UV exposure has increased over the last 30 years, but stabilized since the mid-1990s
From NASA Goddard press release here
NASA scientists analyzing 30 years of satellite data have found that the amount of ultraviolet (UV) radiation reaching Earth’s surface has increased markedly over the last three decades. Most of the increase has occurred in the mid-and-high latitudes, and there’s been little or no increase in tropical regions.
The new analysis shows, for example, that at one line of latitude — 32.5 degrees — a line that runs through central Texas in the northern hemisphere and the country of Uruguay in the southern hemisphere, 305 nanometer UV levels have gone up by some 6 percent on average since 1979.
The primary culprit: decreasing levels of stratospheric ozone, a colorless gas that acts as Earth’s natural sunscreen by shielding the surface from damaging UV radiation.
The finding reinforces previous observations that show UV levels are stabilizing after countries began signing an international treaty that limited the emissions of ozone-depleting gases in 1987. The study also shows that increased cloudiness in the southern hemisphere over the 30-year period has impacted UV.
Jay Herman, a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., stitched together data from several earth observing satellites — including NASA’s Aura satellite, NOAA weather satellites, and commercial satellites — to draw his conclusions. The results were published in the Journal of Geophysical Research in February.
“Overall, we’re still not where we’d like to be with ozone, but we’re on the right track,” said Jay Herman. “We do still see an increase in UV on a 30-year timescale, but it’s moderate, it could have been worse, and it appears to have leveled off.”
In the tropics, the increase has been minimal, but in the mid-latitudes it has been more obvious. During the summer, for example, UV has increased by more than 20 percent in Patagonia and the southern portions of South America. It has risen by nearly 10 percent in Buenos Aires, a city that’s about the same distance from the equator as Little Rock, Ark. At Washington, D.C.’s latitude — about 35 degrees north — UV has increased by about 9 percent since 1979.
The southern hemisphere tends to have more UV exposure because of the ozone hole, a seasonal depletion of the ozone layer centered on the South Pole. There are also fewer particles of air pollution — which help block UV — due to the comparatively small numbers of people who live in the southern hemisphere.
Despite the overall increases, there are clear signs that ultraviolet radiation levels are on the verge of falling. Herman’s analysis, which is in agreement with a World Meteorological Report published in recent years, shows that decreases in ozone and corresponding increases in UV irradiance leveled off in the mid-nineties.
The Many Sides of Radiation
Shorter ultraviolet wavelengths of light contain more energy than the infrared or visible portions of sunlight that reach Earth’s surface. Because of this, UV photons can break atmospheric chemical bonds and cause complex health effects.
Longer wavelengths (from 320 to 400 nanometers) — called UV-A — cause sunburn and cataracts. Yet, UV-A can also improve health by spurring the production of Vitamin D, a substance that’s critical for calcium absorption in bones and that helps stave off a variety of chronic diseases.
UV-B, which has slightly shorter wavelengths (from 320 to 290 nanometers), damages DNA by tangling and distorting its ladder-like structure, causing a range of health problems such as skin cancer and diseases affecting the immune system.
As part of his study, Herman developed a mathematical technique to quantify the biological impacts of UV exposure. He examined and calculated how changing levels of ozone and ultraviolet irradiance affect life. For Greenbelt, Md., for example, he calculated that a 7 percent increase in UV yielded a 4.4 percent increase in the damage to skin, a 4.8 percent increase in damage to DNA, a 5 percent increase in Vitamin D production, and less than a percent of increase in plant growth.
“If you go to the beach these days, you’re at slightly higher risk of getting skin cancer (without protection),” Herman said, though he noted the risk would have been even greater in the absence of regulations on ozone-depleting substances.
Last year, one of Herman’s Goddard colleagues, Paul Newman, published a study showing that the ozone hole likely would have become a year-round fixture and UV radiation would increase 650 percent by 2065 in mid-latitude cities if not for the Montreal Protocol, an international treaty signed in 1987 that limited the amount of ozone-depleting gases countries could emit.
Clouds and Hemispheric Dimming
In addition to analyzing ozone and ultraviolet trends, Herman also used satellite data to study whether changes in cloudiness have affected UV trends. To his surprise, he found that increased cloudiness in the southern hemisphere produced a dimming effect that increased the shielding from UV compared to previous years.
