Saturday, August 25, 2012

Climate Change: The Last Domino


In the next to last week of August, 2012, it became plain that the first domino was falling.

In that week, every single measure of Arctic sea ice extent and area reached a new record low simultaneously.  By the end of that week, area – the best measure available – had gone 8.5% below the previous record low (in 2011). And this was four weeks before the point where Arctic sea ice would reach its minimum for the year.

In that four weeks, the minimum continued its downward slide. For the first time in either 20,000 or 5 million years, major parts of the Central Arctic Basin above 80 degrees North were open water. Currents carried ice that was in most cases less than three feet thick across the North Pole and poured it steadily into the Fram Strait east of Greenland, where it melted. Less than 5% of Arctic sea ice remained by year’s end to build on for multi-year ice. And when October arrived, and the sun set permanently for the winter over the Arctic Ocean, refreezing was delayed, as the warmer water resisted the colder air.

And so it continued, until by 2018, in September, pretty much all of the ice in the Arctic Ocean was gone. And then the period of no ice widened, and widened, until somewhere between 2030 and 2045 there was no ice in the Arctic Ocean year-round. The water was warmer, as the sun in summer beat down and stored heat in that ocean to be released in the fall, and warmer currents from the south no longer were combated by cold ice, and global warming from the south increased the air temperatures to 20 degrees Fahrenheit and above in the depths of winter. And that ocean heat, in turn, warmed the global air by only 1 degree Fahrenheit. But that was only the first domino.

Domino Two: Greenland the Archipelago

Because, already, the first domino was tipping the second. For 20,000 or five million years, Greenland had been surrounded on the north, northeast, and northwest year-round by sea ice. In that time, it had become a cone of ice perched on a plateau of ice to a height of more than 10,000 feet. The plateau was mostly surrounded by mountains, and the fjords formed cracks in the “bowl” of mountains through which glaciers forced their way. But the removal of Arctic sea ice removed the plugs slowing down the flow of the glaciers. They speeded up, faster and faster. Then, in July and August of 2012, for the first time, a Northern-Hemisphere heat wave from global warming put temperatures above freezing all the way to the highest point in Greenland, for several weeks. Melting had doubled in the 1990s and in the 2000s; now it tripled in the 2010s. And the removal of sea ice by the 2020s meant that the glaciers had in some cases melted to the shore line, where melt-water running under the rest of the glacier could “grease the skids” of the glacier as it slid toward the sea. The rate of melt continued to climb, until by 2050 it was releasing a foot of fresh water into the ocean every decade, or a total (with melt from other Northern land sources) of 10-15 feet of increase in the sea by 2100.

Except that this was an underestimate. At the same time, fed partially by increased temperatures, the upper ocean warmed, slowly but surely, expanding and therefore adding another 5% of increase, to 11-16 feet by 2100. And the melt continued, until by 2250 the melt was almost done and 25 feet had been added to the oceans from Greenland and other Northern land sources. In the process, we discovered that despite “springback” of land crushed under miles of central-plateau ice, Greenland was actually not one land but an archipelago of mountains rising in a rough circle around a central sea.

Again, this melting of ice decreased “albedo” (reflectivity of the sun’s light and heat back to space), and therefore increased global temperatures, by perhaps ½ degree Fahrenheit by 2100, especially since black soot from human emissions helped to discolor the off-white of the melting ice. It also increased the “area of ocean” by 10-20 feet beyond the actual sea level rise, because the increased heat in the air allowed greater storage of energy in storms, so that storm surges carrying salt water to poison water supplies now reached 30 feet higher by 2100 than before. But that wasn’t the worst of it. The worst was that dominoes one and two now began to tip dominoes three and four.

Dominoes Three and Four:  Clathrates and Permafrost

In fact, it was evident from inspection as early as 2011 that both the methane clathrate and the permafrost dominoes were beginning to tip. Still, sensor readings of atmospheric methane and carbon did not clearly reflect this until the late 2010s and early 2020s.

Since 15-5 million years ago, methane had been accumulating in the Arctic Ocean in the sea floor 10-1000 feet below sea level. Below the very cold arctic upper-level and lower-level currents lay ground that was several degrees below freezing – the temperature that trapped methane in a “cage” not of ice but of something called a clathrate. And this accumulation of methane in clathrates had been going on for an unusually long time – perhaps, in some places, as long as 20 million years.

Meanwhile, somewhat of the same thing had been going on in permafrost – the frozen ground in the northern reaches especially of Siberia.  Here the problem was not so much clathrates as the fact that the frozen ground contained large amounts of both carbon and water. When the water thawed, swamps replaced the frozen ground – and swamps produce large amounts of methane.  While no one could be certain, it appeared that melting the Siberian permafrost would result in methane production from the resulting peat even larger than that from clathrates. Meanwhile, the increased heat from global warming, starting in 2011, began to set the peat and forests on fire, adding significantly to global carbon emissions.

Put together, and added to global warming from carbon emissions, the resulting methane production per year began to climb sharply, to the point where, combined with human emissions, it had reached 3 times its 2010 level by 2020. But then it continued to climb, reaching 10 times its 2010 level by 2050. And then things got really serious.

