If we are trying to keep global warming to 2 degrees Celsius or less but 4 degrees is possible even within some of our lifetimes, which world do we prepare for? Talks at today’s session on adaptation took on the problem of the multiple futures that decision-makers have to face. Mark Stafford-Smith of CSIRO in Australia talked specifically about long-term decisions – such as planting and managing forests – where the best option depends on which way the climate goes later this century. If you expect strong mitigation that holds down warming, then you try to preserve today’s forests and nurse them through, protecting them from fire and other threats. If a moderately high temperature is in store, forest composition will have to change and you can plant new species to facilitate that. With runaway climate change the best option could be opening up the forests to invading weeds and rapid, radical transformation.
This is no hypothetical choice. During February’s raging wildfires in southeastern Australia, it appears that even the seed stores in the forest floor were destroyed in some burnt areas. Stafford-Smith recommends that conservation managers trying to bring these areas back to life should divide their efforts to follow all three approaches above. Such a hedging strategy may mean two-thirds of forest plans need to be abandoned and altered as the future unfolds, but it’s better then putting all the trees in one basket.
Rob Swart of Wageningen University, The Netherlands, looked at hedging on a much larger scale – the plan Bs we could prepare in case of a true planetary emergency. From geoengineering schemes that risk severe side effects to extreme emissions reductions that would affect the climate only slowly and probably require tight government control, none of the options are attractive. But Swart thinks there should be an international process – separate and parallel to current UN climate policy – for countries to work out ahead of time how they would cooperate on such schemes. If left to a moment of panic, they’re unlikely to be carried out thoughtfully and equitably.