The Impact of Soil Organic Matter on Climate

A research conducted in 2014 during my internship at Université du Québec à Montréal (UQAM), Earth and Atmospheric Sciences.

Presented at Atmospheric and Oceanic Science unit, IGSSA and Physics Department, Addis
Ababa University, Ethiopia

Soil organic matter plays an important role in modulating weather/climate. Increase in greenhouse gas concentrations results in considerable rise in land temperatures as indicated by climate projections. The warming of soil facilitates the decomposition of soil organic matter which further adds carbon dioxide in to the atmosphere. The impact of warming of soil if drifts towards wet soil will increase methane gas release in to the atmosphere. Methane is radiatively more active than carbon dioxide, hence results in more warming. The impact of warming of soil does not stop there. It will increase microbial activity which releases nitrogen from the soil and prompt shrub growth resulting in positive albedo feedback. This study, therefore, is started because of the huge impact that warming of soil has on climate. A climate model experiment with soil organic matter (SOM) and without soil organic matter (WSOM) was designed over the pan-arcitic domain. Comparison of current and future climate in the presence and absence of soil organic matter was made. Results showed that the presence/absence of soil organic matter results in decrease/increase in surface temperature in current and future climate. The decrease in temperature in the presence of SOM is due to an increase in ground evaporation which causes a drop in surface temperature. The increase in temperature in the absence of SOM is because of the dominance in sensible heat flux from the mineral soil. In general, soil organic matter is proved essential component of land system helpful to keep global warming intact. This result, therefore, indicates that dynamical response due to heat flux changes in the presence and absence of soil organic matter affects large-scale atmospheric circulation by reducing and increasing atmospheric temperature.

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