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Global warming means less milk if dairies can’t keep cows cool

Rising temperatures have caused some of America's 9 million dairy cows to produce less milk.

A hell year for milk farmers has gotten even hotter.

As if falling demand and tumbling stock values for publicly traded dairies weren’t enough, rising temperatures have caused some of America’s 9 million dairy cows to produce less milk, sending farmers into a desperate search for efficient ways to cool them off.

“You can’t put air-conditioning units in the dairy barn,” said Rob Barley, co-owner of Star Rock Farms in Lancaster County, Pennsylvania.

When temperatures soared to 95 degrees Fahrenheit (35 degrees Celsius) in July, milk production on Barley’s farm fell about 8% in a week’s time. That was enough milk to fill a trailer.


“If the cow isn’t comfortable, she’s just going to want to lay down,” Barley said. “She’s not going to want to eat as much,” and she’ll produce less.

Dairy cows like it best when the mercury is between 45 and 65 degrees Fahrenheit, but nature may not be cooperating like it used to. The world’s combined land and sea temperature in July was 62.13 degrees Fahrenheit, the highest in records going back to 1880, and August was close behind, according to the National Centers for Environmental Information. Milk production starts slowing when the thermometer rises above 70 or 80 degrees, said Jeffrey Brose of the Dairy Cattle Welfare Council. Signs of heat stress include open-mouth breathing, drooling and more rapid respiration.

Rising temperatures are stressing an already struggling U.S. dairy industry. The industry has been in free fall the past several years as global supplies surge and Americans drink less milk. Exports have also been hurt due to tariffs with Mexico and China. Amid the turmoil, stalwarts such as Dean Foods Co., the biggest dairy company in the U.S., has seen its stock tumble 67% this year.

Many producers, especially small Midwestern farmers, have been forced out of business in the last year by factors including rising labor costs. So many have gone belly up, in fact, that supply has declined enough to raise milk prices, said Dave Kurzawski, a broker at INTL FCStone.


All that’s tough enough for farmers, but the long view isn’t any better. U.S. milk production could fall 6.3% due to climate impacts by the end of the century, according to a University of Washington study. That would cost the industry about 2.2 billion a year.

“Climate change is providing more risk to the dairy industry,” said Dwayne Faber, a dairy farmer in Skagit County, Washington.

Faber is investing in fans to keep his 2,000-cow herd cool in extreme heat, and curtains to protect them from snowstorms. The fans create a 20 mph wind.

In Sharon Springs, New York, Phyllis Van Amburgh is spending about $6,000 for fans and heavy-duty clear plastic curtains to keep her 175 milking cows from harm.

“We absolutely have to deal with those variations in weather,” she said. She called the investment “really significant.”

Summers are getting hotter, so cows need more relief, said Nancy Vander Byl, North American manager for Cow Kühlerz, which uses what’s called an evaporative solution involving variable-speed fans and timed mists that work best in dry weather. Vander Byl said competing cooling systems are mainly soaker systems that get cows wet.

“It’s all about cow comfort,” Vander Byl said. “Heat abatement is a big part of maximizing cow comfort. As we’re experiencing this shift in temperature patterns, you need to be proactive.”


Not surprisingly, southern states like Florida are the ones that will fare the worst in the future, according to the University of Washington study. Florida milk production could fall 25% by the end of the century, whereas a northern state like Washington could lose less than 1%. Farmers may be able to boost production through breeding and management methods faster than climate change can depress it.

“This doesn’t mean it costs nothing to the industry, but that it is well within our capacity to adapt,” said Guillaume Mauger, who co-authored the study.

Rising temperatures are bugging cows in Europe, too, according to Alex Risen, a spokesman for Lexington, Kentucky-based Big Ass Fans, which is seeing more interest from dairies across the Atlantic.

One possible way to adapt to climate change is by providing cool bedding for animals, a project touted by Bob Collier, a University of Arizona emeritus professor. Because today’s cows have been bred to be bigger, it’s harder to cool them off than their less hefty forebears, he said.

Collier and his colleagues found that circulating cold water under sand bedding helped lower body temperatures in dairy cows.

Underground heat exchangers are “just one of the things that a producer could use in addition to shade and fans,” Collier said. “The dairy industry spends a lot of money trying to manage the environment around their cows so that they maximize their production.”