Fossil fuel burning is the primary driver of increasing atmospheric carbon dioxide (CO2), which recently passed the landmark 400 parts per million mark. Most nations have committed to reducing their emissions under the Paris Agreement and many sub-national entities have made similar commitments. To ensure that the promised emission reductions are achieved, an understanding of emission rates from fossil fuel point sources, cities, regions and countries, and of uptake of carbon into the land and oceans, is critical.
Traditionally, "bottom-up" economic information has been used to determine fossil fuel emission rates, and biomass estimates are used to evaluate the land carbon sink. In this presentation, I will discuss the use of a "top-down" approach that uses atmospheric measurements and modelling that complements the bottom-up method. In particular, I will focus on the use of radiocarbon (14C) in CO2 as a tracer for the fossil fuel component of atmospheric CO2. I will showcase how the method can be used to quantify fossil fuel CO2 emissions and land carbon uptake, giving examples from USA and New Zealand.
Jocelyn Turnbull holds joint appointments as a Senior Scientist at GNS Science, New Zealand and a Research Associate at the University of Colorado at Boulder, USA. She leads the Rafter Radiocarbon Laboratory at GNS Science, the world's oldest continuously operating radiocarbon facility. The laboratory maintains expertise in a wide range of radiocarbon applications, and Jocelyn's research is primarily on the modern carbon cycle, particularly fossil fuel derived CO2. She uses radiocarbon and related tracers to understand the sources and sinks of greenhouse gases at the local, urban and regional scales. Current projects include CarbonWatch-NZ which aims to evaluate New Zealand's natural and anthropogenic carbon budget; INFLUX, the Indianapolis Flux Project where methods for evaluating urban greenhouse gas emissions are being developed; and SOAR Southern Ocean Atmospheric Radiocarbon which uses radiocarbon measurements to understand the dynamics of Southern Ocean carbon exchange.