In 2024, concentrations of the three major greenhouse gases—carbon dioxide, methane, and nitrous oxide—reached record highs, marking the largest annual increase on record, according to John Kennedy, the agency’s scientific officer. Early data from 2025 suggest that these levels continue to rise, altering the energy balance of the planet.
Under a stable system, the energy received from the sun would roughly equal the energy radiated back into space. However, increased greenhouse gas concentrations are reducing the outgoing energy, causing a net accumulation of energy in the Earth’s system. This energy imbalance is a newly tracked indicator by WMO and shows a significant acceleration in global warming between 2001 and 2025.
Most of the excess energy, about 90 percent, is absorbed by the oceans, which has serious implications for human populations. Over three billion people rely on marine and coastal resources for their livelihoods, and nearly 11 percent of the global population live on low-lying coasts that are directly exposed to hazards from these changes.
