,
6 tweets,
2 min read
Read on Twitter
The new Nature piece on reforestation has resulted in quite a bit of confusion. They suggest a sequestration potential of 200 GtC, but (incorrectly) suggest it would represent two-thirds of all emissions from human activities so far. This is incorrect. theguardian.com/environment/20…
Cumulative emissions to-date from land use and fossil fuels are ~640 GtC (via the @gcarbonproject), so removing 200 GtC would represent one third of historic emissions.
Similarly, sucking 200 GtC out of the atmosphere doesn't reduce atmospheric concentrations by 200 GtC, just like emitting 200 GtC doesn't increase concentrations by that much. An airborne fraction of ~50% applies to both, as both similarly affect land/ocean carbon sink behavior.
Finally, 200 GtC is a technical potential assuming every hectare of forestland on earth is increased to 100% forest cover. In practice, the economic potential will be substantially smaller, and fragmentation of ownership would make coordinated global efforts challenging.
Thats not to say that reforestation is not an important mitigation strategy, just to caution that like every other climate solution its part of a larger portfolio of strategies rather than a silver bullet.
(Correction: the paper was in Science, not Nature: science.sciencemag.org/content/365/64…)
