1.3 Local effects
These measures – effectiveness and speed – ignore something fundamental to human lives and ecosystems, that is: changes happening at a local level.
CDR methods, of course, ‘undo’ human CO2 forcing and therefore would likely have an exactly opposite effect on local changes.
With SRM methods, it might be possible to ‘fine-tune’ global mean climate change, but it would not be possible to fine-tune climate change in every region. This is because forcings from CO2 and the Sun act in different ways – they have different fingerprints on climate in space and time (Session 3).
In Session 6, you saw GeoMIP predictions for a scenario in which SRM balances a quadrupled CO2 forcing. Even though the global average temperature was adjusted to be the same as the preindustrial climate, the models predicted many local areas would be warmer than preindustrial times.