Novel Entities

So you've seen me mention these 'novel entities' a few times now, and I've kept you waiting to find out exactly what they are!

Novel entities are also known as chemical pollutants, which might help you guess what they are. They're compounds (something composed of two or more elements) that affect not only human health, but the environment too, seen at local and global scales. Radioactive and organic compounds are the main pollutants, including organic polymers and plastic polymers that degrade into microplastics. Heavy metals are also considered to be a novel entity, as are manufactured chemicals.

The reason why they're such a concern is because of how durable they are, and how their chemical make-up can be distorted and changed to something far more harmful. Not forgetting to mention the fact that there's around 100,000 different chemicals being traded globally (the figure is ever increasing as more and more are being produced). Their ability to travel on a global scale is also a problem, and these novel entities can have a major impact on the Earth systems; this is because they release chlorofluorocarbons (CFCs) into the atmosphere. You may have heard of these before, they're released into the atmosphere by aerosols, fridges, solvents, etc.. Once considered completely harmless, but we have seen these CFCs have a negative impact on the stratosphere. Professor Rowland and Dr Molina from the University of California proved in 1974 that they undergo 'photolytic decomposition by UV radiation', which produces inorganic chlorine that has destroyed parts of the ozone layer.

This is a good example for another reason why they're a problem... they can alter some of the other planetary boundaries; the destruction of the ozone layer relates to the 'Stratospheric Ozone Depletion' boundary. The Climate Change boundary can be affected by heavy metals, released into the atmosphere by coal burning - mercury in particular. The Biosphere Integrity boundary can be compromised from the inhalation/digestion of these chemicals, eventually eliminating entire species.

Why are there no threshold boundaries?

Rockstrom and Steffen never went into much detail as to why the boundary had no quantified limits (they have rough estimates), but in their first paper, they suggested to focus on 'persistent pollutants' that are used globally, and to observe long term effects on living organisms from chemical pollutants.

Persson et al 2013 explored the idea and came up with a way to define these limits. They proposed that novel entities aren't a stand alone planetary boundary, but can dictate the behaviour of others if certain conditions are met. These conditions are:

1. The chemical or mixture of chemicals has a disruptive effect on a vital Earth system process.

2. The disruptive effect is not discovered until it is, or inevitably will become, a problem at a planetary scale.

3. The effects of the pollutant in the environment cannot be readily reversed.

If ALL of these conditions are met, only then can a chemical/compound be considered as a planetary boundary threat.

But really, these don't explain anything! (In my opinion) They summarise that we do not know what effects these chemical pollutants are having on the Earth system, and we probably won't find out what effect it does have until it's too late! Not very helpful!

They do however explain that it is important to test all of these chemicals in a controlled environment in order to see what impact they could have on our Earth systems. Things like measuring toxicity levels, for all species, and of course global concentrations of chemicals.

Currently, we do not know what the global levels are for these chemical pollutants, nor do we know their effects. All we can do right now, is keep an eye on these levels, to notice any changes to the Earth system that seems problematic. Sounds like trial and error to me, which isn't very conclusive!