Transcript of the introduction of talk by Nir Shaviv, skeptical Astrophysicist, at the 2009 Heartland Conference entitled: New solar climate links and their implications to our understanding of climate change (listen to audio).
In the introduction, Nir explains the concept of climate sensitivity very clearly. After this, one can understand the origin of such claims as ‘if the hockey stick is wrong, then sensitivity is higher than we thought and global warming will be worse’.
OK I am glad to see the number of people who have evaporated is not very large in this last 5 min break.
To answer a question that was asked before I think one of the problems with the models, first of all with respect to feedback, it is cloud cover. That because you cannot resolve very small scales the cloud cover physics is basically parameterized with a recipe, and because its parameterized with a recipe, whichever recipe you decide to use, whatever you cook depends on the recipe that you use.
So thatâ€™s one thing. The models are incorrect because they donâ€™t include all the related forcing of all physics that the models should include.
Anyway, I am going to talk about relatively new results on the solar climate link. We have seen a lot of evidence even today that the sun has a large effect on climate, but if you want use it or enter it into models you need to know how large is it, not only that it is important qualitatively but also quantitatively how large is this relative forcing. So this is what I am going to talk about today.
So how strong is this radiative forcing and why is it important for example to understand climate change? So I am going to begin with trying to elucidate why knowing the relative forcing is important then I go ahead describing how you can use the oceans as a big calorimeter to measure this relative forcing then talk about implications.
Why is knowing the relative forcing important? First of all itâ€™s interesting because you want to explain the climate — you want to understand whatâ€™s driving it. With respect to global warming itâ€™s interesting because if you look at the 20th century warming you see that there was some type of warming over the 20th century, its 0.6 or 0.7 or who knows what. You want to explain it with some kind of radiative forcing. Of course natural fluctuations can be important as well but I am not going to talk about them.
You know there is a given change in temperature, and you want to know what is the relative forcing, because the radiative forcing times the sensitivity of the climate — namely how the climate behaves following changes in relative forcing — this thing is going to translate into a given temperature. So if you try to explain 20th century temperature increase with a small relative forcing you will necessarily need a model with large sensitivity. If on the other hand the sun is important over the 20th century it means that the total radiative forcing over the 20th century is going to be larger. If you have a larger radiative forcing then the same given change in temperature should be explained with a lower climate sensitivity.
Basically climate sensitivity is the trillion dollar question because if we know what the climate sensitivity is, it will tell us how much the temperature is going to increase because of us humans over the 21st century and so on. The biggest question is what is this radiative forcing of the sun?
This is an example, one of the nicest examples I know of the fact the sun affects the climate. Itâ€™s a qualitative result. What you see here on one, you see a proxy for solar activity, it is in fact a proxy for cosmic rays which we now know is probably the thing which drives climate and thatâ€™s the carbon 14 that you get out of tree rings. Carbon 14 is formed by spallation from cosmic rays which hit the atmosphere by but these are modulated by the sun. So the upper graph that you see is solar activity. The bottom graph is the O18/O16 ration from a cave in Oman. There are other very nice results but this is one that is particularly nice. So you see that there is a big correlation between solar activity and climate and the question is: is it driven for example by changes through total solar irradiance and super high climate sensitivity or is it driven by some other mechanism? So you want to quantify the effect somehow.
So what we want to do is use the oceans.