So Let’s Talk About the Science of How Climate Change Kicked Harvey into Higher Gear

Harvey is finally on the move.

After making a second landfall early Wednesday, the storm is passing slowly out of the East Texas region that has suffered so much first from Harvey’s initial lashing as a rapidly intensifying category 4 storm, and second from its long-lasting and unprecedented rainfall.

(Harvey rapidly intensifies into a category 4 monster just prior to landfall. This rapid intensification and other climate change related factors helped to make Harvey a more dangerous storm. Image source: NASA.)

At this point we can take a bit of a step back to look at the larger situation. Sure, impacts will probably continue and even worsen for some areas. And due to a historic pulse of water heading downstream, the hammered city of Houston is far from out of the woods.

But as with Sandy and so many other freakish strong storms in a present climate that has warmed by around 1.2 C above pre-industrial values, we would be remiss if we didn’t discuss the climate change related factors that gave Harvey more fuel, that helped it to rapidly intensify, that worsened its flooding — both from rains and from storm surge, and that may have helped to produce a still pocket in the upper level winds that allowed it to stick around for so long.

Warmer Ocean Surfaces Mean More Rapidly Intensifying Storms, Higher Peak Intensity of Worst Storms

Hurricanes like Harvey cannot readily form in cool waters below a range between 70 and 75 degrees Fahrenheit. Ideally, the storms require ocean surface temperatures warmer than 80 degrees (F). And the more heat that’s available at the ocean surface, the more energy that’s available for a storm when it does form.

This energy comes in the form of atmospheric lift. In other words, air rises off the water more vigorously as water temperature rises. This lifting energy is called convection. And the more that’s available, the more powerful storms can ultimately become.

(Sea surface temperatures were between 1 and 2 degrees Celsius above average as Harvey approached Texas. Human-forced climate change is causing the oceans to warm. This, in turn, provides more fuel for hurricanes like Harvey — helping them to rapidly intensify and pushing their peak strength higher. Image source: NOAA.)

According to Dr Michael Mann, Ocean surfaces in the Gulf of Mexico are fully 1 to 1.5 degrees Celsius warmer, on average, than they were just 30 years ago. This warming provides more energy for storms that do form. And this, in turn, raises the top potential intensity of storms.

Some scientists, like Dr. James Hansen, refer to this prevalence of worsening extremity as loading the climate dice. If, in the past, we were rolling with a die six with a 1 representing the lowest storm intensity and a 6 representing the highest, we’re now rolling with something like a die six +1. The result is that the strongest storms are stronger and the absolutely strongest storms have an ability to achieve previously unattainable strengths due to the fact that there’s a lot more energy there to kick them into a higher state.

Increased potential peak storm intensity as a climate change factor does not necessarily result in more tropical storms forming overall. That part of the science on hurricanes is highly uncertain. But that heat engine in the form of warmer surface waters is available for the storms that do form to tap. And that can make them a lot stronger and more damaging than they otherwise would have been.

(Loading the climate dice — changes in frequency of cold and warm temperatures also has an impact on heatwaves, droughts, wildfires, storm intensity, and heavy precipitation events. Image source: NASA.)

As Harvey approached land, it tapped the energy of this much warmer than normal ocean surface. And that energy caused the storm to rapidly strengthen — first from a minimal tropical storm to a Hurricane, and then from a minimal hurricane to a Category 4 monster. Meteorologists tend to call such periods of rapid intensification — bombification. This term comes from minimum pressures that rapidly drop in swiftly strengthening storms — seeming to bomb out. And due to warming, the science indicates that rapid strengthening is also more likely. With some models pointing toward a 10-20 fold increase in the frequency of rapidly intensifying storms by the end of this Century if human forced warming of ocean surfaces continues.

