Climate classroom The main drivers of changes in CO2 concentration in the atmosphere


The carbon dioxide (CO2) concentration in the atmosphere is affected by both natural processes and anthropogenic emissions. Distinguishing the short-term variations in CO2 levels due to natural processes from human emissions is important for calculating the carbon budget and pushing for action to mitigate the effects of climate change. 

Here, we explore the four main drivers of the changes in the level of CO2 in the atmosphere in the order of their contributions to weekly and monthly variations (from greatest to smallest).

Ocean acidification in the Arctic will be greater than previously expected


The ocean absorbs around a quarter of atmospheric CO2 released by anthropogenic sources. While this uptake mitigates global warming, it also disrupts the seawater chemistry. The additional CO2 in the ocean reduces its pH and the amount of calcium carbonate minerals, an effect known as ocean acidification. This reduction in calcium carbonate minerals negatively affects the growth and survival rates of calcifying marine organisms, such as corals and shellfish, which depend on these minerals to build their skeletons and shells. 

Temporary drop in CO2 emissions as a result of COVID 19 crisis

Change in global daily fossil CO2 emissions

Confinement measures have been adopted by many nations around the world since the beginning of 2020 in an attempt to contain the spread of COVID-19. With a great part of the world’s population forced to stay at home, these measures have brought about drastic changes in energy demand, transport and consumption patterns.

IPCC AR6 workshop Key issues of climate carbon interactions

Image from: IPCC AR5 Synthesis Report: Climate Change 2014, Figure 3.2. 

A workshop on the Sixth Assessment report of the Intergovernmental Panel on Climate Change (IPCC AR6) and the potential involvement of the 4C project in the report was held on June 12th, 2019 in Brussels, on the second day of the 4C kick-off meeting. The 3-day meeting opened with a summary of the four key objectives of the project, listed below, and the timeline, expectations and budget information were discussed.

  1. Understanding the contemporary carbon cycle.

  2. Predicting the carbon cycle and climate for the global stocktake to the horizon of 2030.

Welcome to the 4C project


The 4C project, funded under the EU Horizon 2020-Research and Innovation program, sets to address the uncertainties in our understanding of the carbon-climate interactions and feedback. 4C will address the crucial knowledge gap in the climate sensitivity to CO2 emissions through innovative integration of models and observations. It will provide new constraints on modelled carbon-climate interactions and climate projections, and support the Intergovernmental Panel on Climate Change (IPCC) assessments and policy objectives.