NASA has issued yet another statement on the deep solar minimum specifically noting that “the changes so far are not enough to reverse the course of global warming.”

The wording is significant. NASA appears to be taking a lead in explaining the “unusually” spotless sun before it gets accused of covering up an “inconvenient truth” that might undermine the case for anthropogenic global warming or AGW.

It is a smart move although it might upset those who fear any degree of public engagement with the issues at any level more complex than a bumper sticker on a petroleum burning car.

There is no cover up, and what is happening on the sun is not the reason why the greenhouse gas atmospheric heat trap effect has been seriously elevated by the release of fossil fuels kicking the concentration of the main offender, carbon dioxide, to more than 385 part per million or ppm and rising.

The latest NASA commentary in language accessible to lay persons follows a call by the director of NASA’s Goddard Institute of Space Studies, Dr James Hansen, for researchers to take advantage of the unusual state of the sun to seek new information about how it interacts with the terrestrial environment, including near space.

Such low solar activity, which tracks low or zero observations of solar sunspots, has only been exceeded since the turn of the previous century in 1901 and 1913, during and after which global temperature recordings continued to rise strongly until about 1945, and then stabilise, with a striking upwards breakout from 1976 onwards.

So much for any hopes of a mini ice age or global warming reprieve courtesy of a natural cycle.

The so called Dalton Minimum, of 1790-1830, began with a deep solar minimum which like the current one, stretched the preceding solar cycle from its average of around 11 years to around 13 years.

Much colder conditions were reported in this period, but a correlation with unusually high volcanic activity, producing clouds of sulphate particles that block solar warming of the lower atmosphere has been proposed as the major factor in this cooling.

Nothing in climate and weather history is ever as simple as the slogan shouters on either side of the global warming debate claim.

However as NASA points out, in this solar minimum science is able to observe more than sunspots. In the 55 years that solar radio emissions have been recorded they have never been so low. And while the sun’s visible brightness has only dropped by 0.02% compared to its value during the previous, and fairly deep, solar minimum in 1996, the solar output of extreme ultraviolet radiation is down by 6% on the same basis.

The pressure of the solar wind–particles streaming off the surface of the sun — has fallen to very low levels, and some researchers argue this may allow deep space cosmic radiation to be felt more strongly in the atmosphere, perhaps causing ‘nebulation’ or a rise in the types of cloud cover or atmospheric opacity that could lead to surface cooling.

These are controversial and unproven claims, whose time for validation or elimination may be at hand.

Will the NASA explanatories prevent yet another slanging match breaking out between climate change deniers, the middle ground sceptics, or the various levels of mainstream supporters of AGW right up to the quasi-religious hysterics who occupy both extremes?

No way. But for a bit of sanity, and an insight into why a “quiet” sun is interesting, the latest NASA statement comes with useful , accessible, unemotional and factual links that will take you deeper into the research.