Positive sensitivity of land carbon sinks in the Northern Hemisphere to both concurrent and preceding Arctic Oscillation

Aim

The Arctic Oscillation (AO), North Atlantic Oscillation (NAO), and Pacific–North American Pattern (PNA) cause climate variability in the Northern Hemisphere (NH), which affects the carbon cycle of terrestrial ecosystems.

Location

Northern Hemisphere (north of 30° N).

Time Period

From 1980 to 2017.

Major Taxa Studied

Plant.

Methods

Based on the dynamic global vegetation modeland oscillation indices, we performed sensitivity analyses to analyse the impacts of the AO, NAO and PNA on changes in terrestrial climate and carbon cycle dynamics.

Results

The positive AO (pAO), positive NAO (pNAO), negative NAO (nNAO) and negative PNA (nPNA) led to warmer and drier conditions in the NH, whereas the positive PNA (pPNA) and negative AO (nAO) resulted in colder and more humid conditions. Furthermore, the pAO and nNAO increased the carbon sinks of terrestrial ecosystems, whereas the pNAO, pPNA, nAO and nPNA reduced the carbon sinks.

Main Conclusions

With respect to direct impacts, increased AO and NAO indices increased the carbon sinks in the NH, whereas an increased PNA index reduced the carbon sinks. With respect to legacy impacts, increased AO and PNA indices enhanced the carbon sinks of the terrestrial ecosystems, whereas an increased NAO index strengthened the carbon source capacity. These results provide a framework for conducting further research on the mechanisms of interannual variability of the terrestrial carbon cycle.