Global Warming or a New Ice Age: Documentary Film (Of interest re soil mineralisation)
This is a thought provoking, some might suggest somewhat ‘nutty’ video from the 1970s?, which is interesting for a number of reasons including the social and aspirational tone of the video, and then view of the world.
The video is linked because of the fascinating and tantilising reports it contains on the effects of remineralisation of land through rock dust on forest, crop and animal health. Mineralising soils with rocks dusts is complex, likely requires the co presence of organic matter both to hold the minerals in the soil and improve their bioavailability, and presents logistics and ecological issues. None the less we know levels of minerals in crops are falling, and limited studies suggest remineralisation will increase plant health and yields, as well as improving live stock health.
It is intended to expand the information of the importance of well minerailsed soils to agriculture as time permits by reference to Howard, Albrect, and others.
The idea of a cycle of remineralisation of soils by ice ages is plausible and interesting, and would clearly affect carbon dioxide levels; what that means for climate change was then and is now still hotly debated. Clearly the projected time scale if nothing else was inaccurate.
Increased atmospheric carbon dioxide from burning of fossil fuels will increase acidification of the oceans independently of any surface climate change effect, be that global warming as currently projected, or as some suggest global cooling, or a net no change, due to weather changes or solar cycles.
Global Warming or a New Ice Age: Documentary Film
“Global cooling was a conjecture during the 1970s of imminent cooling of the Earth’s surface and atmosphere along with a posited commencement of glaciation. This hypothesis had little support in the scientific community, but gained temporary popular attention due to a combination of a slight downward trend of temperatures from the 1940s to the early 1970s and press reports that did not accurately reflect the scientific understanding of ice age cycles. In contrast to the global cooling conjecture, the current scientific opinion on climate change is that the Earth has not durably cooled, but undergone global warming throughout the twentieth century.
Concerns about nuclear winter arose in the early 1980s from several reports. Similar speculations have appeared over effects due to catastrophes such as asteroid impacts and massive volcanic eruptions. A prediction that massive oil well fires in Kuwait would cause significant effects on climate was quite incorrect.
The idea of a global cooling as the result of global warming was already proposed in the 1990s. In 2003, the Office of Net Assessment at the United States Department of Defense was commissioned to produce a study on the likely and potential effects of a modern climate change, especially of a shutdown of thermohaline circulation. The study, conducted under ONA head Andrew Marshall, modelled its prospective climate change on the 8.2 kiloyear event, precisely because it was the middle alternative between the Younger Dryas and the Little Ice Age. The study caused controversy in the media when it was made public in 2004. However, scientists acknowledge that “abrupt climate change initiated by Greenland ice sheet melting is not a realistic scenario for the 21st century”.
Currently, the concern that cooler temperatures would continue, and perhaps at a faster rate, has been observed to be incorrect by the IPCC. More has to be learned about climate, but the growing records have shown that the cooling concerns of 1975 have not been borne out.
As for the prospects of the end of the current interglacial (again, valid only in the absence of human perturbations): it isn’t true that interglacials have previously only lasted about 10,000 years; and Milankovitch-type calculations indicate that the present interglacial would probably continue for tens of thousands of years naturally. Other estimates (Loutre and Berger, based on orbital calculations) put the unperturbed length of the present interglacial at 50,000 years. Berger (EGU 2005 presentation) believes that the present CO2 perturbation will last long enough to suppress the next glacial cycle entirely.
As the NAS report indicates, scientific knowledge regarding climate change was more uncertain than it is today. At the time that Rasool and Schneider wrote their 1971 paper, climatologists had not yet recognized the significance of greenhouse gases other than water vapor and carbon dioxide, such as methane, nitrous oxide, and chlorofluorocarbons. Early in that decade, carbon dioxide was the only widely studied human-influenced greenhouse gas. The attention drawn to atmospheric gases in the 1970s stimulated many discoveries in future decades. As the temperature pattern changed, global cooling was of waning interest by 1979.”