Fig. 4: Regional variability in CO2 budget trends.
From: Wildfires offset the increasing but spatially heterogeneous Arctic–boreal CO2 uptake
a,b, Terrestrial CO2 budgets for NEE and NEE + fire in key regions across the boreal (a) and tundra (b). Terrestrial CO2 budgets are shown for 1-km (blue; 2001–2020) and 8-km (grey; 1990–2016) NEE as well as 1-km NEE + fire emissions (red; 2002–2020). The inset in the Alaskan boreal plot in a shows the time series with a narrower y axis than that in the main figure to better depict interannual variability. The central lines in the figures are derived from the outputs of the final model using the complete training dataset. The standard deviations (shaded areas) are calculated from the outputs of 20 different models, each trained on a unique bootstrapped sample of the original training data. The magnitude of the trend was computed using the Theil–Sen approach, and the P value determined using the Mann–Kendall test.
