Climate Change - Evidence, Attribution, Projections and Remedies

Narrative

The most prominent Substack voice on the instrumental record is James Hansen's Climate Uncensored, where Hansen, Kharecha, Morgan and Vest published December 2025 analysis projecting the 2023–2025 mean at +1.5°C relative to 1880–1920, and arguing that an aerosol-masking shift has accelerated underlying warming to roughly 0.31°C per decade. Hansen's earlier "Global Warming in the Pipeline" (Oxford Open Climate Change, 2023) generated a sustained debate between his higher climate-sensitivity estimates and the more cautious mainstream. Carbon Brief's 2026 state-of-the-climate synthesis - combining NASA GISTEMP, NOAA, HadCRUT5, Berkeley Earth, and ERA5 - placed 2025 as effectively tied with 2023 for second warmest, with ocean heat content registering its own annual record. The Climate Lab Book Substack (Ed Hawkins and colleagues) extended the "warming stripes" concept vertically through the atmosphere, from ocean floor to stratosphere, providing one of the clearest single-image summaries that the human fingerprint extends through every layer. The RealClimate blog, co-founded by Gavin Schmidt, updated its model-observation comparison graphics with 2025 data in January 2026, confirming models published since 1970 have been skillful.

On the cryosphere, NOAA's Arctic Report Card 2025 documented that the last ten years are the ten warmest on record in the Arctic, that multi-year ice thicker than four years has declined by more than 95% since the 1980s, and that glaciers across the Arctic are losing ice at a rate three times higher than the 1990s. The Effective Altruism Forum carried a detailed independent synthesis on AMOC tipping-point science, surveying Ditlevsen and Ditlevsen (2023), van Westen et al. (2024), and Baker et al. (2025), and concluding that the probability estimates span from the IPCC's "very unlikely" within the century to a 59% chance by mid-century in unpublished work - a genuinely contested empirical question, not a settled one. A Substack newsletter on Strategic Climate Risks documented the shift in governmental framing of AMOC from a purely scientific question to a security concern, citing Iceland's 2025 ministerial statement and the UK's ARIA tipping-point programme.

On attribution and the carbon budget, the Global Carbon Budget 2025 (published at COP30 in Belém) established that fossil-fuel CO₂ emissions rose 1.1% in 2025 to a record 38.1 billion tonnes, and that the remaining budget for a 50% probability of staying below 1.5°C is now roughly four years at current rates. Carbon Brief's analysis of the year's most-cited climate papers highlighted two major fault lines in independent commentary: Hansen's aerosol-masking paper arguing the IPCC understates climate sensitivity (reaching 400 news stories and attracting sharp scepticism from some scientists), and the Global Carbon Budget paper itself, which attracted 556 online news mentions. Andrew Dessler's The Climate Brink on Substack, with tens of thousands of subscribers, engaged the "locked-in warming" debate directly, arguing in a December 2024 post that very little warming is in fact committed - a position at odds with Hansen's "in the pipeline" framing and illustrating an active, substantive disagreement between climate scientists, not between scientists and denialists.

On remedies, the Solar Geoengineering Updates Substack documented that the Simons Foundation committed $50 million over five years to SRM research in 2024, while UKRI and NERC launched a £10.5 million five-year research programme. Carnegie Endowment reporting underscored that BECCS, often featured in IAMs, currently removes only 0.00051 GtCO₂ per year against global fossil emissions of 37.4 GtCO₂ - a gap of five orders of magnitude. The CS Monitor's 2024 coverage drew the sharpest demarcation this lane requires: the shift from "old denial" (the planet is not warming) to "new denial" (attacking solutions and scientist integrity), with the Center for Countering Digital Hate finding 70% of YouTube denial content in 2024 focused on one of those two attack lines rather than the basic physics.