# Research and Evidence Back to [[Topics/Climate Change Science and Policy Debate/Climate Change Science and Policy Debate|Climate Change Science and Policy Debate]] The evidence behind the verdicts, grouped by the sub-debates this hub covers. Numbers are from the sources linked; anything from memory is marked ⚠️. ## 1. Emission scenarios: RCP8.5, SSP5-8.5 and CMIP7 - **Origin.** RCP8.5 was built by IIASA ([[Topics/Climate Change Science and Policy Debate/People/Keywan Riahi|Keywan Riahi]] et al. 2011, *Climatic Change* 109:33, [doi](https://doi.org/10.1007/s10584-011-0149-y)). It was one of four RCPs chosen for CMIP5 ([[Topics/Climate Change Science and Policy Debate/People/Detlef van Vuuren|Detlef van Vuuren]] et al. 2011, [doi](https://doi.org/10.1007/s10584-011-0148-z)). It is not a "UN prediction"; it was a high-end scenario. - **AR6.** Very-likely warming by 2081–2100 under SSP5-8.5 is **4.4°C (3.3–5.7°C)**. AR6 states that high-emission scenarios like SSP5-8.5 have low likelihood given recent trends ⚠️ (paraphrase) ([AR6 WG1 SPM](https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf)). - **Plausibility critique.** [[Topics/Climate Change Science and Policy Debate/People/Zeke Hausfather|Zeke Hausfather]] & [[Topics/Climate Change Science and Policy Debate/People/Glen Peters|Glen Peters]] 2020, "Emissions – the 'business as usual' story is misleading" ([Nature](https://doi.org/10.1038/d41586-020-00177-3)). [[Topics/Climate Change Science and Policy Debate/People/Roger Pielke Jr|Roger Pielke Jr]] & Ritchie 2021 ([ERSS](https://doi.org/10.1016/j.erss.2020.101890)) on misuse of RCP8.5 as a baseline. - **CMIP7 ScenarioMIP** (van Vuuren et al. 2026, [GMD](https://doi.org/10.5194/gmd-19-2627-2026)) drops the SSP5-8.5 emissions level. Its new **High** scenario reaches about **3.3–3.5°C by 2100** and is still rising. - **IPCC-65 (Addis Ababa).** Chair [[Topics/Climate Change Science and Policy Debate/People/Jim Skea|Jim Skea]] suspended the session on **Oct 16, 2026** without agreement on AR7 Working Group timelines and budget ([IPCC](https://www.ipcc.ch/2026/10/16/65th-plenary-session-of-ipcc/)). This was unrelated to scenario plausibility. ## 2. Deep time: "Earth is historically cold" - **Judd et al. 2024** ([Science](https://doi.org/10.1126/science.adk3705); [[Topics/Climate Change Science and Policy Debate/People/Emily Judd|Emily Judd]], [[Topics/Climate Change Science and Policy Debate/People/Jessica Tierney|Jessica Tierney]]). GMST ranged from ~11 to ~36°C over 485 Myr. CO₂ is "the dominant control", with apparent ESS ~8°C per doubling. - **Antarctic glaciation** (~34 Ma) followed a CO₂ decline below a threshold (DeConto & Pollard 2003, [Nature](https://doi.org/10.1038/nature01290)). - **Eemian** (~125 ka): global temperature roughly comparable to today or slightly warmer, with sea level ~5–10 m higher (AR6 WG1 Ch. 9) ⚠️ (range from memory). It shows how large the effects of modest warming are on long timescales. - **Key point.** Life thrived in hot climates. Today's infrastructure, coastlines and agriculture, however, are adapted to the Holocene, and the rate of current change is extremely fast by geological standards. ## 3. CO₂ physics: "trace gas" and "logarithmic" - CO₂ is ~0.042% of the atmosphere (~425 ppm, [NOAA GML](https://gml.noaa.gov/ccgg/trends/)). Trace amount is not the same as trace effect: N₂, O₂ and Ar are nearly transparent to infrared. - **Forcing** ΔF = 5.35 ln(C/C₀) W/m² ([[Topics/Climate Change Science and Policy Debate/People/Gunnar Myhre|Gunnar Myhre]] et al. 1998, [GRL](https://doi.org/10.1029/98GL01908)). Equal *ratios* give equal forcing, so 380→480 ppm gives ~77% of the forcing of 280→380, not half. - **Control knob.