In the higher latitudes especially, he detected a slight reduction — typically of 2 to 4 percent — in the amount of UV passing through the atmosphere and reaching the surface due to clouds. “It’s not a large amount, but it’s intriguing,” Herman said. “We aren’t sure what’s behind it yet.”
Vitali Fioletov, a Canadian scientist and member of the World Meteorological Organization’s advisory group on ultraviolet radiation, agreed that Herman’s findings about cloudiness warrant additional investigation. “I found the cloud effects on the global scale to be the most interesting aspect of the study,” he said. “This isn’t something you could see without satellites.”
Herman synthesized measurements from the Total Ozone Mapping Spectrometer (TOMS) aboard Nimbus 7 and Earth Probe, the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite, NASA’s Sea-Viewing Wide Field-of-view sensor (SeaWiFS) on the commercial SeaStar satellite, and the Solar Backscatter Ultraviolet Instrument (SBUV) on several polar orbiting NOAA weather satellites.
Related Links:
Global increase in UV irradiance during the past 30 years (1979–2008) estimated from satellite data
h/t to Dr. Leif Svalgaard
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Do the Yamal pines show a hockey stick for this too?
Enacting the Montreal Protocol was SO important because of the longevity of CFCs in the atmosphere. It was explained to all of us who enjoyed cheap freon that we must give it up right away to ‘save our children’, because it would take 50 years just to start to see an improvement.
Therefore, if CFCs really were responsible for stratospheric ozone depletion, there is no way that the depletion would have stabilized in the mid 1990s!
To proclaim that the Montreal Protocol resulted in the stabilization of the ozone layer is a lie. There were more CFCs in the atmosphere in the mid 1990s than there were in the late 1980s. Obviously, something else is controlling the concentration of stratospheric ozone. It is very likely a natural cycle.
Of course, the banning of CFCs made air-conditioning and refrigeration less efficient, causing us to burn more fossil fuels for the same amount of cooling, releasing more CO2!
Dupont made a fortune selling less efficient, more expensive coolants in the 1990s. They weren’t making hardly anything selling freon. Dupont was the major benefactor from the Montreal Protocol. The rest of us paid more for no measurable gain. Skin cancers are still on the rise despite the stable ozone from the mid 1990’s. Again, there are other factors involved that the grant seeking scientists refuse to mention.
Finally,
As I understand it, a decrease of about 6% in the stratospheric ozone layer has an equivalent health effect as moving about 80-100 miles closer to the equator. If this is such a major health issue, shouldn’t we force people to move north, in addition to banning CFCs? Certainly, moving south or to a higher elevation should be expressly forbidden. Think of the children!
Here is a supposed reconstruction of solar UV output. Perhaps Leif can point to something better.
http://www.astro.phys.ethz.ch/papers/fligge/GL10884W01.pdf
You can clearly see (notice the y-axis scale) the larger variability in UV wrt TSI. I don’t find this NASA report particularly interesting as the UV output of the Sun is also increasing.
R. Gates (09:52:36) :
More to the point, the damage done to the ozone layer was serious, did increase UV, but we caught it in time and did something about it. It did prove that humans can both cause and solve problems on a global scale.
Oh, utter self-serving BS. The so-called ozone hole is there always, varying according to the Sun. It is not caused by humans and has not been solved by humans. IT IS PERFECTLY NATURAL.
John Galt (10:46:33) :
Are we all going to die then?
Yes. Each and every one of us.
But in 1000 years, maybe not. We are learning more and developing technology all the time. Now, if we can avoid the death of politicised science, then progress will continue.
Didn’t that scientific wonder, Sue Solomon, spend about 6 months amongst the penguins (I feel bad for them) at McMurdo to come home and conclude that Polar Stratospheric Clouds are the reason CFC are destroying the ozone layer and not elsewhere?
Is there some atmospheric phenomena making PSC appear in the Tropics?
The whole thing was a colossal fraud, now Sue is on the leading edge of perpetrating another with CO2
Rowland won a Nobel prize for coming up with the “mechanism” for CFC and ozone depletion. Nobody has reproduced this in a lab! Think about that – this is equivalent to Fleishman and Pons winning a Nobel for cold fusion and nobody can reproduce this
Hey, no fair! I want a linear trend! What’s this “leveling off” business???
