Ep 236 | Zeke Hausfather
Climate Uncertainty: The Coolest Year for the Rest of Our Lives?
Description
The El Niño now building in the tropical Pacific is unlike anything in the historical record, and it’s arriving on top of decades of warming. Together, they could push global temperatures to roughly 1.8°C (3.2ºF) above pre-industrial levels next year, offering a preview of what may become the new normal within a decade. As the rate of warming continues to accelerate and public attention swings between alarm and fatigue, how can we clearly understand where the planet is actually headed and what it will take to adapt?
In this episode, Nate is joined by climate scientist Zeke Hausfather to break down the numbers and metrics within climate science, and translate what they will actually feel like for humanity. He explains how global temperature is measured, what the new generation of IPCC scenarios reveals about plausible futures, and why there’s still uncertainty in just how much warmer we’ll get by the year 2100. Zeke also unpacks how declining aerosol pollution has sped up warming and other climate variables that have actively emerging research behind them. While certain amounts of warming are locked in, he emphasizes that there is still a wide difference between every degree of warming, and the actions we take now will determine climate futures for centuries to come.
How does the IPCC attempt to incorporate the most unpredictable factor for climate models – human behavior – and what do their current projections estimate? If we reached zero emissions tomorrow, would the planet cool back down, or are we locked into the warming we already have? And in a world growing weary of crisis headlines, how can we hold the reality of climate change without tipping into denial or despair?
About Zeke Hausfather
Zeke is a lead author of the IPCC Seventh Assessment Report, and was a contributing author to the Sixth Assessment Report. He also authored the climate trends chapter of the Fifth U.S. National Climate Assessment, and has testified as an expert witness before the U.S. House Committee on Science, Space, and Technology. At Berkeley Earth, Zeke helps produce one of the world’s primary global surface temperature records. He is also a Climate Science Contributor at Carbon Brief. At Stripe, Zeke leads climate research for Frontier, a $2 billion advance market commitment accelerating permanent carbon removal.
Show Notes & Links to Learn More
Download transcriptGuest:
Grab-and-Go Resources:
New? Start here:
From the Archive:
- Ep 105: Leon Simons, Aerosol Demasking & Global Heating
- Ep 219: Tad Patzek, Why Each American Lives Like a 40-Ton Whale
- Ep 134: Johan Rockström, Planetary Boundaries
Episode Foundations:
- The Climate Brink Dashboard by Zeke
- CMIP7 scenarios for the Seventh Assessment Report (ScenarioMIP)
- Recent strengthening of eastern Pacific ENSO in the last millennium paleorecord
- The real energy use of agentic AI
Next Steps:
- NOAA Climate Prediction Center ENSO diagnostic discussion
- Rewiring America home electrification planner
- Citizens’ Climate Lobby
Resources by Timestamp:
02:35 – Efficiency 2.0, PhD in energy and resources
02:47 – Berkeley Earth, Stripe Climate, Frontier, The Climate Brink, Carbon Brief
03:06 – Lead author, chapter two of the IPCC Seventh Assessment Report
03:39 – Research-to-deployment gap in climate solutions
04:21 – Human macroecology as a lens on the climate predicament
04:50 – Persistence of behavior change from home energy reports
05:10 – Set-and-forget efficiency: LED bulbs, Efficient appliances, Electric vehicles
05:55 – Social norms and peer pressure as drivers of energy behavior
06:12 – Zeke’s Climate Dashboard, Global heating updates, histories, and projections
06:39 – Calculating global mean surface temperature, Sea surface temperature from ship bucket measurements, Evaporative cooling bias from deck height
07:26 – *No substantial Antarctic station network before the 1957-1958 International Geophysical Year, Kriging for spatial gaps
07:50 – Independent global surface temperature datasets, Berkeley Earth temperature record
08:21 – Wider spread between records in the 19th century from sparse sampling
08:37 – 1.44 C of warming in 2025 relative to 1850-1900
