Northern hemisphere winters in the big picture
by Juraj Vanovcan (Slovakia)
According to the climate models, anthropogenic warming is supposed to predominantly manifest itself by increasing the winter temperatures th the middle latitudes – caused by the increased “greenhouse effect“ or increased amount of long wave infrared radiation LWIR from the sky to the surface. Children won’t know what the snow is, was the meme in 2000s after a string of warm winters in Europe.
Central England temperature vs Arctic oscillation index.
Only a decade later, things changed and cold and snowy winters are now becoming the norm and not the exception over all of Europe. Now the warming is the cause of invasions of cold Arctic air into mid-latitudes, some climatologists insist. They are basically admitting that not LWIR, but prevailing direction of air circulation makes a winter season warmer or colder than average. Of course there is another popular ad-hoc theory plugging the hole. It relates to the loss of summer ice to weather half a year later.
Coming back to air circulation, its direction is dependent on atmospheric highs and lows and the stability of their position. This known phenomenon is characterized by Arctic Oscillation (AO) or North Atlantic Oscillation (NAO) index. Negative AO means increased frequency of Arctic air plunging to the mid-latitudes, while a positive AO means milder winters with persistent southwestern flow into Europe.
Looking back at history and combining AO index with the winter temperatures from Central England Temperature record (CET), there is a clear relation between the two. A decade of mild winters during the 1920s is indistinguishable, temperature-wise, from the decades after 1990. Cold winters coincide with periods of negative AO, the last one in early 1980s and again in recent years.
What’s interesting is the trend in AO since 1990, which is clearly negative. Now, let’s compare this observation with Chapter 10.3.5.6. in the last IPCC AR4 report, which says:
…In the recent multi-model analyses, more than half of the models exhibit a positive trend in the NAM (NAO)…
…Although the magnitude of the trends shows a large variation among different models, Miller et al. (2006) find that none of the 14 models exhibits a trend towards a lower NAM index and higher arctic SLP (sea level pressure)…
…In another multi-model analysis, Stephenson et al. (2006) show that of the 15 models able to simulate the NAO pressure dipole, 13 predict a positive increase in the NAO index with increasing CO2 concentrations…
…The average of IPCC-AR4 simulations from 13 models suggests the increase of the NAM index becomes statistically significant early in the 21st century (Figure 10.17a, Miller et al., 2006)…”
In summary, the future changes in the extratropical circulation variability are likely to be characterized by increases in positive phases of both the NAM and the SAM.”
Again, observations are in stark opposition to climate models. Claims, that warming basically causes negative AO period is nowhere to be found in “peer-reviewed” literature from those times when winters were mild and spring came in March as usual.
Be sure, that in case of mild winter, it should be exactly as scientists predicted because in today’s world of climate, everything is exactly “as models predicted”, even if it contradicts itself and none of the models had actually predicted it.
To sum it up:
1) It is obvious that winters, at least in NW Europe, are dominated by AO/NAO.
2) During the the last century, AO cycles bear no relation to CO2 level or “human influence”.
3) Since a 1990 positive AO spike, its trend has been negative, which is in agreement with the increasingly colder observed winters.
4) None of the models predicted negative phase of AO.
5) AGW theory is just riding on the warm period of the NAO (and AMO), which has already ended.
As Albert Einstein once said, a good theory predicts things in advance and a bad theory needs additional adjustments after each new discovery. The problem with the anthropogenic warming theory is: it cannot sustain anything new. For every new and unexpected climate or weather trend a special sub-theory must be developed, and it doesn’t matter if they often completely contradict each other.
“There are 3 roads to ruin yourself: women, gambling and scientists. The most pleasant is with women. The quickest is with gambling. But the surest is following the advice of scientists.”