You may be led to believe that climate change is a recent issue- it isn't! (the first publication regarding climate change dates to 1900s, Fig.1). Kyoto, 1997 was a milestone proposing a global solution to climate change (the reduction of 6 greenhouse gases (GHGS) by 5.2% below 1990 levels), succeeded by the Conference of Parties (COP), occurring annually since 1995 and the International Panel on Climate Change (IPCC). These conferences are fundamental in our quest to tackle climate change.
But are we really any closer to a solution?
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| Fig.1 Screen capture analysing the total publications with 'climate change' in its title (source: Web of Science [Last accessed: 11/10/17]). |
James Hansen, the founder of modern global climate change awareness, strongly disagrees. Branding the recent Paris, COP21 conference as a "fraud" and "fake" stating:
“It’s just bullshit for them to say: 'We'll have a 2C warming target and then try to do a little better every five years.’ It’s just worthless words. There is no action, just promises. As long as fossil fuels appear to be the cheapest fuels out there, they will be continued to be burned.”
Atmospheric concentrations of carbon dioxide (CO2) have risen drastically over the past century, ∼280 ppm (pre-industrialisation) to >380ppm (present day). Environmental reconstructions indicate that CO2 (and other GHGS) in the atmosphere are at their highest.
Stimulating the development of geoengineering techniques that remove CO2 from the atmosphere, and counteract anthropogenically driven greenhouse effects and ocean acidification. Known as Carbon Dioxide Removal (CDR) (Fig.2).
Stimulating the development of geoengineering techniques that remove CO2 from the atmosphere, and counteract anthropogenically driven greenhouse effects and ocean acidification. Known as Carbon Dioxide Removal (CDR) (Fig.2).
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| Fig. 2 Illustration of CDR approaches that 'suck' carbon from the atmosphere storing elsewhere (source: Sheperd, 2015) |
Afforestation & Artificial Trees
- A Global-scale tree planting effort to capture CO2 through photosynthesis - deforestation accounts for the second largest anthropogenic source of CO2 emissions in the atmosphere.
- Implementing artificial trees, a large, fly-swat shaped construction that absorbs passing air by using a sorbent (sodium hydroxide), results in CO2 in the atmosphere being separated and stored naturally in the Earth.
Biochar & Bioenergy
- Biochar can be produced through the heating biomass under reduction of oxygen (processes are known as pyrolysis or gasification). Therefore, no CO2 is produced and released into the atmosphere and "carbon negative".
- Bioenergy is produced alongside biochar and could displace our global fossil fuel usage - the primary source of CO2 in our atmosphere. Aiding in the reduction of other GHGS emissions. The carbon sequestered in biochar is stable (for up to 2000 years) and can be used as a fertiliser.
Direct Air Capture
- The construction of large machines that extract CO2 directly from the ambient air and sequestered underground or in the ocean.
Iron Fertilisation
- Roughly 30% of the world's oceans have low rates of primary production because of low iron concentrations. Therefore, the addition of micronutrients particularly iron onto oceans are shown to promote large-scale planktonic blooms that draw down CO2 from the atmosphere via photosynthesis.
Enhanced Weathering & Ocean Alkalinity Enhancement
- When fresh exposed olivine is in contact with CO2, magnesium carbonate and silicic acid are formed. Stimulating the removal of atmospheric CO2 stored in the rock that can be deposited onto soil or the ocean bed, tackling ocean acidification.
- Scientists suggest that enhanced weathering and dusting of finely ground minerals over surfaces, enables more CO2 to be sequestered and promote ocean biological productivity, sucking more CO2 in.
Conclusion
The CDR techniques present key opportunities for society to mitigate against climate change. These should be methods to be implemented with global reductions of CO2 and not as a means to justify the business as usual approach. Much of the science and implications of implementing these approaches is unknown and expensive (seen in upcoming posts).
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Climate change is a 'hot' issue that is heavily politicised, and like James Hansen, I believe we are no closer to finding a global solution to climate change and geoengineering may be pointless. We could tackle the issue head-on and address the politics of fossil fuels, but instead, we direct efforts towards technology to mitigate, despite not fully understanding its implications on earth systems. A decision must be made: Continued economic growth? or, reversing climate change?