08:43 – Proposed multi-dataset temperature ensemble for IPCC AR7, 10,000-member global mean surface temperature ensemble, Peter Thorne
09:52 – Intergovernmental Panel on Climate Change (IPCC), Seventh Assessment Report
10:06 – Three IPCC working groups
10:29 – IPCC is policy-relevant but not policy-prescriptive
10:45 – AR6 Working Group I assessed more than 14,000 scientific papers
10:58 – Is global warming accelerating, Have we passed 1.5 C, Climate sensitivity, Plausible future warming pathways
12:04 – IPCC shifting toward adaptation as well as mitigation
12:28 – Working Group I: physical science basis, Working Group II: impacts and adaptation, Working Group III: mitigation
13:13 – Nate’s Frankly series on scenario planning for Earth social systems
13:30 – Representative Concentration Pathways (RCPs), Shared Socioeconomic Pathways (SSPs)
14:12 – Scenario choice as ~54% of the uncertainty in end-of-century warming
14:27 – Future coal demand, Solar and renewable cost declines, Carbon pricing
15:01 – IS92 scenarios (1992), SRES scenarios (2000)
15:24 – CMIP7 scenarios released for the Seventh Assessment Report
16:10 – Backcasting emission pathways from an end-of-century temperature target
16:53 – RCP8.5, RCP6.0, RCP4.5 and RCP2.6, Radiative forcing in 2100, in watts per square meter
17:27 – New scenario names: high, medium, low and very low
17:55 – Forcings versus feedbacks
18:41 – Emission scenarios extended to 2150
19:13 – Ocean acidification, Carbonate and bicarbonate partitioning
19:28 – CO2 fertilization of plant growth, Wildfire, drought and drier soils releasing carbon
19:55 – Carbon cycle feedbacks
20:09 – Climate models moving from prescribed concentrations to a dynamic carbon cycle
21:12 – Cloud feedback, Water vapor feedback, Snow and ice albedo feedback
21:25 – Equilibrium climate sensitivity assessed at 2.6 to 3.9 C (66% range)
21:34 – Very likely range of 2 to 5 C with a best estimate of 3 C
22:08 – Equilibrium climate sensitivity, Transient climate response, Earth system sensitivity
23:18 – Doubling CO2 from a pre-industrial 280 ppm to 560 ppm
24:29 – Ice sheet loss exposing darker surfaces over millennia
24:53 – Oceans storing an estimated 91% of the excess heat trapped in the climate system
25:05 – Zero emissions commitment: a 50-year multi-model mean of -0.07 C after emissions cease
25:30 – Carbon dioxide removal, Climate engineering
25:49 – Strong El Niño and the 2026-2027 temperature outlook
26:25 – Three to five month lag between El Niño peak and peak global temperature, 1997-1998, 2015-2016 and 2023-2024 El Niño analogues
27:30 – *2027 forecast around 1.71 C above pre-industrial, against a 1.5 C record
28:02 – Strong El Niño as a preview of average global temperatures a decade from now
28:19 – A very strong El Niño adding up to 0.2 C to the following year’s global temperature
28:27 – Human-induced warming rising 0.27 C per decade over 2016-2025
28:43 – SSP3 regional rivalry as the scenario that feels close to home
28:57 – SSP1 sustainability, SSP2 middle of the road, SSP4 inequality, SSP5 fossil-fueled development
29:31 – Resurgent nationalism, weakened cooperation and regional conflict, Adaptive capacity
30:11 – Persistent poverty in sub-Saharan Africa limiting adaptation
30:33 – *CMIP7 high scenario reaching 55 gigatons of CO2 a year in 2100
30:57 – Global fossil CO2 emissions up 31% from 2001 to 2010, 25 to 33 gigatons
31:21 – RCP8.5 and SSP5-8.5 as implausible high-emission baselines
32:00 – Embodied energy in wind and solar infrastructure, Rebuildables
32:16 – *Global solar generation up from 256 TWh in 2015 to 2,778 TWh in 2025, Fossil fuel consumption over the long run
32:56 – Global coal demand at a record 8.85 billion tonnes in 2025, plateauing to 2030
33:25 – Close to 30% of cars sold globally in 2026 set to be electric
33:37 – Middle East conflict raising oil prices
33:51 – Wind and solar out-generating gas worldwide for the first time in April 2026
34:11 – Fossil CO2 emissions up 1.0% in 2025, China’s CO2 emissions on a plateau for more than two years since a March 2024 peak
34:31 – U.S. energy-related CO2 emissions down about 18% from 2005 to 2025, UK emissions down 2.4% in 2025 as coal hit a 400-year low, UK phase-out of coal power
