I see they are starting from the SSP1-1.9 scenario as their baseline, which their graphs depict as the blue-line projections. By overlaying the emissions graph, the atmospheric CO2 graph, and the global mean temperature graph, it looks like they are assuming 1) a precipitous decline in fossil fuel CO2 emissions beginning almost immediately (at around 37 gigatonnes per year) and reaching zero tonnes emissions per year by around 2050. Which sounds great, but how is that going to happen? 2) The peak for atmospheric CO2 seems to occur before the zero net emissions point, and then falls steeply by about 50 PPM in the last 50 years of this century. This would correspond to around 8 billion tonnes CO2 removed from the atmosphere per year--beginning before there is any significant progress below zero emissions, and before there is any noteworthy increase in forest area, so what is removing all that CO2? And then the global mean temperature curve tracks right on top of the atmospheric CO2 curve, and warming stops only around 15 years after peak CO2. So this scenario seems to assume it takes only a few years for the Earth to reach its thermal equilibrium point for a given level of CO2 (I don't see a lot of consensus on this), and it assumes the loss of the shading/cooling effect from aerosol particulates results in roughly zero increase in the rate of warming, and it assumes the knock-on feedback effects at higher temperatures (due to melting permafrost methane release, reduced ice reflectivity, etc) will be small.
And then the authors of this report greatly shrink the carbon capture component of SSP1-1.9, add in a slight increase in forest area, and a lot more emphasis on equity and social justice, and suggest this can be even more successful at rapidly reducing CO2 levels and combating climate change. The tiny detail of how that would work apparently wasn't important enough to merit description. Also curious that in a scenario concerning a major transition in energy, there is no graph depicting the projected change in energy. But they did note that their proposal *may be* a challenge to implement. That part, at least, seems completely uncontroversial.
I think the equity/social justice issue is presented adequately, given that the 1% or even 10% of top income earners are responsible for so much energy consumption. But, as I mention in the next post, getting these people to accept world-average energy use is complicated. I am hoping that these authors will make some comments on these issues.
Were you able to glean how they greatly reduced the carbon capture component of SSP1-1.9 and still expect to remove as much CO2 from the air? Because that extra forest area would hardly begin to cover the loss.
I see they are starting from the SSP1-1.9 scenario as their baseline, which their graphs depict as the blue-line projections. By overlaying the emissions graph, the atmospheric CO2 graph, and the global mean temperature graph, it looks like they are assuming 1) a precipitous decline in fossil fuel CO2 emissions beginning almost immediately (at around 37 gigatonnes per year) and reaching zero tonnes emissions per year by around 2050. Which sounds great, but how is that going to happen? 2) The peak for atmospheric CO2 seems to occur before the zero net emissions point, and then falls steeply by about 50 PPM in the last 50 years of this century. This would correspond to around 8 billion tonnes CO2 removed from the atmosphere per year--beginning before there is any significant progress below zero emissions, and before there is any noteworthy increase in forest area, so what is removing all that CO2? And then the global mean temperature curve tracks right on top of the atmospheric CO2 curve, and warming stops only around 15 years after peak CO2. So this scenario seems to assume it takes only a few years for the Earth to reach its thermal equilibrium point for a given level of CO2 (I don't see a lot of consensus on this), and it assumes the loss of the shading/cooling effect from aerosol particulates results in roughly zero increase in the rate of warming, and it assumes the knock-on feedback effects at higher temperatures (due to melting permafrost methane release, reduced ice reflectivity, etc) will be small.
And then the authors of this report greatly shrink the carbon capture component of SSP1-1.9, add in a slight increase in forest area, and a lot more emphasis on equity and social justice, and suggest this can be even more successful at rapidly reducing CO2 levels and combating climate change. The tiny detail of how that would work apparently wasn't important enough to merit description. Also curious that in a scenario concerning a major transition in energy, there is no graph depicting the projected change in energy. But they did note that their proposal *may be* a challenge to implement. That part, at least, seems completely uncontroversial.
I think the equity/social justice issue is presented adequately, given that the 1% or even 10% of top income earners are responsible for so much energy consumption. But, as I mention in the next post, getting these people to accept world-average energy use is complicated. I am hoping that these authors will make some comments on these issues.
Were you able to glean how they greatly reduced the carbon capture component of SSP1-1.9 and still expect to remove as much CO2 from the air? Because that extra forest area would hardly begin to cover the loss.