Hurricane Harvey - wettest ever. Irma - strongest ever (maybe). And now Grayson. Is this global warming in action?

BG9 said:

Possibly:

Harvey was almost certainly more intense than it would have been in the absence of human-caused warming, which means stronger winds, more wind damage and a larger storm surge. (As an example of how this works, we have shown that climate change has led to a dramatic increase in storm surge risk in New York City, making devastating events like Hurricane Sandy more likely.)

Finally, the more tenuous but potentially relevant climate factors: part of what has made Harvey such a devastating storm is the way it has stalled near the coast. It continues to pummel Houston and surrounding regions with a seemingly endless deluge, which will likely top out at nearly 4ft (1.22m) of rainfall over a days-long period before it is done.

The stalling is due to very weak prevailing winds, which are failing to steer the storm off to sea, allowing it to spin around and wobble back and forth. This pattern, in turn, is associated with a greatly expanded subtropical high pressure system over much of the US at the moment, with the jet stream pushed well to the north. This pattern of subtropical expansion is predicted in model simulations of human-caused climate change.

https://www.theguardian.com/commentisfree/2017/aug/28/climate-change-hurricane-harvey-more-deadly

Stoppppppppppppppppppppppppp

Yes, warmer waters amplify the hurricane's ability to grow in strength. But the main question here lies solely within the steering flow. Does climate change influence the placement of the jets? Ultimately? Maybe. But those are long term average positions of the jets. These jets are transient in nature and are moving constantly. We can not attribute any one give event, aside from maybe the water temperature to AGW. Period. That having been said, if you look at the season average GOM SSTs (below), they are actually roughly 0.5º above average. Not exactly a huge anomaly. The Hurricane intensified as it traveled over something known as a "warm eddy" in the gulf. It was a very localized warm patch of water similar to what allowed Katrina to intensify so quickly. 

This issue has become so politicized that it's neglecting science. I can flip this the other way pretty easily. Per something known as the thermal wind relation, the vertical shear of the atmosphere is directly proportional to the north to south temperature gradient. Water warms/cools slower than land. So lets say we heat the water and it stays warm. But the land itself doesn't do that. Now we've amplified the thermal gradient. Warmer than average water, same temperature on land. This in turn must, by immutable physics, increase the vertical shear of the atmosphere. Vertical shear kills hurricanes. You can have a 9000º GOM but 50 knots of shear in the same location will kill any chance of a hurricane. 

Finally, once again, the locations of the jets are to be expected. They are seasonally normal. I'd be far more concerned with them if they were that south this late in the summer. That would to me be a lot weirder than where they were. 

Additionally, and this goes for the both comments posted before this one. The ocean heat content, a measure of the vertically integrated heat within a layer of the ocean and a good indicator of maximum tropical cyclone strength, lessened drastically as Harvey approached the shore. This was due simply to the water becoming more shallow due to the continental shelf and is totally normal. Interestingly enough however, the hurricane went into arguably its most rapidly intensifying phase during that time. So It effectively went over colder water and continued to strengthen. Why? The answer is the upper air pattern above it was so favorable for strengthening, that it continued to do just that. Theres a lot more to this than just warm water people, but that's all that the non-scientists pushing this stuff can feed you.

This is again the problem here. People are keying on to things that they otherwise wouldn't have thought about and calling it abnormal. None of whats happening on a large scale here is abnormal, aside from the hurricane. Hurricanes are, by their very definition, abnormal within the flow field. If one wants to make the argument that perhaps we see more stationary hurricanes in a warmed climate, then fine. But there is no numerical or observational data to back that up, and once again, a single point can not define the mean. Yes, this is yet another event that is occurring within the public eye. Hurricane Patricia, the strongest Hurricane in Pacific Basin history hit Mexico a couple years back. Why was there no fuss then? We don't have a dataset that can verify the claims that this is a warming driven event. The burden of proof is on those who are insisting that it is. But if you're going to try to prove it, make sure you understand the science top to bottom first, and not simply what some op-ed writer in the Atlantic is trying to scare you into thinking. Climate change is real. But to call this a symptom of that is short-sighted and dangerous. 

this was exactly my point.  This thread started with an overtly political accusation -- this specific event is thanks to Republicans and other deniers.

And making it political, and making it specific to one event allows the deniers to use real science to come up with a strong rebuttal. It's giving them an easy way to continue to muddy the waters on the global warming debate.

Of course we should be talking about larger trends and probabilities of calamities worsened by global warming.  But we lose the argument when we try to blame Sandy or Harvey specifically on global warming.

WxNut2.0 said:

This issue has become so politicized that it's neglecting science. I can flip this the other way pretty easily. 