** Lacis et al. 2010 ([Science](https://doi.org/10.1126/science.1190653)) and Schmidt et al. 2010 ([JGR](https://doi.org/10.1029/2010JD014287)) show water vapour and clouds are feedbacks that follow non-condensing gases, CO₂ chief among them. - **Oceans.** SROCC 2019 ([IPCC](https://www.ipcc.ch/srocc/)) and AR6 Ch. 9 ([IPCC](https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-9/)) are full assessments of the ocean. Ocean net primary production is ~48.5 of ~105 PgC/yr (Field et al. 1998, [Science](https://doi.org/10.1126/science.281.5374.237)). NOAA says ocean phytoplankton produce "at least half" of Earth's oxygen ([NOAA](https://oceanservice.noaa.gov/facts/ocean-oxygen.html)). ## 4. Ice cores: does CO₂ lag temperature? - [[Topics/Climate Change Science and Policy Debate/People/Nicolas Caillon|Nicolas Caillon]] et al. 2003 ([Science](https://doi.org/10.1126/science.1078758)): CO₂ lagged Antarctic temperature by 800 ± 200 years at Termination III, and the authors still called CO₂ an amplifier. - [[Topics/Climate Change Science and Policy Debate/People/Joel Pedro|Joel Pedro]] et al. 2012 ([CP](https://doi.org/10.5194/cp-8-1213-2012)): smaller lag ⚠️. - [[Topics/Climate Change Science and Policy Debate/People/Frédéric Parrenin|Frédéric Parrenin]] et al. 2013 ([Science](https://doi.org/10.1126/science.1226368)): synchronous within about ±200 years. - [[Topics/Climate Change Science and Policy Debate/People/Jeremy Shakun|Jeremy Shakun]] et al. 2012 ([Nature](https://doi.org/10.1038/nature10915)): **global** temperature lagged CO₂. Orbital forcing starts deglaciation, and CO₂ feedback drives most of the global warming. ## 5. Greening and food - [[Topics/Climate Change Science and Policy Debate/People/Zaichun Zhu|Zaichun Zhu]] et al. 2016 ([NCC](https://doi.org/10.1038/nclimate3004)): greening on 25–50% of vegetated land; ~70% attributed to CO₂ fertilisation. - [[Topics/Climate Change Science and Policy Debate/People/Chi Chen|Chi Chen]] et al. 2019 ([Nat Sustain](https://doi.org/10.1038/s41893-019-0220-7), with [[Topics/Climate Change Science and Policy Debate/People/Ranga Myneni|Ranga Myneni]]): China and India lead the greening through land management. - Global cereal production rose ~257% and yield ~211% since 1961, mostly from technology and inputs ([OWID](https://ourworldindata.org/grapher/index-of-cereal-production-yield-and-land-use)). ## 6. Energy and policy - **Wind ageing.** [[Topics/Climate Change Science and Policy Debate/People/Iain Staffell|Iain Staffell]] & Green 2014 ([Renewable Energy](https://doi.org/10.1016/j.renene.2013.10.041)) found ~1.6%/yr decline, against the REF/[[Topics/Climate Change Science and Policy Debate/People/Gordon Hughes|Gordon Hughes]] 2012 claim of collapse after 10–15 years. - **Solar supply chain.** China has >80% of every manufacturing stage of solar PV ([IEA](https://www.iea.org/reports/solar-pv-global-supply-chains/executive-summary)). - **Emissions share.** China accounts for ~32% of global fossil CO₂ ([Global Carbon Budget](https://globalcarbonbudget.org/)). - **Net-zero cost.** McKinsey (Jan 2022) estimated $275T of cumulative 2021–2050 spending on physical assets, about $9.2T/yr ([McKinsey](https://www.mckinsey.com/capabilities/sustainability/our-insights/the-net-zero-transition-what-it-would-cost-what-it-could-bring)). That is total spending, not added cost. - **Oil recovery.