Arctic “Amplification” Not What You Think

H\T to Dr. David Whitehouse writing at GWPF regarding a recent study claiming Arctic Amplification is causing a wavey polar vortex, resulting in winter warming and cooling extremes.  His critique is Extreme cold snaps and global warming: A speculative explanation.

This post is challenging the notion of Arctic Amplification itself.  The term is bandied about with the connotation that man-made global warming is multiplied in the Arctic and responsible for weather extremes.

As the animation above shows, there have been in recent years alternating patterns of unusually cold or warm weather in the Northern Hemisphere.  There are several problems in the attempt to link these events to global warming/climate change, that is claiming causation for a slow increase in baseline global average temperatures.

  1. Arctic Amplification is an artifact of Temperature Anomalies
  2. Arctic Surface Stations Records Show Ordinary Warming
  3. Arctic Warmth Comes from Meridional Heat Transport, not CO2

Clive Best provides this animation of recent monthly temperature anomalies which demonstrates how most variability in anomalies occur over northern continents.

1. Arctic Amplification is an artifact of Temperature Anomalies

Beyond the issues with the measurements and the questionable adjustments, there is a more fundamental misconception about air temperatures in relation to “climate change.” Clive Best does a fine job explaining why Global Mean Temperature anomalies do not mean what people think. Below is my synopsis of his recent essay entitled Do Global Temperatures make sense? (link)

Background: Earth’s Heat Imbalance

ERBE measurements of radiative imbalance.

The earth’s temperature at any location is never in equilibrium. It changes daily, seasonally and annually. Incoming solar radiation varies enormously especially near the poles which receive more energy per day in summer than the equator.

The earth cools primarily by moving heat from hot tropical regions towards high latitudes where net IR radiation loss cools the planet, thus maintaining a certain temperature profile.

Key Point: GMT Anomalies Are Dominated by the Highest Latitudes

The main problem with all the existing observational datasets is that they don’t actually measure the global temperature at all. Instead they measure the global average temperature ‘anomaly’. . .The use of anomalies introduces a new bias because they are now dominated by the larger ‘anomalies’ occurring at cold places in high latitudes. The reason for this is obvious, because all extreme seasonal variations in temperature occur in northern continents, with the exception of Antarctica. Increases in anomalies are mainly due to an increase in the minimum winter temperatures, especially near the arctic circle. 

To take an extreme example here is the monthly temperature data and calculated anomalies for Verkoyhansk in Siberia. Annual temperatures vary from -50C in winter to +20C in summer. That is a seasonal range of 70C each year, and a year to year anomaly variation of ~8C is normal. The only global warming effect evident is a slight increase in the minimum winter temperatures since 1900. That is not due to any localised enhanced greenhouse effect but rather to an enhanced meridional heat transport. Temperatures in equatorial regions meanwhile have only ~4C seasonal variations, and show essentially no warming trend.

2. Arctic Surface Stations Records Show Ordinary Warming

Locations of 118 arctic stations examined in this study and compared to observations at 50 European stations whose records averaged 200 years and in a few cases extend to the early 1700s

A recent extensive analysis of Northern surface temperature records gives no support for Arctic “amplification” fears.

The Arctic has warmed at the same rate as Europe over the past two centuries. Heretofore, it has been supposed that any global warming would be amplified in the Arctic. This may still be true if urban heat island effects are responsible for part of the observed temperature increase at European stations. However, European and Arctic temperatures have remained closely synchronized for over 200 years during the rapid growth of urban centres.

And the warming pattern in Europe and the Arctic is familiar and unalarming.

Arctic temperatures have increased during the period 1820– 2014. The warming has been larger in January than in July. Siberia, Alaska and Western Canada appear to have warmed slightly more than Eastern Canada, Greenland, Iceland and Northern Europe. The warming has not occurred at a steady rate. Much of the warming trends found during 1820 to 2014 occurred in the late 1990s, and the data show temperatures levelled off after 2000. The July temperature trend is even slightly negative for the period 1820–1990. The time series exhibit multidecadal temperature fluctuations which have also been found by other temperature reconstructions.

The paper is: Arctic temperature trends from the early nineteenth century to the present W. A. van Wijngaarden, Theoretical & Applied Climatology (2015).  My synopsis: Arctic Warming Unalarming

3. Arctic Warmth Comes from Meridional Heat Transport, not CO2

Key Point: Heat Distribution Changes, not Global Temperatures

Rising CO2 levels modify that radiation imbalance profile slightly. Surface temperatures in the tropics are not really warming at all. Any excess heat induces more clouds and more convection while surface temperatures remain constant. What really happens is that the meridional radiation profile changes. Slightly more heat is transported polewards so that hot places are shifting more heat to cold places which are doing the warming. If CO2 levels stop rising then a new temperature and radiation profile would rather quickly be reached. This is then called ‘climate change’ but any such changes are concentrated in colder regions of the world. The global ‘temperature’ itself is not changing, but instead the global distribution of temperature is changing.

Key Point: More Atmospheric Heat means Warming in the Coldest Places

Temperatures at the poles during 6 months of darkness would fall well below -150C if there was no atmosphere, similar to the moon. Instead heat is constantly being transported from lower latitudes by the atmosphere and ocean and so that temperatures never fall much below -43C. If more heat is transported northwards than previously, then minimum temperatures must rise, and this is what we observe in individual measurements.

Long term changes in temperature anomalies occur mainly in northern continents in winter months. This is not because the earth as a whole is warming up but rather that meridional heat transport from the equator to the poles has increased and the largest effect on ‘anomalies occurs in winter. The average absolute temperature of the earth’s surface is unknown. Basing the evidence for climate change on the 150 year trend in global averaged temperature anomalies still biases the result towards higher latitudes where most of the stations are located.

Summary

When heat is released into the atmosphere from the oceans, it is transported toward the poles to dissipate into space. Places in higher latitudes are warmed, not by radiative effects of greenhouse gases in those locales, but by the incursion of warmer air from the equator.

What happens if more CO2 is added into the atmosphere? No one knows, but there are many opinions, a popular one being that more heat is retained in the atmosphere. But in that case, that additional heat will be shed by the planet in exactly the same manner: transport to the poles with slightly less extremely cold air at the higher latitudes.

Why in the world would we pay anything to prevent a little bit of warming in the world’s coldest places?

Clive Best takes the analysis further and relates to work by Christopher Scotese in a later post Fact: Future Climate Will Be Flatter, not HotterMore explanation at The Climate Water Wheel

via Science Matters

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September 13, 2021 at 12:31PM

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