Climate Feedback

Warming dries up dairy herds

You may have heard already that cow farts are a climatic threat. Scientific American points out some research that turns the problem around: climate change can also affect cows and dry up dairy production.

In Climatic Change this month, Terry Mader of the University of Nebraska and colleagues model the impact on Midwestern dairy cows if carbon dioxide doubles or triples. Their simulation combined two different global climate models with a model of cow physiology – which, says Mader, is rather more tractable than the Earth system.

SciAm erroneously reports that the group concluded US milk yields would fall 16-30% during summer, about twice the decline farmers normally expect. Actually, this is a the conclusion of another study mentioned in the paper’s Discussion section. The authors say these figures are “slightly greater but still in close agreement” with their own data, which show that a doubling of carbon dioxide would decrease the already-low summer production by an additional 1-3%, and a tripling would drive it down by up to 7.5%.

Hot spells do costly damage to dairy farming, notes the story:

In July 2006, a month long triple-digit heat wave scorched California, killing more than 25,000 cattle and reducing dairy production in the region. Land O’Lakes Creameries, which normally produces six million liters of milk daily, was short 1.5 million liters per day. All told, experts estimate that the high temperatures caused $1 billion worth of dairy shortfalls.

One strategy for beating the heat is to breed more tolerant herds. A study in PLoS One this week catalogs genetic markers that are associated with cows’ sensitivity to environmental conditions. This seems more promising than the adaptation alternative that occurred to me, which is for the Land O’Lakes Creameries to return to the Land O’Lakes.

Anna Barnett


  1. Report this comment

    Frank S said:

    A doubling of atmospheric CO2 would lead to increased growth of grass and other cattle feeds. And, of course, would have a negligible effect on the real climate as evidenced by recent history. But it would have a big effect inside GCMs which are programmed to respond to CO2 is dramatic ways.

Comments are closed.