Earth’s air pressure 2.7 billion years ago constrained to less than half of modern levels

Som, S.M., Buick, R, Hagadorn, J.W., Blake, T.S., Perreault, J.M., Harnmeijer, J.P. & Catling, D.C.

Nature Geoscience, available online.

doi:10.1038/ngeo2713, 2016.

[Science] [The Economist] [UW Today] [Reuters]

Brief summary


Air pressure has changed markedly over time. In a paper published in Nature Geosciences, Dr. Sanjoy Som (Blue Marble Space Institute of Science / NASA Ames Research Center) and co-authors measure the air pressure on the Earth 2.7 billion years ago, at a time when the Earth was markedly different compared with the modern day. Using gas bubbles trapped in ancient lava flows that solidified at sea-level, the researchers found that the air weighed at most half of what it does today.

As the lava cooled, it solidified from the bottom-up, trapping the bubbles at the base of the flow, and from the top-down, trapping bubbles at the top of the flow. By measuring the difference in size between the bubbles at the top and at the bottom using sophisticated instruments, the researchers were able to determine how much the air was pushing down on the lava flows as they cooled. An imbalance in the biological cycle of nitrogen, the dominant constituent of air pressure on Earth, is thought to be the reason for this surprising result.

This result has two important implications. First, it shows that biology can have a very strong influence on the evolution of a planetary atmosphere. Scientists have known for along time that biology can affect the chemistry of an atmosphere, such as the oxygenation of our air which began halfway through our planet’s history, but it had not been appreciated that biology can affect that actual amount of air around a planet. Secondly, this study demonstrates that microbial life can survive and thrive on planetary surfaces that are very different than modern Earth. This is important for astronomers as they seek out evidence of life far beyond our home planet.

Experimental evolution of protein–protein interaction networks

Kaçar, B. & Gaucher, E.A.

Biochemical Journal, 453, pp 311-319.

doi:10.1042/BJ20130205, 2013.

[Sciworthy]

Brief summary


Molecular networks play crucial role in an organism’s adaptation to its environment. What is unknown is the evolution of molecular interaction networks. This article asks this very question: how do the networks change their inter- and intra-molecular interactions over time? Further, how do molecular networks keep their main function and robustness and contribute to an organism’s evolvability? In the presented article, in order to understand what kind of evolutionary mechanisms underlie this behavior, the authors propose an experimental system whereby replacing existing nodes of a modern network with the reconstructed ancestral components and tracking them in a modern organism. Such an experimental system in which laboratory evolution experiments are combined with ancestral sequence resurrection techniques would provide insights into how protein-protein interaction networks evolve and potentially shape the evolutionary trajectory of a given organism.

Evaluation of rodent spaceflight in the NASA animal enclosure module for an extended operational period

Moyer, E.L., Dumars, P.M., Sun, G.-S., Martin, K.J., Heathcote, D.G., Boyle, R.D. & Skidmore, M.G.

npj Microgravity, 2, #16002.

doi:10.1038/npjmgrav.2016.2, 2016.

[Sciworthy]

Brief summary


The NASA Space Shuttle program may have ended, but its hardware which enabled rodent research in space lives on into the International Space Station and other flight vehicles. New research published by NASA in the Nature Partner Journal: Microgravity tested if Animal Enclosure Module hardware, which facilitates rat and mouse experiments in space, could accommodate longer stays than their rated 20-day flight window. Following minor modifications to feeding system, the enclosures supported ground-based 35-day rat and mouse experiments, and suggested no ill effects for animal health or astronaut comfort. These results enabled further rodent research in current and future NASA spaceflight experiments.

Isolated refuges for surviving global catastrophes.

Baum, S.D., Denkenberger, D.C., & Haqq-Misra, J.

Futures, 72, pp 45-56.

doi:10.1016/j.futures.2015.03.009, 2015.

Brief summary


Refuges could help small populations survive global catastrophes if certain refuge design criteria are met.

Extended summary


Global catastrophes are events that could severely cripple or destroy the foundations of civilization. Potential global catastrophes include nuclear winter, large asteroid impacts, super-volcanic eruptions, and pandemics. Humans may not necessarily become extinct under such scenarios, but, without adequate advance preparation, rebuilding civilization following such a catastrophe could prove difficult.

In this paper, we present several concepts of “Isolated refuges for surviving global catastrophes.” Although catastrophic events could destroy a significant portion of the human population, isolated refuges would provide a way to protect a small group of humans so that they survive long enough to rebuild civilization. We discuss several factors that are critical for ensuring the success of a refuge, including self-sufficiency, a continuous population, secrecy, and adequate monitoring of the outside world.

We also discuss the concept of surface-independence, suggesting that an underground, underwater, or space-based refuge might provide the greatest protection of its inhabitants from the effects of global catastrophes. Any of these refuges could significantly make the human species more resilient to catastrophic threats. Space-based refuges provide an exceptional degree of isolation from Earth, and the cost of such an extraterrestrial refuge might be best “piggybacked” onto existing scientific endeavors that seek to establish a permanent presence on the moon or elsewhere in space.

Should we geoengineer larger ice caps?

Haqq-Misra, J.

Futures, 72, pp 80-85.

doi:10.1016/j.futures.2015.07.002, 2015.

[arXiv] [Scientific American]

Brief summary


With millenia of effort, humanity may be able to create larger ice caps, making the global climate cooler and more stable.

Extended summary


Earth’s climate is vulnerable to potential climate catastrophes that could threaten the longevity of civilization. Continued increases in greenhouse gas forcing could lead to the collapse of major ice sheets, which would cause catastrophic sea level rise and could cause the oceanic thermohaline circulation to halt. Further warming could cause the heat stress index to exceed survival limits, inducing hyperthermia in humans and other mammals. Even more extreme warming could shift Earth into a runaway greenhouse regime that would lead to the loss of all oceans, and the end of all life.

Geoengineering refers to the large-scale use of technology to alter Earth’s global climate, and geoengineering has been suggested as a way to ameliorate contemporary climate change. Addressing these immediate climate challenges through a combined strategy of adaptation, mitigation, and (if needed) geoengineering is a critical issue facing us today. Whether or not we decide to engage in geoengineering today, we must still devise a long-term strategy to address our changing climate.

But in the longer-term, could we also use geoengineering techniques to increase the size of the polar ice caps? This paper raises the question, “Should we geoengineer larger ice caps?” By doing so, the global average temperature of Earth could be lowered from its current state to a new stable regime with much larger ice caps. Earth has experienced shifts in ice coverage in its past, and a prolonged program of geoengineering–say, lasting a thousand years or more–could allow us to permanently shift the energy balance of Earth. More ice at the poles increases the amount of sunlight reflected back to space, leading to cooler temperatures.

Of course, the unfortunate side effects of this idea would be mass migration of populations near the poles, shifts in global agricultural zones, and a required commitment of millenia in order to avoid undesired side-effects. Human civilization today probably lacks the fortitude to embark on such a long-term goal. Nevertheless, thinking about the long-term management of our planetary system helps us realize that we have already entered the epoch of the Anthropocene. Our civilization itself is fundamentally intertwined with our global climate, and we should allow humility, rather than hubris, guide decisions to control our environment.