Moth Eyes

Navigating a demon-haunted world

Do Cosmic Rays Cause Global Warming?

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How do you make a cloud? Well, first you start with an aerosol particle, a small particle around which the much larger cloud condensation nuclei (CCNs) can condense. It takes a large CCN – at least 100 nanometres in size – for water vapour to be able to condense from water vapour. Clouds are made up of many CCNs with water condensed on them. Clouds can reflect sunlight back into space, cooling the Earth – but they can also reflect heat back to Earth, warming the Earth instead. The total cooling effect of clouds is about 44W/m2, contrasted with about 31W/M2 of warming from them reflecting heat back to Earth – a net effect of about -13W/m2 (Ramanathan et. al, 1989).

A new paper, Kirkby et. al. (2011), published by scientists at CERN claims to shed light on the role of cosmic rays in the formation of these aerosol particles. Cosmic rays are mostly the remnants of atoms which have been accelerated to near the speed of light, along with some more exotic particles such as stable antimatter. Most cosmic rays reach such speeds while bouncing around in the magnetic fields and remnants of supernova, though some reach even higher energies through not-yet-fully-understood processes. The sun’s magnetic field diverts most cosmic rays away from the Earth, so the solar maximum is the low for cosmic rays, and during the solar minimum is when we get the most cosmic rays here on Earth. As they pass through the atmosphere, they collide with gasses, donating their energy and ionizing the molecules.

Kirkby et. al. used a particle accelerator to create analogs to cosmic rays, ionizing the gasses. They found that this increased the formation – the “nucleation” – of small aerosols – nanometre sized particles – by a factor of 2-10. They also showed a much larger – 100 to 1000 times – increase in nucleation from the presence of ammonia in addition to sulphate. It remains the case that they observed far more nucleation than in previous lab studies, it was still several times lower than is observed in the atmosphere.

Their setup only considered small, nanometre-sized particles – it was in principle incapable of producing larger ones. No doubt, future experiments, including future work by these same scientists, will investigate whether similar increases in the formation of larger, potentially cloud-forming, particles are found. However, other studies have found results that cast doubt over whether this will be the case. For example, Snow-Kropla et. al. (2011) found that the observed variation in cosmic rays made less than a 0.2% difference in the concentration of 80 nm particles. They saw a larger increase (1%) in 10 nm particles, suggesting that the impact of cosmic rays falls off as you look at larger particles. Pierce & Adams (2009) find similar results, and suggest that this could be because of a lack of condensable gasses that would allow the particles to grow larger – that it’s not the lack aerosol particles limiting the growth of potential cloud condensation nuclei. If so, it doesn’t matter how many aerosol particles there are about, so far as CCNs are concerned – they are limited by a different factor. It would certainly be possible for the results of a future experiment to contradict these results – and it would be interesting to see how the question was resolved.

We can see that there’s rather a long way to get from this finding – that cosmic rays increase the production of nanometre-sized particles – to have an effect on cloud formation. And to get to the idea that cosmic ray variation can explain global warming, we must assume that:

  1. An increase in aerosol nucleation increases the concentration of large cloud condensation nuclei (though it’s not out of the question, we’ve already seen that it has been contradicted by other studies).
  2. That an increase in CCNs increases cloud cover (this, at least, seems plausible).
  3. That there is a downwards trend in cosmic rays (which would decrease nucleation, which may reduce CCN formation, which may decrease cloud formation).

So what are cosmic rays doing? Well… not much. The data just doesn’t contain the sort of decline that would be necessary for any possibility that cosmic rays could be the cause for global warming.

Cosmic rays seen by monitoring stations in Climax, New Mexico and Oulu, Finland. Shown as the variation from a 1970-1999 baseline.

Many in the media jumped to the conclusion that cosmic rays were affecting the climate. Lawrence Solomon wrote a hyperbolic article claiming that the paper proved absolutely, beyond a shadow of doubt, that cosmic rays were responsible for all the observed global warming. The International Business Times claimed that anthropogenic global warming had been disproved. James Delingpole has got a wonderful conspiracy theory going. One must wonder why people so “sceptical” about the well-established link between greenhouse gasses and global temperatures would be so quick to jump to conclusions without even a correlation. No such conclusions are supported, or even suggested, in the paper they each claim to be writing about.

