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

Area of Science:

• Environmental Science
• Climate Science
• Ecology

Background:

• High-latitude regions experience accelerated climate warming.
• Short-term warming experiments suggest increased soil organic matter decomposition and positive climate feedback.
• Arctic ecosystems are complex and tightly coupled.

Purpose of the Study:

• To evaluate the accuracy of short-term warming experiments in predicting long-term ecosystem carbon stock responses.
• To investigate the nonlinear dynamics of Arctic ecosystems under climate change.
• To improve predictive models of Arctic carbon cycling.

Main Methods:

• Utilized a mechanistic ecosystem model validated against observed data from four Alaskan field sites.
• Analyzed responses of carbon cycle and active layer depth to short-term summer warming.
• Compared short-term experimental results with emergent multi-decadal ecosystem responses.

Main Results:

• Mechanistic model accurately represented short-term warming effects on carbon cycle and active layer depth.
• Short-term warming experiments failed to capture nonlinear, long-term vegetation and soil organic matter dynamics.
• Significant spatial heterogeneity exists in multi-decadal Arctic carbon cycle trajectories.

Conclusions:

• Short-term warming experiments yield emergent ecosystem carbon stock temperature sensitivities inconsistent with multi-decadal responses.
• Long-term Arctic carbon cycle predictions require models that account for nonlinear vegetation, thermal, hydrological, and nutrient transformations.
• Mechanistic models are crucial for improving the predictive capabilities of Arctic carbon dynamics under climate change.