The connection between cosmic rays and clouds has always been tenuous. The connection between cosmic rays and climate even more so.
But that hasn’t stopped the cosmic ray driven climate (and therefor not caused by GHG emissions) theory from getting more attention than it deserves. From every single study that doesn’t outright disprove the notion that cosmic rays influence the climate from getting undue attention.
And so I suppose we shouldn’t be surprised that the latest study looking into these effects is being blow out of all proportions.
CERN, the people responsible for the ultra-cool (literally) Large Hadron Collider, the worlds most powerful particle accelerator, are conducting a series of experiments, conveniently titled CLOUD, to gather data on the effects cosmic rays have on cloud formation, and thus potentially the climate.
The basic theory goes something like this:
- Cosmic rays produce aerosol nuclei
- These aerosol nuclei seeds clouds
- Clouds have an effect on the climate
So far so good, even if based on very tentative evidence (so lets not go making any grand sweeping claims). In fact even the first part of this theory, that cosmic rays produce aerosol nucleation is tentative (again no grand sweeping claims).
Where people get into trouble is when they extrapolate this to say that cosmic rays control the climate and are responsible for the recent warming trend (aka make a grand sweeping claim).
But thanks to the blogger Things Break we know that the evidence simply doesn’t back this up:
- The current warming trend exhibits “fingerprints” consistent with GHG driven warming, not by cosmic rays.
- We can look at the paleoclimatic record during periods of significant changes in GCR [galactic cosmic ray] activity, and there is no corresponding change in climate, e.g. the Laschamp excursion ~40kya (Muscheler 2005).
- We can examine the change in GCRs in response to solar variability over recent decades or the course of a solar cycle, and find there is no or little corresponding change in climate (Lockwood 2007, Lockwood 2008, Kulmala 2010).
- We can look at alleged correlations between GCRs and climate in the geologic past due to our sun passing through galactic spiral arms, and find that these “correlations” were based on an unrealistic, overly-simplified model of spiral structure and are not valid (Overholt 2009). Standard climatic processes (like CO2) more parsimoniously explained the climatic changes even before taking the flawed spiral model into account (Rahmstorf 2004).
- We can examine the specific mechanisms by which Svensmark and others have claimed GCRs influence climate via cloud behavior and show that alleged correlations between GCRs and clouds were incorrectly calculated or insufficiently large, proposed mechanisms (e.g. Forbush decreases) are too short lived, too small in magnitude, or otherwise incapable of altering cloud behavior on a large enough scale to drive significant climatic change (Sloan 2008, Erlykin 2009, Erlykin 2009a, Pierce 2009, Calogovic 2010, Snow-Kropla 2011, Erlykin 2011).
So where does that leave the CERN CLOUD project?
Well why not get the answer straight from the lead author of the study in question, Jasper Kirkby:
It is important to stress we are only looking, at the moment, at the production of nanometre sized embryonic particles. These are far too small to seed cloud droplets at this stage so at the moment it actually says nothing about a possible cosmic ray effect on clouds and therefore climate.
And if you want more detail there is always Real Climate.
Seems pretty clear to me. This research says nothing about climate and nothing about clouds.
So what does it show? It mostly focused on the most basic part of the climate/cosmic ray theory: do cosmic rays produce aerosol nuclei? Even at this most basic level there is still significant uncertainty, but the CLOUD research does provide some evidence that yes, cosmic rays might produce some very small aerosol nucleii.
This is the first step in determining what, if any, effect cosmic rays might have on clouds and therefore climate, but on its own, like the lead author Jasper Kirkby, stated this says nothing about the climate.
The effects of aerosols and clouds on the climate represent significant uncertainties, and the CERN CLOUD (which is just getting started) will hopefully allow scientists to reduce some of these remaining uncertainties.
But anyone making grand sweeping claims can just be ignored as nothing but spin.