Global temperature response to radiative forcing: Solar cycle versus volcanic eruptions
Abstract
I show that the peak-to-peak amplitude of the global mean surface temperature response to the 11-year cyclic total irradiance forcing is an order of magnitude less than the amplitude of a cyclic component roughly in phase with the solar forcing which has been observed in the temperature record in the period 1959-2004. If this cyclic temperature component were a response to the solar forcing, it would imply the existence of strong amplifying feedbacks which operate exclusively for solar forcing, such as top-down mechanisms responding to the large variability in the ultraviolet part of the solar spectrum. I demonstrate, however, that the apparent cyclic component in the temperature record is dominated by the response to five major volcanic eruptions some of which incidentally took place a few years before solar minimum in four consecutive solar cycles, and hence that the correlation with the solar cycle is coincidental. A temperature rise of approximately 0.15 K over the 20th century ascribed to an increasing trend in solar forcing is more than offset by a cooling trend of about 0.3 K due to stratospheric aerosols from volcanic eruptions.
- Publication:
-
Journal of Geophysical Research (Atmospheres)
- Pub Date:
- March 2012
- DOI:
- Bibcode:
- 2012JGRD..117.6115R
- Keywords:
-
- climate response;
- solar cycle forcing;
- volcanic forcing;
- Global Change: Abrupt/rapid climate change (4901;
- 8408);
- Global Change: Climate variability (1635;
- 3305;
- 3309;
- 4215;
- 4513);
- Global Change: Climate dynamics (0429;
- 3309);
- Global Change: Coupled models of the climate system;
- Global Change: Water cycles (1836)