“Think of the climate change issue as a closet, and behind the door are lurking all kinds of monsters — and there’s a long list of them,” — Steve Pacala.
It has been said that Nature is a serial killer. Within her vast managerie of life, climate, and the physical world, there are many, many terrible processes that could mortally impact individuals, larger groups, entire species and even families of species. And if you were to look for the means by which Nature performs her worst violence, the mass extinction events, your eyes would almost immediately settle upon the uncomfortable issue of climate change, an issue all too relevant today.
Of twelve major mass extinction events identified in past geological epochs, ten were likely caused by climate change. Marked by layers of rocks almost entirely devoid of complex life, these periods in which Earth became little more than a tomb should serve as a stark warning against our own rapidly increasing insults to Earth’s climate. The very worst of these ‘tomb epochs,’ the Permain or ‘Great Dying’ in which 90 percent of all species went extinct was clearly caused by a series of worsening insults brought on by a terrible switch in climate brought on by a raging global warming nightmare. And though the Permian Extinction raged about 200 million years ago, it has some rather disturbing similarities to today. For one, it was an era in which a cold glacial period emerged into a far warmer period. And secondly, a large greenhouse gas emission source forced warming to drastically accelerate resulting in not one but three major extinction crises over the course of about 165,000 years. It was the worst of the worst of all tomb epochs and it was most likely set off by a massive chain of events brought on by very rapid warming.
Scattered across the wreckage of the Permian and these other tomb epochs are the foot prints of the three climate monsters from Pacala’s horde that we most definitely do not want to unleash. Monsters we are through our current actions and choices, even now, causing to stir.
Three to Keep Behind the Door
Human beings, through their carbon emissions, risk prodding the very worst monsters in Nature’s death brigade to awaken — the ones that set off previous mass extinction events through a combination of terrible weather, unleashing carbon stocks sequestered over millions of years, and, eventually, turning the ocean into an enormous killing machine. These three, worst of the worst, climate monsters which we most certainly want to keep behind Pacala’s door are: Heinrich Events, Rapid CO2 and Methane release, and Anoxic and Canfield Oceans. Though these three are identified here as separate catastrophic events, they are related in that they can set in motion a chain of self-reinforcing effects that may enhance the likelihood for the other events to occur. They also unleash a set of more minor but still terrible associated difficulties.
In this particular blog, I’ll explore the first and arguably mildest of these catastrophes — Heinrich Events.
Pulses of De-glaciation
As Earth moved through its far more milder, nature-caused, phases of glaciation and deglaciation, previous warm phases often resulted in sudden surges of ice burgs and melt flows from the Earth’s ice sheets. Large pulses during warm trends set off armadas of these maritime brutes which flooded the ocean, causing drastic consequences to weather and climate.
The ice bergs unleashed during these warming-induced pulse events were enormous floating collections of rock and ice. As they melted, the glaciers disgorged the rocks frozen in their bellies, leaving layers of pebbles littering the sea floor and creating a record of their passage. Hartmut Heinrich was the first to describe these events. So now they bear his name.
Greenland and West Antarctica: Gateways For the Heinrich Monsters
In the emergence from the last ice age, it is thought that sudden melt pulses from the vast but now entirely melted Laurentide ice sheet resulted in the majority of these events. Since only the ghost of this ice sheet remains in the form of a thin patina of frozen tundra over the Northern Hemisphere’s Arctic regions, there is no longer any risk for Heinrich melt and ice burg pulse events from this now ephemeral source.
But the great Greenland and West Antarctic ice sheets remain. Greenland is a vast store of ice. Nearly two miles high at its center, it contains enough ice to raise the world’s sea levels by 23 feet. West Antarctica is yet one more great pile of ice. In total, if the two were to melt together, they could contribute as much as 75 feet of sea level rise.
But these melt events, as we see the in the geological past, don’t happen neatly. The great glaciers sit mostly still for long, boring periods and then they surge in brief, catastrophic instances unleashing massive flows of both water and ice bergs. Heinrich Events.
Alone or together, Greenland and Antarctica bear more than enough ice to set off this particularly nasty brand of climate induced catastrophe.
The Human Forcing is Far More Brutal
In the past, a slower build up of heat set off by the warm phase of gradual orbital cycles eventually passed tipping points that led to rapid ice sheet disintegration and related melt-pulse Heinrich Events. Today, the human greenhouse gas forcing is far, far more powerful. At the last ice age’s end, a combined forcing of about 100 parts per million of additional CO2 and the steady but ever so slight forcing caused by the warmer orbital cycle was enough to set off these powerful events. Today, CO2 has risen by 120 ppm and continues to rise by 2-3 parts per million each year even as other rising greenhouse gasses, primarily methane, add an additional 28% to this strong and growing forcing.
