by Judith Curry
This week I am at the Fall Meeting of the American Geophysical Union in San Francisco.
The website for the meeting is [here]. The meeting is huge, with over 20,000 attendees, so it is difficult to take in even a small fraction of what is going on. Here are some highlights that I encountered, either at the meeting or from the virtual meeting website, and blog reports (notably the Yale Forum, which has a large number of posts on selected highlights).
The ‘new’ AGU
The YaleForum has an article on this entitled The New AGU . . . Talking up its Policy Backbone. The subtitle is “AGU leadership professes its willingness to head-up an aggressive public policy and ‘education’ campaign directed at congressional skeptics.” Some excerpts from the Yale Forum article:
[Chris] McEntee [AGU Executive Director] had spoken formally during her presentation about having AGU lead an effort involving major scientific societies in “educating” Congress on what unquestionably is an overwhelming consensus among climate scientists on a full range of issues. AGU earlier had led the groups in bringing leading society officials to Washington on climate change issues, but the new effort seems destined to go beyond that in intensity and duration, including strategic targeting of specific legislators.
“It’s not something the old AGU would do,” Rutgers’ Alan Robock said from the floor, but McEntee’s statements received overwhelmingly favorable reaction from those in attendance.
I am 200% opposed to this new level of activism by the AGU, but I seem to be in the minority among AGU members.
Renowned British climate scientist Sir Robert Watson pulled few punches today during a talk about the warmer world humans will face in coming decades.
Watson, who was IPCC chair from 1997 to 2002, all but dismissed the possibility of keeping the rise in average global temperatures to 2 degrees Celsius above pre-industrial levels — a temperature rise that corresponds to an atmospheric concentration of CO2 of 450 parts per million. It now stands at about 390 ppm.
Average global temperatures could rise 2 to 7 degrees C by the end of the century, driving a litany of environmental changes, Watson said. Already, the climate of the 2020s and 2030s already is locked in, or as Watson put it, “pre-ordained.” “Therefore, we must adapt,” he said.
“The only way to get to a 2 degree world is to de-carbonize immediately, and I see no political signs we’re doing this …. We need moral leadership and political will, and they are in short supply.”
I have to wonder about Watson’s basis for all this certainty.
The Atmospheric Sciences section Charney lecture was given by Drew Shindell, titled Mitigating near term climate change while advancing human development. Shindell’s ideas were discussed previously on a Climate Etc. thread Climate fast attack plan. Shindell gave an excellent presentation and this plan makes a lot of sense to me.
Unfortunately, Shindell is getting a lot of push back for this idea from many climate scientists, who think that this strategy should not be adopted because it will detract from implementing CO2 stabilization policies. Its a good thing the climate scientists aren’t in charge of policy.
The Tyndall Lecture was given by Ray Pierrehumbert, entitled Successful Predictions. I did not attend this lecture, but I suspect it will be of interest to many of you.
My (invited) talk was titled ‘Impact of declining Arctic sea ice on Northern Hemisphere Weather [curry agu]. I would be interested in any comments on this.
JC’s best poster award
Most of the posters presented at AGU can be found online. While I only viewed a small fraction of the posters, I was particularly struck by one of the posters in the Nonlinear Geoscience group:
For all natural hazards, the question of when the next “extreme event” (c.f. Taleb’s “black swans”) is expected is of obvious importance. In the environmental sciences users often frame such questions in terms of average “return periods”, e.g. “is an X meter rise in the Thames water level a 1-in-Y year event ?”. Frequently, however, we also care about the emergence of correlation, and whether the probability of several big events occurring in close succession is truly independent, i.e. are the black swans “bunched”ù. A “big event”ù, or a “burst”ù, defined by its integrated signal above a threshold, might be a single, very large, event, or, instead, could in fact be a correlated series of “smaller”ù (i.e. less wildly fluctuating) events. Several available stochastic approaches provide quantitative information about such bursts, including Extreme Value Theory (EVT); the theory of records; level sets; sojourn times; and models of space-time “avalanches”ù of activity in non-equilibrium systems. Some focus more on the probability of single large events. Others are more concerned with extended dwell times above a given spatiotemporal threshold: However, the state of the art is not yet fully integrated, and the above-mentioned approaches differ in fundamental aspects. EVT is perhaps the best known in the geosciences. It is concerned with the distribution obeyed by the extremes of datasets, e.g. the 100 values obtained by considering the largest daily temperature recorded in each of the years of a century. However, the pioneering work from the 1920s on which EVT originally built was based on independent identically distributed samples, and took no account of memory and correlation that characterise many natural hazard time series. Ignoring this would fundamentally limit our ability to forecast; so much subsequent activity has been devoted to extending EVT to encompass dependence. A second group of approaches, by contrast, has notions of time and thus possible non-stationarity explicitly built in. In record breaking statistics, a record is defined in the sense used in everyday language, to be the largest value yet recorded in a time series, for example, the 2004 Sumatran Boxing Day earthquake was at the time the largest to be digitally recorded. The third group of approaches (e.g. avalanches) are explicitly spatiotemporal and so also include spatial structure. This presentation will discuss two examples of our recent work on the burst problem. We will show numerical results extending the preliminary results presented in [Watkins et al, PRE, 2009] using a standard additive model, linear fractional stable motion (LFSM). LFSM explicitly includes both heavy tails and long range dependence, allowing us to study how these 2 effects compete in determining the burst duration and size exponent probability distributions. We will contrast these simulations with new analytical studies of bursts in a multiplicative process, the multifractal random walk (MRW). We will present an analytical derivation for the scaling of the burst durations and make a preliminary comparison with data from the AE index from solar-terrestrial physics. We believe our result is more generally applicable than the MRW model, and that it applies to a broad class of multifractal processes.
I have asked Nicholas Watson to send me his papers, I plan on doing a thread on his work in a future post.
AGU gives out a plethora of awards each year. The new Fellows are listed [here]. Additional awards from the Atmospheric Sciences section are found [here]. I’ll take this opportunity to brag about three of my colleagues at Georgia Tech who are receiving awards at this meeting:
- Josef Dufek, Macelwane Award
- Athanasios Nenes, Atmospheric Sciences Ascent Award
- James Belanger, Natural Hazards Focus Group Award for Graduate Research