Let's have some background!

To aid understanding of the future posts on this blog, I feel that it is important to familiarise you with the Anthropocene and the debate around it. In 2002, the Nobel Prize-winning chemist, Paul Crutzen proposed the term 'Anthropocene' to denote the current interval of anthropogenic influence in global environmental change (Crutzen, 2002). Zalasiewicz (2008) stated that this influence was primarily through increased human population and economic development. Crutzen (2002) has suggested that the Anthropocene represents a new geological epoch from 1800 AD onwards based on analyses of trapped air in polar ice cores that highlighted the significant change in the global atmospheric composition of carbon dioxide (CO₂) and methane (CH₄). These increases can be accredited to the industrialization of the developed world and Crutzen (2002) notes that this date coincides with the production of the steam engine in 1784. 

However, there is much debate surrounding this hypothesis. The debate over the beginnings of the Anthropocene is centered on the ‘early anthropogenic hypothesis’ that was proposed by William Ruddiman in 2003. Whilst Crutzen (2002) stated that the Anthropocene began from around 1800 AD, Ruddiman (2003) presented a comprehensive set of evidence that pointed towards human modification from as early as 8000 years ago. This modification is identified through the variations in CO₂ and CH₄ concentrations, driven by Earth-orbital changes, in the atmosphere since the start of the Holocene. Here is a diagram that illustrates this for CO₂ from Ruddiman (2003)...

So what does the Anthropocene have to do with coral? Well, due to the substantial impact of anthropogenic influence on the Earth since the original hypothesis of the Anthropocene started in 1800 AD, it has resulted in distinct stratigraphic signatures (which are used to formalized a new geological epoch) such as novel geochemical, biotic and sedimentary change (Zalasiewicz, 2008). The key impact on coral results from distinct changes in the composition of the atmosphere. As of September 2012, the concentration of CO₂ was 391 ppm, which equates to a level 40% greater than preindustrial concentrations, whilst CH₄ concentrations have doubled (Steffan et al., 2007). As a consequence of this dramatic change in atmospheric composition, the global temperature by the end of the century could match those of the Tertiary, being 1.1 °C to 6.4 °C greater than the current level (IPCC, 2007). Over the course of the past two hundred years, the modification of ocean temperature has resulted in biotic and geochemical change. In terms of coral, this is fundamental. Bellwood et al. (2004) states that the shallow ocean environment has become particularly vulnerable due to ocean acidification, bleaching and a whole load of other factors that are and aren't related to climate change, that have caused a reduction in diversity and abundance of coral.

Oh, abrupt ending, but I've got to stop there otherwise I will get carried away. The next instalment will focus on the importance of coral. 

(P.S. That coral seahorse on the last post was a cartoon. I knew it was too good to be true!)