Disclaimer: I am now retired, and am therefore no longer an expert on anything. This blog post presents only my opinions, and anything in it should not be relied on.
As I have argued before, human metrics on how well we are coping with climate change can be highly misleading, usually on the side of false optimism. Two metrics that are clearly not thus biased are:
1. Measurements of atmospheric CO2 at Mauna Loa in Hawaii, which have been recorded since 1959;
2. Estimates of Arctic sea ice volume (with extent serving as a loose approximation), especially at minimum in September, which have been carried out since the 1980s.
Over the past few years, I have covered the drumbeat of bad news from those two metrics, indicating that we are in a “business as usual” scenario that is accelerating climate change. In the first half of 2018, what has happened in both cases is that the metrics are not following a “worst possible case” path – hence the “relatively good” part of the title. At the same time, there is no clearly apparent indication that we are deviating from our “business as usual” scenario – mitigation is not clearly having any effect. It is possible, however, that we are seeing the beginnings of an effect; it’s just not possible to detect it in the statistical “noise.” And given that scientists are now talking about a “tipping point” in the near future in which not only a frightening 2 degrees C temperature by 2100 is locked in, but also follow-on feedbacks (like permafrost melt) that take temperature rise eventually to a far more disastrous 3-4 degrees C – well, that’s the underlying, ongoing bad news.
Of course, this summer’s everlasting heat waves in the US, Europe, and the Middle East – heat waves clearly caused primarily by human-generated CO2 emissions and the resulting climate change – make the “new abnormal” obvious to those of us who are not wilfully blind. But for anyone following the subject with an open mind, the heat waves are not a surprise.
So let’s take a look at each metric.
The El Nino Effect Recedes
From late 2016 to around June of 2017, the El Nino effect crested, and, as it has done in the past (e.g., 1998) drove both temperatures and the rate of CO2 rise skyward. Where 2013-2015 saw an unprecedented streak of 3 years of greater than 2 ppm atmospheric CO2 growth, 2016 and 2017 both saw record-breaking growth of around 3 ppm (hiding a brief spurt to almost 4 ppm). 1998 (2.86 ppm) was followed by a year or two of growth around 1 ppm – in fact, slower than 1996-7. But the percentage rate of rise has also been rising over the years (it reached almost 1% in early 2017, 4 ppm over 404 ppm). Therefore, it seemed a real possibility that 2018 would see 2.5 ppm growth. Indeed, we saw 2.5 ppm growth as late as the first month or two of 2018.
Now, however, weekly and monthly growth has settled back to a 1.5-2 ppm rate, consistently since early 1998. Even a 2 ppm rate gives hope that El Nino did not mean a permanent uptick in the rate of rise. A 1.5 ppm rate would seem to indicate that 2018 is following the 1999 script – a dip in the rate of rise, possibly because of the follow-on La Nina. It might even indicate a slight – very slight – decrease in the underlying rate of rise (i.e., the rate of rise with no El Nino or La Nina going on). And that, as I noted above, is the first indication I have seen that things might possibly be diverging from “business as usual”.
Of course, there’s always the background of bad news. In this case, it lies in the fact that whereas ever since I started following CO Mauna Loa 6 or 7 years ago CO2 levels in year 201x were about 10 ppm greater than in year 200x (10 years before), right now CO2 levels are about 13.5 ppm greater than in year 2008. So, even if the El Nino effect has ended, the underlying amount of rise may still be increasing.
The best indicator that our efforts are making a difference would be two years of 1 ppm rise or less (CO2 Mauna Loa measures the yearly amount of rise by averaging the Nov.-Feb. monthly rises). Alas, no such trend has shown up in the data yet.
Arctic Sea Ice: Not In Stasis, Not in Free Fall
Over the last 2 years, the “new normal” in Arctic sea ice advance and retreat has become apparent. It involves both unprecedented heat in winter, leading to new low extent maxima, and a cloudy and stormy July and August (key melt months), apparently negating the effects of the winter melt. However, volume continues to follow a downward overall trend (if far more linear and closer to flat-line than the apparently exponential “free fall” until 2012, which had some predicting “ice-free in 2018”).
As Neven’s Arctic Sea Ice blog (neven1.typepad.com) continues to show, however, “ice-free in September” still appears only a matter of time (at a best guess, according to some statisticians, in the early 2030s). Subsea temperatures (SSTs) in key parts of the Arctic like above Norway and in the Bering Sea continue to rise and impact sea ice formation in those areas. As the ice inherited from winter thins, we are beginning to see storms that actually break up the weaker ice into pieces, encouraging increased export of ice to the south via the Fram Strait. The ice is so thin that a few days ago an icebreaker carrying scientists had to go effectively all the way to the North Pole to find ice thick enough to support their instruments for any length of time.
So the relatively good news is that it appears highly unlikely that this year will see a new low extent, much less an ice-free moment. The underlying, ongoing bad news is that eventually the rise in SSTs will inevitably overcome the counteracting cloudiness in July and August (and that assumes that the cloudiness will persist). Since 1980, extent at maximum has shrunk perhaps 12%, while extent at minimum has shrunk perhaps 45% (volume shows sharper decreases). And in this, unlike CO2 Mauna Loa, there is no trace of a hint that the process is slowing down or reversing due to CO2 emissions reductions. Nor would we expect there to be such an indication, given that we have only gotten globally serious about emissions reduction in the last 3 years (yes, I recognize that Europe is an exception).
The question the above analysis raises is: What will it take to really make a significant impact on our carbon emissions – much less the dramatic reductions scientists have been calling for? I see no precise answer at the moment. What I do know is that what we are doing needs to be done even faster, far more extensively – because the last few years have also seen a great increase in understanding on the details of change, as I have tried to show in some of my Reading New Thoughts posts. The ways are increasingly there; the will is not. And that, I think, along with countering the disgustingly murderous role of President Trump in particular in climate change (I am thinking of Hurricane Maria and Puerto Rico as an obvious example), should be the main task of the rest of 2018.