Question 3. How does climate variability affect carbon dynamics along the terrestrial-aquatic continuum?

Theoretical linkages between environmental variability and ecosystem properties point to the severity of the arctic environment as an extreme and thus useful case for studying ecological function. The Arctic is experiencing accelerated rates of climate change and variability and the future of northern latitudes as a sink or source of C is in question. The release of thawed soil C to the atmosphere in the next 50-150 years is the strongest potential impact on the atmosphere from any natural system, and this arctic amplification could dramatically increase global warming. Our research focuses on the importance of climate variability on C dynamics, and using models compare the effect of variability to the effect of mean climate. What we need to know is how variability in climate, in hydrology, and in permafrost thaw dampens or accelerates this DOM processing along the continuum. We use models, observations, and experiments to answer the following questions:

How does variability in climate control C balance in tundra ecosystems?

How does variability in permafrost thaw control microbial degradation of DOM?

How does variability in hydrology control the abiotic degradation of DOM by iron-me- diated redox reactions?

How does variability in climate and hydrology control the coupled microbial and pho- tochemical oxidation of DOM in streams and lakes?

Theoretical responses of landscape net C loss to the atmosphere as a function of disturbance.  Not only is the magnitude of the response unknown but so is the shape of the response.

Summary of the terrestrial-aquatic continuum with the four new activities illustrated
to answer research Question 3.