New Science: Clouds And Solar Cycles Play Role In Climate Change
Scientists have barely scratched the surface of the task of recognising and modelling natural cycles of climate change.
“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.]]>