The Arctic is warming more rapidly, causing heat waves that are a threat to human health and economies. Damage from heat waves has doubled in frequency in this century. The 2012 record heat wave in the U.S. that destroyed cornfields and fed wildfires isn’t the only incident. From 1980 to 2003, an average of two heat wave events occurred every four years.

While climate change is breakfast talk these days, few people know how big a role something called Rossby waves have in the increasing prevalence of heat waves.

In 1939, Rossby waves were discovered in jet streams and were linked to high and low pressure systems at ground level, which form Earth’s daily weather. The weather on Earth’s surface is controlled by jet streams, which are high winds in the atmosphere. A jet stream travels 124 miles an hour, and wanders north and south.

As a Rossby wave develops in a jet stream flying north to Europe or the U.S., it brings warm air from the tropics with it. As a jet stream with Rossby waves heads south, it does the opposite, dragging colder Arctic air along. These waves morph shape continuously, making rapid variations in weather patterns.

New research reports a tendency for Rossby waves in jet streams to grow and stick, however, particularly in July and August. The research, published in the Proceedings of the National Academy of Sciences of the USA, explains why heat waves last for weeks, not just a few days, and reports on the resultant health and economic threat. The new data suggests a link between Rossby waves and the warming of the Arctic.

The Arctic has been heating up twice as fast as the rest of the Earth since 2000, due not to Rossby waves at all but to greenhouse gases, the melting of the ice in the Arctic causes a warmer Arctic — with less ice, less sunlight gets reflected back into space and leaves more dark, open ocean, which is warmer and absorbs more warmth. Rossby waves that used to suck cold Arctic air into a jet stream and pull it to Europe are now bringing warmer Arctic air. Temperature differences are decreasing and everywhere is warming as the Arctic warms, further evidence of the interconnectedness of Earth’s systems.

— Cassie Moore


The Colorado Department of Agriculture has reported that there are confirmed cases of both vesicular stomatitis Indiana virus and West Nile virus in horses in Colorado. Cases of vesicular stomatitis virus in horses nearly doubled in Colorado over one week. As of August 13, the Colorado Department of Agriculture’s State Veterinarian’s Office had placed 133 locations under quarantine for the disease, 49 of which were in Boulder County and 57 in Weld County. All confirmed cases of vesicular stomatitis have been horses with the exception of three cows.

Vesicular stomatitis is an acute viral vesicular disease that infects insects, cattle, horses and pigs. Its symptoms are very similar to foot and mouth disease, including vesicles, erosions and slack skin on the muzzle, tongue, teats and above the hooves. Because vesicular stomatitis is transmitted from insects, one of the best prevention methods is fly control.

Though rare, humans can contract vesicular stomatitis, and it is usually found in people who have worked with infected animals. In humans it causes flu-like symptoms.

There are no USDA-approved vaccines for the disease, and animals with signs of vesicular stomatitis are quarantined until determined healthy.

The first equine case of West Nile virus has also been reported in Adams County. Livestock owners and veterinarians who suspect their animals may have contracted either vesicular stomatitis or West Nile virus should contact state or federal animal health authorities.

— Cassie Moore