Nov

12

In pure spirit of "contrarianism", I like this article about global cooling:

Statisticians Reject Global Cooling

In a blind test, the AP gave temperature data to four independent statisticians and asked them to look for trends, without telling them what the numbers represented.

….Global warming skeptics base their claims on an unusually hot year in 1998. Since then, they say, temperatures have dropped — thus, a cooling trend.

….if you analyze the trend during that 10 years, the trend is actually positive

….to find the cooling trend, the 30 years of satellite temperatures must be used.

….It's what happens within the past 10 years or so, not the overall average, that counts

….the 10-year average for the past 10 years is higher than the previous 10 years

….You're going to get a different line depending on which year you choose

….The trend disappears if the analysis starts in 1997. And it trends upward if you begin in 1999

….it's important to look at moving averages of about 10 years

….looking back 31 years, temperatures have gone up

Oceans, which take longer to heat up and longer to cool, greatly influence short-term weather…..the current El Nino is forecast to get stronger, probably pushing global temperatures even higher next year

The quote I liked when I studied statistics at the University (although it could be perceived as politically incorrect nowadays) looks appropriate to me in this case:

Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital. Aaron Levenstein

These discussions recall those about the stock market. Is it better a 50-days moving average or 13-days? Is the secular up drift over because of the recent downturn or what we are living is just another historical buy opportunity?

It looks like a discussion at a sports bar in Italy about the winner of the next soccer season.

In the meantime, let's take a look at El Niño and its effects on commodities and stock markets. In fact, the pattern of winds and ocean temperatures during an El Niño changes the jet streams steering storms over North and South America. It affects also monsoons carrying away moist air that would produce monsoon rains.

Provided that the forecast is statistically significant.

Paolo Pezzutti writes:

From Bloomberg Beijing's Heaviest Snow in 54 Years Strands Thousands

….the heaviest snowfall in the Chinese capital in at least 54 years blanketed the city for the third day this month. ….The government induced snowfall in the capital on Nov. 10 by seeding clouds with silver iodide, the China Daily newspaper reported yesterday, citing an unidentified official at the Beijing Weather Modification Office. Zhang Qiang, head of the office, said the agency induced snow on Nov. 1 by seeding clouds with 186 doses of silver iodide, according to a separate Xinhua report. The seeding brought an additional 16 million tons of snow, according to the report. Beijing takes every opportunity to induce precipitation as the city is suffering from drought, Xinhua cited Zhang as saying.

Maybe a global cooling could be induced artificially.

Anton Johnson comments:

Though theoretically possible, is induced global cooling really what we want? Looking at the Chinese snow example, what is happening? When seeding clouds, atmospheric super-cooled water completes nucleation and freezes, and then precipitates as snow. At liquid-solid phase change, latent heat is released. The converse occurs at the solid-liquid phase change, thus environmental heat energy nets out. That is, assuming the snow melts.

However, the higher albedo of snow compared to most of the earth’s surfaces causes increased solar energy to be reflected into space. So what happens when this cycle is taken to the extreme, that is, if we get the temperature balance wrong? A net increase in global snow cover will cause a net decrease in total solar energy absorbed globally, causing more precipitation to fall as snow, etc, etc; thus plunging the earth into an ice-age. Good-bye New York, Chicago and London. That is until the oceans cool sufficiently, reducing evaporation and precipitation to an inflection point that reverses the cycle – maybe after 10K-20K years.


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