A Modeling Perspective of Global Carbon Cycle Science: From a Missing Sink to Net Zero

[Geoengineering News]

https://tellusjournal.org/articles/10.16993/tellus.4176

Authors: Pierre Friedlingstein

17 June 2026

Abstract

Global carbon cycle research significantly started in the late 1950s with the beginning of continuous monitoring of atmospheric carbon dioxide (CO2), revealing the increase in concentration due to anthropogenic CO2 emissions and the existence of carbon sinks needed to close the global carbon budget.

From a modeling perspective, these observational findings initiated worldwide research on process understanding and representation in ocean and land carbon cycle models. These models have been developed, first as a stand-alone, to understand the respective roles of the oceanic and terrestrial ecosystems to act as carbon sinks, and later as a part of global climate models, to reveal the climate–carbon cycle feedback.

These coupled climate–carbon cycle models, also called Earth System Models (ESMs), identified that this feedback is positive; warming leads to a weakening of the carbon sinks, leaving a larger fraction of the anthropogenic CO2 emissions in the atmosphere, further amplifying the warming. These ESMs led to the recognition of the irreversibility of climate change, as well as the near-linear relationship between cumulative CO2 emission and global warming, allowing to define the transient climate response to CO2 emissions and the remaining carbon budget. These scientific advances on climate and carbon cycle modeling were central to the United Nations Framework Convention on Climate Change (UNFCCC) Paris Agreement and the acknowledgment that humanity needs to reach net-zero anthropogenic emissions to stop climate change.

Source: Tellus