Warmer Atmosphere Means Heavier Rainfall

Related to a warming of the ocean surface (and land surfaces as well) is the basic scientific fact that such warming causes the amount of water vapor in the atmosphere to increase. In total, with each 1 degree Celsius of warming near the Earth’s surface, the atmosphere ends up holding about 6-7 percent more moisture. The properties of this warming-driven increase in atmospheric moisture are described by the scientifically proven Clausius–Clapeyron relation which defines, in meteorology, how atmospheric water vapor content is driven by various factors, including temperature.

If we dig just a little bit further into our understanding of how this scientific driver impacts the atmosphere in a warmer world, we find that not only does the moisture content of a warmer atmosphere increase, but both the rates of evaporation and precipitation increase.


(Global warming has brought with it a sharp increase in the number of record-breaking daily rainfall events. This is due to the fact that a warmer world holds more storm-fueling moisture in its atmosphere. This warmer, wetter atmosphere increased the peak potential rainfall from Harvey enabling it to smash records for rainfall rates and precipitation totals. Image source: Increased Record-Breaking Precipitation Events Under Global Warming.)

It is here that we return to the loaded climate dice mentioned above. If, as we find today, the Earth is about 1.2 degrees Celsius warmer than in the past, then the atmosphere holds more moisture. About 7-8 percent more. And since there’s more heat, evaporation is more intense where it does happen. This loads the climate dice for more intense droughts. But since what goes up in the form of evaporation results in a heavier load of moisture in the higher clouds and in the storms that do form, the rains that follow will also tend to be more intense. This loads the dice for more severe rainfall events. And we have a very clear scientific observation that the most extreme rainstorms are becoming much more intense overall (see above graphic).

For Harvey, this meant that more moisture was available to provide the record-setting rainfall amounts coming from that system. Peak rainfall totals from the storm are now at nearly 52 inches. This is the most rainfall ever to occur in Texas from a tropical system in our records. A measure that may also break the all-time U.S. record for rainfall from a tropical storm. And Harvey was enabled to produce such high rainfall amounts by a warmer atmosphere.

Harvey a Brown Ocean Cyclone?

Increasing rates of evaporation and precipitation had one obvious effect in Harvey — they increased the potential severity of rains coming from this kind of storm. But they also increase the ability of storms like Harvey to maintain strength or even intensify over land. If, for example, a storm like Harvey dumps a very heavy load of rainfall over land and if the evaporation from these recent rains has increased in a warming world, then storms like Harvey can tend to draw strength back from what amounts to a small ocean on land.

A recent NASA scientific paper on this issue describes a Brown Ocean effect. The 2013 NASA paper noted:

Before making landfall, tropical storms gather power from the warm waters of the ocean. Storms in the newly defined category derive their energy instead from the evaporation of abundant soil moisture – a phenomenon that Andersen and Shepherd call the “brown ocean.”

…The research also points to possible implications for storms’ response to climate change. “As dry areas get drier and wet areas get wetter, are you priming the soil to get more frequent inland tropical cyclone intensification?” asked Shepherd.

In essence, cyclones are better able to maintain strength or even re-intensify over wet areas of land in a warmer world due to increasing levels of evaporation and it was Harvey’s ability to maintain tropical storm strength over land for up to three days that helped to enable it to keep dropping such heavy volumes of rain.

Higher Seas Mean Worse Storm Surge Flooding

A warmer climate also brings with it the melt of continental glaciers and the thermal expansion of ocean waters. As glaciers flood into the world’s oceans, they rise. And since fossil fuel burning began at the start of the industrial age this related warming of the Earth and melting of glaciers has caused the oceans around the world to rise by more than 20 centimeters globally.

(Global warming increases the base ocean level which, in turn, worsens storm surge flooding. Harvey’s storm surge came in on this higher ramp. Image source: Sea Level Rise Science.)

Such higher seas alone are causing some coastal settlements to flood even on sunny days. But when storms like Harvey come roaring ashore, they do so on a higher overall launching pad. And this produces a multiplier effect for storm surge damages. A multiplier that would not have been there if the world hadn’t warmed.

