Mathematics – Logic
Scientific paper
May 2000
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000spd....31.0802d&link_type=abstract
American Astronomical Society, SPD Meeting #31, #08.02; Bulletin of the American Astronomical Society, Vol. 32, p.840
Mathematics
Logic
Scientific paper
The course of early biological evolution felt the environmental consequences of changes in the solar output (discussed here), as well as long-term decreases in planetary heat flow and the flux of extraterrestrial impactors. A large, early UV flux fueled the photodissociation of atmospheric water vapor, sustaining a significant hydrogen flux to space. This flux caused Earth's crust to become oxidized, relative to its mantle. Accordingly, reduced gases and aqueous solutes that were erupted volcanically into the relatively more oxidized surface environment created sources of chemical redox energy for the origin and early evolution of life. Although the solar constant has increased some 30 percent over Earth's lifetime, oceans remained remarkably stable for more than 3.8 billion years. Thus a very effective climate regulation was probably achieved by decreasing over time the atmospheric inventories of greenhouse gases such as carbon dioxide and methane. Such decreases probably had major consequences for the biosphere. Substantial early marine bicarbonate and carbon dioxide inventories sustained abundant abiotic precipitation of carbonates, with consequences for the stability and habitability of key aqueous environments. A long-term decline in carbon dioxide levels increased the bioenergetic requirements for carbon dioxide as well as other aspects of the physiology of photosynthetic microorganisms. The long-term trend of global mean surface temperature is still debated, as is the role of the sun's evolution in that trend. Future increases in the solar constant will drive atmospheric carbon dioxide levels down further, challenging plants to cope with ever-dwindling concentrations of carbon substrates. Climate regulation will be achieved by modulating an increasing abundance of high-albedo water vapor clouds. Future biological evolution defies precise predictions, however it is certain that the sun's continuing evolution will play a key role.
No associations
LandOfFree
Long-Term Evolution of the Sun and our Biosphere: Causes and Effects? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Long-Term Evolution of the Sun and our Biosphere: Causes and Effects?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Long-Term Evolution of the Sun and our Biosphere: Causes and Effects? will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1349335