Carbon cycle

Radiocarbon (¹⁴C) measurements are an excellent tool for investigating CO₂ emissions and their ultimate fate. We use ¹⁴CO₂ measurements over the Southern Ocean as a diagnostic for understanding the mechanisms of ocean carbon exchange. Our laboratory uses measurements of ¹⁴C in CO₂, along with atmospheric transport modelling, to quantify fossil fuel CO₂ emissions into the atmosphere at various scales, including individual power plants, urban areas and entire countries and regions.

CO₂ emissions are the primary driver of global warming, yet there are gaps in our understanding of the rate of emissions and in the resulting build-up of CO₂ in the atmosphere. About half of the fossil fuel CO₂ emissions into the atmosphere remains there. The remainder is absorbed into the oceans and terrestrial biosphere. The details of this uptake are still uncertain but critical for predictions of future climate change. The Southern Ocean, in particular, is a strong “sink” for human-produced CO₂, yet it is possible that climate change will reduce its capacity to absorb that CO₂ – a positive climate change feedback.

We must achieve net zero atmospheric carbon emissions by 2050 to avoid a dangerous increase in global mean surface temperature (> 2°C above pre-industrial levels).  Knowing what our current emissions are is key to mitigating them.  Transitioning from fossil fuels as an energy source is key, but we must also avoid actions that turn our natural carbon sinks into a source of carbon. We must also identify parts of our carbon system that could be used to sequester and store carbon as we strive to remove excess CO₂ from the air.

Energy generation in Aotearoa New Zealand has a history of significant environmental impacts. We need new energy developments to replace fossil fuels in the energy mix. We must understand the full consequences of these developments, including changes to land, biosystems, communities and natural systems such as the carbon cycle.