Posted by: ericgrimsrud | September 7, 2017

Second 500-year weather event now upon us

As Hurricane Irma is about to arrive in South Florida, it is instructive to reread my comments on this blog posted about one year ago (see  In that post, the encouragement of the State of Florida for continued and even enhance residential construction in South Florida is related. Since the Governor of that state has been a hard-core denier of the detrimental effects of global warming, it will be interesting to see what spin he places on the effects of Irma.  I expect his response will be that the extraordinary strength of Irma was due entirely to natural causes and was not affected by mankind’s emissions of greenhouse gases into our atmosphere.  Assuming he cares about any other states in the USA, I suspect he will say the same about the origin of Hurricane Harvey in Texas.

Oh sure, Mother Nature caused these two 500-year extreme weather events in less than two weeks from each other without any assistance from the distinctly unnatural emissions of CO2 by human beings, right?  Going forward, Americans should beware of Florida’s snake-oil salesmen, such as Governor Scott.  They might soon be trying to sell you one of their state’s multitude of bridges, for example.  After all, they will soon become “bridges to nowhere” and Florida will need the proceeds of such sales for payments to the contractors who are still  building the infrastructures of South Florida’s latest coastal  communities.  If you need help in believing the existence of this twisted logic, you should read again my previous post indicated above.  Heaven help those Iowa pig farmers referred to there who are counting on retirement bliss in South Florida.



  1. Most “deniers” probably know – on som level – that they are wrong. Their pathology reminds one of anorexia, in that the patients display a total inability to acknowledge a fact that is obviously true for just about anyone else. They get excited about a few months of increasing icecover in the Arctic, fell confident of “victory” after some years of no GW, etc. But when the icecover and the global temperature resume their long term trends, they are unable to accept these observations and turn to new hopeful ideas.

  2. The conventional response to this issue is that no single weather event can be attributed to climate change. It is like a loaded dice that comes up with a six in more than 1/6 of the throws. No single event of getting a six can then be attributed to the fact that the dice was loaded.
    This conventional truth is only partly correct. If we would use high-speed cameras to accurately follow the motion of the dice, we may be able to state, after analyzing the last set of turns by the dice before it comes to rest, that if the dice had not been loaded, it would (given a certain initial state) not have come up with a six, but with, say, a two.
    The situation is similar with hurricanes and simulations of this type have been done. These shows unequivocally that the hurricanes are stronger that they would have been without global warming. Not that that should have come as a surprise. With warmer water the rate of evaporation increases and (given some additional restrictions of atmospheric conditions) the amount of energy that can be supplied to the hurricane will be larger. We regard to natural cycles, the AMO (Atlantic Multidecal Oscillation) is presently in the warm phase, so more energetic hurricanes are not unexpected. However, the global warming effect on surface waters in the Atlantic is already larger than the AMO!! Furthermore, the destructiveness of Harvey was largely due to the fact that it after landfall became nearly stationary. We have observed that the circumpolar jet stream has weakened, presumably due the dramatic warming in the Arctic. The stream has shown an increasing tendency to lock itself into stationary pattern – something that is not at all surprising for turbulent flows in general. For example, the whole of Europe was in such a locked situation all summer. The jet stream swept south in the East Atlantic and turned north over Easter Europe. The weather is the southeast was hot and the weather in Scandinavia was lousy. Every week of the summer! Normally, the system move with a lot of energy from west to east. The storms in the North Atlantic are not as strong as they used to be.
    Thus, it is not at all unlikely that without global warming, Harvey would have been quickly swept away from the Houston area.
    (Of course, should any of this prove to be wrong, I would be more than happy to revise my thoughts and opinions).

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