African maize yields will fall under increasing temperatures

To those following the scientific research on climate impacts on agriculture in Africa, the theme of this post should come as no surprise. Stanford research David Lobell and colleagues merely add to work that has already been published by that research group. Their latest study adds much more empirical data analysis to much modeling already undertaken, with confirmation of the grim scenarios foreseen for agriculture on the African continent.

Using data from maize/corn variety trials carried out over more than ten years across Africa they provide further evidence of the effects of temperature on maize production. In particular, the number of degree days that exceed 30 degrees C has significant effect -- "each degree day spent above 30 degrees C reduced final yield by 1% under optimal rain-fed conditions, and by 1.7% under drought conditions."

High temperatures affect the moisture status of the soil, thereby increasing stress on the plant. As well, high temperatures were especially problematic during silking and pre-silking stages.

Their work concludes with analysis of the cumulative impact of degree days above 30 degrees C -- linking the impacts of daily temperature maximums seen during a season with what would be expected over the next decades with each 1 degree C of warming seen.

For sites with average temperatures above 25 degrees C yields decline rapidly with increasing temperatures, "because of frequent exposure to temperatures above 30 degrees C, with more than 10% yield loss per degree C of warming... Under drought conditions, even the coolest trials are harmed by 1 degree C warming, with losses exceeding 40% at the hottest sites."

The graphs and maps included in the paper are sobering.

Climate change in your coffee cup

Changing climates in Colombia threaten coffee prices and a way of life.

"Heat damages Colombia coffee, raising prices."

Pepsi and IDB

PepsiCo and Inter-American Development Bank Sign Agreement to Spur Development in Latin America and Caribbean

Here's what I wrote to a colleague about this rather lopsided and misguided venture:

Pepsi invests $2.6 million and the farmers take out $40.4 million in microloans. And they (Pepsi) get sunflower oil much cheaper than their current sources -- currently US and Canada i'm guessing. Geez, who wins there? So the farmers can produce oil for the junk food that makes Mexico second only to the US globallly in the number of obese inhabitants.

But I'm guessing that climate change in Mexico means they won't produce sunflowers there for that long. Too bad for the farmers that put all that effort into converting from food to oil production.

Sigh.