There's always the Sun

There is something odd going on with certain newspapers around the world.   Just a few weeks ago, the Intergovernmental Panel on Climate Change, better known as the IPCC, presented the first part of their report on the state of the worlds climate.  It contained a worrying vision of a climate out of control.  Yet almost as soon as the ink had dried, several newspapers suggested there wasn’t too much to worry about.  Many made a huge song and dance about results reported by Henrik Svensmark and colleagues in the Proceedings of the Royal Society (doi:10.1098/rspa.2006.1773).  Here, experimental results suggested that cosmic rays  highly energetic particles that form deep in space  might play a significant role in cloud formation.  The idea is the weaker the Sun, the more cosmic rays reach the Earth and the more clouds that form.  Although the research article stopped short of saying what this might mean for past climate, some of the newspapers seemed to suggest that this explained away much of the change the IPCC had found.  Why?

The IPCC was written by over 800 contributing authors and reviewed by more than 2500 scientific expert reviewers from over 130 countries.  The result is very much a consensus and it took 6 years to get it.  In contrast, the article on a possible role for cosmic rays in cloud formation represents one experimental result.  Even if the experiment is reproduced, cosmic rays have been measured in Colorado since 1953, and despite all the hype, there is no long-term trend. 

Ancient bog oaks from Ireland preserve a stunning record of past climate
One way to test whether the Sun plays a significant role in climate change is to look in the past. I’ve previously mentioned the 7468-year record of trees preserved in Irish bogs. This amazingly detailed record gives a yearly reconstruction of climate.   But there’s more we can do with the wood. I was fortunate to work with a team that looked at the possible influence of the Sun on climate (doi: 10.1002/jqs.927).  To get a handle on its long-term behavior, we used the fact that the Sun plays a significant role in controlling the level of radioactive carbon in the air. By measuring the radioactivity preserved in the tree rings, a precise reconstruction of the Suns activity could be compared to our record of climate on the same absolute timescale.  The bottom line is we found there was no direct relationship between the Sun and climate over several millennia.

What’s really sad is that all this effort is being made clinging to straws when the best thing we could do is focus on sorting out the mess we’ve created.

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