The hypothesis of this paper by Hannah et al. is fairly simple; if the climate is different in the future, the wine growing regions of the world (France, Australia, California etc.) will see different mean conditions and might therefore be better/worse at growing wine grapes. Testing the idea is not so simple, because there are a lot of variables that decide a good growing region; temperature, water availability, humidity, soil quality...the list goes on. So the problem isn't trivial, but like the good viticulturists they are, Hannah et al. have developed a method and published what they found.
I don't want to get too bogged down in the methodology, since it's all in the paper I linked to and it's the pretty figures everybody wants to see, but I'll summarize briefly since it's hard to make conclusions if you don't know what the paper actually did. The authors took the current climatology from weather stations around the world over the period 1961-2000 and compared that to a projected average for 2041-2060 from 17 different global climate models. To condense this into one usable variable, they then applied a sustainability model to map out which areas are most affected, assuming carbon emissions continue to increase as they are now. The map in the paper is included below.
So here, the red areas are currently growing wine, the green areas will continue to grow wine in 2050 and the blue areas are new regions that will be able to support vineyards. As you can see, if the authors are right, there will be some serious shifts in the regions we buy our wine from, particularly in the US and Europe. It's looking good for the North Eastern states and bad for California, while over on the other side of the Atlantic, Devon could be the next champagne (that just sounds wrong) while the Mediterranean might be losing a lot of it's growing potential.
I think there is certainly room for healthy scepticism in a paper like this. For a start, Global climate models are notoriously bad at predicting rainfall regionally and the authors also use a Human Influence Index to account for things such as population changes, which must have quite a large room for error. However, that doesn't mean we should just throw our hands up and stop trying. It's an interesting approach, and changes in wine grape distributions are obviously important economically as well as being indicators of the movement of other types of plant and animals in a warming world.
So I think that's the end of today's blog. Overall, an interesting and ambitious paper which serves as just one example of how things might be different 40 years from now. I'm sure I had something else to add here, but I can't think what it was. I'm drawing a Sauvignon Blanc.
Hannah L, Roehrdanz PR, Ikegami M, Shepard AV, Shaw MR, Tabor G, Zhi L, Marquet PA, & Hijmans RJ (2013). Climate change, wine, and conservation. Proceedings of the National Academy of Sciences of the United States of America, 110 (17), 6907-12 PMID: 23569231