Polar Warming Contributes to Blocking Patterns That Make Weather Stick Around in One Place Longer

Another climate change related factor that contributed to Harvey’s danger was its persist hovering over the same region. Harvey would not have been as damaging for Texas and the Gulf if it hadn’t hung over East Texas for more than five days. But here, again, we find that climate change related factors appear to be contributing to the increased lingering of various extreme weather producing systems.

To understand how, we need to look at the upper level atmospheric circulation pattern that moves weather systems from place-to-place. In other words — the Jet Stream. Climate change influences the Jet Stream by generating more warming at the poles than near the Equator. This in turn, according to the research of scientists like Dr Jennifer Francis, changes atmospheric slope. Warmer poles, in other words, create a taller atmosphere at the poles relative to the Equator.

(A high amplitude ridge-trough pattern helped to create a stagnant upper air slot in which Harvey stalled. This voiding of upper level steering currents enabled Harvey’s persistence. Some scientists are pointing toward increasing prevalence of these kinds of high amplitude ridges and troughs related to polar warming warming which is an upshot of global warming. Image source: Earth Nullschool.)

Since atmospheric slope and temperature differences between the poles and Equator drive the speed of the Jet Stream, warmer poles cause the Jet Stream to slow down and meander. This generates big ridges and deep troughs. It also appears to assist the generation of large blocking high pressure systems. And all of these features can tend to cause weather patterns to get stuck.

This year, a persistent trough in the Eastern U.S. has generated a consistent stormy pattern and aided in the firing of powerful thunderstorms that produced record rains over places like Kansas City, Missouri. In the West, a persistent ridge has produced record heat and very extreme wildfires while aiding the formation of a very intense flash drought in Montana and the Dakotas. Harvey got stuck in a stagnant pocket between these two relatively fixed weather patterns. A climate change related feature that may have increased the duration of Harvey and facilitated its record rains falling over such a long period.

Other Factors — Interaction With The Eastern Trough

Finally, we can state that Harvey’s interaction with the very deep eastern trough also helped to fuel it. The trough provided a moisture and instability kick to Harvey as it moved over Texas — helping to wring out tropical moisture over the Lone Star State. And if we accept the fact that polar warming contributed to the depth of this eastern trough by slowing down the Jet Stream, then its interaction with Harvey was also a climate change related factor.

Qualifying This Discussion

What can be said with certainty is that climate change did not cause the hurricane. That hurricanes do happen in a normal climate. But this is the same same thing as saying that home runs happen in both middle school and major league baseball. It’s all baseball, but the factors from one to the other have qualitatively changed in an obvious fashion. The same thing happens to weather in a warming world. And it is due to the changes in these underlying factors that we can say without a doubt that climate change made Harvey worse.

What we can also say is that our certainty of all these various climate change related factors involved varies. For example, we can say with very high certainty that global warming is worsening rainfall extremes and that sea level rise is worsening storm surges. We can say with a good level of confidence that the peak intensity of the worst storms is also increasing and that bombification is more likely. And we can say with moderate confidence that climate change is altering atmospheric circulation patterns (an issue that is still under considerable debate).

But the varying degrees of certainty with regards to these aspects do not change basic facts. Your climate is your weather averaged over 30 years. And if the world warms, both your climate and your weather change.

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  1. Related


    • eleggua

       /  August 30, 2017

      “The path forward shouldn’t be clearer. Except, perhaps, for the morally conflicted.” –
      Robert Fanney‏ @robertscribbler 2h


  2. wharf rat

     /  August 30, 2017

    Hurricane Ted Cruz drowns Houston?

    350 Action: Name Hurricanes After Climate-Change Deniers …
    Aug 26, 2013 – Activist Group: Hurricanes Should be Named after Michele Bachmann and Marco Rubio

    Liked by 1 person

    • Maybe Hurricane Exxon… It was an excellent proposed action aimed at holding those responsible accountable. Too bad it didn’t go through. Now it’s down to lawsuits and other forms of all-too-appropriate public shaming.