34:49 – Around 2.6 C of warming by 2100 under current policies
35:05 – Global mean atmospheric CO2 at 427.6 ppm in June 2026, Atmospheric CO2 rising linearly while emissions stay flat
35:45 – Land and ocean sinks absorbing about half of emitted CO2 each year
37:03 – Water’s heat capacity and ocean thermal inertia
37:15 – Land warmed 2.03 C versus 1.03 C for the ocean surface in 2025, Sparse observations suggest the ocean below 2,000 metres warmed roughly 0.01 C over two decades
37:31 – Heat transport from the ocean surface to the deep ocean
38:45 – Super El Niño events since 1877, El Niño events peaking between November and February
39:15 – El Niño as a warm pool in the tropical Pacific, Upwelling off the coast of Peru, Westerly wind bursts
39:35 – Niño 3.4 region
40:22 – *NOAA CPC reported a weekly Niño 3.4 anomaly of 2.0 C on 14 September 2026 and a 75% chance of a historic event, *Previous record ONI peaks of 2.6 C in 2015-16 and 2.4 C in 1997-98
40:54 – 1877-1878 El Niño famines with fatalities likely exceeding 50 million, Roughly tied with 2015-2016 as the strongest event on record
41:25 – El Niño rainfall redistribution across the tropical Pacific, Drought risk in Southern Africa, India, Indonesia and Australia
41:45 – 2027 and 2028 growing seasons at risk from the fertilizer crisis, Fertilizer shortfalls, Strait of Hormuz (Frankly on such)
42:34 – World Meteorological Organization’s largest mobilization in its history, Kenya distributing livestock vaccines ahead of heavy rain, Southern African food stocks and drought-tolerant seed
43:03 – USAID funding cuts projected to cause more than 14 million additional deaths by 2030, European aid cuts
43:39 – El Niño as internal climate variability
44:05 – El Niño response to warming in climate models
44:28 – Acceleration of global warming
44:38 – Aerosols hiding about 0.5 C of warming that greenhouse gases have already caused
45:24 – The Day After
46:11 – Public concern about climate as thermostatic, Climate as a political luxury good
47:07 – Leon Simons on aerosol de-masking and bunker fuels
47:36 – Direct aerosol effect: sulfate particles scattering sunlight, Cloud condensation nuclei and low-lying cloud formation
48:06 – *Aerosols cooling the planet 0.50 C, with a 0.22 to 0.96 C range
48:30 – High climate sensitivity correlates with high aerosol masking in models
48:55 – *Global sulfur dioxide emissions down 40% since the mid-2000s, CEDS global emissions data
49:08 – *China’s sulfur dioxide emissions down 75% since 2007, Flue-gas desulfurization scrubbers, Diesel sulfur standards
49:38 – IMO 2020 low-sulfur bunker fuel rule, About 80% cut in shipping sulfur dioxide emissions after 2020
49:57 – *Shipping accounted for 4 to 9% of global anthropogenic sulfur dioxide emissions in pre-IMO 2020 estimates, Ship tracks over clean marine air
50:20 – Warming rate near 0.3 C per decade over the past 15 years, up from 0.18 C
50:55 – *4.2 million premature deaths a year from ambient air pollution, 6.7 million including household
51:08 – Tad Patzek on Earth’s energy imbalance as ~20 times the human economy
51:44 – Earth’s energy imbalance
52:10 – CERES satellite measurement of Earth’s radiation budget
52:18 – Earth’s energy imbalance rising, and rising faster in recent years
52:40 – Low cloud feedback, High-sensitivity models lose more low cloud
53:23 – Separating aerosol reductions from temperature-mediated cloud feedback
53:53 – Methane responsible for around 30% of the temperature rise since the industrial revolution
54:31 – Methane’s short atmospheric lifetime and chemical sink, Hydroxyl radical oxidation of atmospheric methane
55:19 – Methane as a fast lever for cooling, Global warming potential and gas comparison
55:38 – Permafrost thaw and regional methane fluxes
55:58 – Wetland emissions behind much of the last decade’s atmospheric methane growth
56:12 – Methanogenesis in tropical wetlands as a temperature-mediated feedback
57:10 – Feeding climate data to large language models
57:27 – Machine learning applied to physics-based processes
58:01 – AI weather forecasting models
58:23 – AI for downscaling and parameterizing cloud formation
58:53 – Large language models answering climate science questions, Grok