It could easily be argued that the human forcing surpassed that of a natural forcing powerful enough to end an ice age sometime last century. But the ice age is already done and so we head into mostly uncharted territory only vaguely hinted at in the deep geological past. The current pace and path of increased forcing makes a bad situation worse as a CO2 rise to at least 480 ppm is predicted by mid-century. Business as usual end century estimates come in at the catastrophic level of 800 ppm or more of atmospheric CO2 with an unknown additional amount of methane and related greenhouse gasses.
The Greenland Ice Sheet is Starting to Slip
Unfortunately, it seems we may have already begun to let one Heinrich monster off its leash. For reports coming in over the past decade show that the vast two mile high Greenland ice sheet is starting to slip.
Under the current and ever-rising insult of the human climate change forcing, the Greenland ice sheet is sagging and deforming, filling with melt ponds and flows that flush through to its base, and, most ominously, monstrously grinding toward the ocean at an ever increasing pace. Research conducted by Arctic scientists shows that the ice sheet’s speed is increasing by a rate of about 2-3 percent per year. This speed of increase results in the disgorging of vast volumes of ice burgs and melt waters into the North Atlantic. An average of about 500 cubic kilometers of ice bergs and melt waters are now flowing into the ocean from Greenland alone. But with the pace of ice sheet melt and movement picking up, we are, sadly, only at the beginning of what appears to be a very risky situation.
Flotillas of Icebergs Riding a Tsunami Like Melt Pulse
Let’s step back for a minute from this slow motion disaster that we’re both the cause of and captive audience to and consider, for a moment, the structure of Greenland’s ice and land mass. The Greenland coastline is little more than a honeycomb of semi-frozen channels both coming into contact with the larger water bodies of Baffin Bay and the North Atlantic and drilling deep into the interior of Greenland itself. The two mile high glacier slopes gradually down toward and into these hundreds of channel estuaries, creating a slope defined by tall ice sheets terminating in low, ocean-opening waterways.
(Image source: Lance-Modis)
In the above image, you can see just one section of these ice channels that encompass almost the entire coastline of Greenland. Note the dark ocean water coming into contact with the silver-white of Greenland ice. The small white flecks you can see in this Modis shot are nothing less than immense ice burgs riding the winds and tides out into the North Atlantic. If you accurately imagine the entire coast of Greenland perforated by such outlets, what you come to realize is that Greenland is nothing less than an enormous ice burg dispersal mechanism. One that, if it really cranks up, will disgorge vast flotillas of ice bergs riding out upon tsunami-like melt pulses in every direction.
Inherent to this potential is the fact that Greenland ice is continuously in motion. Pulled by gravity, the towering ice sheets constantly seek the sea. Slowly grinding away, the ice moves gradually, steadily until it, at last, finds water, there it explodes in a riotous calving of the immense and monstrous ice burgs. The more solid and cold Greenland becomes, the slower its ice moves toward the ocean. The ice sheet weight increases, depressing the entire island into the crustal plate and keeping more of its ice locked in the center. The ice forms more solid boundaries to other ice flows and the ice grinding slows as it thickens. But the more wet and warm the ice becomes, the opposite is true. Water flows through the ice sheet to lubricate its base, the large pools of water on top further heat and deform the ice, the crustal plates rebound, pushing the island higher and adding gravity as a more and more powerful force attracting ice to ocean, and increasingly large pulses of melt water flush out from the center of the glaciers, drawing both ice and water along in ever greater volumes toward the ocean.
In a Heinrich Event, the melt forces eventually reach a tipping point. The warmer water has greatly softened the ice sheet. Floods of water flow out beneath the ice. Ice ponds grow into great lakes that may spill out both over top of the ice and underneath it. Large ice dams may or may not start to form. All through this time ice motion and melt is accelerating. Finally, a major tipping point is reached and in a single large event or ongoing series of such events, a massive surge of water and ice flush outward as the ice sheet enters an entirely chaotic state. Tsunamis of melt water rush out bearing their vast flotillas of icebergs, greatly contributing to sea level rise. And that’s when the weather really starts to get nasty. In the case of Greenland, the firing line for such events is the entire North Atlantic and, ultimately the Northern Hemisphere. But the Southern Hemisphere has its own set of troubles to contemplate. For there resides the seemingly endless pile of ice that is Antarctica.
