Climate Futures.
What 2050, 2100, and beyond actually look like.
A field manual for thinking about a warming world: what the IPCC scenarios mean, where the tipping points are, what adaptation buys, and what geoengineering can and cannot do. Sober, sourced, plural.
Vital signs · 2026 baseline
2024 was the first calendar year above 1.5 °C. The Paris Agreement target is on multi-decadal averages, so we have not technically blown the threshold — yet. We will, on current trajectories, before 2030.
RCPs & SSPs, decoded
The IPCC's AR6 (2021–22) uses two coupled axes: RCPs describe atmospheric forcing in W/m² (2.6, 4.5, 6.0, 7.0, 8.5); SSPs describe socioeconomic pathways (SSP1 sustainability, SSP2 middle, SSP3 fragmented, SSP4 inequality, SSP5 fossil-fuel growth). The five headline AR6 scenarios are SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5.
Where the system gets non-linear
Armstrong McKay et al. (Science, 2022) identified 16 climate tipping elements. Five are at risk of triggering at current 1.4 °C warming; nine more become probable by 2 °C.
| Element | Threshold (°C) | Timescale | Note |
|---|---|---|---|
| Greenland Ice Sheet | 0.8–3.0 | ~10,000 yr | ~7 m sea-level commitment |
| West Antarctic Ice Sheet | 1.0–3.0 | ~2,000 yr | ~3 m commitment; possibly already triggered |
| Boreal permafrost (abrupt) | 1.0–2.3 | ~50 yr | Methane & CO₂ release |
| Labrador Sea convection | 1.1–3.8 | ~10 yr | NW European cooling effect |
| Amazon rainforest dieback | 2.0–6.0 | ~100 yr | Tropical biome shift |
| AMOC collapse | 1.4–8.0 | ~50 yr | Disputed; recent papers suggest mid-century plausible |
| East Antarctic subglacial basins | 3.0+ | millennial | Largest reservoir, slowest |
What adaptation actually means
Adaptation is the unsexy half of climate work. It does not stop warming; it limits damage from the warming we get. Cooling centers, mangrove restoration, stilted housing, drought-resistant crops, sponge cities, parametric crop insurance, water-rights reform.
Five categories that matter most
- Heat: urban tree canopy, cool roofs, retrofitted ventilation. Heat killed ~61,000 in Europe in summer 2022.
- Coastal: managed retreat, living shorelines, pumped drainage (Jakarta, Lagos, Miami).
- Agriculture: drought-tolerant cultivars, irrigation efficiency, shifting growing zones poleward.
- Water: aquifer recharge, desalination, leak reduction (75% of Mexico City water is leaked).
- Health: vector surveillance, climate-proofing supply chains for medicine.
The mitigation portfolio
Project Drawdown's ranked list of solutions (ed. Paul Hawken, 2017, updated 2020) remains the most practical synthesis. Top ten by cumulative GtCO₂e averted to 2050, Plausible Scenario:
| # | Solution | GtCO₂e (cum.) | Sector |
|---|---|---|---|
| 1 | Reduced food waste | ~88 | Food |
| 2 | Health & education (esp. of girls) | ~85 | Cross-cutting |
| 3 | Plant-rich diets | ~65 | Food |
| 4 | Refrigerant management | ~57 | Industry |
| 5 | Tropical forest restoration | ~54 | Land |
| 6 | Onshore wind | ~47 | Electricity |
| 7 | Utility-scale solar | ~43 | Electricity |
| 8 | Improved clean cookstoves | ~31 | Buildings |
| 9 | Distributed solar | ~28 | Electricity |
| 10 | Silvopasture | ~26 | Land |
2024 cost-curve update: solar & wind have outperformed Drawdown's projections; food-waste programs have underperformed.
Negative emissions, honestly
Almost every IPCC 1.5 °C pathway assumes large-scale negative emissions in the second half of the century. Whether such capacity will exist depends on cost curves we have not yet demonstrated. scenario
Solar radiation modification
Stratospheric aerosol injection (SAI) — injecting sulfate aerosols at ~20 km — could cool the planet within months at low direct cost (~$10B/yr). Its consequences are contested: regional precipitation shifts, ozone effects, and the "termination shock" risk if it stops abruptly.
contested The SRM debate is now a serious one — David Keith (Harvard → Chicago), Daniele Visioni, and the SCoPEx affair (cancelled 2021) frame the science. The Degrees Initiative pushes Global South research participation. Critics: ETC Group, Holly Buck, Raymond Pierrehumbert.
Who to read
| Hans-Otto Pörtner | IPCC WG2 co-chair; impacts & adaptation |
| Friederike Otto | World Weather Attribution; rapid attribution science |
| Kate Marvel | NASA GISS; clear writer on uncertainty |
| Saleemul Huq (1952–2024) | Bangladesh adaptation lead; loss-and-damage advocate |
| Johan Rockström | Planetary boundaries; PIK Potsdam |
| Vaclav Smil | Energy materialism; reality-checks the transition |
| Hannah Ritchie | Our World in Data; data-led optimism |
| Naomi Klein | Political-economy critique; This Changes Everything |
— Amitav Ghosh, The Great Derangement, 2016
What 2050 looks like, by choice
forecast Current policy puts us between SSP2-4.5 and SSP3-7.0. Pledged-NDC implementation ~2.4 °C. Action gap is real and shrinking.
Recommended source
Kurzgesagt · "Could We Stop An Asteroid? · Climate edition"
Their climate trilogy (2020–22) is the cleanest visual primer. Pair with PBS Spacetime's geoengineering episode and Dr Hannah Ritchie's talks for Our World in Data.
youtube.com/@kurzgesagt →PBS Terra · "Weathered"
Long-running explainer series covering AMOC, fire weather, coastal subsidence, urban heat. Source-cited and short.
youtube.com/@pbsterra →Indicators · 2026–2030
- 2025–28 El Niño / La Niña sequence — does the post-2024 record hold?
- AMOC observation arrays (RAPID, OSNAP) — sign of slowdown?
- EV / heat-pump global stock-share inflection
- First DAC plant at 1 MtCO₂/yr scale (Stratos · Texas)
- Loss & Damage Fund disbursements — first real flows
- Litigation: Held v. Montana descendant cases; ICJ advisory opinion