Guy Callendar, the engineer who discovered human-caused global warming

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.