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Unprecedented UV Storms Are a Possible Climate Change Future

Look to record UV levels in the high Andes mountains for a glimpse.
Image: Flickr/David Clow

Compared to even acutely lethal weather like tornadoes and apocalyptic hurricane mutants, there's something uniquely fearsome about radiation. It's invisible, for one, and does its damage relatively behind the scenes, in our DNA and in the micro-scale functioning of living cells. You feel it after it's too late, like a sunburn: today's warm cheeks and scratchy eyes are tomorrow's oozing skin and near-blindness and the year after next's cancer.

Much of the popular radiation alarmism post-Fukushima is based on scare blogs and junk science, and the real truth is that the radiation danger for the vast majority of us is going to come from the Sun, not the Pacific; from ultraviolet rays, not caesium-134. A set of recently released observations provide an ominous postcard from this future.


Those observations are summarized in a study released this week in the journal Frontiers in Environmental Science describing a two-year UV storm that hit the Andes mountains between 2003 and 2004. During that period and for a variety of interconnected reasons, the UV index over a large populated area spiked to an unprecedented 43, remaining there for 61 days, while lower but still shockingly high spikes were recorded throughout the two-year span. These fluxes, an accompanying statement from the SETI Institute notes, are comparable to what one might expect on Mars.

Mars is precisely what the researchers behind this week's study were looking for. The team, led by SETI's Nathalie Cabrol, was conducting astrobiology research in these high-altitute Andean environments because they share a bit in common with the Martian environment in their unusual (for Earth) exposure potential to UV light, both because of their altitude and their frequently clear skies. If you wanted to see how some tiny bit of life might do in the Martian environment, an Andean lake at 20,000 feet is a great place to start.

As part of the research, the SETI team placed a pair of dosimeters, each part of the globe-spanning Eldonet network of solar radiation monitoring devices, on local mountain peaks. Despite losing about 35 percent of their data due to the difficult high-mountain conditions, the devices were able to deliver consistent readings. The stunning result: the highest values of UV radiation ever recorded outside of Antarctica.

Image: Nathalie Cabrol

But first, what exactly is a UV index measurement anyway? It's not exact for one thing, nor does it have physical units. Rather, it's a measurement of sunlight intensity based on human sunburns. If a human burns in five minutes at UV 10, they'll burn in 10 minutes at UV 5. Aa value of about 10 is what most of us would consider a powerful, full-sunlight beach-dose.

"If you're at a beach in the US, you might experience an index of 8 or 9 during the summer, intense enough to warrant protection," said Cabrol in the SETI statement. "You simply do not want to be outside when the index reaches 30 or 40." Doing some beach-math might help illustrate: consider the sunburn you'd get in an hour, and multiply it by four for the same period. So a full eight hours in the Rockaway sun would be like 32 hours or so during the recorded Andean spike. Ouch.

You might think, hey, I don't live at 20,000 feet in the Andes and also wear some wicked sunscreen here on my mid-latitude, low-altitude beach. It's also 2014, not 2004. That's true, the measurements are old. Keeping dosimeters stationed in the very-high Andes is not very feasible. "We don't have any instruments there right now," Cabrol told Motherboard, "but levels are likely to be high in summer because of season, latitude, and elevation. For instance, another study in 2009 showed a UVI of [about] 26 at the same elevation as our lowest instrument at Laguna Blanca only a few hundreds of [kilometers] to the east of our sites."

The causes behind the '03/'04 spikes, according to the study, were something of a perfect storm that included aerosol releases from seasonal fires and storms resulting in local ozone depletion, at least one massive solar flare, and intense wind conditions shoving through the local stratosphere. Again: not your beach in Jersey.

But climate change is set to make a whole lot of places look more like the high Andes in the coming decades. Ozone thinning is considered to be a general phenonomenon of global warming; as the stratosphere cools due to increases in atmospheric CO2 and methane levels, very high altitude clouds form, which facilitate the destruction of stratospheric ozone. Less ozone then leads to an even cooler stratosphere, and you can see the feedback cycle that results.

So, as we tumble into this whole global warming mess, what's needed is more information. Eldonet, spanning hundreds of dosimeter stations across the planet, is a good start. "These were the highest levels ever recorded as far as we know," Cabrol cautioned. "Obviously, we would need a lot more instruments at a lot more locations to be able to answer with certainty. Hence the importance of continuing and expanding monitoring."