Cosmic rays as above, plotted alongside NOAA’s monthly global index (which uses 1901-2000 as a baseline).


Kirkby, J., Curtius, J., Almeida, J., Dunne, E., Duplissy, J., Ehrhart, S., Franchin, A., Gagné, S., Ickes, L., Kürten, A., Kupc, A., Metzger, A., Riccobono, F., Rondo, L., Schobesberger, S., Tsagkogeorgas, G., Wimmer, D., Amorim, A., Bianchi, F., Breitenlechner, M., David, A., Dommen, J., Downard, A., Ehn, M., Flagan, R., Haider, S., Hansel, A., Hauser, D., Jud, W., Junninen, H., Kreissl, F., Kvashin, A., Laaksonen, A., Lehtipalo, K., Lima, J., Lovejoy, E., Makhmutov, V., Mathot, S., Mikkilä, J., Minginette, P., Mogo, S., Nieminen, T., Onnela, A., Pereira, P., Petäjä, T., Schnitzhofer, R., Seinfeld, J., Sipilä, M., Stozhkov, Y., Stratmann, F., Tomé, A., Vanhanen, J., Viisanen, Y., Vrtala, A., Wagner, P., Walther, H., Weingartner, E., Wex, H., Winkler, P., Carslaw, K., Worsnop, D., Baltensperger, U., & Kulmala, M. (2011). Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation Nature, 476 (7361), 429-433 DOI: 10.1038/nature10343

Pierce, J., & Adams, P. (2009). Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates? Geophysical Research Letters, 36 (9) DOI: 10.1029/2009GL037946 [PDF]

Ramanathan, V., Cess, R., Harrison, E., Minnis, P., Barkstrom, B., Ahmad, E., & Hartmann, D. (1989). Cloud-Radiative Forcing and Climate: Results from the Earth Radiation Budget Experiment Science, 243 (4887), 57-63 DOI: 10.1126/science.243.4887.57 [PDF]

Snow-Kropla, E., Pierce, J., Westervelt, D., & Trivitayanurak, W. (2011). Cosmic rays, aerosol formation and cloud-condensation nuclei: sensitivities to model uncertainties Atmospheric Chemistry and Physics, 11 (8), 4001-4013 DOI: 10.5194/acp-11-4001-2011

September 4, 2011 at 2:56 am Comments (3)

Photo #18 – Yellow boxfish

Yellow boxfish (juvenile)

Juvenile yellow boxfish (Ostracion cubicus), photographed in the waters off Pelorus Island, Queensland.

Yellow boxfish have four life stages, each very differently coloured.

August 26, 2011 at 8:56 pm Comments (0)

Photo #17 – Longfin grouper

Longfin grouper

Longfin grouper (Epinephelus quoyanus), photographed in the waters off Pelorus Island, Queensland.

I love these fellows. Their habit of finding a bit of sand or a bit of rock and sitting around on it, instead of darting all over the place like most fish, makes them terribly easy to photograph.

August 15, 2011 at 9:34 pm Comments (0)

Photo #16 – Phyllidia ocellata

Phyllidia ocellata, a species of nudibranch

Phyllidia ocellata, photographed in the waters off Pelorus Island, Queensland.

Nudibranchs (including Phyllidia ocellata) form a “clade” (meaning that all species of nudibranch descend from a common ancestor that no non-nudibranch descends from) of predatory sea slugs. Nudibranchs tend to be vibrantly coloured, and there is a great deal of variation between species in not only the colour patterns but even in the anatomy – which makes them great photography subjects!

August 12, 2011 at 9:25 pm Comments (0)

Photo #15 – Blue-spotted stingray

A blue-spotted stingray, covered in sand as it lurks on the bottom
The blue-spotted stingray, somewhat less covered in sand as it goes for a swim
Blue-spotted stingray (Dasyatis kuhlii), photographed in the waters of Pelorus Island, Queensland.

