The Climate-Change Dog That Did Bark In The Night: CO2 Continues Its Unprecedented 6-Month Streak

In one of Conan Doyle’s Sherlock Holmes mysteries, an apparent theft of a racehorse is solved when Holmes notes “the curious incident of the dog in the night” – the point being that the guard dog for the stable did not bark, showing that the only visitor was known and trusted.  In some sense, CO2 is a “guard dog” for oncoming climate change, signaling future global warming when its increases overwhelm the natural Milankovitch and other climate cycles.  It is therefore distressing to note that in the last 6 months, the dog has barked very loudly indeed:  CO2 in the atmosphere has increased at an unprecedented rate. 

And this is occurring in the “nighttime”, i.e., at a time when, by all our measures, CO2 emissions growth should be flat or slowing down.  As noted in previous posts, efforts to cut emissions, notably in the EU and China, plus the surge of the solar industry, have seemed to lend credibility to metrics of carbon emissions from various sources that suggest more or less flat global emissions in 2014 and 2015 despite significant global economic and population growth.

What is going on?  I have already noted the possibility that a major el Nino event, such as occurred in 1998, can cause a temporary surge in CO2 growth.  In 1998, indeed, CO2 growth set a record that was not beaten until last year, but in the two years after 1998, CO2 atmospheric ppm growth fell back sharply to nearly the previous level.  By our measures, the el Nino occurring in the first 5 months or so of 2016 was about equal in magnitude to the one in 1998, so one would expect to see a similar short surge.  However, we are almost 4 months past the end of this el Nino, and there is very little sign of any major decrease in growth rate.  It already appears certain that we cannot dismiss the CO2 surge as a short-term blip.

Recent Developments in CO2 Mauna Loa

In the last few days, I was privileged to watch the video of Prof. John Sterman of MIT, talking about the “what-if” tool he had developed and made available in which climate models drive CO2 emissions growth depending on how aggressive the national targets are for emissions reduction.  He was blunt in saying that even the commitments coming out of the Paris meeting are grossly inadequate, but he did show how much more aggressive targets could indeed keep total growth at 2 degrees C.  In fact, he was so forthright and well-informed that I could finally hope that MIT’s climate-change legacy would not be the government-crippling misinformation of that narcissistic hack Prof. Lindzen.

However, two of his statements – somewhat true in 2015 but clearly not true at this point in 2016 (the lecture, I believe, was given in the spring of 2016) – stick in my head.  First, he said that we are beginning to approach 1.5 degrees C growth in global land temperature.  According to the latest figures cited by Joe Romm, the most likely global land temperature for 2015 will be approximately 1.5 degrees C.  Second, he said that CO2 (average per year) had reached the 400 ppm level – a statement true at this time last year.  As of April-July 2016, however, the average per year has reached between 404 and 405 ppm.

CO2 as measured at the Mauna Loa observatory tends to follow a seasonal cycle, with the peak occurring in April and May, and the trough in September.  In the last few years, at all times of the year, growth year-to-year (measured monthly) averaged slightly more than 2 ppm.  Note that this was true for both 2014 and most of 2015.  Then, around the time that the el Nino arrived, it rose to 3 ppm.  But it didn’t stop there:  In April, a breathtakingly sharp rise of 4.1 ppm took CO2 up to 408 ppm.  And it didn’t stop there:  May and June were likewise near 4 ppm, and the resulting total average rise through August has been almost 3.6 ppm.  September so far continues to be in the 3.3-3.5 range. 

CO2, el Nino, Global Land Temperature:  What Causes What?

Let’s add another factoid.  Over the last 16 or so months, each month’s global land temperature has set a new record.  In fact, July and August (July is typically the hottest month) tied for absolute heat record ever recorded, well ahead of the records set last year.

