The Toarcian was a geologically fast (80,000-12,000 years) hyperthermal during the early Jurassic at 180 Ma (New et al. 2011).
It is recognised globally by the appearance of jet rock (e.g. in Whitby, UK), this was formed from the widespread ocean anoxia from an increasingly stratified ocean and a swallowing of the CCD to >1 Km e.g. Walves Ridge, South East Atlantic (Ravello et al. 2006).
Ocean anoxia has occurred in all hyperthermal events, and causes complex and varied effects on ecosystems. This was especially true for the Toarcian and the PETM, in the Toarcian between 35-50 % of benthic foraminifera became extinct. In addition, many species changed their geographic range for example ...view middle of the document...
3 m (Dowsett at al. 2010). Present atmospheric CO2 levels have risen episodically until although showed a gradual increase until 1950 when they began to increase at an exponential rate.
It was different to current warming, as there was slow ocean circulation that contributed to ocean circulation (Melchin et al, 2013). This could result from the rapid change from icehouse to greenhouse that is also happening at present (Zalasiewicz & Williams, 2013).
The use of hyperthermal events as analogues to the present climate change has enhanced understanding of the causes of climate change. Therefore, the studying of these can lead to possible solutions to avoid long-term effects of climate change. For example, governments are encouraging renewable energy and efficient building practices as well as planting more trees, which serve in reducing the amount of carbon dioxide in the atmosphere and the ocean (Dowsett. 2007). This serves in reducing the effects of ocean acidification as well as the atmospheric temperatures (Haywood, et al, 2009).
There are various disadvantages associated with the use of hyperthermal events as analogues to the recent climate change.
Some of the most significant hyperthermal events have been a result of the continental drift for example the mid-Pliocene, which triggered changes in ocean currents resulting in eventual changes to the climate. This is not as relevant to today’s climate change as the warming is too rapid to be the result of tectonic movements (Laurens, et al, 2005).
There is also significant uncertainties with many aspects of past climate, for example there is a poor understanding of mid Pliocene ice distribution (Dowsett. 2007), and proxies such as leaves have a discontinuous record (Kurshner et al. 1996).
In addition, man-made emissions such as CFC’s have never occurred naturally so the long term impact these and other gasses will have is not known.
However, there are some possible similarities in the source of greenhouse gasses in these events. Very light carbon of a similar composition to that from burning oil and gas is seen in...