Temperature is shown as an anomaly — the departure from the 1951–1980 average — because anomalies combine consistently across thousands of land and ocean stations. NASA’s GISTEMP v4 blends station records with sea-surface measurements; the value for the current year is a year-to-date mean and firms up as more months report.

Atmospheric CO₂ is the annual mean from NOAA’s Mauna Loa observatory, the longest continuous direct record (the Keeling Curve, since 1958). Fossil CO₂ emissions are the Global Carbon Project’s estimate of CO₂ from fossil fuels and industry, excluding land-use change, distributed via Our World in Data.

Greenhouse gases (fossil & industry) is the broader companion to the fossil-CO₂ line: it adds methane, nitrous oxide and fluorinated gases from energy and industry, all converted to a common 100-year CO₂-equivalent (Jones et al. 2025, via OWID). It excludes land-use change and so is a conservative floor on total warming pollution — already over 43 Gt CO₂e a year.

Two views of the cause: CO₂ per person (Global Carbon Project) is the global average fossil emission per head — it has roughly doubled since 1950 and, tellingly, has barely fallen since, even as efficiency improved. Fossil fuel production (Energy Institute) is the coal, oil and gas we extract each year in petawatt-hours; despite every climate pledge, it has kept climbing decade on decade.

Forest area (FAO, via OWID) is the world’s total forest cover; it has fallen by about a Mexico-sized area since 1990. It is the slow-moving net stock behind the faster `forest loss` series above — the standing forest that is still, on balance, shrinking.

Atmospheric methane (CH₄) is NOAA’s globally-averaged annual mean (parts per billion) from a network of marine surface sites. Methane is a far more potent greenhouse gas than CO₂ — roughly 80× over 20 years — though it is shorter-lived; it has risen from ~1,645 ppb in 1984 to over 1,930, with a sharp acceleration since 2007.

Nitrous oxide (N₂O) — the third major greenhouse gas, ~270× as warming as CO₂ and very long-lived — is NOAA’s global annual mean (the global record begins in 2001). It has climbed steadily from ~316 to ~339 ppb, driven mainly by nitrogen fertiliser and manure in agriculture.

Tree-cover loss (Global Forest Watch / University of Maryland) counts the annual removal of tree canopy from any cause — logging, fire, clearing for farmland — at ≥30 m resolution. It is loss, not net change, so it does not subtract regrowth. This series is currently seed-only: no faithful public year-by-year feed is wired for live refresh (see docs/DATA_SOURCES.md).

And two hopeful counter-trends. Renewables’ share of global electricity (Our World in Data, from Ember + the Energy Institute) stalled near 18% through the fossil-heavy 1990s–2000s, then climbed past a third as wind and solar scaled. And the electric-car share of new sales (IEA, via OWID) has gone from almost nothing to a quarter of all new cars in barely a decade — the clearest signs that the curves CAN bend the right way.