Guy Callendar, the engineer who discovered human-caused global warming
Early work on the greenhouse effect and anthropogenic warming—from Fourier and Arrhenius to Guy Callendar’s 1938 paper—is revisited alongside modern measurements showing a rapid, human‑driven rise in atmospheric CO₂ from ~280 ppm pre‑industrial to over 420 ppm today. Commenters contrast long-known physical mechanisms (radiative properties of CO₂, isotopic “fingerprints” of fossil carbon, ocean uptake limits) with enduring public skepticism, noting how confusion between weather and climate and politicized messaging obscure the strength of the evidence. The exchange also touches on past natural climate swings, the unusually fast rate of current change, and concerns about how societies respond when scientific warnings collide with economic and ideological interests.
Title, attribution, and history of the idea
- Several comments argue the article over-credits Callendar as “discoverer” of anthropogenic warming.
- Earlier work cited: 19th- and early-20th-century scientific papers and popular articles linking CO₂ and climate, plus 19th‑century theory of the greenhouse effect.
- Thread consensus: Callendar’s contribution was more about providing convincing quantitative evidence than originating the concept.
Evidence that recent CO₂ rise is human-caused
- CO₂ increased from ~280 ppm (preindustrial) to ~315 ppm (1958) to ~421 ppm today; about a 50% rise.
- One commenter computes that ~8.8 gigatons of CO₂ raise atmospheric concentration by 1 ppm; observed rises match human emissions, implying anthropogenic origin.
- Isotopic evidence (C‑12/C‑13/C‑14 ratios) is cited as matching fossil fuels, not volcanism or other natural sources.
- Note that much emitted carbon is absorbed by oceans and other sinks; only about half remains in the air.
Rates and magnitudes of change
- Strong emphasis that current rate of CO₂ increase is extremely high compared with past natural changes; graphs described as “vertical” over the last century.
- A dissenting voice claims Earth has warmed and cooled as fast or faster in the past but provides no concrete citation; others challenge this.
Impacts and thresholds
- Discussion of possible cognitive impairment around ~800 ppm CO₂, with indoor urban spaces suggested to already approach such levels.
- Mention that Jurassic CO₂ was much higher (~2100 ppm) and that at ~1200 ppm some cloud regimes may break down; commenters stress differences in timescale.
- Several note that even if final temperatures match past eras, compressing the change into centuries instead of millennia is likely disruptive.
Climate vs. weather and modeling
- Multiple comments push back on “we can’t predict weather, so we can’t predict climate” by distinguishing short‑term chaos from long‑term averages.
- Analogies used: casino odds vs. individual cards, seasons vs. daily weather, center-of-mass trajectory vs. tumbling motion.
- Claim that current models are, if anything, underpredicting observed warming and extremes.
Natural variability and past events
- CO₂ over the last 800k years fluctuated roughly 160–300 ppm; interglacials and glacial cycles discussed.
- Little Ice Age and other abrupt climate events are debated; proposed drivers include solar output, volcanism, land-use change, and disease‑driven depopulation, with timing and causality marked as uncertain.
- Role of silicate weathering as a very long‑term negative feedback (~10k years scale) is mentioned.
Politics, communication, and denial
- Comments argue that fossil-fuel interests funded disinformation campaigns after internal acceptance of the science.
- Some frame the public “debate” as primarily about cost allocation and lifestyle change, not about physical science.
- One skeptical thread accuses climate politics of alarmism and quasi-religious moralism; others respond that observed changes and basic physics are sufficient without ideological framing.
- Broad agreement that outright denial of human influence is concentrated among a vocal minority, often conflating natural variability with current trends.
Observed local changes
- Anecdotes: historically frozen lakes and heavy snow in the U.S. Northeast and Mid‑Atlantic vs. much milder recent winters.
- Mention of a recent deadly West African heatwave as an example of events expected to become more frequent, with implications for climate migration.