August 7, 2011 at 11:13 pm Comments (0)

The difference a few years makes…

June 5, 2011 at 4:27 pm Comments (3)

Photo #14 – Black flying fox

Black Flying Fox
Black Flying Fox

Black flying fox (Pteropus alecto), photographed on Magnetic Island.

In other news, it turns out I’m still alive. Who’d have thunk it?

May 9, 2011 at 1:20 am Comments (0)

DoW2 Retribution Last Stand: Weargear

For Dawn of War II, Gravecat posted a list of wargear unlocks for each race. The Retribution expansion adds a new last stand map (with harder waves – the original map and waves are also retained) and the Lord General as Imperial Guard hero. The other heroes seem to retain their old wargear lists. I’m yet to see a list of wargear unlocks for the Lord General, so I figured I’d start one. I’ll update this as I get new information, and if you’re ahead of me please post in the comments!

Level Description
2 Refractor field: Reduces ranged damage on you and allies around you
3 Medallion Crimson: Combat expert (+30% ranged and melee damage)
4 Master-crafted Carapace Armour: 79 armour rating, immune to suppression, can place a tarantula heavy bolter turret (25 energy)
5 Guardsmen: Deploy a squad of guardsmen (35 energy). If you are armed with a bolter, flamer, grenade launcher or plasma gun they get two of them.
6 Protective Power Sword: 10 DPS, armour piercing (to 100), clear out (knocks back and damages enemy troops), +50 armour
7 Repair: Lord General can repair structures and vehicles (20 energy).
8 Artificer Carapace Armour: 72 armour rating, immune to knockdown, can place a tarantula missile turret. Turret has difficulty with cover but has area of effect and can knock down enemy troops.
9 Sergeant: Adds a sergeant to your minion squads. Grants Battle Hardened (increased defense) to minions.
10 Catachan: Can deploy a Catachan devil squad, which has the Knockdown and Explosives Expert attributes (they have shotguns and frag grenades). They are a commander item, so you can’t use them with guardsmen (35 energy).
11 Reinforce: Reinforce nearby allied minion squadrons (seems to include allies – 10 energy).
12 Mordian Pattern Carapace Armour: 37 armour rating, can deploy executioner turret.
13 Grenade Launcher: 5.5DPS, Area of Effect, Blind Grenade Volley, Knockdown. Equips Guardsmen with grenade launchers as well.
14 Commissar: Increases the damage inflicted by nearby allies, and can be stacked with the sergeant.
15 Ogryn: Tough, resistant troops.
16 Armageddon Pattern Carapace Armor: 30 armour rating, can place Vanquisher Heavy Turret.
17 Take Aim!: Gives ally a temporary damage boost
18 Plasma Gun: 7.3 DPS, armour piercing up to a rating of 100. Equips guardsmen squads with plasma guns as well.
19 Rocket Run: Devastates a strip of ground with rocket pod runs.
20 Storm Troopers: Deploy a squad of elite troops. Can’t be stacked with other minion squads. Allows the general to make a tactical withdrawal (fast run). Also reduces his energy costs by 25%.
Achievement The Black Plate: 125 armour rating, reduces melee damage.
Unlock: Beat 10 waves in a single match whilst holding both strategic points.
Achievement Duelist Honours: Increases melee damage by 40%.
Unlock: Kill 2500 enemies as Lord General

Update: Gravecat’s listing has now overtaken mine.

March 3, 2011 at 12:39 am Comments (0)

Now that *is* the straight dope

February 18, 2011 at 8:13 pm Comment (1)

Photo #13 – Great Eggfly

Great Eggfly
Hypolimnas bolina, photographed in Townsville, Queensland. This species is sexually dimorphic (that is, the different genders look very different to each other) – this is a male.

At this point, I think we can all agree that I’m rather bad at blogging. I recently moved to Townsville, and have more or less settled in by now – so hopefully I can get something a bit more regular going here!

December 28, 2010 at 10:06 pm Comments (0)

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