Anthromes, CO2 , and Terrestrial Carbon

From the deep past to net-zero


Monday 27 March – Thursday 30 March 2023

Washington D.C. (Potomac Maryland), USA

A symposium organised by Oak Ridge National Laboratory with support from the New Phytologist Foundation. Funding for the symposium is provided by the US Department of Energy, Office of Science Biological and Environmental Research program.




The Anthromes, CO2, and Terrestrial Carbon meeting seeks to explore the inter-relationship of CO2-fertilization, people, and land ecosystems through the lens of terrestrial carbon source-sink dynamics during the deep past, through major cultural transitions, and in the net-zero motivated near-future. Speakers will span disciplines, bringing together a group of researchers to provide a global view of the multifaceted impacts of people on terrestrial carbon through time. Goals for the meeting are to: build community, synthesize how developing understanding of anthromes influences our understanding of the natural land sink under altered CO2, discuss the future impacts of human cultures and CO2-fertilization on terrestrial ecosystem carbon, and to consider net-zero culture as a driver of land carbon change, including the equity outcomes of the race to net-zero.

Meeting scope and purpose

Earth’s land ecosystems store vast quantities of carbon in myriad live and dead organic forms. As a result of human activities, these land carbon stores are the most dynamic in the global carbon cycle. Increasing atmospheric CO2 is boosting global photosynthesis and the subsequent effects are thought to remove a substantial quantity of anthropogenic CO2 from the atmosphere, creating a negative feedback loop known as the CO2-fertilization hypothesis. CO2 is the primary driver of the “natural” land sink which results from the indirect effects of people on land carbon and, by slowing the rate of atmospheric CO2 increase, is a global ecosystem service that is slowing the rate of climate change. However, the natural land sink is almost exactly counterbalanced by a net carbon source from land ecosystems through our land use activities. Land use and land cover change (LULCC) activities such as agricultural practices, expansion and abandonment of agricultural land, peatland drainage, timber harvest and plantation establishment, housing and urban development, and fire suppression and management directly affect CO2 exchange with the atmosphere.

Terrestrial biosphere models and global carbon budgets provide some confidence in the size of the natural land sink but model assumptions in the type, extent, and legacies of human land use create uncertainties and potential biases in the estimates of the LULCC net source. Any bias in the LULCC source would imply, via global carbon budgeting, bias in our estimates of the natural land sink and its drivers, in particular the CO2 fertilization hypothesis. The influence of people on Earth’s land surface is so widespread that ecosystems not impacted by humans in some form are almost non-existent, and this has been the case for millennia. Therefore most of the land ecosystems of our home planet, from 12,000 years ago to the present, have been characterized as anthropogenic biomes (anthromes) of various kinds. Anthromes are far more dynamic than their pre-human counterparts and these dynamics are driven by socio-economic factors in addition to ecological factors. Human cultures and their transitions have had major impacts on terrestrial carbon stores that have implications for our understanding of the CO2 fertilization hypothesis. Understanding the inter-relationship of the CO2-fertilization sink and the LULCC source is a truly transdisciplinary problem that requires expertise across multiple disciplines: Earth system science, ecology, agriculture, anthropology, political economy, and economics.

In the coming decades, CO2-fertilization will continue to be a major driver of the natural land sink and the need for and rhetoric surrounding net-zero carbon emissions will drive new types of human land use. Coupled with growing global food demand and concentration of wealth, the emerging net-zero culture will drive economic pressures on land in the coming decades that will be unprecedented and will likely exacerbate injustice if poorly managed.


Understanding the inter-relationship of the CO2-fertilization sink

and the LULCC source is a truly transdisciplinary problem

that requires expertise across multiple disciplines:

Earth system science, ecology, agriculture, anthropology,

political economy, and economics.

Indeed, the direct influence of people on Earth’s land surface is so widespread that ecosystems not impacted by humans in some form are almost non-existent. The mark of human disturbance is apparent in virtually all ecosystems such that the terrestrial ecosystems of our home planet can be largely characterized as anthropogenic biomes (anthromes) of one sort or another. Anthromes are far more dynamic than their pre-human counterparts and these dynamics are driven by socio-economic factors in addition to ecological factors. With growing global food demand, concentration of wealth, and the need for and rhetoric surrounding net-zero carbon emissions, socio-economic pressures on land in the coming decades will be unprecedented. If poorly managed, these unprecedented pressures will likely increase biodiversity loss, exacerbate injustice, and lead to further negative outcomes of human global dominance.

Understanding the terrestrial carbon cycle and its drivers of change is a truly transdisciplinary problem that requires expertise across multiple ecological disciplines: Earth system science, ecology, agriculture, anthropology, political economy, and economics. This meeting seeks to explore the relationship between people, land, CO2 , and the terrestrial carbon cycle during the prehistoric and early historic past, the European colonial and industrial transitions, and the net-zero motivated future. Speakers will span disciplines, bringing together a group of researchers to provide a systems-level view of the multifaceted impacts of people on terrestrial carbon through time. Goals for the meeting will be to build community, synthesize our current understanding of how anthromes influence our understanding of the natural land sink under altered CO2 , and to establish principles to minimize negative outcomes of the race to net-zero.