But Why?

It’s quite an exciting time to blog about this topic, but why you may ask? Many published scientific articles (which there are too many to list here) suggest that the Earth is now leaving (or has already left) the Holocene, which is the name given to the postglacial geological epoch of the past ten to twelve thousand years. During this time, accelerating during the industrial period, humans have become an increasing geophysical force to a point where we are beginning to dominate (Crutzen, 2002). Leading to the suggestion of the ‘Anthropocene’ where humans will be a major force on the Earth System for perhaps many more millions of years. 

Despite the contention surrounding this ‘man-made domination’ human activity is set to leave an undeliable mark on geological history, aside from my own topic; deforestation, mining and road building have released waves of sediment into the oceans and rivers, the increasing acidification of the oceans as they absorb carbon dioxide will dissolve carbonate from deep sediments, and what is likely to be the sixth great mass extinction in Earth’s history will gather speed, adding vivid new markers to the record (Steffan et al, 2007)

But what has this got to do with CO₂?

Fossil-fuel use and land clearance have already emitted perhaps a quarter as much carbon into the atmosphere as was released during one of the greatest planetary crises of the past, the Palaeocene–Eocene Thermal Maximum 55 million years ago (Nature, 2011). Tripati, Roberts and Eagle (2009) stated that the CO₂ levels today have not appeared in the climate record for the past 15 million years.

What have humans got to do with this?

As the most recent IPCC report has stated (AR5) there is >95% confidence that humans have been the dominant driver of warming since the mid-20th century (IPCC, 2013) where atmospheric levels of CO₂ have risen from 310ppm to current levels of just under 400ppm (Steffan et al, 2007) with a drastic increase over the past 100 years (IPCC, 2007) as seen in graph 1. 

Figure 1

Over the next century this trend is very likely to continue as shown in graph 2 as future temperature development in the highest emissions scenario (red) and in a scenario with successful climate mitigation (blue) – the “4-degree world” and the “2-degree world.”

The IPCC is basically stating here that with successful mitigation we can help damper the effects of future warming and this is evidence enough for change in my opinion.

Figure 2

I’ll leave it at that for now, more to come in due course!

Cheers,

Sam.