Companies behind these 'mass timber' projects say that wood is a lower-carbon alternative to steel or concrete and brings other benefits, such as faster construction time and lower cost than concrete and steel. Advocates say the wood materials, made of compressed layers of wood with glue, offer good fire safety as well. As an economist who studies forestry and natural resources, I took an interest in this building trend when I heard that a local bar on campus was going to be replaced by a 13-story building made out of wood. I see any increase in the use of wood in buildings as positive for reducing the substantial carbon footprint of buildings. But it is critical to consider where wood is sourced and whether forests are managed sustainably. One life-cycle analysis found that using mass timber in a 12-story building in Oregon had an 18% lower global warming impact compared with constructing the building with steel-reinforced concrete. The carbon emissions benefits are even greater when comparing timber with steel for low- and mid-rise buildings. In these studies, the global warming benefits mostly result from lower emissions in sourcing, transporting and manufacturing the material for these large wood buildings, compared with steel or concrete components, rather than efficiencies in heating or cooling or disposal of the materials at the end of the building's lifespan....

Cordelia Bahr is part of Nature's 10, a list of people who shaped science in 2024....

One indicator is the number of companies that have set emissions targets as part of the Science Based Targets initiative, or SBTi, a global nonprofit organization. That number grew from 164 companies in late 2018 to over 6,600 by November 2024. And thousands more have committed to lower their emissions. The Paris Agreement, an international treaty on climate change, aims to limit global warming to well below 2 degrees Celsius (3.6 Fahrenheit) and ideally to 1.5 C (2.7 F). Meeting the more ambitious target of 1.5 C will require reaching net-zero greenhouse gas emissions by around 2050. Net zero is the point at which the amount of greenhouse gases released into the atmosphere is balanced by greenhouse gases removed, either through natural sources like forests or technologies such as carbon capture and storage. To join the initiative, companies begin by signing a letter of commitment to set near-term (2030) and long-term (2050) targets for reducing their emissions. Companies have 24 months to develop targets that adhere to SBTi guidelines. If the targets are validated and approved by SBTi, the company announces its targets publicly. The targets must be revalidated every five years, or they expire....

Although it is less abundant than carbon dioxide, methane gas contributes disproportionately to global warming because it traps more heat in the atmosphere than carbon dioxide, due to its molecular structure. 'What to do with methane has been a longstanding problem,' says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the senior author of the study. 'It's a source of carbon, and we want to keep it out of the atmosphere but also turn it into something useful.' Daniel Lundberg PhD '24 and MIT postdoc Jimin Kim are the lead authors of the study, which appears today in Nature Catalysis. Former postdoc Yu-Ming Tu and postdoc Cody Ritt also authors of the paper. Methane is produced by bacteria known as methanogens, which are often highly concentrated in landfills, swamps, and other sites of decaying biomass. Agriculture is a major source of methane, and methane gas is also generated as a byproduct of transporting, storing, and burning natural gas. Overall, it is believed to account for about 15 percent of global temperature increases....