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RE: Scott Adams' "Are hurricanes confirmation of catastrophic climate change?"gdp writes on the forum:
The RRND RSS-feed links to Scott Adams' blog posting "Are the Hurricanes and Temperature Records Confirmation of Catastrophic Climate Change?", in a word, "No."
Adams asks:
First, Harvey was not a "super-hurricane" --- and indeed, it never even made it past "Category 4." Harvey was merely the first hurricane to make U.S. landfall since 2005, thereby ending the so-called "hurricane drought" (note that Sandy was no longer classified as a "hurricane" when it made landfall), and the reason why Harvey was so extraordinarily damaging was that it was so extraordinarily slow-moving, not because it was "strong." Most hurricanes simply die when they hit land, since landfall deprives them of their "fuel," which is warm water. By contrast, Harvey reached the Gulf Coast, and then simply sat there, slowly drifting east --- and as long as the southwestern flank of a hurricane is still over warm water, it keeps getting fed. So Harvey sat there and spun, and spun, and spun, and continued dumping water on the Gulf Coast and causing a lot of damage because it simply refused to die.
As for Irma, while it is a record-breaking storm, as the old saying says, "records are made to be broken" --- and indeed there is an entire branch of statistics called "Extreme-Value Theory" that studies the statistics of "record-breaking events." What is important regarding "record-breaking" is not that a particular "record" was broken, but rather the pace at which records are broken. Extreme-Value theory allows one to make predictions about the mean time before the current record is likely to be broken, so if "record-breaking" events consistently arrive sooner that expected, it's a signal that something out of the ordinary may be happening.
Extreme-value theory is not often used in meteorology, and to the best of my knowledge it has not yet been systematically applied to hurricane intensities. (However, actuaries and others have applied extreme-value theory to hurricane damages (see e.g. this 1.5M PDF), and concluded that the series of "record" hurricane damages prior to the "hurricane drought" said more about people stupidly insisting on moving to the hurricane zone and on building more stuff in the path of hurricanes than it did about increases in hurricane intensity (see e.g. this 1.7M PDF by Pielke et al).)
Adams writes:
Adams is correct that "science doesn’t know one way or another", at least with regard to hurricanes. Hurricanes are complex "self-organizing" systems that are still poorly understood, and there is no consensus even among "Warmists" as to whether "Global Warming" will increase or decrease their intensity. Hurricanes are "heat engines" that are fueled by water-vapor and driven by the temperature difference between the ocean boundary-layer and the tropopause; however, they only occur when the atmosphere is so vertically unstable that it can't get rid of the available heat any other way. While there is a general consensus that a warmer ocean surface leads to more water-vapor in the ocean boundary-layer (ocean boundary-layer air is always close to "saturated" with water-vapor, and it is a basic law of physics called the "Clausius–Clapeyron relation" that saturation vapor content increases exponentially with temperature), it is not yet well-understood even by "Warmists" whether "Global Warming" will increase or decrease the vertical stability of the atmosphere, nor the temperature difference between the surface and the tropopause.
There is also the countervailing factor of "Wind Shear"; hurricanes are self-organized vertical convection systems, and are therefore destroyed by vertical wind-shear (i.e., wind-speeds that are larger at high altitudes, or pointing in a different direction). There is no general consensus even among "Warmists" on whether "Global Warming" will increase or decrease vertical wind-shear. On the one hand, "Global Warming" is supposed to disproportionally increase polar temperatures (which the data do suggest is occurring), thereby decreasing the temperature-contrast between the equator and the poles. Horizontal winds and the latitudinal "cells" or "belts" of air-circulation are basically "heat engines" that convert the equator-to-pole temperature difference into winds, so a smaller equator-to-pole temperature-contrast would, all else being equal, lead to decreased surface winds. The latitudinal airflow aloft is basically just the "return flow" for the latitudinal surface winds, so decreased surface-winds might be expected to decrease the "North-South" component of "wind-shear," all else being equal.
OTOH, "East-West" wind-shear is another matter entirely. The upper atmosphere "super-rotates" (rotates west-to-east faster than the surface), one manifestation of which is the "Jet Streams." "Atmospheric superrotation" is still poorly understood (364K PDF), and there is no consensus even among "Warmists" on whether a warmer ocean surface will increase or decrease atmospheric superrotation, and therefore the longitudinal (East-West) component of vertical wind-shear.
(Of course, science is based on data, not "consensus." But a lack of "consensus" is an indicator of a lack of theory, i.e., that the phenomenon in question is not yet considered "well-understood.")
So the bottom line is, not even the "Warmists" can agree on whether "Global Warming" will increase or decrease either the number of hurricanes nor their intensity.
With regard to surface-temperature record-breaking, the same caveat on "record-breaking" and Extreme-Value Theory applies: Almost none of the analyses of the "pace" of surface-temperature record-breaking have made use of Extreme-Value Theory, but have instead invoked various "ad hoc" statistical methods, so it's not clear whether the pace of "record-breaking" is "statistically significant" or not. Moreover, the surface-temperature data are confounded by a decreasing number of observation stations, an increase in the relative fraction of "urban" over "rural" observing stations, and contamination by use of computer-models to "homogenize" the temperature data by replacing data that appear to be "outliers" with "modeled" values, or to fill in data that are "missing" or at locations or grid-cells where there are no observing stations. So at this point it's almost impossible to say whether the frequent reports of "record-breaking temperatures" are statistically significant or not.
The RRND RSS-feed links to Scott Adams' blog posting "Are the Hurricanes and Temperature Records Confirmation of Catastrophic Climate Change?", in a word, "No."
