From Dr. Roy Spencer’s Global Warming Blog
by Roy W. Spencer, Ph. D.
A new paper by Santer et al. provocative”The exceptional contribution of the stratosphere to the human fingerprint of atmospheric temperature” went where no serious climate scientist should: it combined stratospheric cooling with global warming.
The article begins to summarize the supposed importance of their work, worth quoting in its entirety (emphasis added):
“The difference between troposphere and lower stratosphere temperature trends has long been recognized as a ‘fingerprint’ of human impact on climate. However, this fingerprint missed information from the middle to the stratosphere, 25 to 50 km above the Earth’s surface. Including this information improves human fingerprint detection by fivefold. Enhanced detection occurs because the mid to upper stratosphere has a large cooling signal from anthropogenic CO2 increases, small noise levels of natural internal variation as well as patterns different signals and noises. Extending the fingerprint to the upper stratosphere with long-term temperature records and improved climate models means that natural causes can now barely explain trends measured by satellites. in the thermal structure of the Earth’s atmosphere.“
The authors are taking advantage of the public’s lack of understanding of the temperature impact of increasing CO2 in the atmosphere, making it look like stratospheric cooling is part of the hallmarks of global warming.
It’s not. Cooling does not heat up.
The first mistake researchers make is claiming that they are reporting something new. They do not. The observed stratospheric cooling, even in the middle and upper stratosphere, has been reported for many years (e.g.: This). Lower stratospheric cooling has been demonstrated in our Lower Stratospheric (LS) temperature product for over 30 years (first publication). This). Why haven’t we heard of this before in the news? Because it has almost nothing to do with the topic of global warming and related climate change.
So why mention stratospheric cooling in the context of climate change?
Climate researchers have been searching for a “human fingerprint” of climate change for decades, something that can be measured but cannot be reasonably explained by natural variations in the system. climate.
I would agree with the authors that stratospheric cooling (especially in the mid to upper stratosphere) is probably the best evidence we have for human fingerprints, at least is in places where there is very little air, where there is no human habitation, and where there is no observable effect on the weather here, where life exists. Water vapor remains an uncertainty here, because more water vapor will also cool, and our understanding of the natural variations of water vapor in the stratosphere is rather poor. But for the sake of argument, I will concede the benefit of doubt to the authors and agree that most of the observed cooling is likely due to increased CO2, so it is likely. mainly due to burning fossil fuels.
Cooling of infrared radiation by water vapor and carbon dioxide has long been known to be the primary way in which the stratosphere (and even at higher altitudes) loses thermal energy (gained by absorption of sunlight from the sun). heaven of ozone) into outer space. This cooling mechanism is part of the so-called greenhouse effect: greenhouse gases that warm the lower altitudes of the planet’s atmosphere and cool the higher ones. In fact, without the greenhouse effect, weather as we know it won’t exist. The greenhouse effect is energetically similar to adding insulation to a heated house in winter: with a certain percentage of energy input, the inside of the house becomes warmer and the outside becomes warmer. the house becomes colder.
The stratospheric cooling effect of CO2 and water vapor was first theoretically described by Manabe and Strickler (1964). Adding more CO2 to the atmosphere enhances the cooling of the upper atmosphere, lowering the temperature. The temperature effect up there is huge, a few degrees Celsius, which means it’s easier to measure with current satellite methods, as the authors of the new study correctly point out.
But what then happens in the troposphere (where we live) in response to more CO2 is a lot more complicated. Theoretically, the addition of more CO2 would radiantly warm the lower troposphere. This warming is then mixed throughout the depths of the troposphere from the convective inversion (essentially “weather”).
But how much will tropospheric warming cause by increasing CO2?
After 30 years and billions of dollars spent on the efforts of research centers around the world, the latest climate models (CMIP6) currently disagree on how much stratosphere warming is expected. save more than ever. This is mainly because the effects of water are not fully understood, especially the response of clouds (the sun visor of the climate system) and precipitation processes (which limit the abundance of greenhouse gases). most, steam) for warming.
I consider it irresponsible to cool the stratosphere with global warming. Yes, a sharp cooling in the upper stratosphere could be a sign of increased CO2 in the atmosphere (supposedly due to burning fossil fuels), but for a variety of reasons, it’s not a reason to worry. trust climate models in their predictions of tropospheric (and therefore surface) warming trends. That’s a very different matter, and the models themselves suggest they haven’t completed the task, now disagreeing with each other on three or more parts.
So now hopefully you understand why naming an article like that.”Special contribution of the stratosphere to the human fingerprint of atmospheric temperaturebasically a no sequence on the issue of global warming.
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