New paper finds solar UV-B output is correlated to global mean temperature

Map of correlations suggest it may be affecting biomass and planetary albedo.

From the Hockey Schtick:

A paper published today in Methods in Ecology and Evolution describes a new satellite dataset of solar UV-B radiation for use in ecological studies. According to the authors, “UV-B surfaces were correlated with global mean temperature and annual mean radiation data, but exhibited variable spatial associations across the globe.” The finding is notable, since climate scientists dismiss the role of the Sun in climate change by only looking at the tiny 0.1% variations in total solar irradiance [TSI] over solar cycles, ignoring the large variations in solar UV of up to 100% over solar cycles, and which according to this paper, correlates to global mean temperature. Thus, the role of the Sun and solar amplification mechanisms on climate is only at the earliest stages of understanding.

In the supplemental information (SI) I found this correlation map, which was telling for me. Note the red of highest correlation – mostly in the tropics. This suggests to me that UVB is playing a role with ocean biomass, possibly modulating algae/plankton, which in turn changes the albedo, and absorption of other solar wavelengths into the oceans (which then affects nearby land-mass temperature).

The authors write: Finally, we mapped the four types of local spatial association for each pair of compared variables to show how the strength and type of spatial association vary geographically. Areas with non-significant relationship or negative (inverse) spatial association (Low-High, High-Low clusters) indicate locations where our glUV data provide new information (variability) that is not captured by considered existing climate variables. Below is an example of a LISA map for the above mentioned comparison of annual UV-B radiation versus annual temperature (Figure 4a in the manuscript).

Here is the press release:

Researchers at the Helmholtz Centre for Environmental Research (UFZ) have processed existing data on global UV-B radiation in such a way that scientists can use them to find answers to many ecological questions. According to the paper published in Methods in Ecology and Evolution, an online journal of the British Ecological Society, this data set allows drawing new conclusions about the global distribution of animal and plant species.

Many research projects study the effects of temperature and precipitation on the global distribution of plant and animal species. However, an important component of climate research, the UV-B radiation, is often neglected. The landscape ecologists from UFZ in collaboration with their colleagues from the Universities in Olomouc (Czechia), Halle and Lüneburg have processed UV-B data from the U.S. NASA space agency in such a way that they can be used to study the influence of UV-B radiation on organisms.

The basic input data were provided by a NASA satellite that regularly, since 2004, orbits the Earth at an altitude of 705 kilometres and takes daily measurements of the UV-B radiation. “For us, however, not daily but the long-term radiation values are crucial, as these are relevant for organisms”, says the UFZ researcher Michael Beckmann, the lead author of the study. The researchers therefore derived six variables from the UV-B radiation data. These include annual average, seasonality, as well as months and quarters with the highest or lowest radiation intensity.

In order to process the enormous NASA data set, the UFZ researchers developed a computational algorithm, which not only removed missing or incorrect readings, but also summed up the daily measurements on a monthly basis and determined long-term averages. The processed data are currently available for the years 2004-2013 and will be updated annually.

With this data set, scientists can now perform macro-ecological analyses on the effects of UV-B radiation on the global distribution of animal and plant species. “While there are still many uncertainties”, says Michael Beckmann, “the UV radiation is another factor that may explain why species are present or absent at specific sites.” The data set can also help addressing other research questions. Material scientists can identify strategies to provide better protection to UV-sensitive materials, such as paints or plastics, in specific regions of the world. Human medicine could use the data set to better explain the regional prevalence of skin diseases. “There are no set limits as to how researchers can use these data”, says Beckmann.

The data are now freely available for download on the internet and visually presented in the form of maps. These maps show, for example, that in countries in the southern hemisphere, such as New Zealand, the UV-B radiation is up to 50 percent higher than in the countries in the northern hemisphere, such as Germany. In general, the UV irradiation in winter is lower than in summer due to a shorter daily sunshine duration.

Background: Unlike the rather harmless UV-A radiation, the high-energy UV-B radiation causes health problems to humans, animals and plants. Well known is the higher risk of skin cancer in the New Zealand and Australia population if unprotected and exposed to sun for an extended period of time. Skin damage was also documented in whales and amphibians. In amphibians, UV-B radiation may also reduce survival rates of tadpoles and spawn eggs. In plants, the radiation reduces performance of photosynthesis, a process of using solar energy to convert carbon dioxide and water into sugars and oxygen. This inhibits production of biomass and thus reduces e.g. yields of agricultural crops.

The paper: glUV: a global UV-B radiation data set for macroecological studies