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Peter Clack (@PeterDClack) on X
Earth's current global baseline temperature does not add up to a planetary emergency.
Humanity has evolved and still lives in an Ice Age; Earth'...
Earth's current global baseline temperature does not add up to a planetary emergency.
Humanity has evolved and still lives in an Ice Age; Earth's long-term climate has almost always been 5°C-10°C hotter than today. How can we be facing a climate crisis?
It has been vastly hotter in the past than today's modest 14-15°C range. We are living in an unbroken ice-age ecosystem, which has lasted for 34 million years. We are currently experiencing one of the coldest periods in geological history.
Historical studies show that long-term global temperatures were between 20°C and 25°C. Earth has been in this warmer greenhouse state for roughly 70–80% of the last half-billion years, devoid of polar ice sheets.
The global average temperature of 15°C may be the modern baseline (specifically closer to 14°C or 14.5°C), calculated via global weather stations and satellite anomalies to track current trends. But it is still far colder today than the world's long-term average climate.
Nor is CO₂ the hot button switch from glacial periods to warm interglacials and back—it is orbital mechanics pulling the trigger. Paleoclimate data shows that CO₂ forms a positive feedback loop. But studies do not attribute ice ages - or the glacial or interglacial cycles - to CO₂ levels.
Human civilisation has arisen almost entirely within the current warm interglacial period (the Holocene). The pacing of these glacial-interglacial cycles over the last 2.58 million years is indisputably driven by variations in Earth's orbit, known as the Milankovitch cycles—eccentricity, axial tilt (obliquity), and wobble (precession).
Earth is still within the Late Cenozoic Ice Age, which began 34 million years ago, sparked by the separation of Antarctica from South America and Australia, creating the Antarctic Circumpolar Current. This thermally isolated Antarctica, leading to its oceanic isolation and glaciation.
Humanity has evolved - and still lives entirely within - the Late Cenozoic Ice Age; while world temperatures have been 5°C-10°C hotter for 541 million years.
Why are these fundamental geological realities completely omitted from the modern agenda?
Peter Clack
30.06.26
#peterclack #climatescam