WxNut2.0: Thank you for bringing your expertise to this discussion. BG9's and Elle_Cee's recent posts made me wonder if you could clarify or elaborate on two points (if you get a chance and think it'd be helpful). 

The jet stream: BG9's post suggested that the prevailing winds (or lack of them) may be related to climate change. You indicated they were an expected seasonal pattern, right?

The water temperature: The average is an average, allowing for temps significantly above and below the mean. How unusual are gulf temps as high as those that intensified Harvey? (An observation of my own: The 30 years of records that never recorded a gulf storm that intensified before landfall like Harvey don't seem like a very large sample size in climate time.)

ETA: Cross-posted. You may have beaten me to it. I'll read up on your latest comment.

ETA II: Yup. Thanks again.

DaveSchmidt said:

WxNut2.0: Thank you for bringing your expertise to this discussion. BG9's and Elle_Cee's recent posts made me wonder if you could clarify or elaborate on two points (if you get a chance and think it'd be helpful). 

The jet stream: BG9's post suggested that the prevailing winds (or lack of them) may be related to climate change. You indicated they were an expected seasonal pattern, right?

The water temperature: The average is an average, allowing for temps significantly above and below the mean. How unusual are gulf temps as high as those that intensified Harvey? (An observation of my own: The 30 years of records that never recorded a gulf storm that intensified before landfall like Harvey don't seem like a very large sample size in climate time.)

ETA: Cross-posted. You may have beaten me to it. I'll read up on you latest comment.

ETA II: Yup. Thanks again.

Yes, the expected changes to the jet positions are seasonal/long term averages. The location of the jets currently is to be expected. Far north in the summer. And as for the water temps, they aren't very unusual at all. The fact is, we went through a 12 year period without a significant hurricane in the GOM at all (with the exception of cat. 2 Ike in 2008, not a major). During that time, AGW was happening and water temps were high. Why no hurricanes then? There's more to this story. Thats my whole point.

ml1 said:

this was exactly my point.  This thread started with an overtly political accusation -- this specific event is thanks to Republicans and other deniers.

And making it political, and making it specific to one event allows the deniers to use real science to come up with a strong rebuttal. It's giving them an easy way to continue to muddy the waters on the global warming debate.

Of course we should be talking about larger trends and probabilities of calamities worsened by global warming.  But we lose the argument when we try to blame Sandy or Harvey specifically on global warming.

WxNut2.0 said:

This issue has become so politicized that it's neglecting science. I can flip this the other way pretty easily. 

This is yet another example of why Trump won unfortunately. We have so much polarization within politics that we lose sight of reality. We also have a glut of people who are self-proclaimed experts in everything. Trump won based upon the idea that he, a "normal" guy, was going to go in an fix all the things the experts couldn't because he knew better. Surprise! He doesn't. I despise the guy as much as anyone, but this phenomenon is not distinct to only the conservative movement, as this thread has proven. 

WxNut2.0 said:

 

This is yet another example of why Trump won unfortunately. We have so much polarization within politics that we lose sight of reality. We also have a glut of people who are self-proclaimed experts in everything. Trump won based upon the idea that he, a "normal" guy, was going to go in an fix all the things the experts couldn't because he knew better. Surprise! He doesn't. I despise the guy as much as anyone, but this phenomenon is not distinct to only the conservative movement, as this thread has proven. 

So, if we take this well-stated opinion, along with Drummerboy's assertion that Republicans caused the intensity of Harvey, we can also likely attribute Trump's win to the likes of Drummerboy.  

That actually makes some sense.  But a zealot like him would never recognize that or admit to that.  Political zealots on both sides of the discussion have too little self awareness for that.

ice said:

WxNut2.0 said:

 

This is yet another example of why Trump won unfortunately. We have so much polarization within politics that we lose sight of reality. We also have a glut of people who are self-proclaimed experts in everything. Trump won based upon the idea that he, a "normal" guy, was going to go in an fix all the things the experts couldn't because he knew better. Surprise! He doesn't. I despise the guy as much as anyone, but this phenomenon is not distinct to only the conservative movement, as this thread has proven. 

So, if we take this well-stated opinion, along with Drummerboy's assertion that Republicans caused the intensity of Harvey, we can also likely attribute Trump's win to the likes of Drummerboy.  

That actually makes some sense.  But a zealot like him would never recognize that or admit to that.  Political zealots on both sides of the discussion have too little self awareness for that.