    • Esquire Magazine considered this commercial perhaps The Greatest Commercial of All Time. I doubt the authors of the campaign and literally expected to legislate renaming hurricanes after lawmakers. It was a message all in itself to inform the public about climate denial by our elected policy makers. Sadly, it just gets better as disasters get worse.


  3. eleggua

     /  August 30, 2017

    Great stuff, Robert. Thank you for being on top of things and keeping us so well informed and aware.

    ‘The Energy 202: We asked Texas Republicans about Harvey and climate change. Only one answered.’
    By Dino Grandoni August 30 at 9:02 AM

    When members of Congress from Texas return to work next week, the fallout from Harvey, likely the worst disaster to ever hit the state, will follow them back to Washington.

    Unless it is reauthorized by the end of September, the National Flood Insurance Program, which is nearly $25 billion in debt, will lose most of its borrowing power at a time when it will begin making payouts on claims on the Texas Gulf Coast. And President Trump has promised to work with Congress on a federal aid package for affected communities in Texas.

    From Bloomberg’s Jennifer Epstein:

    Jennifer Epstein


    Harvey aid “going to be a costly proposition,” Trump says, mentioning Cruz & Cornyn. “I think we’ll come through with the right solution.”
    1:56 PM – Aug 29, 2017

    But that aid request puts many Texas Republicans in Congress in a bind four years in the making. In 2013, all but one Texas Republican who was serving in Congress then and is still in office now voted against an aid package for New York and New Jersey following Hurricane Sandy.

    “The congressional members in Texas are hypocrites,” New Jersey Gov. Chris Christie (R), a Trump ally, said this week. “I said back in 2012, they’d be proven to be hypocrites. It was just a matter of time.” See a clip below:

    hristie took direct aim at Sen. Ted Cruz (R-Tex.), who voted against Sandy help four years ago, today on “Morning Joe:”

    Jennifer Jacobs


    Chris Christie on “Morning Joe” raked Ted Cruz for saying 2/3 of Hurricane Sandy relief bill was pork. “He made it up” and “he knows it.”
    4:45 AM – Aug 30, 2017

    The Energy 202 reached out all 38 members of Texas delegation to ask about that and other issues related to Harvey (follow The Post’s comprehensive coverage here) as they prepare to return to Washington.

    Only one Republican, Rep. Lamar Smith, responded to defend his 2013 vote.

    “It is my hope that our funding package for aiding those affected by Harvey doesn’t include funding unrelated to damage caused by the storm,” said Smith, who is the chairman of the House Science Committee and a frequent critic of federal climate scientists. “The Sandy bill was used as an opportunity for fiscally irresponsible politicians to exploit natural disaster spending in order to fund pet projects with taxpayer money.”

    In 2013, many Republicans derided the Sandy aid bill as being laden with spending provisions unrelated to the hurricane, such as fixes to the Smithsonian Institution in Washington, D.C., and the Kennedy Space Center in Florida.

    On MSNBC this week, Cruz claimed that “two-thirds of that bill had nothing to do with Sandy.” (Cruz’s office did not reply to The Post’s request for comment.)

    However, fact checkers have pointed out that a Congressional Research Service report on the bill concluded that it “largely focused on responding to Hurricane Sandy.”

    Texas’s other senator and the No. 2 Senate Republican, John Cornyn, also defended his Sandy vote, noting that he did approve a smaller, $9.7 billion increase in the Federal Emergency Management Agency’s borrowing power before rejecting the larger $50.5 billion aid package. (Cornyn’s office also didn’t reply.)

    Patrick Svitek


    Cornyn tells reporters he’s talked w/ WH about Congress first making a “down payment” on Harvey aid and they seem “sympathetic” to the plan.
    2:28 PM – Aug 29, 2017

    Texas Democrats, however, criticized their Republican colleagues for voting against the Sandy package and said they agreed with scientists who say climate change increases the severity of disasters like Harvey.

