nature | MY SPECIAL DOCTOR

There are some seemingly simple questions that only science can answer. One such question concerns why some clouds “reflect more” than others. A team of researchers from the Institute of Atmospheric and Climate Sciences of the National Research Council (Isac-Cnr) in Bologna recently confirmed experimentally a hypothesis formulated two decades ago that is of important climatological significance. And The results were published in the influential journal Nature.

The explanation

“That clouds form from small particles of atmospheric particulate matter has already been known for several years, but for the first time we have discovered that organic surfactant compounds of marine origin form cloud droplets much more effectively thus increasing the cooling effect of sea clouds”-says Maria Cristina Facchini, research executive at Isac-Cnr and coordinator of the Italian team that collaborated on the study together with other European, U.S. and Canadian universities and research centers. These are nanometer particles rich in organic compounds, resulting in clouds that contain a much higher number of droplets, even up to ten times, and are therefore more reflective and less likely to form precipitation. “The combination of these two factors exerts a cooling effect on the climate that, in light of these new results, can be better quantified.”

The discovery then invests the reflectivity (“albedo”) and precipitation-producing ability of clouds. Theoretical and laboratory studies had suggested the potentially important role in the cloud forma tion process of organic surfactants contained in atmospheric particulate matter. “Such an effect had in particular been hypothesized more than a decade ago in work I conducted (Facchini et al., Nature 1999), but it had never been observed in a real environment, much less simulated by models”-Maria Cristina Facchini points out-“That’s why we are talking about a study that constitutes a real breakthrough in the understanding of cloud formation processes from both experimental and theoretical perspectives. Now the challenge lies in determining the significance of the observed process at the large scale through further refinement of global climate models.

To put it in simpler words

Clouds are fundamental elements of our planet’s radiative balance-that is, the ratio of solar radiation that reaches Earth and that which is reflected back to space; the limited ability of the models currently developed and used by scholars to reproduce the processes of cloud formation and evolution, therefore, was a key uncertainty factor in the analysis and prediction of climate change, but now this study found how organic surfactants increase the ability of marine clouds to reflect solar radiation, affecting precipitation and climate. And we all know how, especially in recent years, temperature, rain and drought are increasingly on the agenda, debated by the media but also by the so-called man in the street.

Virus is not always synonymous with “harmful cause,” carrying negative effects. At least in the deep sea, where plankton viral infections are the engine of the food chain. The news is more than reliable, coming from Spanish-Italian research involving Ismar-Cnr, and published in “Science Advances,” which shows that in the deep oceans, plankton viral infections release 140 gigatonnes of fresh organic carbon each year for the ecosystem food chain. The results? They will help improve estimates of the earth’s global carbon cycle, useful for understanding climate change.

The study

If the depths of the oceans continue to be populated by fish and other sea creatures, the study says, credit is also due to viruses that, by infecting plankton, put essential nutrients back into the ecosystem’s food chain. “The research is based on the analysis of more than a thousand water samples collected, from the surface to depths of 4,000 meters, along the Atlantic, Pacific and Indian oceans during a scientific expedition conducted in 2010 and funded by the Csic called Malaspina Expedition and tracing the eponymous globe circumnavigation expedition led by Alessandro Malaspina in the late 1700s,” explains Gian Marco Luna, an Ismar-Cnr researcher from Ancona and co-author of the study. “We have shown that viruses from deep environments, about which little has been known until now, are able to prey on microbial plankton much more actively than previously thought.”

Specifically, it is estimated that in the global ocean these viruses infect hundreds of trillions of plankton microorganisms every second (one trillion equals trillion). The viruses destroy the infected cells, which thus put their valuable contents, composed of biomolecules of high nutritional quality, back into the surrounding water. Thus, an important fraction of such organic matter becomes nutrients for other microorganisms, according to the effect known as“viral priming,” feeding the entire food web down to the fish.

Effects

Researchers have also shown that viral infection, particularly in the deep ocean, is responsible for the regeneration of a huge amount of dissolved organic carbon. “Using flow cytometry, a laser technique used in biology that allows the detection and counting of cells and viruses in ocean water samples, we showed that viral infection is responsible for the annual release of 140 gigatonnes of carbon (one gigatonnes corresponds to one billion tons), thus contributing to the global ocean carbon cycle,” continues first author of the paper Elena Lara, a Spanish researcher currently with Ismar-Cnr in Venice and associated with Icm-Csic in Barcelona. Viruses, by breaking down the cells of living microbes, then produce fresh organic carbon, made of biomolecules that are more digestible and potentially more usable along the trophic network than the large slice of dissolved organic carbon.