Can't tell if this is sarcasm or not. But either way, point is simply that people are experts in their fields for a reason. I don't purport myself to be a brain surgeon, just like drummerboy shouldn't be purporting himself to be someone well versed in the dynamics of the atmosphere. Trump won because he convinced a lot of dumb people he was an expert in everything. And now that over-zealous self-confidence seems to have become the norm in our country. Anyone who reads anything about anything knows everything about everything. 

I thought we were supposed to blame Obama for everything.

ice said:

So, if we take this well-stated opinion, along with Drummerboy's assertion that Republicans caused the intensity of Harvey, we can also likely attribute Trump's win to the likes of Drummerboy.  

That actually makes some sense.  But a zealot like him would never recognize that or admit to that.  Political zealots on both sides of the discussion have too little self awareness for that.

WxNut2.0 said:

BG9 said:

Possibly:

Harvey was almost certainly more intense than it would have been in the absence of human-caused warming, which means stronger winds, more wind damage and a larger storm surge. (As an example of how this works, we have shown that climate change has led to a dramatic increase in storm surge risk in New York City, making devastating events like Hurricane Sandy more likely.)

Finally, the more tenuous but potentially relevant climate factors: part of what has made Harvey such a devastating storm is the way it has stalled near the coast. It continues to pummel Houston and surrounding regions with a seemingly endless deluge, which will likely top out at nearly 4ft (1.22m) of rainfall over a days-long period before it is done.

The stalling is due to very weak prevailing winds, which are failing to steer the storm off to sea, allowing it to spin around and wobble back and forth. This pattern, in turn, is associated with a greatly expanded subtropical high pressure system over much of the US at the moment, with the jet stream pushed well to the north. This pattern of subtropical expansion is predicted in model simulations of human-caused climate change.

https://www.theguardian.com/commentisfree/2017/aug/28/climate-change-hurricane-harvey-more-deadly

Stoppppppppppppppppppppppppp

You can say Stoppppppppppppppppppppppppp.

But I really tend to give credence to the guy who wrote the above article:

• Michael E Mann is distinguished professor of atmospheric science at Pennsylvania State University, director of the Penn State Earth System Science Center and author of three books, including The Hockey Stick and The Climate Wars, Dire Predictions, and The Madhouse Effect.

https://en.wikipedia.org/wiki/Michael_E._Mann

Here's another one:

Hurricane Harvey Was No Surprise

written by

Noah S. Diffenbaugh is a professor of earth system science at Stanford.

BG9 said:

WxNut2.0 said:

BG9 said:

Possibly:

Harvey was almost certainly more intense than it would have been in the absence of human-caused warming, which means stronger winds, more wind damage and a larger storm surge. (As an example of how this works, we have shown that climate change has led to a dramatic increase in storm surge risk in New York City, making devastating events like Hurricane Sandy more likely.)

Finally, the more tenuous but potentially relevant climate factors: part of what has made Harvey such a devastating storm is the way it has stalled near the coast. It continues to pummel Houston and surrounding regions with a seemingly endless deluge, which will likely top out at nearly 4ft (1.22m) of rainfall over a days-long period before it is done.

The stalling is due to very weak prevailing winds, which are failing to steer the storm off to sea, allowing it to spin around and wobble back and forth. This pattern, in turn, is associated with a greatly expanded subtropical high pressure system over much of the US at the moment, with the jet stream pushed well to the north. This pattern of subtropical expansion is predicted in model simulations of human-caused climate change.

https://www.theguardian.com/commentisfree/2017/aug/28/climate-change-hurricane-harvey-more-deadly

Stoppppppppppppppppppppppppp

You can say Stoppppppppppppppppppppppppp.

But I really tend to give credence to the guy who wrote the above article:

• Michael E Mann is distinguished professor of atmospheric science at Pennsylvania State University, director of the Penn State Earth System Science Center and author of three books, including The Hockey Stick and The Climate Wars, Dire Predictions, and The Madhouse Effect.

https://en.wikipedia.org/wiki/Michael_E._Mann

Thanks, Im familiar with Michael Mann. He's cherry picking plenty of things here and neglecting to mention that LONG TERM AVERAGES DO NOT EXPLAIN TRANSIENT EVENTS. So again, while you've read a single article written by Michael Mann, I can pretty easily refute those claims, as I did. I've had several discussions with professors in my department, again, one who is the former director of the NSF geophysical branch and another who was involved in writing the IPCC report, and both think it's ridiculous. Who's your primary source here?

And to the second article you linked to: where have all the other intense tropical cyclones been over the past 12 years? I'll wait.

STOP ATTRIBUTING TRANSIENT EVENTS TO LONG TERM OSCILLATIONS THAT YOU AREN'T INTIMATELY FAMILIAR WITH. STOP.

