With Earth’s safe temperature determined to be no more than 1.5°C above that in pre-industrial times, scientists are looking in unlikely places to help solve the climate change crisis.
It has been suggested that in order stay within the safe temperature we will have to begin actively removing carbon dioxide from our atmosphere. Of course, this begs the question where would we put the greenhouse gas after it is removed from the atmosphere? Scientists have developed three main storage options:
- Geological storage – involves injecting CO2 into underground geological formations, oilfields, gas fields and saline formations
- Mineral storage – CO2 is reacted with minerals to form carbonates.
- Oceanic storage – either dissolving CO2 at mid-depths or injecting it at great depths
It is the latter of these three options that has recently shown great promise. Steve Goldthorpe, an energy analyst based in New Zealand has suggested that CO2 be injected into deep ocean trenches for storage. His theory is based on the fact that at depths of greater than 3000 meters the density of carbon dioxide exceeds that of water and therefore sinks, forming lakes of liquid CO2 on the ocean floor.
Goldthorpe has identified the Sunda trench as a possible site for this method of carbon sequestering. The Sunda trench has a maximum depth of 7,725 meters and a length of 3200 kilometres meaning it is large enough to hold 19 trillion tonnes of liquid CO2
“It is big enough to accommodate 19 trillion tonnes of liquid CO2, which is greater than all the CO2 from the total global fossil fuel emissions,”- Steve Goldthorpe
However, whilst this seems to be a very promising solution, as with the method of CO2 dissolution, there is the problem of ocean acidification. The carbon dioxide could react with the seawater to form carbonic acid which would make the ocean more acidic having potentially disastrous effects on marine ecosystems.
This isn’t the end of the story though as there is a potential solution. Ken Caldeira of the Carnegie Institution for Science in Stanford has suggested that a physical barrier such as plastic sheeting could be used to trap the liquid CO2 in the deepsea lake
“Something like giant plastic-encased sausage-like tubes of liquid CO2 lying on the sea floor could potentially store CO2 safely and securely for many millennia.” – Ken Caldeira
This method would likely be expensive as the CO2 would have to be pumped to the storage site however it could indeed be the long-awaited solution to the global warming crisis.