Policy Documents

Solar Influence on Climate Change Greater than Previously Thought

James M. Taylor –
May 10, 2011

Solar output increased more during the 20th century than was previously thought, indicating human emissions of greenhouse gases is less responsible for the earth’s emergence from the Little Ice Age than was previously thought, a team of scientists reports in the latest issue of Astronomy & Astrophysics.

The team of astronomers, climate scientists, and meteorologists measured total solar irradiance during the past 9300 years by deriving historical cosmic ray abundance from cosmogenic isotope abundance in tree rings and ice cores. The scientists also analyzed sunspot data – with records dating back to 1610 A.D. – to glean a more complete record of historical solar irradiance that can be analyzing sunspot data alone.

The scientists report, “We obtained a large historical solar forcing between the Maunder minimum and the present, as well as a significant increase in solar irradiance in the first half of the twentieth-century. Our value of the historical solar forcing is remarkably larger than other estimations published in the recent literature.”

The study contradicts assertions by global warming alarmists and the United Nations Intergovernmental Panel on Climate Change that variability in solar output has had little impact on the earth’s moderate warming since the Little Ice Age ended 100-plus years ago.

The study can be found at http://www.aanda.org/index.php?option=com_article&access=doi&doi=10.1051/0004-6361/201016173&Itemid=129.