Storms of My Grandchildren
A long time ago, I read a book called “The Coming Global Superstorm.” The book trivialized the potential effects of Heinrich Events by lumping them into a myopic and artificial single instance that the authors referred to as a Superstorm. The book was also chock full of astrological New Age jargon and other unrelated philosophy that greatly discredited the authors’ notion of Superstorm. Even worse, Hollywood jumped onto the trivialization bandwagon by producing the entirely unrealistic movie “The Day After Tomorrow.”
About this New Age book and its related Hollywood film, I have but one thing to say — if only it were so easy. Both the book and the movie boil the risk of human caused global warming into a single, linear event, which ends in single results. Even worse, both the book and the movie produce the false impression that such storms will result in an ice age. Again, if only it were so easy.
If you want to learn about the potential involved in such events, you should become a student of climate scientist James Hansen. You could start by reading the excellent book “Storms of My Grandchildren” and you could continue by reading his papers pertaining to extreme weather caused by West Antarctic and Greenland Ice melt.
What Hansen describes in his later work is the potential for ‘continent sized frontal storms packing the punch of hurricanes’ to rip across vast swaths of the Northern Hemisphere in association with an extreme weather pattern set up by a Heinrich type event acting in combination with a human warming induced heat amplification of the tropics. In vast difference to the “Day After Tomorrow,” these storms are not single instances, but potentially re-occurring catastrophic weather hazards.
How bad could these storms get? As an example, the freak hybrid superstorm Sandy is but a prelude to the main events.
Yet Sandy’s somewhat unique hybrid structure and location may well provide us with hints as to the nature of future superstorm events. What we see in the above NOAA satellite shot is a storm that is linked both in the tropics and in the Arctic. The storm derives energy from a cold air mass over Greenland and pulls in another ‘arm’ of energy from the tropical Atlantic.
During the Heinrich event, the ice berg cooling effect mentioned by Hansen in his papers and the human caused heat amplification of the tropics will set up a far more disastrous atmospheric storm potential. And the raking effect of continent sized frontal storm systems would have even more damaging consequences to human infrastructure than the related pulse of sea level rise alone.
Ocean Circulation Change to Open the Door for the Hydrate Monster, Anoxic/Canfield Oceans?
Yet one more ominous result of Heinrich Events is a high-stress shock to ocean temperature and saline circulation systems. Such events are likely to shove the northern termination of larger ocean systems further toward the equator. The cold, fresh water pulses would result in less sinking of water at the poles. Related increased heat at the tropics would begin to set up a system where salty waters begin to sink there.
Even more ominously, a wedge of cold water at the surface spreading out from the poles would push hotter, saltier water toward the ocean bottom. Fresh water is less dense than salty water, so the fresh water pulses from glaciers and melting ice bergs will act as a wedge, driving the denser, warmer, saltier water toward the bottom The net effect of such changes would be a shallower and weaker ocean circulation system as more warm water is averted toward the ocean bottom near the equator and then spreads northward and as warmer surface waters toward the poles and temperature regions are driven toward the sea-bed.
Since vast stores of methane lay locked in hydrates on the sea bed, these stores are at risk of greater forcing and more rapid destabilization. To note, the end of the Permian, in which a partially glaciated world transitioned to a hot house, is estimated to have seen methane levels at around 11 parts per million — almost ten times the current level. Large melt pulses are, therefore, a potential mechanism for ocean bottom heating and increasing rates of methane release.
This event sets in place conditions that increase risk for the two other climate monsters — increasing CO2 and methane release from Earth Systems and the perhaps more ugly anoxic and Canfield Ocean states. And both we will visit in future blogs.
How soon could we see Heinrich type events, Hansen-style superstorms, and dangerous changes to ocean circulation? Hansen, in “Storms of My Grandchildren” indicates a risk for such events emerging by mid-century under business as usual fossil fuel emissions. Jason Box and others have shown an increasing speed and melt of the Greenland Ice Sheet occurring during the first and second decades of the 21rst Century. So it appears we are starting to ramp up to such events even now as an ominous ice sheet response begins to show on the climate radar. So the period of risk appears to be sometime between now (low) through 2070 (moderate to high depending on human CO2 forcing growth or mitigation).
That paleoclimate and modeling performed by Hansen show the potential for such powerful events should be cause for serious concern and reason for ever-greater urgency in reducing human greenhouse gas emissions and our related climate risk to the lowest levels possible. And, in the end, we almost certainly do not want to begin to bring forward conditions that will release the other two ‘monsters behind the door’ — rapid CO2 and methane response from Earth Systems and anoxic and Canfield Oceans.