- Research sheds light on 500-year Chinese weather cycle and suggests a cool change could be on the way
- Findings leave no room for complacency or inaction
A
new study has found winters in northern China have been warming since
4,000BC – regardless of human activity – but the mainland scientists
behind the research warn there is no room for complacency or inaction on
climate change, with the prospect of a sudden global cooling also
posing a danger.
The
study found that winds from Arctic Siberia have been growing weaker,
the conifer tree line has been retreating north, and there has been a
steady rise in biodiversity in a general warming trend that continues
today. It appears to have little to do with the increase in greenhouse
gases which began with the industrial revolution, according to the
researchers.
Lead
scientist Dr Wu Jing, from the Key Laboratory of Cenozoic Geology and
Environment at the Institute of Geology and Geophysics, part of the
Chinese Academy of Sciences, said the study had found no evidence of
human influence on northern China’s warming winters.
“Driving
forces include the sun, the atmosphere, and its interaction with the
ocean,” Wu said. “We have detected no evidence of human influence. But
that doesn't mean we can just relax and do nothing.”
Moon Lake, a small volcanic lake hidden in the deep forest of China’s
Greater Khingan Mountain Range, where a team of scientists spent more
than a decade studying the secrets hidden in its sediments. Photo: Baidu
Wu
and her colleagues are concerned that, as societies grow more used to
the concept of global warming, people will develop a misplaced
confidence in our ability to control climate change. Nature, they
warned, may trick us and might catch us totally unprepared – causing
chaos, panic, famine and even wars as the global climate system is
disrupted.
There
are already alarming signs, according to their paper, which has been
accepted for publication by the online Journal of Geophysical Research:
Atmospheres.
Wu
and her colleagues spent more than a dozen years studying sediments
under Moon Lake, a small volcanic lake hidden in the deep forests of the
Greater Khingan Mountain Range in China’s Inner Mongolia autonomous
region. They found that winter warming over the past 6,000 years had not
been a smooth ride, with ups and downs occurring about every 500 years.
Their
findings confirmed an earlier study by a separate team of Chinese
scientists, published by online journal Scientific Reports in 2014,
which first detected the 500-year cyclical pattern of China’s summer
monsoons and linked it to solar activity.
The
2014 research, which drew on 5,000 years’ worth of data, suggested the
current warm phase of the cycle could terminate over the next several
decades, ushering in a 250-year cool phase, potentially leading to a
partial slowdown in man-made global warming.
Wu
said the latest study, with 10,000 years’ worth of new data, not only
helped to draw a more complete picture of the 500-year cycle, but also
revealed a previously unknown mechanism behind the phenomenon, which
suggested the impact of the sun on the Earth’s climate may be greater
than previously thought.
According
to Wu, the variation in solar activity alone was usually not strong
enough to induce the rapid changes in vegetation the research team
recorded in the sediment cores of Moon Lake. Instead, the scientists
found the warming impact was amplified by a massive, random interaction
between surface seawater and the atmosphere in the Pacific Ocean known
as the El Nino-Southern Oscillation.
As a result of the research findings, Wu said she was now more worried about cooling than warming.
“A sharp drop of temperature will benefit nobody. The biggest problem is, we know it will come, but we don’t know exactly when.”
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