Present efforts to counter anthropogenic global warming by reducing greenhouse gas emissions are proving ineffective; annual global emissions have continued to rise over recent decades largely consistent with the IPCC ‘business as usual’ scenario. Even if emissions can be stabilised, without significant ‘negative emissions’ atmospheric pCO2 will continue to rise, we are dumping more carbon into the atmosphere than ever before. Already at ~ 1 °C global temperature increase, we are seeing the beginnings of collapse in earth’s temperature sensitive ecosystems. In Australia, around 50% of the Great Barrier Reef has been lost in just 2 back to back years of coral bleaching during 2016 & 2017. When combined with other losses, perhaps as little as 25% coral cover remains since 1985. Globally, coral reefs cover less than 0.1% of the ocean surface but provide habitat for greater than 25% of marine species, these are critical components of planet earth.
I argue that if society wishes to avoid the most harmful effects of global warming, we must start taking research into options for regional and global technological intervention much more seriously, so called ‘geoengineering’. Very few methods have been identified that have potential for large scale, economic, removal of carbon dioxide from the atmosphere. Enhancement of natural CO2 sinks offers the significant advantage of an existing, and proven end-to-end process, including storage of the carbon. Ocean Iron Fertilisation is one such technology, yet various inefficiencies and offsets have been identified that reduce the net amount of carbon stored over a given period of time, highlighting the uncertainties. An alternative idea of sequestering carbon by adding macronutrient to oligotrophic regions of the ocean should achieve long term carbon storage at a cost comparable to today’s carbon prices, and with less uncertainty in net carbon storage than adding iron to HNLC regions. Solar radiation management appears to be capable of offsetting the entirety of anthropogenic heat forcing, although admittedly does not treat the underlying cause. Nevertheless, the perception of high ecological risk combined with a concerted philosophical objection from some quarters has hampered progress (especially practical) in fully investigating our geoengineering options.
My current research indicates that regional scale, local application of marine cloud brightening technology may be a feasible lifeline for the Great Barrier Reef, and potentially other coral reef ecosystems. There is little doubt that reducing emissions combined with negative emission technologies is the most appropriate short to medium term solution. Yet the moral hazard argument against geoengineering research is looking increasingly obsolete. We should instead be evaluating the risks of action against those of inaction. When it comes to the risks of investing in, and conducting responsible, practical geoengineering research the conclusion should be obvious.