références en Anglais

In a rapidly changing climate, evidence-based decision-making benefits from up-to-date and timely information. Here we compile monitoring datasets (published at https://doi.org/10.5281/zenodo.15639576; Smith et al., 2025a) to produce updated estimates for key indicators of the state of the climate system: net emissions of greenhouse gases and short-lived climate forcers, greenhouse gas concentrations, radiative forcing, the Earth's energy imbalance, surface temperature changes, warming attributed to human activities, the remaining carbon budget, and estimates of global temperature extremes. This year, we additionally include indicators for sea-level rise and land precipitation change. We follow methods as closely as possible to those used in the IPCC Sixth Assessment Report (AR6) Working Group One report.

The total concentration of greenhouse gases and other forcing agents, including cooling aerosols, reached 465 parts per million CO2 equivalents in 2020. This is around the peak level that the International Panel on Climate Change states 'should not be exceeded if — with a 67% likelihood and not allowing a temperature overshoot — the global temperature increase is to be limited to 1.5oC above pre-industrial levels'. When allowing for a temperature overshoot, the peak level could be exceeded in 2024. The peak concentrations corresponding to a temperature increase of 2oC by 2100 could be exceeded between 2027 and 2030.

Unlike carbon dioxide, atmospheric methane concentrations are rising faster than at any time in the past two decades. The fossil fuel, agriculture and waste sectors are equally responsible.

The centerpiece of the early anthropogenic hypothesis is the claim that humans took control of greenhouse-gas trends thousands of years ago because of emissions from early agriculture ( [32] and [33]). A common reaction to this claim is that too few people lived thousands of years ago to have had a major effect on either land use or greenhouse-gas concentrations.

Today, the average global temperature has increased by more than 1°C compared to pre-industrial values (Figure 1-1); atmospheric CO2 concentrations have risen from 280 to more than 400 ppm. At the current pace of emissions, the carbon budget that is left for staying below the 2°C target of the Paris Agreement will be depleted in a few tens of years. For the 1.5°C target, this budget will be exhausted before the decade is out.

Scientists know that global warming is changing clouds, but they haven’t been sure whether those changes would heat or cool the planet overall. It’s an important question, because clouds have been the main source of uncertainty in projecting just how sensitive the climate is to increasing greenhouse gas concentrations, and because clouds have a huge effect on the climate system.

Concentrations of CO2 in the atmosphere have increased from pre-industrial levels of 280 parts per million (ppm) to around 416ppm today. Without actions to reduce emissions, concentrations are likely to reach 560ppm – double pre-industrial levels – around the year 2060.