The Great Global Warming Murder Mystery: Are the Clouds Busted? And, If So, Who or What Did It?
So, is CO2 really the main cause of warming or is it the disappearance of clouds? Well, there’s been a study, the abstract and conclusion of which follow (emphasis and paragraphing added):
Since the late 1980s, air temperature in Kraków (southern Poland) has increased by ~2.2–2.3°C compared to the 1951–1988 average. Over the same period, a significant increase in sunshine duration (SD) (by about 500 hr) has been observed relative to the 1951–1988 baseline.
This pattern of temperature change in Kraków is representative of trends observed across Poland. The aim of this study is to determine the impact of SD on the increase in air temperature in Kraków.
The analysis indicates that the strong rise in SD has resulted from changes in cloud structure since the late 1980s. During this period, the frequency of frontal stratiform clouds (As, Ns, St) decreased, while the occurrence of Sc, Cu, and Cb clouds increased.
These shifts in cloud structure, driven by changes in mid-tropospheric macro-circulation, have led to an increase in SD. An analysis of the combined influence of three factors – annual SD, the NAO PC DJFM index (Hurrell), and radiative forcing (∆F) – on annual temperature trends between 1951 and 2020 shows that the var-iability of these factors explains 67.3% of the variance in annual air temperature (R = 0.83, p << 0.001), fully accounting for the observed temperature increase within the margin of estimation error.
Of this, SD variability explains 58% of the variance, NAO index variability accounts for 7.7%, and ∆F variability contributes 3.6%. These findings indicate that the primary driver of air temperature increase in Kraków is the rise in SD (solar radiation influx) rather than radiative forcing (∆F)…
The research indicates that the most important factor influencing the increase in air temperature in Kraków is the increase in SD. This increase occurred as a result of changes in cloud cover structure – specifically a reduction in the frequency of frontal clouds (As, Ns, St), while the overall cloud cover decreased only slightly. A less significant factor in shaping the temperature increase in Kraków is the rise in the intensity of the western circulation during the winter period, as described by the winter NAO index.
Both factors are natural, not anthropogenic, and result from changes in macro-circulation conditions in the Atlantic-European circulation sector. Between 1987 and 1989, a shift in the middle tropospheric circulation epochs occurred, moving from the meridional circulation epoch (E) to the zonal circulation epoch (W) according to the Wangengejm-Girs classification (Savichev et al. 2015, Marsz, Styszyńska 2022).
This caused a shift in the trajectories of low-pressure systems to the north, an increase in the frequency of high-pressure systems south of 55–60°N, and consequently, an increase in the occurrence of ‘high-pressure weather’ with no frontal clouds (Marsz, Styszyńska 2023, 2024a, b, Marsz et al. 2024).
The role of the anthropogenic factor, namely the increase in CO2 concentration in the atmosphere, described by radiative forcing, in driving the increase in air temperature in Kraków is statistically significant but marginal in terms of its importance. It does not introduce interannual variability and only slightly increases the trend of temperature rise.
Similarly, in Wrocław, located ~250 km from Kraków, a small impact of radiative forcing on temperature increase (~6%) was detected (Marsz et al. 2021). There, the main factor driving the rise in temperature after 1988 was also a radical increase in sunshine.
These results indicate the fundamental role of changes in cloud structure, and consequently sunshine, in shaping the observed rise in air temperature.
Research by Norris and Slingo (2009) suggested that even small changes in cloud cover can have a greater effect on Earth’s radiation balance than corresponding changes in greenhouse gas concentrations. They note that a 15–20% increase in low cloud cover can cause changes in the radiation balance comparable to doubling the CO2 concentration.
Additionally, van Wijngaarden and Happer (2025) estimated that the role of low cloud cover in shaping the transfer of solar energy to Earth’s surface is even greater, and a reduction in low cloud cover by just a few percent produces the same effect as doubling the CO2 concentration.
It’s the clouds, baby, but who or why? Well, maybe this is the answer.
Hat Tip: JoNova
#Sunshine #Clouds #CloudCover #Climate #Warming
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It makes perfect sense that more sunshine causes more warming.
However, I don't know how we can extrapolate from Krakow to global. Maybe when there's less stratus clouds in Poland, there's more somewhere else.
But Global Boiling is caused by CO2? Never the 4.6 billion years of changing climate, continental drift over a molten core, asteroid collisions, volcanic activity and 400,000, 100,000, 20,000 year cycles in the earths orbit and orientation to the sun. Nor the fact that our solar system is travelling at over 500,000 mph through space and takes about 230 million years to rotate around our galaxy. Thus our earth has travelled 20 times around the milky way - exposing itself to vastly different gravitational pulls from the sun and far distant other suns and closer large planets, which slightly alter the earths axis tilt and eccentricity, and thus the sunlight it recieves. But it's the CO2, the gas of life, that causes all the weather we see (right now?).