THREAD
2020 #carbonbudget @gcarbonproject contains loads of info on 2019 carbon budget (in addition to 2020 emission forecast making the news). Lets look at 2019:
Sources:
Fossil Fuel=9.7 GtC
Land Use=1.8 GtC
Sinks:
Atmosphere=5.4 GtC, 2.54 ppm
Ocean=2.6 GtC
Land=3.1 GtC

Based on 2019 carbon sources & sinks, the #carbonbudget shows that land & oceans absorbed the equivalent of 50% of fossil fuel & land-use change emissions!!

Because of this biospheric 'freebie' atm. growth of CO2 was just half as much as total emissions (shown below, 19.8 GtCO2)

Fraction of emitted CO2 staying in atmos. each year is referred to as 'Airborne Fraction (AF)' - a key Earth system metric tracked over time to detect carbon-climate feedbacks.

Fig. below shows how AF changes year-to-year as land & ocean respond to climate, disturbance, CO2, etc

The airborne fraction has remained amazingly consistent over past 50 years, but concerns the AF will increase as land & ocean sinks absorb CO2 less efficiently - e.g., a study published yesterday ( http://bit.ly/3gy1uhZ ) suggest land CO2 fertilization is already on the decline.

For past 9 years, the TRENDY ensemble of dynamic global vegetation models (DGVMs) have provided the Global Carbon Budget with the estimate of the land sink.

The land sink has increased from 1.3 PgC/yr (1960-1969) to 3.4 PgC/yr (2010-2019), w 2019 land sink below decadal mean.

The #carbonbudget also provides a 'budget imbalance' term, indicating how well we balance sources & sinks. In 2019, the budget imbalance was 0.3 GtC, slightly higher than past decade average of 0.1 GtC.

The #carbonbudget evaluates the fossil fuel emissions projection of the previous year with the 'actual' year emissions. For 2019, the projection was for a 0.5% increase in global emissions, and the actual was 0.1%. For 2020, expect a -7% decrease due to #COVID19 impacts.

The growth of atmospheric CO2 in 2020 measured by @NOAA_esrl is roughly 2.5 ppm - and doesn't show any impact of reduced emissions related to #COVID19 - we need to look at the 2020 land and ocean carbon sinks to understand why...

All said, the 2020 @gcarbonproject #carbonbudget shows we're rapidly burning through our carbon budget needed to stay below 1.5 or 2.0 degree warming.

https://www.unenvironment.org/emissions-gap-report-2020