In July 2013, Geoengineeringwatch.org made the claim that UVB levels were at incredibly high levels, or around 9 mw/cm2 (milliwatts per square centimeter). That was a rather extreme claim, as the levels of UVB in space are just 2.5 mw/cm2, and given that the atmosphere block a lot of that, it's impossible to get MORE UVB actually reaching the ground. So obviously this must be wrong. The questions of WHY is was wrong were not immediately apparent, but they helpfully showed the instruments they were using, and it turned out that the most likely source of their error was that they were calculating UVB by subtracting UVA measured on one meter from UVA+UVB measured on another. That would be fine, except that the UVA+UVB meter was actually measuring quite a bit more UVA than the UVA meter, so the end result was a vastly inflated UVB number. This makes perfect sense. Even though it does not sound like a lot, the actual amount of extra radiation (reaching the surface)in those UVA bands is much higher than all the UVB radiation. So that seemed to settle the matter. Unfortunately it was just brought up again: http://www.geoengineeringwatch.org/record-shattering-uv-radiation-levels-finally-confirmed/ The actual report is here: http://journal.frontiersin.org/Journal/10.3389/fenvs.2014.00019/full And it does indeed say "Record solar UV irradiance in the tropical Andes", but what are these records? And how do they compare to the Geoengineering Watch figures? Their record levels of UVB were on one day, Jan 17, 2004, measured at around 5000m (16,400 ft). 8.15 W/m2 is 815 µW/cm2, or 0.815 mW/cm2 So that's the new record. 0.815 mW/cm2. While the record GeoengineeringWatch is claiming is 9.0 mW/cm2. That's ten times higher than the value they say confirms their result. Another metric used by the study is the ratio of UVA to UVB: So we have a record value of 0.129, while the record Geoengineeringwatch is claiming is around 0.800 So far from "confirming" their original measurements, this study quite roundly debunks them.