Atmospheric CO2 Rebuild Guide (First Principles)

This guide explains how atmospheric CO2 data is measured and reconstructed across time windows, where to obtain each source, and how to assemble a clear long-run chart for non-specialist visitors.

BP convention: in ice-core datasets, BP means years before 1950 CE.

Deep time: use Ma (million years ago) rather than BP for Cenozoic and older windows.

Main split: NOAA NCEI for 0-800 kyr; paleo-co2.org for 800 kyr and older.

Static Time-Window Guide (Log Years BP)

Orientation map. Horizontal position uses a logarithmic years-BP axis (older left, recent right), with a small right-edge extension for post-1950 CE observations.

Current year

1 billion

100 million

10M (10^7)

1M (10^6)

100,000

10,000

1,000

100

0 BP = 1950 CE

Direct atmospheric (NOAA GML): 1958 CE to current year

Law Dome ice-core (NOAA NCEI): 1 CE to 2006 CE (about 1,949 BP to modern)

Antarctic composite ice-core (NOAA NCEI): 803,718 BCE to 2001 CE

Vetted CenCO2PIP source window: about 66 million years ago to near-present

Archive extension (original published proxy estimates, mixed methods): about 540 to 66 million years ago

Proxy method: phytoplankton (listed in current CSV metadata)

Proxy method: boron

Proxy method: stomata

Proxy method: leaf gas exchange

Proxy method: liverworts

Proxy method: land plant d13C

Proxy method: palaeosols

Proxy method: nahcolite

How to read BP: BP means years before 1950 CE. So 0 BP = 1950 CE. Mauna Loa starts in 1958 CE, which is after the BP origin; that is why the blue direct bar sits just to the right of the BP line. The current year is shown in the top-right label.

Direct atmospheric source

Law Dome ice-core source

Antarctic composite ice-core source

Vetted Cenozoic synthesis

Archive extension

Proxy method: phytoplankton

Proxy method: boron

Proxy method: stomata

Proxy method: leaf gas exchange

Proxy method: liverworts

Proxy method: land plant d13C

Proxy method: palaeosols

Proxy method: nahcolite

Each row has one continuous segment, and colors are now one-to-one with row meaning (no duplicate ice-core color).

These rows describe source availability windows for data you can obtain, not just what is currently loaded in one local parsed file.

Proxy-method rows above reflect the method list present in the current proxy_type metadata string. This file does not yet carry row-level per-method tags, so these method rows show source-availability scope rather than method-isolated ranges.

Start Here (60-Second Decision Rule)

If you need modern atmospheric CO2, use NOAA GML direct observations.
If you need late Quaternary through 800 kyr BP, use NOAA ice-core records and the Antarctic composite.
If you need Cenozoic deep time (66 Ma to 800 kyr), use CenCO2PIP vetted product.
If you need older than 66 Ma, extend with CO2PIP archive data and keep that layer visually separate.

For non-expert visitors, the safest chart is a tiered hybrid: direct + ice-core + vetted product by default, with archive proxy data optional and clearly labeled as lower-standardized extension material.

First Principles: What These Data Types Mean

Direct instrumental (highest certainty): modern atmosphere sampled directly.
Ice-core trapped air (high but not perfect): ancient atmosphere measured from bubbles in ice; age models and smoothing still matter.
Proxy reconstruction (inferred): atmospheric CO2 estimated from geochemical or biological indicators (method-dependent uncertainty).
Vetted product: harmonized synthesis intended for direct comparative use.
Archive: study-level values with heterogeneous methods and metadata quality; excellent for extension, not ideal as the only front-facing layer.
Time-axis rule: BP for ice-core means before 1950 CE. Never treat publication year as sample year.

How The Releases Fit Together

CO2PIP Archive: broad source-data release of per-study spreadsheets (deep-time breadth, variable uniformity).
CenCO2PIP Product: vetted Cenozoic synthesis from consortium processing.
CenoCO2 code: companion modeling and figure-generation code on GitHub.
Paleo-co2.org: access portal for archive, vetted product, and related resources.
Rae et al. compilation: optional cross-check source; do not treat it as the default canonical local pipeline input unless you explicitly choose to integrate it.

Canonical Local Build Output (Single Source of Truth)

Every source should be converted into one harmonized table before plotting: ../../data/paleo_co2/co2_unified.csv.

key: source key from manifest
archive: source family label used for layer/tier controls
proxy_type: method family
filename: original file name
year_CE: normalized year axis (negative = BCE)
co2_ppm: CO2 value in ppm

Provenance file: ../../data/paleo_co2/manifest_downloads.csv.

Rebuild From Scratch (Only This Page Needed)

Prerequisites

Python 3 installed and available as python3.

Parser dependencies installed (minimum):

cd /Users/mintz/code/jim/trumps-tariffs.com
python3 -m venv .venv
source .venv/bin/activate
python3 -m pip install --upgrade pip
python3 -m pip install pandas openpyxl

Rebuild harmonized CSV from raw downloads

cd /Users/mintz/code/jim/trumps-tariffs.com
python3 frontend/jim_cornelius_site/scripts/parse_all_co2_to_csv.py

Validate parse output immediately

python3 - <<'PY'
import csv
from collections import Counter
from pathlib import Path
p = Path('frontend/jim_cornelius_site/data/paleo_co2/co2_unified.csv')
rows = list(csv.DictReader(p.open()))
print('rows', len(rows))
print('archives', dict(Counter(r['archive'] for r in rows)))
PY

Current expected shape for this repository (as of May 2026): row count around 9.3k, with archive families including Modern instrumental, Merged Antarctic ice-core CO2, Byrd ice core, and CenCO2PIP vetted product.

Serve and open chart page

cd /Users/mintz/code/jim/trumps-tariffs.com/frontend/jim_cornelius_site
python3 -m http.server 8000
# default: http://localhost:8000/pages/climate/co2_long_run_hybrid.html
# optional custom host if configured: http://jim-cornelius.localhost:8000/pages/climate/co2_long_run_hybrid.html

Chart Behavior Spec (For Non-Expert Visitors)

If you rebuild or replace the chart, keep these controls and defaults so the output is interpretable.

Layer toggles: Direct + ice-core, vetted proxy, archive proxy.
Default on load: direct + ice-core ON, vetted proxy ON, archive proxy OFF.
Proxy outlier cap: ON by default with a visible threshold control.
Scale controls: explicit log/linear y-axis switch.
View controls: single-panel plus split-panel mode (top: direct/ice-core, bottom: proxies).
Legend language: labels must expose evidence tier, not just data source names.

Quality Gates Before Publishing

No future-year artifacts in paleo/ice-core layers.
No unresolved cross-product duplicates in overlapping vetted/product families.
Archive extension is visibly distinct from vetted and direct evidence.
Axis text clearly explains BCE/CE and log/linear mode.
Default view is readable for non-specialists without touching controls.

Troubleshooting Fast Path

Chart says failed to fetch: you are likely using file protocol; run the local HTTP server and open localhost URL.
Dates look wrong (future paleo years or weird jumps): check BP conversion assumptions and whether publication-year columns leaked into sample-year mapping.
Chart looks sensational or noisy: ensure archive proxy layer is optional and proxy cap is enabled by default.
Too many overlapping traces: use split-panel mode and keep archive proxy off for default public view.