Trees

 The level of carbon dioxide in the atmosphere continues to rise in spite of the reduction in man-made CO2 this year. There were hopes that the Covid-19 lockdowns would have at least one beneficial effect, that of reducing greenhouse gases. One reason is that carbon dioxide is a long-lived component of the atmosphere. It has been calculated that, without the intervention of humankind, natural processes would keep the CO2 concentration steady, even tending to reduce it slightly. Human activity is enough to force it to accumulate.

It seems to me that even if we globally cut our carbon emissions tomorrow, positive feedback has already taken hold. A prime example is that of the wildfires currently devastating the north American west coast. Global warming has reduced the annual snowfall in the Rockies. What snow does fall dissipates more quickly rather than its water being released gradually over the following season. Higher temperatures draw water from the soil. Destructive pine beetles are moving further north as the climate warms (pdf here) leaving dry defoliated tree skeletons which act as tinder. More storms mean more lightning strikes, starting fires, which are then fanned by increasingly hot winds, All this is happening naturally, without the intervnetion of thoughtless party-givers or the forest clearances permitted by governments in Brazil and Indonesia.

So it is not enough to reduce man-made carbon dioxide. It is also necessary to increase the volume of carbon sinks. Encouraging scrub, an underrated absorber of carbon, is one way. Almost as good but more eye-catching is tree-planting. Ethiopia has embarked on a massive scheme which should have the added benefit of reducing the effect of floods. The African Union's Great Green Wall also offers hope, though it is proceeding much more slowly than originally planned. There are more examples in Peter Gibbs' report on Radio 4 earlier this year, and in the glimmer of hope provided by the cooperation of three African governments in preserving the gorilla redoubt made famous by Sir David Attenborough. 

It seems to be a case of three steps forward, but at present at least three steps back. There needs to be a global political change, removing populist leaders who do not listen to scientists in favour of a more progressive set who do.