Environment Counts | Cosmoclimatology offers an alternative theory of Earth’s climatic paleohistory
Author: John Ross – Published At: 2013-02-05 13:00 – (1050 Reads)
This article summarizes the evidence for the climatic role of cosmic rays including bservations of variations of low cloud cover correlated with cosmic-ray variations and experimental evidence that cosmic rays act as catalysts accelerating the formation of small clusters of sulphuric acid and water molecules, the building blocks for cloud condensation nuclei. The paper offers explanations for what drove the alternations between ice free and glaciated climates over the past half billion years, suggesting that cosmoclimatology offers a more persuasive explanation of the alternations between hot and cold climatic periods to our solar system’s encounters with the spiral arms of the Milky Way Galaxy, where explosive blue stars and cosmic rays are more concentrated. Henrik Svensmark 2007 Astronomy and Geophysics 48 (1) 1.18 â€“ 1.24 Cosmoclimatology: A new theory emerges.
The article starts by summarizing the evidence for the climatic role of cosmic rays, which underpins cosmoclimatology:
- Observations of variations of low cloud cover correlated with cosmic-ray variations;
- Experimental evidence that electrons released in the air by cosmic rays act as catalysts accelerating the formation of small clusters of sulphuric acid and water molecules, the building blocks for cloud condensation nuclei;
- The Antarctic climate anomaly as a symptom of active forcing of climate by clouds;
- Quasi-periodic climate variations over thousands of years that match the variations in energetic unstable atomic nuclei production by cosmic rays;
- Calculations that remove an apparent difficulty which is related to the screening effect of geomagnetic field variations on cosmic ray influx.
To consider the relevance of cosmic rays to climate change we have to look at broader time scales that reach back to when the Earth was young. The climatic effects of the Sunâ€™s quasi â€“cyclic variations (Milankovitch cycles) on millennial time scales are seen throughout the last 550 million years. But more emphatic changes in climate become apparent on longer timescales when the galactic environment of the solar system changes and the variations in the cosmic-ray flux are an order of magnitude greater than those due to the Sun.
What drove the big alternations ?
The paper offers explanations for what drove the alternations between ice free and glaciated climates over the past half billion years, implying that the greenhouse warming paradigm doesnâ€™t account for the changes, but cosmoclimatology offers a more persuasive explanation which attributes the alternations between hot and cold to four encounters with the spiral arms of the Milky Way Galaxy, where explosive blue stars and cosmic rays are more concentrated.
Figure 8 The matches between spiral-arm encounters and icehouse episodes are as follows:
- Perseus Arm: Ordovician to Silurian Periods; (490 -417 Million years ago)
- Norma Arm: Carboniferous; (345 – 280 My)
- Period Scutum-Crux Arm: Jurassic to Early Cretaceous Periods; (206 -99 My)
- Sagittarius-Carina Arm: Miocene Epoch, 23. (7-5.3 My) leading almost immediately (in geological terms) to
- Orion Spur: Pliocene to Pleistocene Epochs. (5.3 – 0.1 My)
The first clear evidence of glaciers 140 million years ago was published in 2003. For the greenhouse theory of climate change, the Mesozoic glaciation (225 million years â€“ 65 million years ago) does not fit because the carbon dioxide concentrations in the atmosphere were high then. Further evidence in favour of cosmoclimatology is presented in the original paper.
Why did the Earth freeze over ?
Cosmoclimatology provides a cosmic time-frame to help explain climate changes since the earthâ€™s formation. The discovery of widespread glaciations in the tropics during the Proterozoic (2.5 billion years – 542 million years ago) and in the â€œSnowball Earthâ€ episodes around 2300 million and 700 million years ago set a conundrum for traditional climate theory. The article suggests an explanation for not only what might have caused such events, but why they occurred just when they did, when the Earth was between 50% and 15% of its present age. It also provides an explanation for why there was a long warm interval between them with no icy interludes like those seen in the past 550 million years.
Cosmic rays may have accelerated evolution
A surprising by-product of this line of enquiry is a new perspective on the changing fortunes of life over 3.5 billion years. By combining calculations about the changing ability of the Sun to repel cosmic rays with data on the changing star-formation rate, one can reconstruct the resulting cosmic-ray flux.
Figure 10 compares the cosmic ray flux with data from an entirely different source, concerning variability in the overall productivity of the biosphere, gauged by the proportion of carbon-13 in carbonate rocks. The biggest fluctuations in productivity between boom and bust coincided with the highest cosmic-ray rates. Conversely, during the billion years when star formation was slow and cosmic rays were less intense, the biosphere was almost unchanging in its productivity. This reveals a link more subtle than any straight forward idea of, say, a warm climate being life-friendly or a cold climate deadly.
What remains for investigation ?
The past 15 years have seen the reconnaissance of a new area of research by a small number of investigators. The multidisciplinary nature of cosmoclimatology is both a challenge and an opportunity for many lines of inquiry.
An example comes from the astrophysics of Gouldâ€™s Belt, the tumultuous region of the galaxy into which the solar system has wandered. The possibility that cosmic rays from a nearby supernova provoked the onset of northern glaciation 2.75 million years ago has been suggested. This is of special interest because of the replacement of some African forests by grassland and the emergence of human beings. The earliest known stone tools date from 2.6 million years ago. Whether or not the particular event was responsible, gamma-ray astronomers are alert to the need to identify supernova events within Gouldâ€™s Belt during the past few million years if climate change on that timescale is to be fully understood.
It is stated that better knowledge of the spiral arms and star-formation history of the galaxy should clarify the climate connection over longer spans of time. At the same time, the onus falls on Earth scientists to improve knowledge of climate history before 200 million years ago with an on-shore drilling programme.
The changes in the Earthâ€™s attitude and orbit identified by Milankovitch show up persistently in the oxygen-18 record of recent ice ages, notably at high latitudes. They pose conundrums for both the greenhouse and cosmic-ray theories of climate change.
The physics of the Sun and the heliosphere runs through the story on all timescales from the early Earth to the present day. Whatever the verdict may be about the relative importance of cosmic rays and greenhouse gases in current and future climate change, there is an obvious need to predict future solar behaviour better, by clearer observations of the magnetic field at the Sunâ€™s poles.
Submitted by John Ross
EC Editor Geoff Zeiss