Policy Documents

Research & Commentary: Solar Forcing of Climate

Nongovernmental International Panel on Climate Change –
October 16, 2013

In its series of assessment reports reviewing the latest climate science, the United Nations’ Intergovernmental Panel on Climate Change (IPCC) has concluded solar forcings (the changes in the average amount of solar energy absorbed per square meter of Earth’s area) are too small to explain twentieth century warming. They infer CO2 must be responsible for the remainder. However, observations indicate variations occur in total ocean-atmospheric meridional heat transport and that these variations are driven by changes in solar radiation rooted in the intrinsic variability of the Sun’s magnetic activity.

The IPCC has failed to consider the importance of the demonstrated empirical relationship among solar activity, the ingress of galactic cosmic rays, and the formation of low clouds. The IPCC also ignores x-ray, ultraviolet, and magnetic flux variation, the latter having particularly important implications for the modulation of galactic cosmic ray influx and low cloud formation.

Evidence is accruing that changes in Earth’s surface temperature are largely driven by variations in solar activity. Examples of solar-controlled climate change epochs include the Medieval Warm Period, Little Ice Age, and Early Twentieth Century (1910–1940) Warm Period.

Policymakers should resist pressure from lobby groups to silence scientists who question the IPCC’s scientific claims. A report from the Nongovernmental International Panel on Climate Change (NIPCC), an independent group of some 50 scientists from 15 countries, titled Climate Change Reconsidered II: Physical Science, summarizes a large body of research revealing a scientific community deeply uncertain about the reliability of the IPCC’s computer models, its postulates, and its interpretation of circumstantial evidence. This criticism doesn’t come from a “fringe” of the climate science community: It is stated plainly and repeated in thousands of articles in the peer-reviewed literature.

The above introduction is based on text from Climate Change Reconsidered II: Physical Science and its Summary for Policymakers, published by the Nongovernmental International Panel on Climate Change (NIPCC).

The following documents provide additional information about the solar forcing of climate.


Chapter 3 of Climate Change Reconsidered II
In Chapter Three of Climate Change Reconsidered II: Physical Science, Anthony Lupo and William Kininmonth evaluate climate models against real-world climate and biospheric data, and find the IPCC overestimates the ability of current state-of-the-art GCMs to accurately simulate both past and future climate.

Summary for Policymakers of Climate Change Reconsidered II
The IPCC claims to know, with rising certainty over time, that “most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations” (IPCC AR4 SPM, p. 10). This Summary for Policymakers summarizes and interprets Climate Change Reconsidered II, a major scientific report that refutes this claim. 

Climate Hypersensitivity to Solar Forcing?
In this paper published in Annales Geophysicae in 2000, scientists Willie Soon, Eric Posmentier, and Sallie Baliunas compare the equilibrium climate responses of a quasi-dynamical energy balance model to radiative forcing by equivalent changes in CO2, solar total irradiance (Stot), and solar UV (SUV). They find the response is largest in the SUV case, in which the imposed UV radiative forcing is preferentially absorbed in the layer above 250 mb, in contrast to the weak response from global-columnar radiative loading by increases in CO2 or Stot. 

CO2-Induced Global Warming: A Skeptic’s View of Potential Climate Change
In this 1998 paper published in Climate Research, scientist Sherwood Idso professes his skepticism toward the predictions of significant CO2-induced global warming that were (and still are) being made by state-of-the-art climate models, due to the number of planetary cooling forces that are intensified by warmer temperatures and by the strengthening of biological processes that are enhanced by the same rise in atmospheric CO2 concentration that drives the warming. Several of these cooling forces have individually been estimated to be of equivalent magnitude, but of opposite sign, to the typically predicted greenhouse effect of a doubling of the air’s CO2 content, which suggests little net temperature change will result from the ongoing buildup of CO2 in Earth’s atmosphere. 

Influence of Cosmic Rays on Earth’s Climate
In this 1998 paper published in Physical Review Letter, Henrik Svensmark examines the link between cosmic rays (high-energy particles from space that wash over the planet) and climate change, and presents the theory that Earth’s rising temperature at that time may be caused by extraterrestrial factors. 

Solar Forcing of Climate
In this 2005 paper published in Space Science Reviews, Cornelis de Jager examines the properties of the Sun and discusses the likely cause of solar variations and how they affect the climate.


Nothing in this Research & Commentary is intended to influence the passage of legislation, and it does not necessarily represent the views of The Heartland Institute. For further information on this and other topics, visit the Environment & Climate News Web site at http://news.heartland.org/energy-and-environment, The Heartland Institute’s Web site at http://www.heartland.org, and PolicyBot, Heartland’s free online research database, at www.policybot.org.

If you have any questions about this issue or The Heartland Institute, or would like a scientist to testify in your state, contact Heartland Institute Policy Analyst Taylor Smith at tsmith@heartland.org or 312/377-4000.