sea-ice and the Greenland ice sheet, and at least five other elements could surprise us by exhibiting a nearby tipping point.”

A “tipping point” is a point beyond which, once a process has started, it will not stop, or reverse, but continue — and most likely accelerate in pace — until the imbalance of energy driving the process reaches a new state of equilibrium. These are the elements they’ve ranked in their order of importance, and the time they would take to undergo a major transition once their tipping points are crossed:

Melting of Arctic sea-ice (about 10 years)
Decay of the Greenland ice sheet (about 300 years)
Collapse of the West Antarctic ice sheet (about 300 years)
Collapse of the Atlantic thermohaline circulation (including the Gulf Stream) (about 100 years)
Increase in the El Nino Southern Oscillation (about 100 years)
Collapse of the Indian summer monsoon (about 1 year)
Greening of the Sahara/Sahel and disruption of the West African monsoon (about 10 years)
Dieback of the Amazon rainforest (about 50 years)
Dieback of the Boreal Forest (about 50 years)

Apart from the collapse of the Indian monsoon season, there’s no other mention of climatic collapse within a single year, or a single season — but still, considering how many people on the Indian sub-continent rely on the annual monsoon, that’s reason enough for the world to be concerned. Usually occurring from June through to September, some areas of the sub-continent receive up to 10,000mm of precipitation during the south-west summer monsoon — that’s around 393 inches, or an incredible 33 feet of rain. There are other branches of this monsoon too: there’s the Arabian Sea Branch and the Bay of Bengal Branch and, after September, the Retreating Monsoon also provides further rainfall. A sustained collapse of the Indian monsoon season would be a catastrophe of unimaginable proportions that would threaten many, many millions of lives throughout some of the world’s poorest and most densely-packed countries.

The annual melting of the Arctic sea ice is something I covered in my post The Maya And The Arctic Meltdown — where scientists confirmed that the pace of the melt is such that Arctic waters could be ice-free each summer (with ice returning each winter) by 2012, confirming the PNAS research team’s findings. This event is one of the indicators that conditions conducive to superstorm formation could be intensifying.

Another superstorm formation indicator, the collapse of the Gulf Stream, part of the Thermohaline Circulation, was covered in Superstorm Authors Vindicated — where a previous collapse of the Gulf Stream 8,000 years ago, caused by a massive and sudden influx of fresh water into the north Atlantic from the north American continent, shut down the Gulf Stream within a decade or so and caused a drop in the region’s temperature of about 8°C. The Thermohaline Circulation, of which the Gulf Stream is an integral part, is a worldwide oceanic circulation pattern and, as such, it may well be that it would take 100 years to shut down. Research suggests that it has completely collapsed in the past, causing oceanic anoxic events (lack of oxygen in the water) which in turn led to global mass extinction events. My immediate concern, however, is that the Gulf Stream section of the circulation could be disrupted far more quickly by a localised influx of fresh water from the Arctic meltdown. This could cause a sudden and dramatic lowering of temperature in the northern hemisphere. Many years of freezing conditions could follow — made worse still by a superstorm, triggered as the energy imbalance seeks to redistribute itself.

The researchers warn that these systems that influence the Earth’s weather patterns could begin to collapse suddenly if there’s even a slight increase in global temperatures. They also argue that society should not be lulled into a false sense of security by the idea that climate change will be a gradual process. On a more positive note, they demonstrate how, in principle, early warning systems could be established using real-time monitoring and modelling to detect the proximity of certain tipping points.

Such a system of monitoring will require considerable financial investment from governments and other agencies, as well as time to set up and put in place. It’s to be hoped they don’t dither for too long, otherwise the opportunity for adaptation will be lost and, without sufficient warning, we might find ourselves overwhelmed by catastrophic events.

Read my Climate Change posts in chronological order by using the Climate Change Log.

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