    “Natural disasters know no party, and it was regrettable that Texas Republicans played politics with the Hurricane Sandy aid package in their time of need,” Rep. Marc Veasey (D-Tex.) said.

    Calling from a school in his Houston-area district that has been converted into a shelter, Rep. Al Green (D-Tex.) added that Congress should pass an aid package not only to help the people of Texas, but “because we want every American to know that your government is going to be there for you in a time of crisis.”

    The lone Republican “yes” vote from the Lone Star State for that Sandy bill came from Rep. John Abney Culberson, whose district encompasses parts of Houston and its suburbs.

    On the question of climate change, Republicans from Texas were also mute.

    Meanwhile, the six Texas Democrats who responded to The Post’s request for comment — Reps. Joaquin Castro, Henry Cuellar, Lloyd Doggett and Eddie Bernice Johnson along with Green and Veasey — agreed with scientists who say climate change increases the severity of disasters like Harvey.

    “The flooding in Houston caused by Harvey marks the third ‘500-year’ flood to hit the city in the past three years,” said Johnson, who serves with Smith on the House Science Committee as its top Democrat. “It is hard to believe these catastrophic events can be occurring so frequently by chance.”

    However, Smith pointed to an interview that Bill Read, the former director of the National Hurricane Center, gave on CNN, in which Read declined to attribute the Harvey’s intensity to climate change.

    “This is not an uncommon occurrence to see storms grow and intensify rapidly in the western Gulf of Mexico,” Read said. “That’s as long as we’ve been tracking them, that has occurred.”

    Indeed, climate scientists say singling out this one hurricane as a global-warming-driven anomaly would be a mistake. But they also argue that climate change can worsen the hurricanes that do occur.

    “The storm is a bit more intense, bigger and longer lasting than it otherwise would be,” Kevin Trenberth, a climate researcher with the National Center for Atmospheric Research in Boulder, Colo., told The Post over the weekend.

    As for the National Flood Insurance Program, The Post’s Mike DeBonis offers this breakdown:

    Even before stormwaters swept across metropolitan Houston, debate on how to restructure the NFIP exposed fissures in Congress that crossed traditional partisan lines, pitting conservatives who want to scale back the government costs for the program against lawmakers from flood-prone regions wary of jacking up their constituents’ premiums.

    “Leaving millions of homeowners without flood insurance is not an option,” Castro, a Texas Democrat, said. “Congress must either modify the program in a way that keeps rates affordable or simply pass an extension of the current program.”

    Meanwhile, Harvey made landfall for a second time early Wednesday as a tropical storm in Louisiana. The storm hit west of Cameron, La., around 4 a.m. local time, according to the National Hurricane Center. The center predicted another 3 to 6 inches of rain would fall from southwestern Louisiana and between the area near the border with Texas and into western Kentucky, with “isolated amounts up to 10 inches.” The center warned of “catastrophic and life-threatening flooding” that would continue in and around Houston and into southwest Louisiana for the remainder of the week.
    You are reading The Energy 202, our must-read tipsheet on energy and the environment.
    Not a regular subscriber?



    • Well, the republicans have been terrible on this issue. And so far they haven’t paid the price. It’s partly due to the fact that the public has been slow to wake up on climate change. But the other thing that republicans rely on is people not paying attention to what they actually do with legislation. Once people realize how bad this legislative agenda has been, there will be hell to pay for republicans.


      • eleggua

         /  August 30, 2017

        ‘Charlie Sykes Is Unsure About the Future of the G.O.P.’
        AUG. 21, 2017
        (From 1993 to 2016, Sykes hosted a conservative talk show on WTMJ in Milwaukee, Wisconsin. He is also the editor of Right Wisconsin which he co-owns with WTMJ’s parent company E. W. Scripps.)

