CLIM-02 / SPM.A / Research primer
How do CO2 emissions and atmospheric growth differ?
What accounts for the difference between annual anthropogenic CO2 emissions and the annual increase in atmospheric carbon?
NASA/Apollo 17 crew. Earth with Africa and Antarctica visible, photographed by the Apollo 17 crew on December 7, 1972. Contextual image; not used to estimate a trend. Image credits.
The question
The atmosphere records a stock, while emissions describe a flow. A compact carbon account can examine their relationship without mistaking slower emissions growth for falling concentrations.
Why it matters
The distinction explains why stabilizing annual emissions is different from stabilizing temperature, and why natural sinks belong in the comparison.
The AR6 anchor
Human greenhouse gas emissions have caused warming; limiting human-caused warming requires global net zero CO2 emissions (high confidence).
AR6 Synthesis Report (2023) / A.1; B.5.
Evidence and comparison
- Unit of analysis
- World-year, with distinct concentration and carbon-flow units.
- Baseline and denominator
- Compare flows in the source's common carbon unit, documenting any GtC-to-GtCO2 conversion. Concentration levels remain in ppm on a separate axis panel.
- First descriptive test
- Reconcile emissions with atmospheric growth, sinks and the reported budget imbalance. Display annual quantities beside five-year means rather than assuming exact annual closure.
- Deeper analysis
- Calculate the airborne fraction only for compatible positive emissions denominators; compare its variability with sink estimates and flag anomalous accounting years.
- Attribution status
- descriptive observation
- Uncertainty
- Carry reported component ranges and explain their dependence. The budget residual is an accounting uncertainty, not evidence of an unidentified emitting actor.
Principal sources
- NOAA GHG Trends
Global annual CO2 concentration (ppm); Annual concentration growth (ppm/year).
Target 1980-2025; complete-year and release checks pending. Candidate source; import and publication checks are still required. - Global Carbon Budget
Fossil and land-use CO2 emissions; Atmospheric growth and land/ocean sinks; Budget imbalance.
Target 1980-2024; GCB 2025 projections separate; release verification pending. Candidate source; import and publication checks are still required.
Alternative explanations
- Land-use uncertainty
- Ocean and terrestrial variability
- Shared atmospheric measurements
The visual argument
Provisional: aligned flow panels with a year selector; annotate emissions, atmospheric growth and the residual in common units, keeping concentration levels separate.
- Native ppm concentration series
- Five-year airborne fractions
- Land versus ocean sink comparison
- Carbon-account reconciliation table
What these data do not show
- A short-term sink change does not establish a permanent weakening.
- NOAA and GCB are not independent replications of atmospheric growth.
Reproducibility and next release
Plan src/build.mjs to preserve versioned data/raw extracts, create data/processed/carbon-account.csv, and test units, component signs, complete years and residuals; record hashes and rights in provenance.
- After approval: web carbon-account study
- Article and methods
- Responsive figures and exact table
- 16:9 hero and LinkedIn launch
- Optional PDF carousel
- Chart exports and processed CSV