So here we have three factors:  CO2, el Nino, and variations in global land temperature.  Clearly, in this heat wave “surge”, the land temperature started spiking first, the full force of el Nino arrived second, and the full surge in CO2 arrived third.  On the other hand, we know that atmospheric CO2 is not only a “guard dog”, but also, in James Hansen’s phrase, a “control knob”:  in the long term, for large enough variations in CO2 (which can be 10 ppm in some cases), the global land temperature will eventually follow CO2 by rising or falling in proportion.  Moreover, it seems likely that el Nino’s short-term effect on CO2 must be primarily by raising the land temperature, which does things like expose black carbon on melting ice for release to the atmosphere, or increase the imbalance between carbon-absorbing forest growth and carbon-emitting forest fires by increasing the incidence of forest fires.

But I think we also have to ask whether the effect of increasing CO2 on global temperatures (land plus sea, this time) begins over a shorter time frame than we thought.  The shortest time frame for a CO2 effect suggested by conservative science is perhaps 2000 years, when a spike in CO2 caused Arctic melting indicative of global warming less than a million years ago.  Hansen and others, as well, have identified 360 ppm of atmospheric CO2 as the level at which Arctic sea ice melts out, and we only passed that level about 20 years ago – a paper by a Harvard professor projects that Arctic sea ice will melt out at minimum somewhere between 2032 and 2053.  In other words, we at least have some indication that CO2 can affect global temperature in 50-100 years or so.

And finally, we have scientific work showing that global land temperature increases that melt Arctic sea and land ice affect albedo (e.g., turn white ice into blue water), which in turn increases sea and land heat absorption and hence temperatures, and these changes “ripple down” to the average temperatures of temperate and subtropical zones.  So part of global land temperature increase is caused by – global land temperature increase.  It is for these reasons that many scientists feel that climate models underestimate the net effect of a doubling of CO2, and these scientists estimate that rather than 500 ppm leading to a 2 degree C temperature increase, it will lead to a 4 degree C increase.

I would summarize by saying that while it seems we don’t know enough about the relationship between CO2, el Nino, and global land temperature, it does seem likely that today’s CO2 increase is much more than can be explained by el Nino plus land temperature rise, and that the effects of this CO2 spike will be felt sooner than we think.

Implications

If the “guard dog” of CO2 in the atmosphere is now barking so loudly, why did we not anticipate this?  I still cannot see an adequate explanation that does not include the likelihood that our metrics of our carbon emissions are not capturing an increasing proportion of what we put into the air.  That certainly needs looking into.

At the same time, I believe that we need to recognize the possibility that this is not a “developing nations get hit hard, developed ones get by” or “the rich escape the worst effects” story.  If things are happening faster than we expect and may result in temperature changes higher than we expect, then it is reasonable to assume that the “trickle-up” effects of climate change may become a flood in the next few decades, as rapid ecosystem, food, and water degradation starts affecting the livability of developed nations and their ability to feed their own reasonably-well-off citizens. 

The guard dog barks in the night-time, while we sleep.  We have a visitor that is not usual, and should not be trusted or ignored.  I urge that we start paying attention. 

In Which We Return to Arctic Sea Ice Decline and Find It Was As Bad As We Thought Seven Years Ago

For the last 3 years or so, I have rarely blogged about Arctic sea ice, because my model of how it worked seemed flawed and yet replacement models did not satisfy. 

Until 2013, measures of Arctic sea ice volume, trended downward, exponentially rather than linearly, at minimum (usually in early September).  Then, in 2013, 2014, and 2015, volume, area and extent measures seemed to rebound above 2012 almost to the levels of 2007, the first “alarm” year.  My model, which was of a cube of ice floating in water and slowly moving from one side of a glass to the other, with seasonal heat increasing yearly applied at the top, bottom, and sides, simply did not seem to reflect what was going on. 

And now comes 2016 (the year’s melting is effectively over), and it seems clear that the underlying trends remain, and even that a modified version of my model loosely fits what’s happening.  This has been an unprecedented Arctic sea ice melting year in many ways – and the strangest thing of all may be this glimpse of the familiar.

