On Climate Sensitivity and why it is probably small

What is climate sensitivity?

The equilibrium climate sensitivity refers to the equilibrium change in average global surface air temperature following a unit change in the radiative forcing. This sensitivity (often denoted as λ) therefore has units of °C/(W/m2).

Often, instead &\lambda;, the sensitivity is expressed through the temperature change &Delta Tx2, in response to a doubled atmospheric CO2 content, which is equivalent to a radiative forcing of 3.8 W/m2. Thus, &Delta Tx2 = 3.8 W/m2 λ

Comments on nature's "A cosmic connection"

Last week, a report by Jeff Kanipe appeared in nature. In it, Kanipe explains the solar → cosmic-ray → climate connection, and the planned CLOUD experiment in CERN, expected to finally resolve the issue. Given that my work is mentioned in the review, I through I should mention a few relevant points.

The Critique of Knud Jahnke and a New Meteor Exposure Age Analysis

General Remarks

The manuscript submitted by Jahnke is an attempt to repeat analyses previously carried by myself (Shaviv PRL, 2002, New Astronomy, 2003). Although Jahnke raises a few interesting aspects, his analysis excludes several critical problems, because of which he obtains his negative result, that is, that there is no statistically significant periodicity in the data. By far, the most notable problem is that Jahnke's analysis does not consider the measurement errors. In his analysis, poorly dated meteorites were given the same weight as those with better exposure age determinations. As I show below, this has a grave effect on the signal to noise ratio (S/N) and consequently, on the statistical significance of any result.

The Milky Way Galaxy's Spiral Arms and Ice-Age Epochs and the Cosmic Ray Connection

On long time scales, it appears that our journey through the Milky Way is responsible for large climate variations. Each time we pass through spiral arms of the galaxy, we witness a higher flux of cosmic rays, which in turn reduce the global temperature. Read more about the effect and the evidence in this article.