Science Friday: Antarctic CO2 Hit 400 PPM For First Time in 4 Million Years | Do Zebra stripes confuse biting flies?

Remember this scene from An Inconvenient Truth?

By Brian Kahn, Climate Central | June 16, 2016 02:53pm ET

We’re officially living in a new world.

Carbon dioxide has been steadily rising since the start of the Industrial Revolution, setting a new high year after year. There’s a notable new entry to the record books. The last station on Earth without a 400 parts per million (ppm) reading has reached it.

A little 400 ppm history. Three years ago, the world’s gold standard carbon dioxide observatory passed the symbolic threshold of 400 ppm. Other observing stations have steadily reached that threshold as carbon dioxide spreads across the planet’s atmosphere at various points since then. Collectively, the world passed the threshold for a month last year.

In the remote reaches of Antarctica, the South Pole Observatory carbon dioxide observing station cleared 400 ppm on May 23, according to an announcement from the National Oceanic and Atmospheric Administration on Wednesday. That’s the first time it’s passed that level in 4 million years (no, that’s not a typo).


Do Zebra stripes confuse biting flies?

May 25th, 2016 @ 11:00 am by Andy Fell

Zebra stripes have fascinated people for millennia, and there are a number of different theories to explain why these wild horses should be so brightly marked. A handful of laboratories around the world – including one lead by UC Davis wildlife biologist Tim Caro – have been putting these theories to the test. A new paper from Caro’s group, led by Ken Britten at the UC Davis Center for Neuroscience, puts a hole in one idea: that the stripes confuse biting flies by breaking up polarized light.

The paper is published in the May 25 issue of PLOS ONE.

Britten said Caro brought him in as a vision specialist on the project to understand why flies would or would not be attracted to zebra stripes. Horse flies and tsetse flies are common in the regions of Africa where zebras live. Not only do they suck their host’s blood, but they also carry diseases – for example tsetse notoriously spread trypanosome parasites that cause disease in wild animals, livestock and people (the human disease is known as sleeping sickness). Horse flies in particular can carry diseases fatal to equids.

It’s also known that many flies, mosquitoes and other insects are attracted to dark objects. Work by Hungarian researchers suggests that light reflected from black shapes is polarized. Unlike humans, many insects can distinguish polarized light, so this might be the signal that they use to track prey. The Hungarian team proposed that the white stripes break up the polarization pattern from black stripes, thereby confusing the flies.


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