        “…I’m less upset with Trump himself than watching all the other conservatives who decided to roll over and support him. The real horror for me is watching people who I thought were principled conservatives become sycophantic propagandists for this guy.”

        “NYT: How do you think the elevation of hard-liners has affected the party?

        Sykes: I wake up every day in disbelief. It’s not that just that Donald Trump is president. It’s that he has empowered the worst people in the world: people who would’ve been regarded as misfits and crackpots just a few years ago. We’re being tested in a fundamental way, and I think we operate in a system that simply assumes that you have honorable people who will be constrained within political norms. Now they’re being violated on a daily basis. I don’t think America comes out on the other end of this unaffected. We’re not immune to history.

        NYT: Is the Republican Party done for?

        Sykes: It’s a moral, intellectual and political defining moment for the party. I just don’t see any long-term future if they don’t confront this. All this reveals something deeply troubling about the party itself but maybe also reveals something very troubling about what the electorate wants.

        NYT: If Republican elected officials won’t change the party, who do you think will?

        Sykes: This is the moment where the business community could play a decisive role. If American industry pushes back in tangible ways, that’s something Republicans can’t resist.

        NYT: I’m assuming you’re not surprised by Trump’s inability to condemn the white-supremacist march.

        Sykes: I’m shocked but not surprised. Denouncing Nazis is the easiest thing in the world: All it requires is a modicum of historical perspective and a working moral compass. Instead, we got this Dumpster fire.”


  4. Note that with the temperature anomaly graphs, the probability of “Extremely Hot Summers” (3 standard deviations above normal or “3-sigma”) have increased ~50X in the past 50 years so when a 3-sigma event happens, you can say there was a ~98% chance that it was caused by global warming. If we had similar probability distribution charts for rain events, I’m sure the probabilities would be similar (that’s why “500-year events” are common now).


  5. wili

     /  August 30, 2017

    I didn’t click on all the links in the text of your post, so apologies if these have already been reference (and thanks to jaim at asif for drawing these to my attention):

    Why Harvey Is Stuck Near Texas

    “Hurricanes gain strength from warmer oceans, but climate change might be causing another problem higher in the sky.

    In March, Mann and several colleagues published a study in the journal Scientific Reports that demonstrates a relationship between extreme events, such as the 2011 Texas drought and 2010 Pakistan flooding, and a rare stationary phase that upper atmospheric currents sometimes go through in the mid-latitudes.

    Stefan Rahmstorf, a co-author of that paper and head of Earth Systems Analysis at the Potsdam Institute for Climate Impact Research, explained that there may really be several things going on. In general, the jet stream, the high-flying river of air that flows west-to-east, has slowed and gone all wavy in recent summers, with pronounced north-south meanders. That’s one thing that may have helped hold Harvey in place. Researchers have sparred since 2012 over whether Arctic warming, which is occurring at twice the global average, is driving this atmospheric wobble, consequently creating more opportunities for persistent weather farther south.

    In a number of extreme cases analyzed by their paper—California drought, Russia’s 2010 heatwave and Pakistan’s related flood—the meandering north-south river of the jet-stream stabilizes for periods of time in some places, creating an insurmountable wavelike band. The researchers looked for some kind of misbehavior in atmospheric circulation after realizing that heat-related effects alone couldn’t explain the extreme nature of some disasters.”


  6. Reblogged this on sdbast.


  7. eleggua

     /  August 30, 2017

    Hurricane Harvey Coverage LIVE on CBSN


  8. coloradobob

     /  August 30, 2017

    At the Beaumont-Port Arthur Airport, 26.03” of rain fell on Tuesday, which is more than double Beaumont’s previous calendar-day record of 12.76″ on May 19, 1923, in records going back to 1901. Between 10 pm last night and 1 am this morning, 11.86” fell. So far on Wednesday, 4.71” has been reported (as of 11 am CDT), bringing their 5-day storm total rainfall to a staggering 47.98”.


