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posted by CoolHand on Thursday May 07 2015, @08:42PM   Printer-friendly
from the don't-mess-with-my-coffee dept.

For years, studies have warned that a warmer planet might mean fewer cups of morning coffee--but a new study claims that rising temperatures are already taking their toll on East Africa's coffee crops.

The study, conducted by researchers at the University of Witwatersrand in South Africa, found that Tanzania's production of Arabica coffee--the most-consumed coffee species in the world--has fallen by 46 percent since 1966. Over the same period of time, the average nighttime temperature in Tanzania increased 1.4 degrees Celsius.

[...]The researchers analyzed the impact of climate variables on crop yield. Through statistical analysis, they found that increasing temperature had a negative effect on coffee yields --- but the specific interaction between temperature and coffee growth surprised them.

"We've always known that high temperatures and low rainfall impact coffee," [Alessandro Craparo, a co-author of the study] said. "What this study found, and what's really important, is its nighttime temperatures that are increasing at a rapid rate and having a bigger impact on coffee than what's happening in the day."

Arabica coffee is a sensitive plant that needs cool nights in order to thrive. For each 1-degree Celsius rise in nighttime temperatures, the researchers found, Arabica coffee yields declined by an average of 302 pounds of coffee per hectare, almost half of the typical small producer's entire yield. If trends continue as they have in previous decade, the study says, Arabica yields in Tanzania will drop to around 320 pounds per hectare by 2060.

 
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  • (Score: 1) by khallow on Friday May 08 2015, @10:52PM

    by khallow (3766) Subscriber Badge on Friday May 08 2015, @10:52PM (#180537) Journal
    Eh, I think he has a point. The elephant in the room, poor agricultural practices is mostly missing from the list except in indirectly citing some symptoms of it like pest and disease stress, and aging coffee trees. Keep in mind that this paper was supposed to be presented as an argument for a substantial AGW effect (they stated as their objective that they would "quantify the impact of climate change on Tanzania’s arabica coffee production"), so why fail to even mention an obvious avenue of criticism from the usual suspects?

    For my take on that question, I suspect the reason is more to diplomatically avoid local anti-colonialist opprobrium than to conform to some climate change narrative. This actually looks to me like changes you would expect from early stage AGW. They have a reasonable model of how crops would be affected by a significant increase in night time temperatures which in turn is an early onset effect reasonably predicted by AGW models. I don't quite buy the claim that the current increase in temperature has such a profound effect on crop production due to the variety of confounding effects, but it isn't that much of a stretch. Further, their references apparently demonstrate a correlation between higher night time temperatures and reduced crop production in tropical areas which would be a concrete and significant example of AGW harm.