Science1 publisher2 min readPublished
Extinction peaks cluster at the switches between Earth's five recurring climate states
An international team sorted 539 million years of CO2 and temperature proxies into five recurring regimes and found elevated extinction near the transitions between them. What makes those transitions harmful is still open.
The Scientist · Science desk
What happened
- A Nature Communications study of the past 539 million years finds Earth's climate largely stayed inside five recurring states, with relatively abrupt transitions between them.
- Elevated extinction rates, including those of all five of the Big Five mass extinctions, tended to fall near the transitions between those states.
- The team's early warning sign analysis found evidence of increasing instability inside the climate data around the transitions themselves.
- The study also tracks biosphere vulnerability, meaning how readily biodiversity declines when extinction rates outpace the rate at which new species arise.
- The project began at a two-week workshop in summer 2024 at the Futures Institute in Edinburgh, where five researchers from mathematics, climate modeling and paleobiology worked together.
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Why it matters
- capability Early warning statistics are normally applied to systems whose future nobody knows. Here they can be checked against transitions whose biological consequences are already sitting in the fossil record.
- decision Myers points the next round of work at the transitions. That would concentrate proxy and field effort on the shortest intervals in a 539-million-year series and leave the long persistent stretches aside.
- exposure A five-state framing invites reading present-day warming as a regime transition in progress. The reported analysis does not assign a duration in years to a transition, so that inference comes from outside the study.
A climate that wanders and a climate that keeps returning to the same few conditions can produce curves that look much alike. Telling the two apart was the exercise. The team asked whether Earth's climate behaved more like a system moving randomly through different conditions or one that repeatedly settled into recognizable patterns [8]. They went at it with recurrence analysis, dynamical mathematical modeling and early warning sign analysis, run alongside compiled extinction and biodiversity data [7].
If the five states account for the whole eon, five across 539 million years works out to roughly 108 million years of occupancy each [16]. That average sums every episode in which a state was in play. It does not tell you how long any single one lasted. Myers said the analyses "identified five major 'mega-climate' states with relatively abrupt transitions" [4]. She was careful about what the series is: "The behavior of CO2 and temperature in the Phanerozoic can be approximated as transitioning between these identified states" [5].
Biosphere vulnerability sets losses against replacement, so a peak in it can come from extinction rising or from origination slowing [11]. "Biosphere vulnerability overall was higher for nearly all periods of elevated extinction and particularly high at the Big Five mass extinctions," Myers said [12].
The phys.org account does not report how many transitions the analysis identified, or how large the extinction rates ran near them. It does not say whether absolute temperature and rate of change were tested against each other as predictors [18]. Those are the numbers an effect size would be built from. On the record as published, the result is about where extinction peaks fall relative to regime boundaries; the stronger reading, that instability matters more than heat, would need that head-to-head test. The workshop that started the project set out to examine mass extinctions in the context of global climate change [20].
The paper is titled "Transitions between persistent climate-carbon regimes coincide with elevated Phanerozoic biosphere vulnerability" [2]. Coincide is a claim about timing. The data behind it came from Myers' laboratory at the University of New Mexico [14]. The lab has spent nearly a decade compiling climate proxy data and developing methods for estimating extinction rates, and several former graduate students collected parts of it. The team informally called the five states "Haggis bins," after the Scottish setting where the project began and the look of the data in plots [6]. "Future work should target Haggis bin transitions to help pinpoint the nature of increased stress these transitions place on the biosphere," Myers said [15].
What to watch
- Whether the Nature Communications paper itself reports transition counts and extinction rate magnitudes that the phys.org account leaves out.
- Whether an independent proxy compilation reproduces five states, or lands on a different number of bins.
- Myers' proposed work on the transition intervals, and whether it names a specific stressor acting on the biosphere.