Alaskan carbon-climate feedbacks will be weaker than inferred from short-term experiments

• Published in: Nature Communications
• Main Authors: Bouskill, Nicholas J., Riley, William J., Zhu, Qing, Mekonnen, Zelalem A., Grant, Robert F.
• Language: unknown
• Published: 2021
• Subjects: 54 ENVIRONMENTAL SCIENCES; Arctic; Climate change
• Online Access: http://www.osti.gov/servlets/purl/1763682; https://www.osti.gov/biblio/1763682; https://doi.org/10.1038/s41467-020-19574-3

Climate warming is occurring fastest at high latitudes. Based on short-term field experiments, this warming is projected to stimulate soil organic matter decomposition, and promote a positive feedback to climate change. We show here that the tightly coupled, nonlinear nature of high-latitude ecosystems implies that short-term (<10 year) warming experiments produce emergent ecosystem carbon stock temperature sensitivities inconsistent with emergent multi-decadal responses. We first demonstrate that a well-tested mechanistic ecosystem model accurately represents observed carbon cycle and active layer depth responses to short-term summer warming in four diverse Alaskan sites. We then show that short-term warming manipulations do not capture the non-linear, long-term dynamics of vegetation, and thereby soil organic matter, that occur in response to thermal, hydrological, and nutrient transformations belowground. Our results demonstrate significant spatial heterogeneity in multi-decadal Arctic carbon cycle trajectories and argue for more mechanistic models to improve predictive capabilities.