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The world renowned Danish-Greenland geology Professor Minik Rosing has released a scientific paradox that has plagued astronomers and geologists for 40 years. The result is not only important for understanding our planet's geological history, but can also have far reaching implications for climate research.
The weak sun paradox
The sun and the earth was created for small 4.5 billion years ago. But a young star must first have time fusion engine before it really sends energy out. Therefore the earth should have been frozen in the first 3 billion years. But all geology shows that it was certainly not.
- The current scientific explanation for the paradox has since the 1990s been that the young earth was kept warm because of an extreme greenhouse effect, said Professor Minik Rosing. 30 percent of CO2 in the atmosphere, which is 100 times more CO2 than we have today
No extreme greenhouse effect
But Minik Rosing has studied the oldest rocks in the world, the rocks at Isua in Greenland. They are 3.8 billion years old.
- Tests show that the CO2 content of the young Earth was much higher than today. Only 0.9 per thousand, said Professor Minik Rosing.
Ergo, there was no extreme greenhouse effect on the young Earth.
But what about the paradox. It is probably still?
- No, says Minik Rosing. There is nothing paradoxical.
Minik Rosing and his research colleagues have, through the stones found a simple explanation. The young Earth was largely covered by sea. The continents were only starting to emerge, so there was almost no mainland.
Seawater is dark, and when cloud cover was also thinner, the soil was better at keeping in the heat because the sun's rays were not reflected back into space to the same degree as today.
Impact on climate debate
Minik Rosing findings have great significance for today's climate, because it shows that atmospheric CO2 content has remained much more constant than previously thought.
- It is not the case that the Earth of its own motion fluctuates wildly in CO2 content, says Minik Rosing. So the anthropogenic changes that we observe now is striking even seen with geological eye.
"The analyses of the CO2-content in the atmosphere, which can be deduced from the age-old Isua rock, show that the atmosphere at the time contained a maximum of one part per thousand of this greenhouse gas. This was three to four times more than the atmosphere's CO2-content today. However, not anywhere in the range of the of the 30 percent share in early Earth history, which has hitherto been the theoretical calculation. Hence we may conclude that the atmosphere's CO2-content has not changed substantially through the billions of years of Earth's geological history. However, today the graph is turning upward. Not least due to the emissions from fossil fuels used by humans. Therefore it is vital to determine the geological and atmospheric premises for the prehistoric past in order to understand the present, not to mention the future, in what pertains to the design of climate models and calculations," underscores Minik Rosing.
Nature 464, 744-747 (1 April 2010) | doi:10.1038/nature08955; Received 13 July 2009; Accepted 9 February 2010
No climate paradox under the faint early Sun
Minik T. Rosing1,2,4, Dennis K. Bird1,4, Norman H. Sleep5 & Christian J. Bjerrum1,3
Environmental niches in which life first emerged and later evolved on the Earth have undergone dramatic changes in response to evolving tectonic/geochemical cycles and to biologic interventions1, 2, 3, as well as increases in the Sun’s luminosity of about 25 to 30 per cent over the Earth’s history4. It has been inferred that the greenhouse effect of atmospheric CO2 and/or CH4 compensated for the lower solar luminosity and dictated an Archaean climate in which liquid water was stable in the hydrosphere5, 6, 7, 8. Here we demonstrate, however, that the mineralogy of Archaean sediments, particularly the ubiquitous presence of mixed-valence Fe(II–III) oxides (magnetite) in banded iron formations9 is inconsistent with such high concentrations of greenhouse gases and the metabolic constraints of extant methanogens. Prompted by this, and the absence of geologic evidence for very high greenhouse-gas concentrations10, 11, 12, 13, we hypothesize that a lower albedo on the Earth, owing to considerably less continental area and to the lack of biologically induced cloud condensation nuclei14, made an important contribution to moderating surface temperature in the Archaean eon. Our model calculations suggest that the lower albedo of the early Earth provided environmental conditions above the freezing point of water, thus alleviating the need for extreme greenhouse-gas concentrations to satisfy the faint early Sun paradox.