Canada’s extreme wildfires dominate the decline in global land carbon sinks in 2023

Terrestrial land carbon sinks are strongly influenced by climate extremes,
and 2023 is the warmest year on record, accompanied by an El Niño event,
extreme wildfires, and extreme precipitation and drought, but their impact
on global land sinks in 2023 remains unclear. Here, we used the Global
Carbon Assimilation System, version 2, to estimate recent global land
sinks by assimilating the OCO-2 ACOS v11.1 XCO2 retrievals. We estimate
the global land sink to be -1.63 ± 0.52 PgC/yr in 2023. Compared to
2017-2022, it decreases by 0.59 PgC/yr, in which net ecosystem exchange
decreases by only 0.14 PgC/yr, but wildfire emissions increase
significantly by 0.45 PgC/yr, mainly in Canada. Our findings suggest that
extreme wildfires are an important threat to land sinks under global
warming.