What is a fair way forward after the 1.5°C warming limit of the Paris Agreement has been breached?  In a new study, IIASA researchers explore the concept of ‘net-zero carbon debt’ — a measure for assessing who bears greater responsibility for minimizing the climate overshoot.

A new study provides fresh insight into traditional acid-base chemistry by revealing that the mutual neutralization of isolated hydronium (H₃O⁺) and hydroxide (OH⁻) ions is driven by electron transfer rather than the proton transfer that is expected in bulk liquid water. Using deuterated water ions and advanced 3D coincidence imaging of the neutral products, researchers found two electron-transfer mechanisms that produce hydroxyl radicals (OH), which are crucial in atmospheric chemistry. These findings reshape our understanding of fundamental reaction dynamics and help explain the surprising finding of high OH and H2O2 concentrations at water microdroplet surfaces. This discovery is significant because OH radicals play a key role in air quality, climate science, and even biochemical processes in the human body. By uncovering unexpected chemical reaction pathways, the study could influence future research on planetary and interstellar medium chemistry, as well as pollution control and medical applications.