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David Madsen
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Crandles: For when we will break the 450 ppm mark for CO2 I refer you to the comments of Ralph Keeling the director of the Scripps Institute C02 group ( You will note that he says 2035, not 2030, and I apologize for my mistake. I was doing it from memory (which I should learn not to do as it increasingly fails me). However, again in the greater scheme of things, 2030 or 2035 makes little difference. I in no way am suggesting that we should not struggle to shift to renewables. We obviously must do that. However, I think that will be almost impossible to do it in the next 14 or 19 years. Remember that the Paris accords are geared to reaching only modest reduction goals by 2030. It is highly unlikely that you, or I, or the readers of this blog, or the billions of other people on this planet are likely to give up our cars, our microwaves, our computers, our furnaces and air conditioners, our high calorie diets and all the other things that go into creating the increasing C02 concentrations. While not everyone has such things, those that don’t are struggling mightily to get them. Even if we all switched to solar-powered electric cars tomorrow, we are pretty well locked into the current rate of increase that Keeling is talking about. What I do think is that the campaign to switch totally to renewables is likely to be, at best, only partially successful. I wish, hope, and work towards that goal, but think it unlikely within my lifetime and probably yours that it will be achieved. If not, that means we need to start thinking about and working on technological solutions. I have no idea what those might be or even if such solutions are possible, but to rely only on a total shift to renewables and the elimination of our dependence on fossil fuels simply betrays a complete lack of understanding of human behavior.
While a debate about whether the arctic will become ice-free (in summer and year-round) this year, next year, in the next decade or in the next 25 years is certainly interesting on a micro level (and, of course, particularly interesting to readers/contributors to this blog), on a larger scale it is meaningless whether it a happens in 2016, 2023, or 2036. It is going to happen, and, on a geological scale, in essentially a nanosecond. What is critical is that global CO2 levels are going to exceed 450 ppm by 2030 (not may exceed, will exceed). Global average temperatures are already about 1.5 degrees C above the long-term average andt by 2040 or earlier they will exceed 2 degrees. Barring some unforetold technological solution for extracting CO2 from the atmosphere we will be crossing the 500 ppm and the +3 degrees thresholds a few decades thereafter. The arctic is about to change dramatically, as is the world, and those of us younger than about 60 or 70 will be unfortunate witnesses to that shift.
Unless fossil fuel emissions soon drop significantly below current levels, I expect CO2 levels will surpass the 450 mark by around 2035 and the 500 mark around 2065. "Barring some major breakthrough that allows excess CO2 to be scrubbed from the air, it is currently an impossibility for us to reach the target of 350 ppm that many consider the threshold of dangerous climate change effects. I expect it will take at least 1,000 years before CO2 drops again below 350 ppm." – Ralph Keeling, director of Scripps CO2 Group
Toggle Commented Apr 22, 2016 on Beaufort quick update at Arctic Sea Ice
I have been a lurker here for some years, but do not post because the Arctic is not my area of expertise. I follow things here because my interests are in paleoenvironmental change on the Tibetan Plateau (sometimes called the “third pole”), and much of what is presented here is relevant there (particularly the graphics….thank you all!). Now, however, R.Gates has hit on something I do know a bit about as I have actually collected sediment samples from northern Chinese deserts for use in analyzing dust found in Greenland ice cores. There are multiple sources of dust in the cores. The primary source is, indeed, the Taklamakan Desert in the Tarim Basin. Dust from this source is produced primarily in the spring and transported across the Pacific to North America and Greenland by the prevailing Westerlies. Secondary sources are other Chinese deserts, such as the Badain Jaran, the Tengger, and the Ordos, which supply dust to Greenland during the summer through winter months. In other words, December is not when dust from the Taklamakan usually gets transported to Greenland. That is not to say that some unusual event could not trigger such a winter dust storm, but that is not the norm. In short, I am not sure what the dust in Greenland ice cores has to do with your SSWs. That does not necessarily mean your basic thesis is wrong, but, rather, it simply means I would not recommend you use the provenience of ice core dust to support your argument. As an aside, I follow modern climate syntheses for the region rather closely in order to acquire comparative analogues for the paleoenvironmental records I study. I have not seen the kind of event you discuss….a plume of warm air heated above the Taklamakan in the winter and driven south by Mongolian cyclones into the Kunluns and up into the higher atmosphere….mentioned in that literature. Again, that is not to say such events do not occur or that I may simply have missed reference to them. However, I would think that if they were common enough to a major explanation for dust in Greenland ice cores, then I would have probably run across some discussion of them. It is an interesting idea, but you might want to dig a little more deeply into work from the region before pursuing it.
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