59:47 – Fragmentation of the information ecosystem, Climate change as a Chinese hoax
1:00:11 – Walter Cronkite and the loss of shared trusted sources, AI as a consensus machine recentering scientific expertise
1:01:07 – Zeke’s analysis of AI energy use and environmental impact
1:01:48 – AI labs’ lack of transparency about model energy use
1:01:55 – Median Gemini text prompt at 0.24 Wh, OpenAI CEO Sam Altman’s estimate: an average ChatGPT query uses about 0.34 Wh, Google search at 0.0003 kWh in Google’s 2009 estimate
1:03:00 – A reasoning model drawing 29 Wh on a long prompt
1:03:31 – AI agents spawning sub-agents and running for hours
1:04:00 – Zeke Hausfather’s estimate: median Claude Code session at 0.6 kWh, ranging from 0.25 to 1.2 kWh
1:06:06 – Jevons paradox, LED rebound effect in lighting demand
1:06:47 – Rebound effects in compute as AI gets cheaper and more capable
1:07:53 – Planetary boundaries (The Great Simplification Ep highlighting such)
1:08:13 – Uncertainties behind current-policy warming estimates
1:09:16 – Current-policy warming with a median of 2.7 C by 2100, 2.3 to 3.0 C
1:09:37 – 42.4 gigatons of total anthropogenic CO2 emitted in 2024, Record 57.7 gigatons CO2-equivalent including methane and nitrous oxide
1:10:28 – Tail risk in climate planning
1:10:45 – Climate tipping points
1:10:50 – Land warmed 1.59 C against a 1.09 C global average in 2011-2020
1:11:00 – CMIP7 high scenario at 3.3 C by 2100, range 2.5 to 4.4 C
1:11:26 – Intergenerational ethics of long-horizon warming
1:12:40 – Land and ocean sinks after emissions reach zero
1:13:24 – Biosphere response uncertainty growing with temperature
1:13:37 – *Land-use CO2 emissions averaged 1.4 gigatons of carbon a year over 2015-2024, Reforestation as a net sink
1:14:10 – Fuelwood harvesting under energy scarcity, Illegal logging for fuel during the Greek financial crisis
1:14:44 – Ocean sink at 29% and land sink at 21% of total emissions over 2015-2024
1:15:08 – U.S. withdrawal from the IPCC, Cuts to climate.gov, Billion-Dollar Weather and Climate Disasters database, *End of forward processing for one 47-year passive-microwave sea ice dataset
1:15:42 – Ocean observing sensors saved by congressional action
1:15:52 – NOAA climate data aggregation and public presentation
1:16:13 – Copernicus Climate Change Service
1:16:34 – Earth observation satellite data gaps
1:17:40 – Chinese hoax framing of climate science
1:18:31 – Politicization of climate and biosphere science
1:19:00 – Alarm fatigue and repeated crisis headlines
1:19:24 – Stephen Schneider (referenced quote)
1:19:37 – Existential framing of climate risk, Parallels with the AI risk debate
1:19:53 – The world is awful, the world is much better, Climate as a normal problem, AI as normal technology
1:20:25 – Crisis-driven policymaking
1:21:16 – Political engagement, voting and contacting policymakers
1:22:00 – Early adoption of rooftop solar, electric vehicles and heat pumps, Learning curves driving down technology costs
1:22:57 – Climate anxiety in young people
1:23:23 – 91% chance that at least one year in 2026-2030 temporarily exceeds 1.5 C
1:23:31 – Climate doomism and apathy
1:24:52 – Growing political polarization worldwide
1:25:37 – Internalizing social costs into private costs, Carbon pricing
1:26:28 – Stripe’s carbon removal purchases, Frontier’s carbon removal portfolio
1:27:02 – Nan Ransohoff‘s estimate: roughly 90% of the solution from emissions reductions, with removal at 5 to 10 gigatons a year by 2050
1:27:19 – Enhanced rock weathering
1:27:26 – Volcanism and silicate weathering as the long-term climate thermostat, Basalt weathering, carbonate formation and the long-term carbon cycle
1:27:38 – Deccan Traps, Siberian Traps, Volcanism-driven mass extinctions (Nate and DJ’s book covering such)
1:28:20 – Rock dust spread on croplands, Soil acidity and crop yields
1:28:48 – River liming, Legacy of acid rain in freshwater systems, Carbon Run, Salmon fishery restoration as carbon capture
1:29:27 – Ocean alkalinity enhancement, Biomass carbon removal and storage, Direct air capture
1:30:09 – $2.3 trillion of global energy transition investment in 2025, ~$5.6 billion of grant funding for carbon removal since 2005
1:30:34 – Counterfactual emissions reductions from renewable investment
