Skip to content

“The Sun-Weather Relationship Is Becoming Increasingly Important”

Dr David Whitehouse

Scientists are gathering this week in Arizona for the 2011 SORCE (Solar Radiation and Climate Experiment) Science Meeting at which there is much discussion of the link between the Sun and climate change given the many new findings in the subject.

Dr Hari Om Vats of the Physical Research Laboratory in India said at the conference, “The Sun-weather relationship is becoming increasingly important. It is true that our understanding of the Sun and solar processes has increased dramatically during recent years, however, it is realised that the Sun affects the Earth’s environment is a much more complicated manner than we had imagined.”

In the wake of news about the CERN cloud chamber experiment that demonstrated a link between cosmic rays and the first stage of the cloud formation process Hiroko Miyahara of the University of Tokyo suggests that cosmic rays modulated by the Sun’s magnetic field played an important role in the so-called Little Ice Age – a period of cooling in the 17th century.

Robert Cahalan of the NASA Goddard Climate and Radiation Laboratory says that the Earth’s surface has been warming in recent decades, while the stratosphere has been cooling, especially the upper stratosphere. This is usually interpreted as evidence that the climate forcing is primarily due to the greenhouse effect, and not the Sun.

However, in his presentation Dr Cahalan says, evaluating the Sun’s impact on climate requires knowledge of variations not only in Total Solar Irradiance (TSI, formerly “solar constant”) but also variations in the Spectral Solar Irradiance (SSI). Initial findings indicate that multiyear changes in visible and near-infrared parts of the spectrum may be out of phase with those of TSI, while near ultraviolet changes are in phase, but larger than expected. To consider the climate impact of such changes, we compute climate responses to two classes of SSI variations, both having the same variations in TSI. We find that out-of-phase forcing leads to much larger temperature variations in the upper stratosphere, but smaller variations in the troposphere and upper ocean.

Global Temperature To Rise Dramatically in “Next Three To Four Years”

Judith Lean of the Naval Research Laboratory, Washington DC, says that evidence is accumulating of the Sun’s role in altering the Earth’s climate and atmosphere, including the ozone layer, in ways that can mitigate or exacerbate anthropogenic effects on time scales of decades. To untangle the mixture of man-made and natural effects on climate Dr Lean reproduces the effects in a computer model to look at changes in the ozone layer and the Earth’s temperature.

The key point to emerge from Dr Lean’s paper is a prediction of what the Earth’s surface temperature will do in the near future. Dr Lean predicts that during the next three or four years global surface temperatures will rise very rapidly, at a much faster rate than due to the greenhouse effect alone.

Ozone levels, it is predicted, have already reached their lowest levels, and by 2050 will exceed levels seen in the 20th century.