Adams asks:
Has science updated its opinion to say the two super-hurricanes and our heat extremes are indeed a credible signal of the beginning of a climate catastrophe?
First, Harvey was not a "super-hurricane" --- and indeed, it never even made it past "Category 4." Harvey was merely the first hurricane to make U.S. landfall since 2005, thereby ending the so-called "hurricane drought" (note that Sandy was no longer classified as a "hurricane" when it made landfall), and the reason why Harvey was so extraordinarily damaging was that it was so extraordinarily slow-moving, not because it was "strong." Most hurricanes simply die when they hit land, since landfall deprives them of their "fuel," which is warm water. By contrast, Harvey reached the Gulf Coast, and then simply sat there, slowly drifting east --- and as long as the southwestern flank of a hurricane is still over warm water, it keeps getting fed. So Harvey sat there and spun, and spun, and spun, and continued dumping water on the Gulf Coast and causing a lot of damage because it simply refused to die.
As for Irma, while it is a record-breaking storm, as the old saying says, "records are made to be broken" --- and indeed there is an entire branch of statistics called "Extreme-Value Theory" that studies the statistics of "record-breaking events." What is important regarding "record-breaking" is not that a particular "record" was broken, but rather the pace at which records are broken. Extreme-Value theory allows one to make predictions about the mean time before the current record is likely to be broken, so if "record-breaking" events consistently arrive sooner that expected, it's a signal that something out of the ordinary may be happening.
Extreme-value theory is not often used in meteorology, and to the best of my knowledge it has not yet been systematically applied to hurricane intensities. (However, actuaries and others have applied extreme-value theory to hurricane damages (see e.g. this 1.5M PDF), and concluded that the series of "record" hurricane damages prior to the "hurricane drought" said more about people stupidly insisting on moving to the hurricane zone and on building more stuff in the path of hurricanes than it did about increases in hurricane intensity (see e.g. this 1.7M PDF by Pielke et al).)
Adams writes:
My working hypothesis is that science doesn’t know one way or another whether the current weather extremes are predictive of things to come. And if they are not yet sure, they would say as much. And that would be a problem for news organizations dedicated to reporting climate science risks as real and dire.
Adams is correct that "science doesn’t know one way or another", at least with regard to hurricanes. Hurricanes are complex "self-organizing" systems that are still poorly understood, and there is no consensus even among "Warmists" as to whether "Global Warming" will increase or decrease their intensity. Hurricanes are "heat engines" that are fueled by water-vapor and driven by the temperature difference between the ocean boundary-layer and the tropopause; however, they only occur when the atmosphere is so vertically unstable that it can't get rid of the available heat any other way. While there is a general consensus that a warmer ocean surface leads to more water-vapor in the ocean boundary-layer (ocean boundary-layer air is always close to "saturated" with water-vapor, and it is a basic law of physics called the "Clausius–Clapeyron relation" that saturation vapor content increases exponentially with temperature), it is not yet well-understood even by "Warmists" whether "Global Warming" will increase or decrease the vertical stability of the atmosphere, nor the temperature difference between the surface and the tropopause.
There is also the countervailing factor of "Wind Shear"; hurricanes are self-organized vertical convection systems, and are therefore destroyed by vertical wind-shear (i.e., wind-speeds that are larger at high altitudes, or pointing in a different direction). There is no general consensus even among "Warmists" on whether "Global Warming" will increase or decrease vertical wind-shear. On the one hand, "Global Warming" is supposed to disproportionally increase polar temperatures (which the data do suggest is occurring), thereby decreasing the temperature-contrast between the equator and the poles. Horizontal winds and the latitudinal "cells" or "belts" of air-circulation are basically "heat engines" that convert the equator-to-pole temperature difference into winds, so a smaller equator-to-pole temperature-contrast would, all else being equal, lead to decreased surface winds. The latitudinal airflow aloft is basically just the "return flow" for the latitudinal surface winds, so decreased surface-winds might be expected to decrease the "North-South" component of "wind-shear," all else being equal.
OTOH, "East-West" wind-shear is another matter entirely. The upper atmosphere "super-rotates" (rotates west-to-east faster than the surface), one manifestation of which is the "Jet Streams." "Atmospheric superrotation" is still poorly understood (364K PDF), and there is no consensus even among "Warmists" on whether a warmer ocean surface will increase or decrease atmospheric superrotation, and therefore the longitudinal (East-West) component of vertical wind-shear.
(Of course, science is based on data, not "consensus." But a lack of "consensus" is an indicator of a lack of theory, i.e., that the phenomenon in question is not yet considered "well-understood.")
So the bottom line is, not even the "Warmists" can agree on whether "Global Warming" will increase or decrease either the number of hurricanes nor their intensity.
With regard to surface-temperature record-breaking, the same caveat on "record-breaking" and Extreme-Value Theory applies: Almost none of the analyses of the "pace" of surface-temperature record-breaking have made use of Extreme-Value Theory, but have instead invoked various "ad hoc" statistical methods, so it's not clear whether the pace of "record-breaking" is "statistically significant" or not. Moreover, the surface-temperature data are confounded by a decreasing number of observation stations, an increase in the relative fraction of "urban" over "rural" observing stations, and contamination by use of computer-models to "homogenize" the temperature data by replacing data that appear to be "outliers" with "modeled" values, or to fill in data that are "missing" or at locations or grid-cells where there are no observing stations. So at this point it's almost impossible to say whether the frequent reports of "record-breaking temperatures" are statistically significant or not.
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