** The typical recovery factor is ~35%; EOR can raise it ([IEA](https://www.iea.org/articles/whatever-happened-to-enhanced-oil-recovery)). BP 2021 proved reserves: oil 1,732 bn bbl (R/P 53.5), gas 188 tcm (R/P 48.8), coal 1,074 bn t (R/P 139) ([BP](https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2021-full-report.pdf)). - **Hambach.** The NRW Leitentscheidung 2023 caps remaining extraction at ~110 Mt, with mining to end in 2030 ([NRW](https://www.wirtschaft.nrw/system/files/media/document/file/leitentscheidung-2023.pdf)). ## 7. Deep-time CO₂ and biodiversity: "high-carbon epochs fostered the richest expansions" Added for the [[Users/@PeterDClack/Post Analyses/Post Analysis - PeterDClack on High-CO2 Epochs and Biodiversity (2026-10-23)|Oct 23 high-CO₂ epochs analysis]]. - **Which CO₂ curve?** GEOCARB III ([[Topics/Climate Change Science and Policy Debate/People/Robert Berner|Berner]] & Kothavala 2001, [AJS](https://doi.org/10.2475/ajs.301.2.182)) is a 10-Myr-step carbon-cycle model. It gives Cambrian CO₂ ~25× pre-industrial and the Late Ordovician ~17× (RCO₂, [NOAA data](https://www.ncei.noaa.gov/pub/data/paleo/climate_forcing/trace_gases/phanerozoic_co2.txt)). PhanDA's data-assimilated CO₂ ([CSV](https://github.com/EJJudd/PhanDA/blob/main/5_Outputs/PhanDA_GMSTandCO2_percentiles.csv)) peaks at ~3,330 ppm in the Early Ordovician (~8× today's 426 ppm). Its Late Paleozoic values are 326–789 ppm. - **Ordovician "paradox".** Glaciation under very high CO₂ was modelled in the 1990s (Poussart et al. 1999, [Paleoceanography](https://doi.org/10.1029/1999pa900021)). Proxies since then lower glacial CO₂: Vandenbroucke et al. 2010 ([PNAS](https://doi.org/10.1073/pnas.1003220107)) infer ~8× → ~5× pre-industrial, and [[Topics/Climate Change Science and Policy Debate/People/Gregory Retallack|Retallack]] 2015 ([J. Geol.](https://doi.org/10.1086/683663)) reports paleosol estimates as low as ~166 ± 83 ppmv in the Hirnantian. PhanDA's Hirnantian median is 624 ppm. - **Faint young Sun.** Solar output has risen over time, adding ~+9 W/m² of forcing over 420 Myr. Falling CO₂ roughly offset it, so the same CO₂ is "worth" more warming today ([[Topics/Climate Change Science and Policy Debate/People/Gavin Foster|Foster]], Royer & Lunt 2017, [Nat. Commun.](https://doi.org/10.1038/ncomms14845)). - **Biodiversity.** - Warm greenhouse phases had lower standing diversity and higher extinction and origination ([[Topics/Climate Change Science and Policy Debate/People/Peter Mayhew|Mayhew]], Jenkins & Benton 2008, [Proc. R. Soc. B](https://doi.org/10.1098/rspb.2007.1302)). - The Ordovician radiation coincided with tropical seas cooling to ~23°C ([[Topics/Climate Change Science and Policy Debate/People/Julie Trotter|Trotter]] et al. 2008, [Science](https://doi.org/10.1126/science.1155814)). - Mass extinctions match warming of more than ~5.2°C or faster than ~10°C per Myr ([[Topics/Climate Change Science and Policy Debate/People/Haijun Song|Song]] et al. 2021, [Nat. Commun.](https://doi.org/10.1038/s41467-021-25019-2)). - The end-Permian extinction was triggered by Siberian Traps intrusions releasing carbon (Burgess, Muirhead & Bowring 2017, [Nat. Commun.](https://doi.org/10.1038/s41467-017-00083-9)). - **Low-CO₂ stress on plants.** At glacial ~180–190 ppm, C3 photosynthesis was ~40–60% lower and biomass ~50% lower than modern (Gerhart & Ward 2010, [New Phytol.](https://doi.org/10.1111/j.1469-8137.2010.03441.x)). There is no single "150 ppm" cut-off. - **Sea level.