You see, methane is 7-20 times more potent a greenhouse gas per ppm than carbon. At the rates of 2010, that had a miniscule effect on global warming, because methane (CH4) would recombine to form water (H2O) and carbon dioxide (CO2) in relatively small amounts, and so on average it would stay up as methane only 8 years. But at the rates of 2050, the amounts of methane being pumped into the atmosphere were enough to add another degree Fahrenheit to global warming. And then, as the methane emissions from clathrates and permafrost continued to climb, things got even worse.

You see, there is a saturation rate at which there isn’t enough carbon (?) around in the atmosphere to combine with  methane and so remove it. And so, methane began staying in the atmosphere longer – and longer. By 2150, it was hanging around for 15 years and longer, and it was adding 4 degrees Fahrenheit to global temperature instead of 1.

But even that wasn’t the worst of it. Eventually, that methane was going to convert to carbon dioxide, in the atmosphere; and carbon dioxide hangs around for 100-200 years – with a significant fraction hanging around for 1000 years and longer. So by 2150, the methane that was being pumped into the atmosphere by clathrates and permafrost had ensured an increase in temperature of 2 degrees Fahrenheit (compared to 1950) until about 5000 AD, on top of the 2 degrees increase from carbon emissions up to 2012 and the probable additional 2 degrees of increase at minimum from carbon emissions from 2012 to 2100.
Meanwhile, all that heat was already, in 2012, beginning to tip domino five.

Domino Five: West Antarctica

It was hard to believe, in 2012, that Antarctica would start melting significantly in less than a time scale of thousands of years. After all, the sea ice surrounding Antarctica was, if anything, increasing by 1% per decade (for complicated reasons having to do with indirect temporary effects on currents of global warming); and Antarctica is mostly well under freezing temperatures year-round, and surrounded by a “moat” of cold ocean.

Except that the signs were there. A long-time visitor to the Antarctic Peninsula (the long arm that reaches up to South America) reported that areas frozen year-round in the 1970s were now melting three or more months of the year. Unprecedented “calving” of Peninsula glaciers was taking place by 2010. Under the cold ocean current was a warmer one, and this one was reaching further and further south, until in about 2010 it began reaching the Peninsula and points south – and helping to melt glacier ice now stuck in the middle of the Ross Sea from beneath.

And so, sometime between 2015 and 2020, the ice in the Ross Sea that had been blocking the slide of West Antarctic glaciers began to weaken, and the removal of the “plug”, as in Greenland, began to speed the glaciers’ slide into the sea. Then, in the 2020s, the warm ocean current began to reach south of the Peninsula to the rest of West Antarctica, the Ross Sea and the “bowl” of land surrounding it, and the “plug” began to erode from the north as well. Now, as in Greenland, the rate of melt began to double every decade. And by the 2050s, the warmth in the air and the sea began to reach freezing even in winter, as in the Arctic Ocean, and now the rate tripled, until by 2060-2070 West Antarctica began to contribute its own fresh water to sea level rise. And so, by 2250, another 20 feet had been added to sea level, and by 2450 another 25 feet beyond that, all from West Antarctica. And, of course, add another 10-20 feet from yet greater storm surges – say, a total of 100 feet.

And, just as with Greenland, these decreased albedo and raised temperatures by ½ degree Fahrenheit, while the removal of winter sea ice around Antarctica added another ½ degree Fahrenheit. But that even that wasn’t the worst. Yes, domino five falling inevitably led to domino six, the last domino.

The Last Domino: East Antarctica

Mostly, East Antarctica is like a Greenland separate from West Antarctica – except there’s a big crack at the end of the Ross Sea where ice can flow directly from the central EA plateau directly down to the Ross Sea. Once West Antarctica goes, that’s one source of EA melt; but the very warming at the edges and loss of sea ice that caused West Antarctica to go also meant that East Antarctica was going as well.
In fact, the signs were there in 2012, as well. Measurements were showing that EA was already beginning to lose ice. On Christmas Day in 2011, the South Pole set a new high temperature record, some 10 degrees Fahrenheit. Still, the measurements showed only slight melting.

By 2050, the melt was perceptible. By 2150, it was beginning to rival West Antarctica. By 2250, it was clearly outstripping it. And we are talking more than 100 feet of sea rise, here. By 2350, 50 feet. By 2550, 100 feet. By 550 years from 2000, the Earth had seen 170 feet of sea rise, with perhaps 70 feet more to go before it all ended. Again, add on 10 feet of storm surge. Places that in 2000 were 250 feet above sea level were uninhabitable 550 years later – including 60-80% of all agriculturally productive areas.

And still, that wasn’t the worst of it. The fresh water and other sources were making the ocean more acidic, killing off most ocean life. On the continental shelves, toxic “iron blooms” were growing periodically (this may be avoidable), which when they died released sulfuric acid into the atmosphere, killing those living near the sea who breathed it. Inland for many miles from the sea was a zone of living only if you could afford a breathing mask – assuming, at that stage, that you could afford one.

Envoi

I don’t claim that I have every detail right, or that these things are unavoidable. But I am telling you, as I watch Arctic sea ice amounts tumble, what gives me nightmares. For these things might, just might, already be baked in by what we have already done. Note that, in my description, there are very few if any places where major additional human-caused carbon emissions beyond today’s rates are required to move from one domino tipping to the next.

I shall almost certainly be dead by 2050, when the effects of dominoes two through six may start showing up.  Still, I care. And I pray, not for a miracle, but for enough others to care to make a difference in the outcome.

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