Why this score The UN's consensus climate-assessment body. Reports synthesize peer-reviewed literature under documented multi-stage review; its published projection ranges since 1990 are the spine of the projections-vs-observed record and have proven broadly well-calibrated.
The global mean surface temperature change for the period 2016–2035 relative to 1986–2005 will likely be in the range of 0.3°C to 0.7°C (medium confidence).
Not yet due — the window does not close until the 2035 average is in. Observations through 2022 sit in the middle-to-warmer half of the projected range, which Ed Hawkins, revisiting the projection in 2023, judged still reasonable though perhaps cautious at its lower bound.
For the mid-range IPCC emission scenario, IS92a, the model-projected global mean warming is about 2°C by 2100. This estimate is approximately one third lower than the “best estimate” in 1990.
Not due until 2100. On the interim record the report ran cool: after cutting the 1990 estimate by a third — adding aerosol cooling and a lower 2.5°C sensitivity — its projected warming came in about 28% slower than observed over 1990–2016, the series' steepest under-shoot (Carbon Brief/Hausfather).
Under the IPCC Business-as-Usual (Scenario A) emissions... a rate of increase of global mean temperature during the next century of about 0.3°C per decade (with an uncertainty range of 0.2°C to 0.5°C per decade); this is greater than that seen over the past 10,000 years.
The central estimate ran high: warming since 1990 has averaged about 0.2°C per decade, at the bottom of the stated 0.2–0.5 range and roughly a third below the 0.3 central. The First Assessment Report overestimated the 1970–2016 warming rate by about 17% because its business-as-usual case assumed faster CO₂ and halocarbon growth than occurred — but observed warming stayed inside its stated range (Carbon Brief/Hausfather).