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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - TRAIT (Exploring the biogeography of thermal acclimation in heterotrophic microbes)

Teaser

Summary

My primary research has provided a tangible linkage between the activity of soil microbial communities and the global carbon cycle by quantifying the effects of warming on soil carbon losses at a global scale.
This information is critical for society as it helps projecting future climate change scenarios.
Objectives are:
- use a combination of trait-based and community-scale approaches to explore the relative importance of microbial community composition and climate conditions in governing patterns of acclimation potential across landscapes.
- Incorporating this microbial physiological information into Earth System Models (ESMs)
- incorporate aspects of microbial physiological biology, community ecology and ecosystem ecology to address a critical uncertainty in current climate models.

Work performed

During my fellowship, I performed a comprehensive analysis of warming-induced changes in soil carbon stocks by assembling data from 49 field experiments located across North America, Europe and Asia. We find that the effects of warming are contingent on the size of the initial soil carbon stock, with considerable losses occurring in high-latitude areas. By extrapolating this empirical relationship to the global scale, we provide estimates of soil carbon sensitivity to warming that may help to constrain Earth system model projections. This empirical relationship suggests that global soil carbon stocks in the upper soil horizons will fall by 30 Â± 30 petagrams of carbon to 203 Â± 161 petagrams of carbon under one degree of warming, depending on the rate at which the effects of warming are realized. Under the conservative assumption that the response of soil carbon to warming occurs within a year, a business-as-usual climate scenario would drive the loss of 55 Â± 50 petagrams of carbon from the upper soil horizons by 2050. This value is around 12â€“17 per cent of the expected anthropogenic emissions over this period. Despite the considerable uncertainty in these estimates, the direction of the global soil carbon response is consistent across all scenarios. This provides strong empirical support for the idea that rising temperatures will stimulate the net loss of soil carbon to the atmosphere, driving a positive land carbonâ€“climate feedback that could accelerate climate change.

Final results

My results improve our capacity to model and benchmark earth System Model projections about future climate change scenarios. By combining our fundamental understanding of soil microbial physiology, with a global understanding of Earth system dynamics, this research is a stepping stone for how to incorporate critical ecological information into the structure of Earth System Models that generate the IPCC projections.