Tilley's Track
by Prof Allen Tilley
Disclaimer: The material in this section is not necessarily the policy of the Sierra Club. The referenced materials are the responsibility of the publishers/writers and Mr. Tilley’s analysis is intended to provoke thought and action, but not necessarily endorsed.
Sent 4/23
The impending move of the Atlantic Meridional Overturning Circulation to a lower flow should be the lead story and fascination of every news source, given its implications for our collective future as a planet. George Monbiot suggests why it is not. https://www.theguardian.com/commentisfree/2026/apr/23/catastrophic-climate-event-scientists-atlantic-system-collapse-billionaire-existential-crisis
Monbiot assumes that the decline of the AMOC is simply the end of our story. We need to look past that, as distressing as the view will be. It is not too early to ask what adaptation will mean, and what we can do now to prepare.
Of course we should cease now to burn fossil fuels. We should concentrate what resources we can on drawing down and sequestering carbon. We should prepare politically for intense international collaboration. These are actions which might yet prevent the AMOC slowdown, and which will lay the ground for adaptation if the catastrophe comes upon us. What else need we do? What else more deserves our attention?
Sent 4/21
1. 99% of new power generated globally last year was from renewables. Battery prices continue to fall rapidly, leading to the growing cost advantage of renewables plus batteries over commercial methane. This Australian story is a comprehensive portrait of the global energy picture. https://reneweconomy.com.au/solar-wind-meet-99-pct-of-new-global-demand-as-batteries-help-deliver-round-the-clock-resource/
2. An AI study projects that renewable energy will grow rapidly enough to limit warming to 2C, but that a limit of 1.5C, while possible, is unlikely. https://www.anthropocenemagazine.org/2026/04/an-ai-trained-on-13000-virtual-worlds-just-projected-our-renewable-energy-future/
Sent 4/18
1.A Guardian article clarifies the newly increased expectations of a slowdown in the AMOC. https://www.theguardian.com/environment/2026/apr/15/critical-atlantic-current-significantly-more-likely-to-collapse-than-thought
I have been watching for news coverage of this significant issue and have found little outside the Guardian. Perhaps the necessary lack of a date definite prevents publicity. The Guardian article pursues the probabilities, though yet more might be done toward a profile of likelihood. A more detailed depiction of the effects of an AMOC slowdown in a realistically hotter world would also be welcome. Things are going to get worse before they get better, and the sooner we set about a serious program of carbon removal, and the establishment of model sustainable communities, the better.
2. The Chinese-backed firm Greater Bay Technology (GBT) has announced that it will produce a solid-state auto battery this year. Chief among the advantages over existing batteries are its improved safety, charging speed, and longevity, and the improved power storage which will allow auto ranges of 600 miles and more on a single charge. May GBT's battery be good enough to set a new standard immediately. https://electrek.co/2026/04/15/solid-state-ev-batteries-coming-sooner-than-expected/
Sent 3/24
1. Antarctic sea ice suffered a sudden melt in 2015. In 2022 it collapsed again. This time it may not recover. If so, the effect on global sea level rise will be marked, and the likelihood of a midcentury slowdown of the AMOC increases. An 11.5-minute PBS video Why Antarctic Sea Ice is Suddenly Disappearing provides a clear explanation.
https://www.youtube.com/watch?v=Dka4mcVQ4mA
3. We have been warned before of a pronounced rise in sea level due to Antarctic conditions. Margaret Davidson was the Senior Advisor for Coastal Inundation and Resilience Science and Services at the National Oceanic and Atmospheric Administration. In April 2016 she addressed over 10,000 attendees at the annual RIMS conference for risk management and insurance professionals in San Diego, CA.
https://www.insurancejournal.com/news/national/2016/04/12/405089.htm Davidson told the conference that current studies in the Antarctic indicated we could expect about nine feet of sea level rise by mid-century (a figure she later modified to 2-3 meters). She warned that procedures for publication meant that it might be a decade until the data and conclusions became publicly available. I suspect that the previous year's precipitous decline in Antarctic sea ice may have been on her mind, along with the discovery that the West Antarctic Ice Sheet is less stable than we had thought.
4. A series of warnings over several decades of imminent sea level rise out of scale with current projections has come from James Hanson and his many coauthors. Hanson looks for periods in the past when conditions resembled those we are creating. He found that our projections of sea level rise had been far too modest. In an early paper he depicted an increasing rise which would reach a meter a decade by the end of this century. At that point, some unanalyzed feedback seems to limit further growth in the rate, which would continue as long as heating persisted. His 2016 paper foresaw a rise of "several meters" over the coming century.
https://www.theguardian.com/science/2016/mar/22/sea-level-rise-james-hansen-climate-change-scientist
5. The new concern with the effect of declining Antarctic sea ice comes because we now better understand the cause of the decline as described in the PBS video of item 1. The mechanism was outlined in an article published in Nature Climate Change on 18 March 2026.
https://www.nature.com/articles/s41558-026-02601-4
Until we understood what was causing the decline we did not have a grounded understanding of the possibility of a fast-approaching major increase in sea level rise. That now seems more clearly indicated. What are we to do?
6. All low-lying coastal regions could be inundated in the near future. We do not yet have firm projections of sea level rise. Still, we have sufficient reason to believe they are coming. State and regional planning councils, city planners, and citizens of threatened areas need to make provisional plans based on reasonable assumptions, including relocation plans if indicated. If we wait for projections, we may find that we have too little time for sound planning. If we leave planning to commercial interests, we may expect guarded enclaves for the wealthy and storage camps of one sort or another for the rest of us with an accompanying degradation of living conditions.
7. We can plan sustainable communities which produce most of their own food and power and provide opportunities for play and work to a full range of people. These communities should be fully connected to one another and to such supports as health and educational centers. We should plan to make viable habitats available to fellow life forms in our region. That indicates lots of green in the communities and in areas reserved from human use.
Charrettes of community members along with such experts as architects, governmental representatives, builders, health providers, and planners should be engaged from the beginning. Initial planning for relocation sites and conditions will be crucial.
We have a lot to do. We are unlikely to be able to continue indulging the current politics of greed, wrath, and folly, so we will need to make a success of elections this fall. Still, this is the time, stressed as it is, to begin to plan to cope with rising waters as we await realistic projections of sea level rise under the new conditions.