Solar dip warms planet
26 Nov 2010 by qmwwwtqmqt.d qmwwwtqmqt.d
A decrease in the Sun’s activity doesn’t always mean it gets cooler here on Earth; scientists believe that even though the Sun is waning, the Earth has become warmer.
A decrease in the Sun’s activity doesn’t always mean it gets cooler here on Earth; scientists believe that even though the Sun is waning, the Earth has become warmer.
It’s well established that the Sun’s activity waxes and wanes over an eleven year period and as the activity declines the overall amount of radiation reaching the Earth drops – or so scientist thought. In fact, a study of the Sun’s activity between 2004 and 2007 – when the Sun was in a waning cycle – showed that the amount of energy reaching the Earth at visible wavelengths increased rather than decreased causing the Earth to become warmer.
“These results are challenging what we thought we knew about the Sun’s effects on our climate,” said Professor Joanna Haigh, lead author of the study and Head of the Department of Physics at Imperial College London, “However they only show a snapshot of the Sun’s activity and its behaviour over the three years of our study could be an anomaly.”
Scientists from Imperial College London – together with colleagues at University of Colorado – used satellite data from the NASA-sponsored SORCE satellite and computer modelling to analyse how the spectrum of radiation and the amount of energy from the Sun has been changing over 2004. They fed the data from SORCE into an existing computer model of the Earth’s atmosphere and compared their results with results obtained using earlier, less comprehensive data on the solar spectrum.
They believe that if the Earth can warm while the Sun wanes, the opposite must also be true. They based their hypothesis on what is already known about the Sun’s activity and its total energy output.
“We cannot jump to any conclusions based on what we have found during this comparatively short period and we need to carry out further studies to explore the Sun’s activity, and the patterns that we have uncovered, on longer time scales,” said Haigh, “However, if further studies find the same pattern over a longer period of time, this could suggest that we may have overestimated the Sun’s role in warming the planet.”
