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Tibetan pollen speaks inconvenient truth

03 Jun 2020 | Science Notes

It used to be a lot warmer than it is now and the climate follows cycles driven by solar activity. Don’t call us deniers because it’s not us talking, it’s samples of ancient pollen collected by Chinese scientists and used to reconstruct temperatures on the Tibetan plateau back to 10,000 years before the present. The climate appears to have warmed from the end of the last ice age up to about 6,000 years ago, then it cooled and has stayed relatively cool ever since. Around the long-term trend there is a 500-year cycle that correlates well with indicators of solar activity. And, the authors note, since we’re near the peak of one of the cycles we could be in for cooling in a few decades.

Kenneth Richard at NoTricksZone has helpfully extracted the diagrams from the Chinese study and reoriented them to make them easier to read, but bear in mind that the horizontal axis is backwards, with time running from right (the past) to left (the present):

In the three regions the study examined the pattern is clearly visible: warming after the end of the last ice age, then a long cooling or plateau, and some warming in the last 2000 years, but without reaching the earlier peak.

Will warming continue? The authors note that we’re near the peak of a 500-year solar cycle, and they conclude: “Our data indicate that we are in the middle of the 500-yr-long relatively warm period and suggest that this climate will persist for about some decades before the next relatively cold climate. That is, with the end of this cycle, some decades later, the natural cooling cycle would begin and this will offset the global warming induced by human activities to some degree.”

Another prediction to revisit down the road.

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