Some brutal storms over the past year or so, such as the recent one that dropped 1-2 feet of snow from Tulsa to Chicago and beyond with sometimes hurricane force winds, have been labeled with all sorts of monikers, “Frankenstorm”, “snowmageddon”, etc., to emphasize how bad, and perhaps, how unique they were. Some incautious observers have assigned such events to signs of global warming. Moreover, there have been seemingly oxymoronic, perhaps ad hoc statements due to recent record cold spells that purport that it will be getting colder as it gets warmer (that is, we’ll have more severe cold winters as global warming progresses).
The impact of global warming to date is “relatively” slight, and no one can discern that a particular flood, typhoon, tornado, drought, that cloud over there, etc., was due to global warming.
We meteorologists know that “what goes around comes around”; that the “50 year”, the “100 year” floods will recur. Namely, we know that extreme events will occur without the need to implicate global warming.
Furthermore, proxy climate records, such as tree rings that are rather good at delineating past droughty and wet periods–they are problematic in reconstructing temperature–but, you can get quite a good handle on the precipitation regimes of the past few hundred years. These, too, can tell us about the extremes of past climate over hundreds of years, and therefore, what to expect in the future sans global warming effects.
Perhaps one of the most important papers published in this proxy climate domain in this writer’s opinion was in 1994. It was a study of rainfall epochs deduced from tree rings in central California by Haston and Michaelsen, published in J. Climate. It is fortunate that this study was published before the global warming “media blitz” in which otherwise reasonable people/media assign all kinds of anomalous weather events to signs of global warming.
What was the main conclusion of that J. Climate paper regarding rainfall regimes over the past 600 years in California???
It was astonishing.
The authors concluded that the California water retention and flood control infrastructure had been built based on an unusually low degree of climate variability during the instrumental record, largely confined to the period after 1900. The longer tree ring record, however, CLEARLY indicated that much LARGER fluctuations in the rainfall regimes of California had occurred prior to the instrumental record. These findings led the authors to suggest that California was not likely to be well prepared for the floods and droughts of the future since it can be assumed that larger variability in rainfall found in the past will occur in the future.
The record rains of the 1997-98 El Nino and 2004-2005 rainfall seasons accompanied by an almost unheard of water flows into the basins of Death Valley in 2005,and the “unprecedented” drought of the 2001-2002 rainfall season in which some coastal southern California sites received less than 2 inches (!) were largely foretold by those 1994 findings. Moreover, due to the “teleconnection” aspect, the larger climate variance found in central California prior to record keeping can be expected to have repercussions in the adjacent states.
What “goes around”, has already begun to come around.
But in today’s world, these anomalous weatther events will not be seen as just, “what goes around comes around”, but rather will be labeled en toto as evidence of the pernicious effects of global warming.
That’s just plain wrong, and most meteorologists understand this.
The extreme events of late, if you are onboard the GW bandwagon, could reasonably have been said to have been “tweaked” by GW at best. Perhaps without GW, that snowstorm in Chicago would have dropped “only” 18.3 inches instead of 20 associated with overall slightly higher temperatures and the attendant enhanced moisture content.
The late Prof. Joanne Simpson, former president of the American Meteorological Society, warned, in the early days of global warming claims in 1989, claims that many scientists were dubious of at that time, about the dangers of exaggeration. She recounted her experiences with the exaggerated claims promulgated in the cloud seeding domain in which she worked. In her talk at the Conference on Statistics and Probabilty in the Atmosphere, Monterrey, 1989, and as President-elect of the American Meteorological Society, Dr. Simpson warned:
“Lacking that lesson, our community has once again stumbled into the weather modification paradox concerning global warming-where again we may be damaging our credibility again for the same basic reason.
“What is the weather modification paradox? It is the tendency to exaggerate man-made alterations to the atmosphere owing to the great difficulty in distinguishing definitively between natural variability in the system and anthropogenic effects-whether the perceived man-made change is small-scale rain produced produced by intentional cloud seeding or whether in it long-range global warming as a by-product of industry and agriculture.”
and, near the end of her talk that day, she re-emphasized this point:
“While it is not entirely clear what the decision makers of the world can and should do, I hope at least that we meteorologists have learned some hard lessons. I hope that we have learned enough from the harm that we and our colleagues have caused over the years by exaggerated claims and exaggerated scare stories. I hope that we will be more cautious in how we express ourselves, especially to the media–that is a difficult challenge to say the least.”
Joanne Simpson was not too skeptical about a global warming future, but she was concerned about how we spoke to the public about it.
PS: Prof. Simpson’s full address, which she provided to me soon after it was delivered, can be found here: all of Joanne Simpson’s banquet talk wx mod and GW_1989.
BTW, and unexpectedly, global temperatures have stabilized over the past 10 years or so in spite of continuing increases in CO2, as many of you knowWhat happened to GW_Sci_Oct 2, 2009. One explanation posited for this is a drying of the stratosphere, something that would allow more of the earth’s heat to escape into space–Solomon et al. 2010, Science). Another explanation for at least part of this “stabilization” arises from an climate model using recent ocean current data. The output from this model predicted that cooling of the northern hemisphere continents was due to a recent slowing of Atlantic Ocean currents, and furthermore, that this slowing and continental cool spell was likely to last 10-20 more years (Keenleyside et al. 2008 in the journal Nature, summarized by Richard Kerr in Science). Finally, we have an aerosol “wild card” out there. Aerosols are thought to have the net effect of lowering global temperatures, but the models used by the IPCC4 were only able to crudely parameterize those effects. One down-sized climate model (20-25 km grid spacing instead of 200-250 km), in preliminary runs has suggested a larger role for aerosols in cooling the planet, a kind of inadvertent “geoengineering.” (These latter results have not been published that I know of, and so this comment can only be considered little more than gossip at this time, but it was from a good “insider” source.)
However, imagine how pathetic such a smoggier world would be, with smog everywhere, views of the Grand Canyon mucked up, even thin, smog-laden stratocu looking dark and ugly on the bottom as as more light was reflected back into space from their tops due to smaller drops, etc. Getting upset here even thinking about how awful that smoggier, less warm, world would be! Don’t “geoengineer” in this way!!!