** The satellite-era rate doubled, from ~2.1 mm/yr (1993) to ~4.5 mm/yr (2023) (Hamlington et al. 2024, [Commun. Earth Environ.](https://doi.org/10.1038/s43247-024-01761-5)). - **The Eschenbach chart.** [[Topics/Climate Change Science and Policy Debate/People/Willis Eschenbach|Willis Eschenbach]]'s chart plots GEOCARB III CO₂ against PhanDA temperature. Using PhanDA's own CO₂ would show the correlation (r = 0.72) that Judd et al. report. ## 8. Carbon-isotope attribution: the Keeling intercept Prompted by [@cohler's Oct 24, 2026 post](https://x.com/cohler/status/2114198804849103346) ([[Users/@cohler/Post Analyses/Post Analysis - cohler on the Keeling Intercept and Fossil CO2 (2026-10-24)|analysis]]), which claims a −13.2‰ Keeling intercept proves fossil carbon contributes "≈ZERO" to the CO₂ rise. - **The −13.2‰ number is real.** [[Topics/Climate Change Science and Policy Debate/People/Demetris Koutsoyiannis|Demetris Koutsoyiannis]] 2024 ([Sci 6:17](https://doi.org/10.3390/sci6010017)) fitted Keeling plots to four Scripps stations and got about −13‰. [[Topics/Climate Change Science and Policy Debate/People/Peter Köhler|Peter Köhler]] et al. 2006 ([Biogeosciences 3:539](https://doi.org/10.5194/bg-3-539-2006)) got a similar intercept from the Law Dome ice core. - **It is not the source signature.** Köhler 2006 states: "the intercept found in the anthropogenic rise in Law Dome does not record the δ13C signal of the carbon released by anthropogenic activity". Its model, forced only by human emissions, reproduces intercepts of −9.2 to −15.7‰ "Due to the non-negligible effect of a third reservoir, the ocean". - **Why.** The air swaps about 200 GtC a year with ocean and land. That gross exchange pulls atmospheric δ13C back toward the ocean and land values (the disequilibrium flux) without changing the net CO₂ amount. [[Topics/Climate Change Science and Policy Debate/People/Heather Graven|Heather Graven]] et al. 2020 ([GBC](https://doi.org/10.1029/2019GB006170); [PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC7757245/)) review this and record δ13C falling from about −6.6‰ (1850) to −8.4‰ (2015). - **Ocean record.** [[Topics/Climate Change Science and Policy Debate/People/Florian Böhm|Florian Böhm]] et al. 2002 ([G-cubed](https://doi.org/10.1029/2001GC000264)) show the industrial ¹³C decline in Caribbean sclerosponges. Their comparison curve uses ice-core and firn data, so it is not independent of Law Dome. - **Mass balance.** Global Carbon Budget 2025 ([ESSD 18:3211](https://doi.org/10.5194/essd-18-3211-2026)): fossil 10.4 GtC plus land-use change ~1.1 GtC; ocean sink 3.2, land sink 3.1; atmospheric growth 4.4 GtC (2.1 ppm), to about 425.6 ppm. The air gains less than humans emit, so nature is a net sink. Köhler 2006: "Without carbon uptake by the ocean and the terrestrial reservoirs this would have led to a rise in atmospheric CO2 by more than 200 ppmv." - **Ocean uptake.** [[Topics/Climate Change Science and Policy Debate/People/Nicolas Gruber|Nicolas Gruber]] et al. 2019 ([Science](https://doi.org/10.1126/science.aau5153)): 34 ± 4 PgC of anthropogenic carbon taken up by the ocean in 1994–2007, about 31% of emissions. - **Residence time.** The short-residence-time argument of [[Topics/Climate Change Science and Policy Debate/People/Hermann Harde|Hermann Harde]] confuses turnover with adjustment time; Köhler et al. 2018 ([GPC 164:67](https://doi.org/10.1016/j.gloplacha.2017.09.015)) call his model "too simple, based on invalid assumptions". - **Other fingerprints.