Extreme weather. It’s something that’s tough to predict 2 weeks out, much less 2 decades. But for more than twenty years Dr James Hansen has been warning that the out-flush of cold water from glaciers in Greenland and Canada into the North Atlantic could set up a storm-producing weather pattern the likes of which human civilization has never seen. An atmospheric wrecking ball in the form of an intense cold-hot dipole that, once firmly established over Atlantic Ocean waters between North American and Europe, would carry on in brutally destructive fashion for decades and decades. In other words, as Dr. Hansen says in the below video, “all hell would break loose.”
His recent and, what might well be called, earth-shattering paper on the subject — Ice Melt, Sea Level Rise, and Superstorms — takes a good, hard look at both the potential for exponentially ramping rates of ice melt and sea level rise over the coming decades and the impact those thousands of cubic kilometers of fresh water ramming out into the North Atlantic would have in producing a barrage of increasingly intense superstorms.
(Hansen addresses his concerns about the potential for increasingly severe storms and rapid sea level rise if human fossil fuel emissions do not stop soon in the above video.)
Early Evidence That All Hell is Starting to Break Loose
How could this happen? And what might it look like?
These are questions Hansen valiantly attempts to tackle. And according to him, in addition to a growing number of top climate researchers like Dr. Jason Box and Dr. Stephan Ramhstorf (please see Dr. Jason Box’s very salient take on the new Hansen study here), we may already be starting to witness signs of the wrenching oceanic and atmospheric shift that would produce these terrible weather systems.
For what we see now is the visible formation of a large cool pool in the North Atlantic. One that appears to be developing due to an increasingly rapid rate of Greenland melt. One that may be setting up atmospheric conditions for the age of storms that Hansen has feared could arise. An event resulting from a rampant human fossil fuel emission and a related very rapid injection of heat into the Earth System.
(Composite global temperature anomaly data from NOAA for 2013 through 2015 provides evidence of the early start to the formation of a possible superstorm-producing North Atlantic cool pool. Image source: Climate Crocks.)
How might this cool pool become such a powerful storm generator? It could well be thought of as an ironic matter of atmospheric and ocean physics. Ironic in the sense that overall global heating produces a severe weather hazard in the form of a large area of cool ocean surface water.
Increased warming of the Earth results in more rapid warming at the poles, especially in the Northern Hemisphere. In turn, this polar amplification sets off a number of feedback loops in which ice in Greenland and West Antarctica begin to melt faster and faster. The ironic atmospheric relationship to large slabs of ice sliding off the great ice sheets and into the ocean begins to come into play. For a thin veil of fresh water from these increasingly massive volumes of melting ice begin to lock more and more heat into the local ocean system.
Over hundreds of thousands of square kilometers, the fresh water begins to cut off the ocean’s ability to ventilate heat into the airs above. As a result, the surface of the ocean and the local atmosphere cools. More heat is shoved into the deeper waters — where it can melt the sea facing glaciers ever more rapidly even as it gets to doing the dangerous work destabilizing carbon stores on the sea bed. Dangerous — not only for its potential to add more greenhouse gasses to the world atmosphere, but also for its ability to develop anoxic dead zones in the ocean depths and to expand those life-killing layers toward the sea surface.
Climate Change’s War Between Hot and Cold — Understanding the Warning Signs
In scientific terms, we call this a stratified ocean state. But in plainer words, we could think of it as a big mechanism for heat exchange and ocean and atmospheric chemistry change.
(Anyone who knows anything about ocean and atmospheric physics should be concerned about this picture. Here we see the April 8, 2016 ocean surface temperature anomaly reanalysis provided by Earth Nullschool and developed from data collected by NCEP and the National Weather Service. Here we see a large swath of Gulf Stream waters ranging from 5-8 C above average temperatures coming into collision with waters in a North Atlantic cool pool ranging from 1-10 C below average. It is the increasing difference in temperature, or thermal gradient, between these two ocean zones that Hansen and others identify as having a high potential for very severe storm generation.)
Changing the ocean’s heat relationship with the atmosphere is bound to alter the weather. And Hansen’s paper points toward a serious risk that this fundamentally altered relationship will result in much more powerful storms. A cooler North Atlantic will collide with all kinds of expanding heat from various regions. A backed up Gulf Stream will warm up — it already has. The tropics will begin to heat up, increasing the temperature gradient between the lower Latitudes and the cool pool in the North Atlantic. Such conditions amp up the atmospheric storm potential by producing an abundance of what storms feed on — very extreme differences in temperatures, related strong winds and atmospheric vortexes, strong south to north and north to south air flows that link the tropics to the pole, and an ever-growing abundance of moisture bleeding off the record warm waters that come into increasing collision with the expanding pool of cold to the north. Such conditions risk the development of extraordinarily powerful storms in this region. Storms the likes of which our civilizations have never seen before. Storms that may leap the boundaries of their formation zones to have far broader impacts.
Hansen, in his paper found evidence that such conditions may well have existed during the last warm period between ice ages around 115,000 years ago. Back then, a huge flush of ice bergs running out from a melting Greenland during the peak period of warmth appears to have produced terrible storms in the North Atlantic. Storms powerful enough to pluck 2,000 ton boulders up out of the sea bed and hurl them 100 feet above sea level before depositing them onto the hills of places like Bermuda and the Bahama islands.
During that period, the rate of warming was slower. So the pace of melt was likely also slower than what we would see due to human warming. The atmospheric changes were thus milder than those we are likely to experience if human warming continues along its current path and sets the dramatic melt and related atmospheric wrenching into motion. Already, we see storms the likes of which history has never seen running into the UK and Ireland, aiming their increasingly powerful winds and rains at Western Europe. Already we see climate change enhanced superstorms. New forms of severe weather. Hellacious mergings of devastating hurricanes with extraordinary nor’easters.
But what we see now is nothing compared to what we will see if Hansen’s research is anywhere near the mark and if human fossil fuel burning continues unabated. What we risk, and what Hansen has warned us about in what he considers to be his most important work of science, is setting off a severe chain of events that includes rapid sea level rise and powerful, powerful storms. In addition, the ocean stratification that is the cause of all this atmospheric and oceanic trouble would set off further consequences not touched on in Hansen’s work — hitting ocean health hard and, likely, liberating more carbon stores from the Earth System to add to the troubles that humans (and particularly the fossil fuel special interests) are already rapidly bringing to the fore.
One final point — the Hansen paper has and will continue to generate a huge controversy in the science. But from the point of view of this threat analyst, there is a high potential for dangerous outcomes similar to those the Hansen paper warns of together with a number of additional troubles so long as the human-forced warming continues. And we already see visible evidence of those kinds of dangerous atmospheric and ocean changes starting to happen now.