  9. eleggua

     /  August 30, 2017

    This video was posted by commentors Vic and CD to Robert’s previous article here.
    It’s worth a look, in case you missed it.

    ‘Mainstream Media Misrepresents Hurricane Harvey’s Climate Change Connection’
    Aug 29, 2017

    “It’s “extremely annoying when all of these extreme events occur, whether it’s a wildfire or an extreme hurricane like this, and there’s no mention of the fact that climate change has actually exacerbated the situation,” says Dr. Kevin Trenberth of the National Center for Atmospheric Research”


  10. coloradobob

     /  August 30, 2017


    While most Americans are fixated on Hurricane Harvey, which continues to break rainfall records since making landfall along the coast on Friday, an even deadlier disaster is unfolding in South Asia. Across Nepal, Bangladesh, and India, an exceptionally strong monsoon season has left almost 1,200 dead and displaced or affected tens of millions more. Heavy rains led to unprecedented landslides and floods—as much as a third of Bangladesh is under water—leaving communities cut off as they face food and fresh water shortages and disease threats that will remain long after the water recedes.


  11. coloradobob

     /  August 30, 2017

    Houston floods have created massive colonies of floating fire ants


  12. coloradobob

     /  August 30, 2017

    New study: We’re outpacing the most radical climate event we know of
    Lots of carbon got dumped into the atmosphere 56 million years ago.



    This article shows an interesting but often overlooked cause of the intensification of the strongest hurricanes. As the troposphere warms, the stratosphere cools, and the greater temperature differential fuels the heat engines that are hurricanes.


  14. Greg

     /  August 30, 2017

    Thank you for this Robert. A well written story you’ll have to tell over and over again, unfortunately.
    “this is the same same thing as saying that home runs happen in both middle school and major league baseball.” Amen.


  15. Leland Palmer

     /  August 31, 2017

    Very interesting and informative. Thank you for all you do, Robert.

    This hovering in place behavior of hurricanes may be an emergent property of our destabilizing climate system. This hovering in place behavior could possibly become much more common, it seems. Our weather machine sometimes…gets stuck, these days, it looks like. Chaos is entering the stratosphere.

    The colder stratosphere heat engine explanation for possibly increasing hurricane severity seems plausible, sad to say. I had read about the colder stratosphere, but hadn’t made the possible connection to hurricanes. This blog is a great place to be exposed to such ideas.

    The idea that we can predict such complicated interactions of our climate system before they occur seems kind of dubious.


    • Leland Palmer

       /  August 31, 2017

      Just watched the Kevin Trenberth video above. He says that, no, the storm tracks of hurricanes are primarily determined by the weather at the time, I think.. So, whether this hovering in place behavior is an emergent property of a destabilizing climate system is an open question, according to Trenberth.


    • Leland Palmer

       /  September 1, 2017

      Maybe I’m just too ignorant to say this, but I’ll say it anyway. To me, it seems like Keven Trenberth and scientists like Michael Mann are talking past one another on the issue of whether this possibly emergent stalling behavior of hurricanes is more likely now under global warming than it used to be. Since this is possibly new behavior, there is naturally going to be some controversy and free exchange of ideas and opinions.

      Trenberth seems to be saying that hurricane tracks are determined by factors traditionally associated with weather – jet streams, blocking high pressure areas and so on. Mann and Francis seem to be saying that global warming is having a statistical effect on factors traditionally associated with weather, like strength of jet streams, persistence of loops in the jet stream and Rossby waves, and chaotic behavior of the jet stream. Some of these now statistically more common weather phenomena might affect hurricane tracks, according to Mann, is my understanding.

      I lean toward Mann, not saying that means anything:

      Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events


  16. As a visual indication of the tremendous heat moved by Harvey, an arc of ocean along the Texas coast is now really blue, about -2C cooler than normal.



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