** Atmospheric O₂ is falling about 19 per meg a year ([Scripps O₂](https://scrippso2.ucsd.edu/faq.html)), as expected from combustion; ¹⁴C is diluted by fossil carbon (Suess effect). The Keeling plot itself is named after [[Topics/Climate Change Science and Policy Debate/People/Charles David Keeling|Charles David Keeling]]. ## Sources | Source | Type | Used for | |---|---|---| | [Judd et al. 2024, *Science*](https://doi.org/10.1126/science.adk3705) | Peer-reviewed | 485-Myr GMST; CO₂ as dominant control | | [van Vuuren et al. 2026, *GMD*](https://doi.org/10.5194/gmd-19-2627-2026) | Peer-reviewed | CMIP7 scenarios; SSP5-8.5 retired | | [Hausfather & Peters 2020, *Nature*](https://doi.org/10.1038/d41586-020-00177-3) | Comment | RCP8.5 plausibility | | [Pielke & Ritchie 2021, *ERSS*](https://doi.org/10.1016/j.erss.2020.101890) | Peer-reviewed | Scenario misuse | | [Riahi et al. 2011](https://doi.org/10.1007/s10584-011-0149-y) · [van Vuuren et al. 2011](https://doi.org/10.1007/s10584-011-0148-z) | Peer-reviewed | RCP origins | | [IPCC AR6 WG1 SPM](https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf) | Assessment | Warming to date; SSP projections | | [IPCC AR6 WG1 Ch. 9](https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-9/) · [SROCC](https://www.ipcc.ch/srocc/) | Assessment | Oceans, sea level | | [IPCC-65 release, Oct 16, 2026](https://www.ipcc.ch/2026/10/16/65th-plenary-session-of-ipcc/) | Official | Session suspension | | [DeConto & Pollard 2003, *Nature*](https://doi.org/10.1038/nature01290) | Peer-reviewed | CO₂ threshold for Antarctic glaciation | | [Myhre et al. 1998, *GRL*](https://doi.org/10.1029/98GL01908) | Peer-reviewed | CO₂ forcing formula | | [Lacis et al. 2010, *Science*](https://doi.org/10.1126/science.1190653) · [Schmidt et al. 2010, *JGR*](https://doi.org/10.1029/2010JD014287) | Peer-reviewed | CO₂ as control knob; water vapour as feedback | | [Field et al. 1998, *Science*](https://doi.org/10.1126/science.281.5374.237) · [NOAA ocean oxygen](https://oceanservice.noaa.gov/facts/ocean-oxygen.html) | Peer-reviewed / Official | Ocean productivity | | [NOAA GML CO₂ trends](https://gml.noaa.gov/ccgg/trends/) | Data | Current CO₂ | | [Caillon 2003](https://doi.org/10.1126/science.1078758) · [Pedro 2012](https://doi.org/10.5194/cp-8-1213-2012) · [Parrenin 2013](https://doi.org/10.1126/science.1226368) · [Shakun 2012](https://doi.org/10.1038/nature10915) | Peer-reviewed | CO₂–temperature lead/lag | | [Zhu 2016](https://doi.org/10.1038/nclimate3004) · [Chen 2019](https://doi.org/10.1038/s41893-019-0220-7) | Peer-reviewed | Greening | | [OWID cereal index](https://ourworldindata.org/grapher/index-of-cereal-production-yield-and-land-use) | Data | Crop yields | | [Staffell & Green 2014](https://doi.org/10.1016/j.renene.2013.10.041) | Peer-reviewed | Wind-farm ageing | | [IEA PV supply chains](https://www.iea.org/reports/solar-pv-global-supply-chains/executive-summary) · [IEA EOR](https://www.iea.org/articles/whatever-happened-to-enhanced-oil-recovery) | Agency | China PV share; recovery factor | | [Global Carbon Budget](https://globalcarbonbudget.org/) | Data | National emissions shares | | [McKinsey 2022](https://www.mckinsey.com/capabilities/sustainability/our-insights/the-net-zero-transition-what-it-would-cost-what-it-could-bring) | Consultancy | $275T net-zero spending | | [BP Statistical Review 2021](https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp-stats-review-2021-full-report.pdf) | Industry data | Reserves and R/P ratios | | [NRW Leitentscheidung 2023](https://www.wirtschaft.nrw/system/files/media/document/file/leitentscheidung-2023.pdf) | Government | Hambach cap of 110 Mt | | [ISD/CAAD, *Deny, Deceive, Delay Vol. 2* (2023)](https://www.isdglobal.org/wp-content/uploads/2023/01/Deny-Deceive-Delay-Vol.