Read maybe 10 years ago that the Ozone depletion/ hole was first detected back in 1958 the International Geophysical Year. (The first one) and that it was a natural occurrence….
Anyone know about this?…
Well, if there was a connection between UV and the small amount of warming (after correcting for UHI and decimation of the sensor populatoin), it would explain that the observation that the temperature increase is highest toward the poles, just where the UV change is the highest.
Urederra (09:12:20) :
There is no ozone hole. […]
I seem to basically agree. Do you by chance know if the difference of north to south ratio is magnetic field related or not? I can’t imagine anything else.
If you do, and even better, do you also know how the magnetic field affects the incoming highly energetic solar rays (particles) to keep even more from the south pole? Possibly positive charged energetic particles (H+ He++) curved toward north pole but away from the south pole?
Or is that way off base?
WASHINGTON — It may sound far-fetched, but federal regulators are studying whether sudden acceleration in Toyotas is linked to “cosmic rays”.
This sounds like a repeat of the 64k DRAM problem, which was solved by adding additional coatings to integrated circuits to fight off stray alpha particles.
The ozone hole existed before CFC’s. It was first reported using weather ballons, and then expanded when satellites could do the job. No one knows the extent of the antartic ozone hole was in 1900, for example. Cargo cult science at its finest.
“wayne (18:44:05) :
Do you by chance know if the difference of north to south ratio is magnetic field related or not? I can’t imagine anything else.?”
I have no idea. But davidmhoffer (09:07:11) : seems to have a plausible explanation. (it is actually 2 posts over mine, so I didn’t see his post because it must had been awaiting moderation when I was typing mine. Here it is again:
“O3 filters UV, but not all
O2 mostly lower in atmosphere than O3
UV strikes O2 breaking the molecules up and producing O3
O3 layer increases in size
filtering out more UV
resulting in less O3 production
At top of O3 layer different UV frequencies break O3 down to O2 plus O. Left over O finds another left over O to party with.
So… thickness of O3 layer depends on intensity variations of UV destroying O3 at top, and rate of production of Ozone at bottom production going up in a thin ozone layer, and going down in a thick one, maintaining it at a reasonably constant thickness.
But at the poles sun’s radiance is steeply inclined so destruction rates fall, but production rates fall further. Hence a depression or “hole” appears. [b]The arctic depression is smaller than the antarctic depression because the arctic’s summer “recovery period” happens when earth orbit is closest to sun, hence stronger rays and the antarctis further, hence less recovery when incliniation to the sun favours additional production.[/b]
As I recall, the CFC catalyst reaction that kicks of the ozone destruction thing needs a temperature range higher than what the ozone layer is at.
At poles”
Urederra (19:31:31) : Thanks to you and David, very interesting explanation. Modulated by the elliptic orbit and axis tilt relation. That would mean very long cycle time. Physics never ceases to amaze!
Pat Moffitt:
Great posts, on both the ozone issue and the “acid rain” bs that some of my environmental friends always like to cite when they talk about how “cap and trade” worked to reduce SO2 in the Northeast (at great cost, I might add, on electric bills), so it should work for CO2.
Background levels of ozone, even here in Texas, can range from 55 to 60 ppb because of plant VOC emissions as well as the other phenomenon you cited. So I have no idea where EPA gets off thinking they are going to save the country from this problem. It’s just another device for control of the world.
Robert Austin said:
“CFC scare looks too much like a practice run for the main event, climate change…”
Sorry, this is too grassy knoll for me. Since I personally know several scientists in the climate research field and know how dedicated they are, and have been since their undergraduate days, I simply don’t accept a conspiracy notion. Yes, there are a very few who are trying to capitalize on the AGW hypothesis (or hype, if you prefer), but for every one of those, there are 100 or even 1,000 honest researchers who meticulously gather data, record it, have their findings peer reviewed, and then publish. This is probably what turns me off the most about AGW skeptics…too much distrust, when only a little skepticism and “prove it to me” attitude is required and even necessary to keep the science honest throughout. Hence I am 75% convinced the AGWT is correct, and a 25% skeptic. This 25% drives my climate research friends crazy, as I am always asking questions, but in addition to making them ticked off at my stupid questions, I at least hope it makes them take an occasional brief moment to consider other interpretations of their data though they never waiver from being 95 to 99% certain that AGWT is correct. But I do sense that many skeptics are 100% certain that AGWT is incorrect, and this kind of certainty scares me even more…
How does this tie in with Meehl et al 2009 I wonder. if at all.
