Clear numbers need
clear boundaries.

Atmospheric CO₂

For dates with a valid NOAA daily mean, we show that measurement. Otherwise we use the corresponding NOAA monthly mean. Before the continuous Mauna Loa record, we interpolate between annual historical anchors derived from NOAA-hosted Antarctic ice-core and firn records. Historical results are labelled estimates and never presented with false day-level precision. The deep-time chart uses NOAA’s revised Antarctic 800,000-year composite (Bereiter et al., 2015; dataset DOI 10.25921/ff81-7s34).

Live when available, bundled for reliability

The site’s same-origin atmospheric data layer checks NOAA’s public record and caches successful responses for six hours. The emissions learning layer checks four fixed Our World in Data chart endpoints once per day. Neither receives a selected date, country choice or visitor input. If either source is unavailable, the browser automatically uses a versioned bundled snapshot. Airport search always uses a bundled public-domain OurAirports directory, and no visitor location is detected.

Freshness: every automatically refreshed view displays its newest available data year or month and upstream update date. Annual emissions estimates are never presented as real-time measurements. Factors remain versioned separately and never change silently.

Source review and corrections

Automatic NOAA and OWID feeds are checked for structure, freshness, parsing failures and fallback behaviour every quarter. Manually curated emissions factors are reviewed every six months and receive a new version whenever a value, boundary, geography or source changes. IPCC material receives an annual source and errata review, plus a major review when a new assessment becomes available.

Methodology changes are recorded even when a numerical value stays the same. Time-sensitive social material expires when a newer underlying dataset is published; evergreen material is reviewed annually. If a material source or calculation error is found, affected material is replaced or withdrawn and a dated correction note records the cause and remedy.

Global emissions learning data

The Learn page uses production-based CO₂ emissions from fossil fuels and industry, excluding land-use change, from the Global Carbon Budget through Our World in Data. Its sector view is a separate Climate Watch dataset covering carbon dioxide, methane and nitrous oxide on a 100-year CO₂e scale. Because those boundaries and gases differ, the page does not compare the sector total directly with the CO₂-only total. Country figures are territorial estimates; international aviation and shipping are included only in the world total.

IPCC AR6 learning snapshot

The gases, sector, regional-contribution and pathway modules are a bundled, versioned snapshot of the Sixth Assessment Report. They do not call an IPCC service at runtime and therefore cannot silently change. Pathways are modelled ranges, not predictions. The policy baseline is permanently labelled as reflecting policies implemented through the end of 2020.

Dataset: ipcc-ar6-learning, version ar6-2022.1; assessed 2022; reviewed 2026-08-05. Regional shares and pathway values can differ slightly from 100% or the displayed global total because published IPCC values are rounded and land-use estimates carry substantial uncertainty.