PIOMAS Volume as at 31st March 22,218 KM3.
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Wow. It is too early to make any firm projections. However, I think this one plot (and the plots of the various ocean segments) is quite suggestive and telling about where we are and where we may be headed.
It appears (presuming there isn't some anomaly) that we may have seen a break and change into a new regime and set of conditions since about March 21. We should know whether that is true or not within just a few weeks.
As with 2007, we may see a dramatic drop from the previous year. We have been on the high side of the statistical error band for a few years. It is unrealistic to think that will continue. A jump to the low side appears as likely as a jump to the mean.
However, if the exponential decline and its error band is anywhere near correct, the low side error band for 2019 is awfully close to an effective 0. This is not a prediction by any means. I still suspect that the exponential decline in volume projected takes us to zero volume in September in about the year 20025. With the low side statistical band, we are likely (though not certain) to reach that a few years before. That could possibly be as soon as 2021-2022.
I suspect too that natural variability (due to the various oscillations ...) have caused us to be abnormally on the high side for a few years and that this has distorted the exponential downward trend upward slightly. And that in turn has moved the most likely intercept with zero ice in September into the future by 1 to 3 years. If true, this suggests a most likely intercept in about the years 2022-2024. and with variation, possible actual first zero ice occurring 2-3 years earlier, so about 2020-2022.
In geologic terms of course, all of these AND all of the IPCC projections are indistinguishable from one another (even those that project zero ice out beyond 2100). We focus so much upon our own lifetimes and timescales, that it is extremely easy to forget that no matter which projections and models best fit reality, that in the geologic scale there is no difference at all.
We are crashing toward a new dynamic for the Earth at a vastly faster pace than any in any time in the ~4.5 billion year geologic record of Earth. The PETM was glacially slow in its transition by comparison. Ironic pun intended. Glaciers aren't so slow any more. And they are getting faster by the day.
Even the most pessimistic of the IPCC authors seem to think that about the years 2030-2040 are the earliest we might see an ice free period in the Arctic summer of the Arctic Ice. The reality suggests that is folly and that the focus on extent particularly, but also on area, has mislead us to dramatically underestimate the rate at which the world is changing.
And through it all, I believe that the evaluation of what the consequences of that are has been thoroughly missed. Our analyses tend to use variations on what is and to strenuously avoid looking at discontinuous shifts in state and the consequences of those.
It is well worth re-reading and thinking deeply about René Thom's 1960 mathematical treatise "La Théorie des Catastrophes". The treatise is about mathematics, not Arctic ice or the science of the Arctic. But it has potential application. The treatise portrays a series of complex mathematical formulations. Each shows and represents different fold structures for surfaces in multidimensional space which can and sometimes have been found at least in general form to represent real world behaviors in fields as diverse as hysteresis and the behavior of animals when cornered. The theory suggests a very different future than a linear or even exponential progression. It can be used to mathematically describe tipping points with state transitions into new domains, where once a threshold is truly crossed, the system enters a new state, and return to the old state cannot be had by simply backing up. There are huge policy warnings in the implications of that, which our scientific and political leaders seem not at all to grasp.
And depending on which of the many fold equations actually may apply to the transition to an ice free Arctic, one of the warnings is that this may not be the case of simply single state transition. This may result in multiple and successive state transitions, none of which can be reversed directly, and which ultimately take us to some distant and unrecognizable future set of conditions and dynamics. Attempting to return from any one of these to a previous state may itself invoke yet other domain transitions to new and unfamiliar dynamics and processes. Worse yet, we may not be likely to spend a great long time in any one of these, meaning that we may not get enough data to even understand what makes that domain stable, or how to try to stabilize there. We may instead embark on a series of catastrophic shifts, one after the other until we achieve some new stable or quasi-stable dynamic.
Or, if the actual conditions are well represented by the simplest equations we may simply see a large on-going shift from our current domain to a radically different domain. i.e. a tipping point.
Sam