I understand the desire to attribute something in the here and now to global warming.  It's attention-getting.  And there's also the tendency within human nature not to care about things that aren't immediate, and aren't going to affect us personally.  Why should we care about the effects of global warming if it's going to cause us inconvenience now, and the worst of it won't happen until we're long gone, if it happens at all?

I get why it might be satisfying to say to a Texas Republican -- still think global warming is a hoax?  Still think we shouldn't do anything about it even as your house washes away?

But the reality is that it's not known whether or not that Texan's house washed away because of global warming.

This. No responsible scientist would disagree.

ml1 said:

I understand the desire to attribute something in the here and now to global warming.  It's attention-getting.  And there's also the tendency within human nature not to care about things that aren't immediate, and aren't going to affect us personally.  Why should we care about the effects of global warming if it's going to cause us inconvenience now, and the worst of it won't happen until we're long gone, if it happens at all?

I get why it might be satisfying to say to a Texas Republican -- still think global warming is a hoax?  Still think we shouldn't do anything about it even as your house washes away?

But the reality is that it's not known whether or not that Texan's house washed away because of global warming.

I'll say it again. If we start seeing these storms every year, with impacts like this every year, then sure, attribute away. But don't use a single data point to define the time series. It doesn't work like that.

WxNut2.0 said:

I'll say it again. If we start seeing these storms every year, with impacts like this every year, then sure, attribute away. But don't use a single data point to define the time series. It doesn't work like that.

It's not a single data point, though. I know it's too soon to see a definite pattern, but we have been told to expect bigger extremes, and we are seeing bigger extremes. Andrew in 1993, Floyd in 1999, some more in Florida whose names and years I can't remember, Katrina in 2005, the Halloween storm in 2010, Irene in 2011, Sandy in 2012, and now Howard. For the time being, the degree of certainty in predictions is lower, but clearly we are seeing new things happen. We need to (1) be prepared for the new trends and (2) see what we can do to reverse the trends.

You could not be more wrong about most of these assertions. The strongest Hurricane in US history was in 1935. One of only two landfalling official cat. 5's was in 1969, the other was 1992 (Andrew). Every one of those storms that you mentioned is unique and can not be binned into one category. And for what its worth, Harvey was arguably the most well predicted tropical cyclone in the modern era. The north american GFS model had its minimum central pressure off by one millibar and its landfall location dead on. You are only mentioning storms that are memorable to you. That's not a pattern, sorry.

And again: This was the first major hurricane in the GOM since 2005. If we're all about extremes, where did they go. Stop.

Tom_Reingold said:

WxNut2.0 said:

I'll say it again. If we start seeing these storms every year, with impacts like this every year, then sure, attribute away. But don't use a single data point to define the time series. It doesn't work like that.

It's not a single data point, though. I know it's too soon to see a definite pattern, but we have been told to expect bigger extremes, and we are seeing bigger extremes. Andrew in 1993, Floyd in 1999, some more in Florida whose names and years I can't remember, Katrina in 2005, the Halloween storm in 2010, Irene in 2011, Sandy in 2012, and now Howard. For the time being, the degree of certainty in predictions is lower, but clearly we are seeing new things happen. We need to (1) be prepared for the new trends and (2) see what we can do to reverse the trends.

Also, since we're on the topic: what exactly made Katrina so memorable? Why do you remember it? Do you know what its intensity upon landfall was?

As for Sandy btw, that storm was not exceptional. It behaved in a way that was pretty expected and it was predicted almost a week out. It impacted an area close to home, so you view it as extreme. NYC was overdue for a storm like that, and the geometry of the coastline accentuated its impacts. Had a similar storm hit somewhere else in the country, you might not even remember its name.

Certainly my perspective plays a big part in my perception. I know I can't categorize these storms accurately, so I follow what you're saying. At least I think I do. Even though we were, as you say, "due" for Sandy, it was still unusual for us. If we don't have another like it for another hundred or so years, then calling it not unusual makes sense. But if we do, then, it's something else.

There is no question that predictions have become more accurate. It is still fashionable to ridicule the science even though it has improved vastly.

Tom_Reingold said:

Certainly my perspective plays a big part in my perception. I know I can't categorize these storms accurately, so I follow what you're saying. At least I think I do. Even though we were, as you say, "due" for Sandy, it was still unusual for us. If we don't have another like it for another hundred or so years, then calling it not unusual makes sense. But if we do, then, it's something else.

There is no question that predictions have become more accurate. It is still fashionable to ridicule the science even though it has improved vastly.

The fact that there hadn't been a significant tropical (ish) storm landfalling near NYC for a long time is almost more out of the ordinary. The point simply remains, don't make attributions based upon conjecture. Could Harvey be influenced? Maybe. Is it likely? Not sure. Is it definite? Absolutely not.

