Is the missing carbon dioxide hiding in Fiordland?

Published 2 November 2017

Dr. Peter Sperlich in NIWA’s atmospheric laboratory in Wellington

To predict the impacts of climate change on New Zealand we need to be able to estimate future levels of carbon dioxide (CO₂) in the atmosphere. This requires a good understanding of the amount of CO₂ that is both entering and leaving the atmosphere (CO₂ flux) today. Yet, there is currently large disagreement in the estimates of land-based CO₂ fluxes. In particular, the CO₂ flux for Fiordland, one of the largest indigenous forests in New Zealand, has recently been contested.

A recent study indicates that the amount of CO₂ absorbed from Fiordland’s atmosphere may be underestimated. Forests play an important role in the flux of carbon. They release CO₂ during plant and soil respiration, and uptake CO₂ during plant photosynthesis. Dr Peter Sperlich from the National Institute of Water and Atmospheric Research (NIWA), in collaboration with a multinational team of researchers, has been awarded a Marsden Fund Fast-Start grant to determine if Fiordland’s forest is more productive than previously thought and can account for the missing CO₂.

Dr Sperlich will make extensive use of isotopic analyses to probe the processes that affect CO₂ flux, and how these processes are affected by different environmental conditions. In particular, he will measure CO₂ and related trace gases in coastal background air, before and after it has passed over Fiordland. This will lead to an in-depth understanding of the CO₂ flux in Fiordland, and whether it can account for the difference in current atmospheric estimates in this region.

Findings from this study will improve current methods for estimating regional carbon fluxes. This will increase our certainty in New Zealand’s inventory of greenhouse gas emissions that are reported to the United Nations Framework Convention on Climate Change.