Net-zero emissions, in other words: achieving carbon neutrality - is a state in which the carbon dioxide emitted by a given country is fully balanced by the absorption or capture of CO2.

This level can be approached, for example, by attempting to reduce greenhouse gas emissions, but also by methods of binding gases (e.g. carbon dioxide, CO2) that have already been emitted and are in the atmosphere. One possible strategy for fairly permanent removal of CO2 from the atmosphere concerns the construction sector, specifically - building materials. Elisabeth Van Roijen from the University of California, Davis (USA) and colleagues propose in Science that conventional building materials should be replaced with materials modified to bind carbon dioxide.

The researchers have calculated the global potential to store carbon in concrete, brick, asphalt, plastic, and wood. While wood naturally contains carbon, other materials (e.g. concrete) would require alterations such as mixing carbon aggregates in concrete or using bio-based materials in bricks.

According to their calculations, full replacement of conventional building materials with these CO2-sequestering alternatives could store as much as 16.6 (± 2.8) gigatons of CO2 each year. This is equivalent to about 50% of the anthropogenic CO2 emissions in 2021.

Removing carbon dioxide from the atmosphere, along with decreasing emissions, is important for slowing global climate warming. he researchers point out that building materials are good candidates for such efforts due to their widespread use and longevity.

The researchers note that the carbon-sequestering potential of these changes has more to do with the amount of material used than with the quality of the processes. For example, cement aggregates store relatively little carbon but cement is used on a large scale.

One challenge to overcome is the reluctance of builders to use new structural materials. Industry representatives may fear liability if these materials fail. Other challenges include finding enough carbon-sequestering minerals to use in building materials. Another issue is establishing a rigorously monitored supply chain, Christopher Bataille from the Center on Global Energy Policy at Columbia University points out in an accompanying Perspective.

Construction has long been listed as one of the industries that emits the most greenhouse gases. According to UN data, buildings and the entire construction industry are responsible for about 38 percent of global carbon dioxide emissions, of which about 10 percent comes from the construction industry, the rest - from operation. Concrete and steel, used mainly in foundation slabs, contribute the most to these emissions.

Find out more in the source paper in Science (www.science.org/doi/10.1126/science.adq8594) and the accompanying Perspective (www.science.org/doi/10.1126/science.adu7379). (PAP)

zan/ agt/