Nothing of It But Doth Change, Into Something Strange

The line is from early in Shakespeare’s Richard III, in which a character talks of his father’s drowning:  “Full fathom five my father lies/Of his bones are coral made/ … /Nothing of him but doth change,/Into something rich, and strange.”  And, indeed, the changes in this year’s Arctic sea ice saga deserve the title “sea-change.”  Here’s a list:

1. 1.       Lowest sea-ice maximum, by a significant amount, back in late March/April.
2. 2.       Lowest 12-month average.
3. 3.       Unprecedented amount of major storm activity in August.
4. 4.       Possibly greatest amount of melt during July for years when generally cloudy conditions hinder melting.
5. 5.       First sighting of a large “lake” of open water at the North Pole on Aug. 28, when two icebreakers parked next to an ice floe and one took a picture.  Santa wept.
6. 6.       First time since I have been monitoring Arctic sea ice melt when the Beaufort Sea (north of Canada and Alaska) was almost completely devoid of ice to within 5 degrees of the pole.

These events actually describe a coherent story, as I understand it.  It begins in early winter, when unusual ocean heat shows up at the edges of the ice pack, especially around Norway.  The ocean temperature (especially in the North Atlantic) has been slowly heating over time, but this time it seemed to cross a threshold:  parts of the Atlantic near Norway stayed ice free all the way through the year, leading to the lowest-ever Arctic-ocean maximum.

In May and early June, the sun was above the horizon but temperatures were still significantly below freezing in the Arctic, so relatively little melting got done. Then, when cloudy conditions descended and stayed late in June or thereabouts, the relative ocean heat counteracted some of the loss of melting energy from the sun.  But another factor emerged:  the thinness of the ice.  Over 2013, 2014, and 2015, despite the lack of summer melt, multi-year ice remained a small fraction of the whole.  So when a certain amount of melt occurred in July and August, water “punched through” in many places, so that melting was occurring not just on the top (air temperature) and bottom (ocean heat) but also the sides (ocean heat) of ice floes.  And this Swiss cheese effect was happening not just at the periphery, but all over the central Arctic – hence the open water at the Pole.

Then came the storms of August.  In previous years, at any time of the year, the cloudiness caused by storms counteracted their heat energy.  This year, the thin, broken ice was driven by waves that packed some of the storms’ energy, further melting them.  And, of course, one of the side effects was to drive sea ice completely out of the Beaufort Sea.

Implications For The Future

It is really hard to find good news in this year’s Arctic sea ice melting season.  Years 2013-2015 were years of false hope, in which although it seemed that although eventually Arctic sea ice must reach zero at minimum (defined as less than 1% of the Arctic Ocean covered with ice), we had reached a period of flat sea ice volume, which only a major disturbance such as abundant sunshine in July and August could tip into a new period of decline. 

However, the fact of 2016 volume decrease in such unpromising weather conditions has pretty much put paid to those hopes.  It is hard to see what can stop continued volume decreases, since neither clouds nor storms will apparently do so any longer.  One can argue that the recent el Nino artificially boosted ocean temperatures, although it is not clear how it could have such a strong relative effect; but there is no sign that ocean heat will return to 2013-2015 levels now that the el Nino is over.  

Instead, the best we can apparently hope for is a year or two of flatness at the present volume levels if such an el Nino effect exists, not a return to 2013-2015 levels.  My original off-the-cuff projection “if this [volume decreases 2000-2012] goes on” was for zero Arctic sea ice around 2018, and while I agree that the 2013-2015 “pause” makes 2018 very unlikely, 2016 also seems to make any “zero date” after 2030 less likely than zero Arctic sea ice at some point in the 2020s. 

