We will be uploading our talks to Slide Share without audio during July 2014. In July and August we will add audio and also provide these talks linked to YouTube.
THE AZOLLA STORY: HOW AN AMAZING PLANT CHANGED OUR CLIMATE 50 MILLION YEARS AGO
by Jonathan Bujak
The talk is split into two because of its length.
The presentation describes a remarkable event that occurred in the Arctic 50 million years ago, when a unique floating freshwater plant called Azolla repeatedly covered the surface of the ocean for almost a million years. Due to its phenomenal growth, Azolla sequestered enormous quantities of the greenhouse gas carbon dioxide, and changed the Earth’s climate from a greenhouse world towards our modern icehouse climate with its permanent ice and snow at both poles. ‘The Arctic Azolla Event’ was discovered by the Arctic Coring Expedition (ACEX) when it recovered sediments beneath the North Pole in 2004. The discovery was featured in the New York Times (November 20, 2004) and National Geographic (May 2005), and its validity has now been confirmed by international teams of scientists who have investigated and published on the cores, including a series of papers in the scientific journal ‘Nature’.
The talk was presented by Dr Jonathan Bujak as the invited Keynote Address and various symposia, as well as lecture tours in Europe and North America.
Summary of talk
The modern icehouse world is characterised by bipolar glaciation, resulting from relatively low levels of atmospheric CO2 and thermal isolation of the poles from warm lower latitude oceanic currents. In contrast, the Mesozoic greenhouse world had no permanent glaciation at either pole, with the greenhouse state continuing through the K/T boundary into the Paleocene.
At the end of the Paleocene, extreme warming during the Paleocene Eocene Thermal Maximum (PETM) was triggered by high levels of greenhouse gases due to extensive volcanism associated with the Greenland mantle plume, and the expulsion of submarine methane hydrates. This resulted in the highest temperatures known for the Cenozoic, characterising a supergreenhouse state that persisted through the Early Eocene. It is therefore surprising that various independent parameters indicate that the supergreenhouse climate was truncated in the earliest Middle Eocene by the initial shift towards modern icehouse regime. Estimates of atmospheric CO2 values show a major decrease at this time, but this cannot be explained by ‘normal’ sequestration processes. Instead, a unique geological event is proposed to explain this fall, centred on processes within the Arctic Ocean Basin.
“The Azolla Model” is based on ACEX (Arctic Coring Expedition) cores from the Lomonosov Ridge plus unpublished data from 65 Arctic petroleum exploration wells. The model combines oceanographic reconstructions for the basin with a major decrease in greenhouse gases during the middle Eocene. The Early Eocene Arctic Ocean Basin was largely enclosed following uplift of the Greenland Mantle Plume, with elevated temperatures, evaporation and precipitation leading to increased runoff and the development of extensive surface freshwater plumes. These were colonised in the earliest Middle Eocene by floating mats of the opportunistic freshwater fern Azolla, which occurred periodically for about a million years as a series of repeated cyclical events.
Modern Azolla is one of the fastest growing plants on the planet and draws down large quantities of carbon and nitrogen. Calculations of carbon drawdown combined with the large potential areas of Azolla development in the Arctic, plus the million year time frame indicate levels of CO2 sequestration that are easily sufficient to shift the world from Mesozoic-Early Eocene greenhouse towards the modern icehouse world. The model also indicates the deposition of potentially widespread petroleum source rocks across the Arctic due to the massive carbon drawdown. It is currently being tested by multidisciplinary teams at ACEX and various universities worldwide, and it has already attracted considerable attention including articles in the New York Times (November 20, 2004), National Geographic (May 2005) and Nature (2006 to 2011).