Second graph mis-spells January 😉
REPLY: tell the authors, not a WUWT error
How do we know the ‘ozone hole’ wasn’t there before we detected it? Or that it was there always?
Because people in New Zealand get sunburned in 20 minutes. That was not the case 30 years or more ago.
To anyone who denies that it is worse now than in the past I have a challenge. Fly to New Zealand and do a couple of hours work in my garden with your shirt off without sunblock. After we get you back out of the hospital you won’t want to talk about “there’s no ozone hole”.
NZ has lots of climate sceptics, but we have few or no ozone-hole sceptics. I have never met or heard from one. It is too much part of our daily lives. It would be like denying that it ever rains.
I also doubt that it was ever part of our history prior to 1980’s. The Maori did not wear hats, which pretty much clinches it.
@Henry Chance
How about the thousands of lightning strikes ever 24 hours on this planet that create ozone. What about the dry copiers and printers in offices that create ozone.
This is not scepticism. It is not bothering to learn even basic chemical facts before you spout.
Ozone is unstable, so any produced at ground level breaks down well before it reaches the top layers – otherwise NZ would make tons of it.
Natural processes can produce ozone, which is why we have some in the upper atmosphere, rather than none.
Something new in the system is causing it to break down faster than usual. If you think it is a natural process, then you really need to find the cause. Until you can find a better cause, CFCs seem to fit the bill.
Leif Svalgaard (10:09:12) :
The largest increases in UV (shown in white, red, orange, and yellow) have occurred in the southern hemisphere during summers.
During winters….
Not quite eg McKenzie et al 2006
UV measurements from instruments maintained by USDA at 16 mid-latitude sites were analysed to
investigate geographic differences. Fifteen of the sites are in North America, and one is in New
Zealand. The instruments measure erythemally weighted UV radiation, and the results are presented in
terms of UV Index (UVI). The focus of this work is on data from 2003, but the main results are also
shown for years 2002 and 2004. In the North American sites, the peak UVI values increase by ∼15%
between latitudes 47◦ N and 40◦ N, and they show an increase with altitude of ∼15% in the first
kilometer, but much smaller rates of increase above that level. Peak UV intensities in the New Zealand
site (45◦ S, alt. 0.37 km) exceed those at comparable latitudes and altitudes in North America by
41 ± 5%, and are more comparable with those over 1 km higher and 5 degrees closer to the equator.
The number of observations on these days that exceeded various thresholds of UVI showed similar patterns. Furthermore, the number of days in which the peak values exceeded various thresholds also showed similar patterns, with the number of extreme values in New Zealand being anomalously high.For example, the only sites in North America where UVI exceeded 12 were at the high altitude sites in Colorado and Utah, for which there were 53 days, 6 days and 2 days respectively at the 3.2 km, 1.6 and 1.4 km sites. By contrast, the peak UVI at Lauder (0.37 km) exceeded 12 on 17 days. Lauder was the only site under 1 km altitude where the UVI exceeded 11 on a regular basis (48 days). The optical depths at Lauder were significantly lower than at all North American sites. These, together with the
lower ozone amounts and the closer Earth–Sun separation in summer all contribute to the relatively high UV intensities at the New Zealand site. Other sites in New Zealand show similar increases compared with corresponding sites in North America, and the differences persist from year to year. The contrast in UV between New Zealand and North America is similar to that observed previously between New Zealand and Europe. During winter months, the UVI in New Zealand is not particularly high, giving a larger summer/winter contrast in UVI, which may be important from a health perspective.
Hello from the southern hemisphere!
Totally agree Mooloo, its the same in Australia. I regularly holiday in Europe, and I can tell you, there is a big difference in UV radiation between northern and southern hemisphere.