A second conclusion I draw is that my old model, while far overestimating the effects of “bottom heating” pre-2016, now works much better in the “fragmented ice” state of today’s Arctic sea ice in July and August.  In this model, as ice volume approaches zero at minimum, volume flattens out, while extent decreases rapidly and area more rapidly still (unless the ice is compacted by storms, as occurred this year).  This effect will be unclear to some extent, as present measurement instruments can’t distinguish between “melt ponds” caused by the sun’s heat and actual open water.

Finally, the Arctic sea “ice plug” that slowed Greenland glacier melt by pushing back against glacier sea outlets continues to appear less and less powerful.  This year, almost the entire west coast of Greenland was clear of ice by early to mid June – a situation I cannot recall ever happening while I’ve been watching.  Since this speeds glacier flow and therefore melting at its terminus entering the sea, it appears that this decade, like the 1990s and 2000s, will show a doubling of Greenland snow/ice melt.  James Hansen’s model, which assumes this will continue for at least another couple of decades, projects 6-10 feet of sea rise by 2100.  And even this may be optimistic – as I hope to discuss in a follow-on post on 2016’s sudden CO2 rise.

Most sobering of all, in one sense we are already as near to zero Arctic sea ice as makes no difference.  Think of my model of an ice cube floating in water in a glass for a minute, and imagine that instead of a cube you see lots of thin splinters of ice.  You know that it will take very little for that ice to vanish, whereas if the same volume of ice were still concentrated in one cube it will take much more.  By what I hear of on-the-ground reports, much of the remaining ice in the Arctic right now is those thin chunks of ice floating in water. 

“Because I do not hope to turn again/Because I do not hope/ … May the judgment not be too heavy on us/ … Teach us to care and not to care.”  T.S. Eliot, Ash Wednesday

And the CO2 Keeps Rising Faster

It appears pretty evident from the Mauna Loa weekly data that the April CO2 level will average around 407.5.  That’s more than 4 ppm more than April 2015.  Moreover, with March having come in below 405 ppm, it will be the first time on record that we have passed the 405, 406, and 407 ppm mark on a monthly basis.  Based on past behavior, it seems likely that May 2016 will be above 408 ppm.  If memory serves me right, that will be less than 1 ½ years since the monthly average was less than 400 ppm.  And finally, given that the CO2 underlying “rate of rise” is much greater than in 1998, there is a strong possibility that we will cross 410 ppm on a monthly basis next April or May – less than 2 ½ years since we were under 400 ppm.

Guesstimating and extrapolating the new “underlying rate of rise” farther out into the future at a conservative 2.5 ppm/year to a still realistic 3.3 ppm/year, we reach 420 ppm in 2020 or 2021.  Why is this significant?  It marks the point at which atmospheric carbon reaches 50% above its pre-industrial value of about 280 ppm.  Most estimates of the warming effect of atmospheric carbon base themselves on a doubling, with somewhere between 2 and 2.8 degrees C  warming as a direct effect of the carbon, and between 4 and 5 degrees C (delayed) due to related increases in other GHGs (greenhouse gases) and additional warming due to changes in the Earth’s albedo.  The best estimates are based on previous episodes of large global warming 55 and 250 million years ago, which according to Hansen et al. resulted in about 4 degrees C increase in global temperature eventually per doubling of atmospheric carbon.  [Note that this may underestimate the effect of today’s atmospheric carbon increases over a 100s of times shorter period compared to previous global warming episodes] If we follow Hansen et al., then, we will have 2.67 degrees C of warming already “baked in” as of 2121.  Somewhere between 1.33 and 1.75 degrees C will happen pretty quickly, apparently, by 2050; and while we don’t know how fast the rest will happen, much of it will happen in the period 2050-2100. 

We may also note a recent Hansen et al. article that revises the estimated sea level rise due to this warming to between 5 and 9 feet by 2100 – and, again, the model that projects this, as noted by the authors, may still underestimate the effects of “business as usual”.   Finally, scientists have now noted several new catastrophes that would happen even with a 2 degrees C rise.

We continue to underestimate what the planet will do to us on our present path.

That is all.