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Chain Reaction

MCM scientists documented how even small variations in climate can drive major changes in polar ecosystems: seemingly slight changes in temperature can set off a cascade of magnified responses that affect stream flow, nutrient cycling, and biodiversity.

Foreman, C. M., B. Sattler, J. A. Mikucki, D. L. Porazinska, and J. C. Priscu (2007), Metabolic activity and diversity of cryoconites in the Taylor Valley, Antarctica, J. Geophys. Res., 112, G04S32, doi:10.1029/2006JG000358.
Fountain, A. G., T. H. Nylen, M. Tranter, and E. Bagshaw, (2008), Temporal variations in physical and chemical features of cryoconite holes on Canada Glacier, McMurdo Dry Valleys, Antarctica, J. Geophys. Res., 113, G01S92, doi:10.1029/2007JG000430.
Tranter, M., A. G. Fountain, C. H. Fritsen, W. B. Lyons, J. C. Priscu, P. J. Statham, and K. A. Welch (2004), Extreme hydrochemical conditions in natural microcosms entombed within Antarctic ice, Hydrol. Processes, 18, 379-387.
Soil plots in a reactivated wetland (summer 2008-09).
Conceptual model of climate driven presses and pulses in the MDV ecosystem. Influences of presses (grey line) are a linear function of duration and magnitude whereas pulses (events represented as variability in the black line) influence climate disproportionally to their duration. Pulses and presses can elicit non-linear responses from ecosystems depending upon initial conditions and nature (sign, magnitude, duration) of the changes. For example, in the MDVs a long-term cooling press limited meltwater generation and streamflow, decreasing productivity in lake and soil biota over a decadal time scale. In contrast, the warm windy summers of 2001-02 and 2008-09 enhanced hydrological connectivity, offsetting previous changes from a decade of cooling. Climate models predict that the role of pulses in driving the behavior of the MDV ecosystem will increase in the immediate future.



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