Scientists have barely scratched the surface of the task of recognising and modelling natural cycles of climate change.

Sand deposits near the Gobi Desert in China may seem a strange place to look for evidence that cosmic rays can control how clouds are formed and the impact they have on Earth’s climate.

But Japanese scientists have measured the size of sand grains
and the distance they travelled 780,000 years ago to add a new level of
understanding to one of the questions that continues to baffle climate science:
clouds.

The findings, published in Nature, point to big trends in
natural variation of past and future climate that operate apart from greenhouse
gas levels.

The study
adds weight to a contentious theory by Danish researcher Henrik Svensmark, of
the Danish National Space Institute in Copenhagen, which uses cosmic rays and
clouds to question the sensitivity of climate to carbon dioxide in the
atmosphere.

And it
follows a study of 120,000 years of solar cycles by Valentina Zharkova, of
Britain’s Northumbria University, which says a natural sun cycle will add 2.5C
warming to Earth’s climate in coming centuries on top of any impact from rising
greenhouse gases.

Neither the
researchers nor the Japanese research team dispute that carbon dioxide is a
greenhouse gas with implications for the climate. But if they are to be ­believed,
our understanding of the sun’s role in climate cycles is starting to burn
brighter.

Zharkova’s
research, published in Scientific Reports, concentrates on a cycle that
varies the distance between the Earth and the sun. She was previously best
known for research on sunspot cycles that indicate a cooling influence on the
Earth’s climate across the next two decades. Through statistical analysis of
data gathered during the sunspot research, Zharkova and her colleagues
identified that this cycle of movement, known as a super-grand cycle, takes
about 2000 years to complete.

She and her
team have been able to re-create almost 60 super-grand cycles, going back
120,000 years. Their research has established that the current super-grand
cycle began between 1645 and 1715, during the Maunder Minimum period in which
the sun was experiencing far fewer sunspots and the Earth’s temperature
decreased as a result.

The authors
say we are now in the growing — or warming — phase of the cycle, which is
expected to reach its peak by the year 2600. By this time the Earth’s
temperature is expected to have increased by between 2.5C and 3C.

They say this
rise is expected to happen in addition to any rise related to man-made activity
such as carbon emissions.

The cycle
then will enter the cooling phase, during which the sun will move slightly
farther away from the Earth. This is expected to last until the year 3700.

Meanwhile,
researchers at Japan’s Kobe University provide an opportunity to rethink the
role of clouds in climate.

Lead author
Masayuki Hyodo has found a new way to test a theory that when galactic cosmic
rays increase, so do low clouds, and when cosmic rays decrease, clouds follow
suit.

“The Intergovernmental Panel on Climate Change has discussed the impact of cloud cover on climate in their evaluations, but this phenomenon has never been considered in climate predictions due to insufficient physical understanding of it,” Hyodo says.

The research
builds on the so-called Svensmark Effect, which is a hypothesis that galactic
cosmic rays induce low cloud formation and influence the Earth’s climate.

In December
2017, Svensmark published research in Nature Communications he said
indicated the impact of changes in solar activity on Earth’s climate was up to
seven times greater than climate models suggested.

The claimed
breakthrough was in understanding how cosmic rays from supernovas interact with
the solar magnetic field, with variations in that magnetic field reflected in
the intensity of cosmic rays reaching the Earth.

These
variations influence the density of cloud cover, which in turn has an effect on
the Earth’s climate.

This has
implications for how sensitive climate is to rising levels of carbon dioxide.

It is an
active field of study with different researchers arriving at different
conclusions.

The IPCC
reports have a wide range of possible figures for climate sensitivity.

Hyodo’s
research approaches the same question posed by Svensmark but from a different,
and unusual, perspective. He says tests based on recent meteorological
observation data show only minute changes in the amounts of cosmic rays and
cloud cover, making it difficult to prove the theory.

In an article
based on the research, Hyodo explains how researchers went looking for clues
during the last geomagnetic reversal transition three-quarters of a million
years ago. The theory was that during the geomagnetic reversal the amount of
cosmic rays increased dramatically and there was also a large increase in cloud
cover. In China’s Loess Plateau, just south of the Gobi Desert near the border
with Mongolia, dust has been transported for 2.6 million years to form layers
of windblown silt up to 200m thick.

The
researchers propose that winter monsoons would become stronger if there were
increased cloud cover during the geomagnetic reversal. They found evidence that
for a period of 5000 years during the reversal, coarser grains of silt had been
deposited over a much greater distance.

The strong
winter monsoons had coincided with the period during the reversal when the
Earth’s magnetic strength fell to less than one quarter and cosmic rays
increased by more than 50 per cent.

“This suggests that the increase in cosmic rays was accompanied by an increase in low-cloud cover, the umbrella effect of the clouds cooled the continent, and Siberian high atmospheric pressure became stronger,” researchers say. There was also evidence of an annual average temperature drop of 2C to 3C.

Svensmark
tells Inquirer the latest research is independent confirmation of the role of
cosmic rays on climate. He says Hyodo’s research deals with Earth’s magnetic
field and is one of three possible ways cosmic rays can affect our planet’s
atmosphere.

One is a
change in the number of supernovas in the solar system’s neighbourhood; another
is that solar activity can modulate the number of cosmic rays reaching the
Earth; and the third is changes in the Earth’s magnetic field.

Svensmark
says he is happy to see a new study that seems to find a connection.

Michael
Asten, adjunct senior research fellow at Monash University’s school of Earth
atmosphere and environment, says scientists have barely scratched the surface
of the task of recognising and modelling natural cycles of climate change.

The
association between cosmic ray activity and global climate is complex because
the cosmic ray record tells us of energy reaching the top of Earth’s
atmosphere.

Global
climate variations are the result of variations in cloud cover, atmospheric
circulation patterns and ocean circulation patterns as well as the actual ­luminosity
of the sun.

Asten says
Svensmark’s explanation is not accepted by the vast majority of researchers,
but in time his theory may well be seen as a seminal part of new insights into
an incredibly complex set of sun-Earth-climate interactions.

The post New Science: Clouds And Solar Cycles Play Role In Climate Change appeared first on The Global Warming Policy Forum (GWPF).

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July 15, 2019 at 07:21AM