You can’t walk around anymore in Australia for more than a few minutes without 30+ sunscreen in an Australian summer… however it certainly isn’t a problem on the Mediterranean where you can get away with light/no protection most of the time.
Just because some climate research is dodgy and being a skeptic is now ‘in vogue’ doesn’t mean everyone who reads this site has to become flat earthers and reject every study that comes out. Seriously, some of the comments here look as stupid as some made by the fanatical alarmists.
Wake up, people.
Ozone is CREATED by UV, in which process UV is absorbed and converted to heat. Life on surface of Earth is safe from UV destruction as long as there is oxygen in atmosphere.
From Wikipedia:
“Ozone is formed in the stratosphere when oxygen molecules photodissociate after absorbing an ultraviolet photon whose wavelength is shorter than 240 nm. This produces two oxygen atoms. The atomic oxygen then combines with O2 to create O3. Ozone molecules absorb UV light between 310 and 200 nm, following which ozone splits into a molecule of O2 and an oxygen atom. The oxygen atom then joins up with an oxygen molecule to regenerate ozone. This is a continuing process which terminates when an oxygen atom “recombines” with an ozone molecule to make two O2 molecules: O + O3 → 2 O2
The overall amount of ozone in the stratosphere is determined by a balance between photochemical production and recombination.”
Ozone hole over Antarctica appears every Antarctic winter for simple reason that Sun does not shine in polar winter (ozone in Arctic region during winter does not disappear because of air transport from temperate zone). And there is no UV at Earth surface under ozone hole – because, sorry, Sun does not shine in this time and location.
TSI:
There are those that claim it varies very little.
(And the Sun has little or nothing to do with climate change.)
But those that claim the above, apparently don’t dispute the observation & measurements that show ultraviolet radiation does vary greatly and per this study, dove-tail nicely with temperature trends.
It’s the Sun…stupid.
Even if you can manipulate historical statistics to say anything you want them to say:
(I understand computer programmers are very good at manipulating statistics.)
Mark Twain: “There are lies, damn lies, and statistics.”
Things haven’t changed much have they?
I asked a simple question.
“How do we know the ‘ozone hole’ wasn’t there before we detected it? Or that it was there always?”
Two replies with insults!
So let’s start again. Instead of anecdotal references to sun-burn, answer the question. Note that it was first detected in 1956 and mapped in detail afterwards.
As a geologist, my problem is the short time scale of measurement. A recent paper questioned ozone chemistry as it is promulgated. http://www.nature.com/news/2007/070924/full/449382a.html
Do we know the whole story yet?
I might disagree with the UV strength in Australia vs Europe. I spend a lot of time in the sun, and build up a fair tan in spring, ready for the summer when it gets harsh. What I try to do is never burn. I figure if I do not burn, the effect is minimal. I may be wrong there, but I am pretty certain almost nobody knows, and it makes a lot of sense to me.
I also have completely unproven feeling that sun block allows you to stay in the sun longer without burning and actually causes problems from some of the things it lets through, as well as the false sense of security it provides.
When I go to Italy, which I tend to every year (my mother lives there) in July, I often get a burn if we stay in the sun too long. The difference is I have less of a tan at that point, and I am only there for a week or so which is not time to build one up.
Now factor in the fact that mid Italy is about the same latitude as Tasmania or even New Zealand, and I think you may see why the sun is a bit stronger in most of Australia – it’s nearer the equator.
Perhaps NZ is much more affected, by the ozone depletion however.
Forget Northern Europe – that is just a cold wasteland that hardly sees the sun!
Biggest two causes of skin cancer in my belief:
1. People who do not spend time in the sun maxing out on two weeks in the sun. I’ve seen it in Malaysian islands: English people so white they hurt the eyes to look at in daylight spending hours in the midday sun – at the equator! All us sensible people were running for cover at about 10 or 11, not to emerge until 3. They were in the sun the entire time. Did they burn? Whatcha think? Like a pair of lobsters!
2. Sun beds. My mother used to have a UV lamp at home, for ‘health’ reasons, no less. She got skin cancer (all fixed now). There are so many cases, and it makes so much sense NOT to flood your skin with harmful rays without the ‘pain response’ protection you get from being in the sun too long.
Still, I don’t know enough about it, just observation.