If your point is that we can't be sure with attributions, sure, I already felt that way.

I remember Hurricane Agnes in 1972 and Hurricane Gloria in 1985. Just wondering, do you call them significant? And what is a long time for you?

My point is and has been that we can't attribute Harvey to climate change. Its necessary vs. sufficient conditions. Is AGW sufficient for intensifying hurricanes? Sure. Is it necessary. No way.

Agnes was a cat. 1, not very significant. Gloria was a cat. 2 at landfall in NJ, slightly more significant. But again, its all about perspective here. To someone in Miami, a cat. 1 looks a lot different than to someone in NJ.

"A marked decline in the number of large storm deposits, which began around 600 years ago, has persisted through present with below average frequency over the last 150 years when compared to the preceding five millennia."

A several thousand year study of hurricane frequency. Granted, this is for one location in particular, but its also one of the more hurricane prone locations in the world. Can't be taken as the gospel, but still pretty significant when looking at how things shake out.

http://www.sciencedirect.com/science/article/pii/S0025322711001472?via%3Dihub

Just for some perspective, Agnes is actually a great example.  It wiped out 80% of my home town the day I was supposed to graduate 8th grade, so yeah, it was memorable. 

The Chemung/Susquehanna valley has a history of flooding.  '23, '35, '48 were some of the bigger ones.  After '48 the Corps of Engineers built massive earthworks along the rivers from just west of Corning all the way to Harrisburg.  They built two large flood control dams on the tributaries...almost had them finished by '72.  So people soon forgot about floods, and started building in the flatlands that used to be farm fields.  Binghamton and Wilkes Barre in particular developed areas that had not been heavily built up before.  The railroads consolidated, and the most level main lines, the ones through the river valleys, were the ones that were kept.

Then the rain came.  Agnes was only a 100-year flood.  But those not-quite-finished dams?  They didn't hold.

Those earthworks?  They failed, too.  And where they didn't fail, they funneled the water into the narrower parts of the valley, like at Wilkes Barre.

Most of the water went where the water usually went in floods.  The high water marks followed the floodplains almost exactly.  But because we had developed the floodplains so much since the last big one in 1948, the effects were greatly magnified.  The train lines were wiped out, and both the Erie-Lackawanna and the Lehigh Valley went bankrupt, the EL as a direct result of the flood.  Because we had thought it couldn't happen again, we had gotten out of practice at evacuation.  Because we trusted the dams, what would have been a gradual 12 hour rise became a wall of water that scraped the valley clear.

Agnes had nothing to do with global warming,  yet the significance was entirely man-made.

And spotting the difference is key. As was previously noted, the build up of Houston has reduced ground-permeability. That is a man made impact right there that the flooding can be more directly attributed to.

WxNut2.0 said:

And spotting the difference is key. As was previously noted, the build up of Houston has reduced ground-permeability. That is a man made impact right there that the flooding can be more directly attributed to.

I would note that the people who are most apt to support policies that promote development with little or no regulation are also most apt to be Climate Change deniers.  (Not an exact correlation, but ...)

Sure, but thats a different argument.

sac said:

WxNut2.0 said:

And spotting the difference is key. As was previously noted, the build up of Houston has reduced ground-permeability. That is a man made impact right there that the flooding can be more directly attributed to.

I would note that the people who are most apt to support policies that promote development with little or no regulation are also most apt to be Climate Change deniers.  (Not an exact correlation, but ...)

WxNut2.0 said:

Sure, but thats a different argument.

And as you like to point out, there are many possible factors, and it's silly to point to just one. On the other hand, it is fair to say that the anti-regulation individualistic sentiment has its perils, and I think Howard is showing that.

Tom_Reingold said:

WxNut2.0 said:

Sure, but thats a different argument.

And as you like to point out, there are many possible factors, and it's silly to point to just one. On the other hand, it is fair to say that the anti-regulation individualistic sentiment has its perils, and I think Howard is showing that.

Look Im on board with most everyone here regarding anti-regulation climate change deniers like Scott Pruitt. Don't get me wrong.

I appreciate that.   

Tom_Reingold said:

WxNut2.0 said:

Sure, but thats a different argument.

And as you like to point out, there are many possible factors, and it's silly to point to just one. On the other hand, it is fair to say that the anti-regulation individualistic sentiment has its perils, and I think Howard is showing that.

Is there a reason you keep calling Harvey, Howard?

max_weisenfeld said:

Is there a reason you keep calling Harvey, Howard?

Simple absentmindedness. Harvey. Is that better?