May 05 2017

Solar Forcing and Climate Change

sun1A recent article in Principia Scientific International summarizes 20 recent studies showing that solar activity correlates with long term trends in climate change. This is an excellent example of how misinformation campaigns meant to sow doubt and confusion work.

First, we need to consider the source. PSI is not a scientific organization or publication, it is a propaganda front group trying to appear as a scientific organization. This is very common – giving an organization a neutral sounding scientific name that does not reflect its true agenda.

PSI claims, completely contrary to the scientific consensus, that CO2 is not even a greenhouse gas. They actually argue that it causes no warming at all, and in fact may have a cooling effect on the environment. They further argue that wind turbines cause illness, a claim that is demonstrably false.

To put their scientific credibility into perspective, they also maintain that:

Educated parents can either get their children out of harm’s way or continue living inside one of the largest most evil lies in history, that vaccines – full of heavy metals, viral diseases, mycoplasma, fecal material, DNA fragments from other species, formaldehyde, polysorbate 80 (a sterilizing agent) – are a miracle of modern medicine.

They claim vaccines don’t even work and are just full of “toxins” – what we call, “The toxin gambit.”

Right about now readers who might be sympathetic to the PSI’s point of view might think I am trying to poison the well. That is only a fallacy, however, when you make or imply connections that are not relevant. PSIs credibility is absolutely relevant – they are curating information for a specific propaganda purpose. They are not a reliable source of scientific information.

Solar Forcing

Regardless of the source, what about the 20 papers themselves? What these studies show is that, over a period of centuries, solar activity correlates with average climate temperature. This effect is known as solar forcing and it is not controversial. No one doubts that the total solar irradiance (TSI) affects the Earth’s temperature.

The temperature of the Earth is essentially determined by the equilibrium point at which TSI is balanced by longwave radiation from the top of the troposphere – energy in has to be balanced by energy out. So essentially the Earth warms until the total radiation out balances the radiation in and equilibrium is achieved.

So obviously TSI affects this equilibrium, but so too does radiation out, which is affected by the greenhouse effect. Greenhouse gases trap longwave radiation, so the temperature has to rise higher before reaching an equilibrium point. The more greenhouse gases there are, the higher the temperature has to be at equilibrium.

Interestingly, over the last 450 million years the TSI has be slowly increases (which is a function of stellar evolution). At the same time total CO2 in the atmosphere has been decreasing because of various negative feedback loops, keeping the Earth’s climate relatively stable.

So, getting back to the PSI article, there is nothing new or controversial over the notion of solar forcing. The question is – how much of a role is solar forcing playing in the recent warming we have been seeing? Scientists have thoroughly investigated that question and the evidence shows that it is minimal. Solar forcing is having only a tiny effect, and cannot explain the recent warming.

Meanwhile, the long term trend of slowly decreasing CO2 content in the atmosphere has been reversed since the industrial revolution with a dramatic increase in CO2.

What the PSI paper shows, however, is how easy it is to sow confusion with selective information. If you do a Google search on solar forcing you will find many climate change denying websites quoting the PSI paper as a source.

This is a common strategy – pile up a bunch of references to make it seem as if there is a compelling case, meanwhile the references are cherry picked, misrepresented, or taken out of context. None of the papers cited call into question the conclusion that recent forcing is due to CO2, or establish that solar forcing can explain a significant portion of recent warming.

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