-2.pdf) | NGO report | Clack named as a climate-denial account | | [La Nación, Jan 27, 2025](https://www.lanacion.com.ar/sociedad/crece-la-polemica-el-periodista-que-retuiteo-milei-para-negar-el-cambio-climatico-ya-estaba-en-la-nid27012025/) | News | Milei repost; Díaz and Vera critiques | | [Berner & Kothavala 2001, *AJS*](https://doi.org/10.2475/ajs.301.2.182) | Peer-reviewed model | GEOCARB III Phanerozoic CO₂ (source of the Eschenbach chart's bars) | | [PhanDA output CSV (Judd et al.)](https://github.com/EJJudd/PhanDA/blob/main/5_Outputs/PhanDA_GMSTandCO2_percentiles.csv) | Dataset | PhanDA CO₂ and GMST by stage | | [Foster, Royer & Lunt 2017, *Nat. Commun.*](https://doi.org/10.1038/ncomms14845) | Peer-reviewed | 420-Myr CO₂; solar brightening offset | | [Poussart et al. 1999, *Paleoceanography*](https://doi.org/10.1029/1999pa900021) | Peer-reviewed | Older modelling of Ordovician glaciation under high CO₂ | | [Vandenbroucke et al. 2010, *PNAS*](https://doi.org/10.1073/pnas.1003220107) | Peer-reviewed | Hirnantian CO₂ ~5× pre-industrial | | [Retallack 2015, *J. Geol.*](https://doi.org/10.1086/683663) | Peer-reviewed | Hirnantian paleosol CO₂ | | [Mayhew, Jenkins & Benton 2008, *Proc. R. Soc. B*](https://doi.org/10.1098/rspb.2007.1302) | Peer-reviewed | Temperature vs. biodiversity over 520 Myr | | [Trotter et al. 2008, *Science*](https://doi.org/10.1126/science.1155814) | Peer-reviewed | Ordovician cooling and biodiversification | | [Song et al. 2021, *Nat. Commun.*](https://doi.org/10.1038/s41467-021-25019-2) | Peer-reviewed | Temperature thresholds for mass extinctions | | [Burgess, Muirhead & Bowring 2017, *Nat. Commun.*](https://doi.org/10.1038/s41467-017-00083-9) | Peer-reviewed | Siberian Traps trigger of the end-Permian extinction | | [Gerhart & Ward 2010, *New Phytol.*](https://doi.org/10.1111/j.1469-8137.2010.03441.x) | Peer-reviewed review | Plant responses to low (glacial) CO₂ | | [Hamlington et al. 2024, *Commun. Earth Environ.*](https://doi.org/10.1038/s43247-024-01761-5) | Peer-reviewed | Sea-level-rise rate doubling 1993–2023 | | [Köhler et al. 2006, *Biogeosciences*](https://doi.org/10.5194/bg-3-539-2006) | Peer-reviewed | Law Dome Keeling plot; intercept is not the anthropogenic signature | | [Graven et al. 2020, *Global Biogeochem. Cycles*](https://doi.org/10.1029/2019GB006170) | Peer-reviewed review | δ13C Suess effect; disequilibrium fluxes | | [Böhm et al. 2002, *G-cubed*](https://doi.org/10.1029/2001GC000264) | Peer-reviewed | Sclerosponge δ13C record | | [Koutsoyiannis 2024, *Sci* 6:17](https://doi.org/10.3390/sci6010017) | Peer-reviewed (contrarian) | Source of the −13.2‰ intercepts | | [Global Carbon Budget 2025, *ESSD*](https://doi.org/10.5194/essd-18-3211-2026) | Peer-reviewed data | 2025 carbon budget; net natural sink | | [Gruber et al. 2019, *Science*](https://doi.org/10.1126/science.aau5153) | Peer-reviewed | Ocean anthropogenic carbon sink 1994–2007 | | [Köhler et al. 2018, *Global Planet. Change*](https://doi.org/10.1016/j.gloplacha.2017.09.015) | Peer-reviewed comment | Rebuttal of Harde's residence-time model | | [Scripps O₂ program FAQ](https://scrippso2.ucsd.edu/faq.html) | Data program | O₂ decline (~19 per meg/yr) |