Geoengineering is the large scale manipulation of the environment to counteract global warming. The UK’s Royal Society has launched a new report which claims to be the world’s most authoritative report on geoengineering to date. Here John Buckeridge shares his thoughts.

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Geoengineering Earth
Some brief comments to address the UK’s proposal to alter the Earth’s climate by “geoengineering”.

1. What heats the Earth? A body like the Earth is heated externally by the sun, or internally by radioactive decay.

1. What causes variation in climate? The Earth’s temperature may vary due to the following:
   1. Variations in solar activity (over which we have no control).
   2. Variations in cosmic activity from outside the Solar System (over which we have no control).
   3. Variations in the ability of the medium between the Earth and Sun to transmit energy (over which we have little control)
   4. Variations in the rate of energy transfer from the Earth’s interior e.g. through volcanism etc. (over which we have no control).
   5. Variations in the disposition of the land masses through tectonic activity, and the resultant oceanic circulation, e.g. the opening of Drake Passage (over which we have no control).
   6. Variations in the atmospheric composition, such that it varies albedo – the amount of energy reflected back into space and the amount of energy reflected back to Earth (over which we do have a little control).
   7. Variations in the Earth’s surface reflectance, such that it varies albedo (over which we have some limited control).
   8. The ability of the Earth’s crust and biosphere to absorb deleterious gases from the atmosphere – this has links with “e” (over which we have a small influence).

1. Has the Earth been “geoengineered” recently? The Earth’s climatic systems are cyclic, and have varied considerably through time. The process is “natural geoengineering”. Much of the change is due to solar activity, although tectonism is very important, e.g. about 55 million years ago, conditions were significantly warmer than they are today, but in the period between, there were ice ages. The most significant event to effect that climatic cooling was the opening of the Drake Passage off South America and the resultant Circum-Antarctic Current that developed, permitting the isolation and freezing of Antarctica. A lesser, but more dramatic event for humans occurred in 1783-1784 when the Laki volcanic fissure erupted on Iceland. The volcanic gases and particulates had immediate and very detrimental effects on Icelandic biota, and caused an extended winter in Europe – with much human mortality.

1. Have there been attempts by humans to deliberately geoengineer Earth? One plan in the last decade attempted seeding of the southern oceans with chemicals that were intended to rapidly accelerate growth of phytoplankton, thus capturing gases like carbon dioxide as part of the biomass. This was an expensive exercise, but not successful. Indeed, there were likely environmentally deleterious outcomes.

1. Is geoengineering by humans possible?
   1. If we assume that current carbon dioxide levels are causing climate change (rather than are rising as an effect of warming), then geosequestration is a viable option;
   2. Deforestation is contributing to climatic instability and increasing atmospheric carbon dioxide levels impacting on marine systems, a reversal of this would be beneficial for numerous reasons, especially to preserve biodiversity;
   3. Technology is available to reflect solar radiation (i.e. in the upper atmosphere), but use of this is unproven and may have unforeseen consequences.  

There is much uncertainty about whether we can effect positive change, and particularly whether this is possible in any window of opportunity that we may now possess. Past activities of humans have changed our world, and much of this is to our discredit. Many things that have been done for good reasons, have turned out to be disadvantageous, e.g. introduction of exotic species for “recreation”. Geoengineering has the potential to reap even greater havoc. What must be immediately implemented are systems to reduce the rampant consumption of natural resources, and the resultant pollution that our ever-growing population is responsible for. The drop in biodiversity that we are now experiencing is a legacy of our development. Rather than geoengineering, we should be engineering human behaviour more effectively…

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