Every pandemic affects life and actions of people, which in turn controls the course of the pandemic. Until now the factors that determine our social, political, and psychological sphere could not be described by mathematical models, making it difficult to venture forecasts for the Corona pandemic. The new study will improve the situation. Researcher Prof. Kai Wirtz of the Hereon Institution for Coastal Systems - Analysis and Modeling quantitatively describes the social phenomena hinted at above. "As a scientist, social modeling has been driving me for a while. It has also reached coastal research in the meantime. The greatest challenge in this development was the integration of human agency into conventional epidemiological models," says Wirtz. 

How Corona changes people

Due to the problems in the predictability of social dynamics, Wirtz uses the uniqueness of the global Corona pandemic for the new study. This comes along with unprecedented data availability, as he emphasizes. The study uses a part of these data sets - primarily presented by Apple, John Hopkins CSSE und YouGov - to quantitatively test a novel model based on the different pandemic course patterns in 20 affected regions. The regions include 11 EU countries such as Germany, Italy and Sweden, Iran, and eight states in the US.

Societies that were affected by the pandemic at the beginning of 2020, mostly Western industrialized countries, succeeded in curtailing the rates of infection through measures such as social distancing. After the societies began to lift the imposed lockdowns in May 2020, some of them achieved very low case figures while others were affected by an enduring high rate of mortality. Later during the fall and winter seasons of 2020/2021, all these regions were hit by a massive second and third wave despite their experiences made during the first lockdown.

The model of the study combines classic equations for viral spreading with simple rules for social dynamics: as a basis it is assumed that societies act rationally to keep the cumulative damage, resulting from COVID 19-caused mortality and the direct socio-economic cost of social distancing, as low as possible. "However, the simulation results show that another mechanism is crucial to describe the dynamics in the 20 regions: the erosion of so-called "social cohesion" with a reduced willingness for and efficacy of social distancing," says Wirtz.

Lost cohesion

It is only the simulation of this erosion process that results in curves of regional mortality rates and mobility and behavioral changes which are almost identical to the empirical data. Thus, the study presents the first model which increases the period of forecasting from so far a few weeks up to one year. In addition, the model can potentially be used to describe the impact of new SARS-CoV-2 mutants.

Based on this study, the regionally diverse second and third waves of the pandemic can be explained as the consequence of differences in social cohesion and climatological factors. The model calculations showed that in many countries a Zero Covid-strategy would have been possible in the summer of 2020. "But only if the social fatigue would have been halted and strict travel bans applied," says Kai Wirtz. Due to the successful validation, the model can guide medium-term strategic planning, for example, more efficient vaccine distribution. Already, at the beginning of 2021, the model predicted for Germany that each delayed day of the mass vaccination causes 178 further Corona deaths on average. With this piece of research, the human approach in dealing with the virus has become better predictable.

Planets tilted on their axis, like Earth, are more capable of evolving complex life. This finding will help scientists refine the search for more advanced life on exoplanets. This NASA-funded research was presented today at the Goldschmidt Geochemistry virtual conference.

Since the first discovery of exoplanets (planets orbiting distant stars) in 1992, scientists have been looking for worlds that might support life. It is believed that to sustain even basic life, exoplanets need to be at just the right distance from their stars to allow liquid water to exist; the so-called Goldilocks zone. However, for more advanced life, other factors are also important, particularly atmospheric oxygen. 

Oxygen plays a critical role in respiration, the chemical process which drives the metabolisms of most complex living things. Some basic life forms produce oxygen in small quantities, but for more complex life forms, such as plants and animals, oxygen is critical. Early Earth had little oxygen even though basic life forms existed.

The scientists produced a supercomputer model of the conditions required for life on Earth to be able to produce oxygen. The model allowed them to input different parameters, to show how changing conditions on a planet might change the amount of oxygen produced by photosynthetic life.

Lead researcher Stephanie Olson (Purdue University) said "The model allows us to change things such as day length, the amount of atmosphere, or the distribution of land to see how marine environments and the oxygen-producing life in the oceans respond."

The researchers found that increasing day length, higher surface pressure, and the emergence of continents all influence ocean circulation patterns and associated nutrient transport in ways that may increase oxygen production. They believe that these relationships may have contributed to Earth's oxygenation by favoring oxygen transfer to the atmosphere as Earth's rotation has slowed, its continents have grown, and surface pressure has increased through time.

"The most interesting result came when we modeled 'orbital obliquity' - in other words how the planet tilts as it circles around its star," explained Megan Barnett, a University of Chicago graduate student involved with the study. She continued "Greater tilting increased photosynthetic oxygen production in the ocean in our model, in part by increasing the efficiency with which biological ingredients are recycled. The effect was similar to doubling the amount of nutrients that sustain life."

Earth's sphere tilts on its axis at an angle of 23.5 degrees. This gives us our seasons, with parts of the Earth receiving more direct sunlight in summer than in winter. However, not all planets in our Solar System are tilted like the Earth: Uranus is tilted at 98 degrees, whereas Mercury is not tilted at all. "For comparison, the Leaning Tower of Pisa tilts at around 4 degrees, so planetary tilts can be quite substantial," said Barnett.

Dr. Olson continued "There are several factors to consider in looking for life on another planet. The planet needs to be at the right distance from its star to allow liquid water and have the chemical ingredients for the origin of life. But not all oceans will be great hosts for life as we know it, and an even smaller subset will have suitable habitats for life to progress towards animal-grade complexity. Small tilts or extreme seasonality on planets with Uranus-like tilts may limit the proliferation of life, but a modest tilt of a planet on its axis may increase the likelihood that it develops oxygenated atmospheres that could serve as beacons of microbial life and fuel the metabolisms of large organisms. The bottom line is that worlds that are modestly tilted on their axes may be more likely to evolve complex life. This helps us narrow the search for complex, perhaps even intelligent life in the Universe."

Timothy Lyons, Distinguished Professor of Biogeochemistry in the Department of Earth and Planetary Sciences at the University of California, Riverside commented, "The first biological production of oxygen on Earth and its first appreciable accumulation in the atmosphere and oceans are milestones in the history of life on Earth. Studies of Earth teach us that oxygen may be one of our most important biosignatures in the search for life on distant exoplanets. By building from the lessons learned from Earth via numerical simulations, Olson and colleagues have explored a critical range of planetary possibilities wider than those observed over Earth history. Importantly, this work reveals how key factors, including a planet's seasonality, could increase or decrease the possibility of finding oxygen derived from life outside our solar system. These results are certain to help guide our searches for that life."