The silicate weathering thermostat
PAPER IV — CHEMISTRY · QUESTION 32 OF 32
In plain terms: The free open journal where the rock–climate feedback is quantified.
The question as set
Silicate weathering is said to thermostat the climate over geological time. State the negative feedback precisely, give its characteristic timescale, and say what it cannot regulate.
The question in Paper IV · Its section on the reference page
The question in context
This is question 32 of the 32 set in Paper IV — Chemistry of The Truly Hardest Exam in the World, the examination of The College of All Minds. In the College’s subject index it is filed under Climate and the Earth system and Ecology and biogeography. Like every question of the College, it carries three references of record, verified live at publication and described twice — technically, and in plain terms — so the ground can be judged before it is walked. The response required is an argument, not a survey, of at most three thousand words, as technical as the question demands and no more.
The references of record
The literature of record on weathering fluxes, the carbonate–silicate cycle, and its measured sensitivity to temperature and runoff.
In plain terms: The free open journal where the rock–climate feedback is quantified.
The carbonate–silicate cycle as a planetary thermostat
The feedback stated with its timescale: weathering rate rising with temperature, drawing down CO₂ over 10⁵–10⁶ years — and the perturbations it is too slow to meet.
In plain terms: A free treatment of the thermostat, including the crucial point that it cannot act on a human timescale.
AR6 Working Group I — the physical science basis
The carbon-cycle assessment of record: reservoir exchange times, and the separation of fast feedbacks from geological regulation.
In plain terms: The free official assessment giving the timescales against which the thermostat must be judged.
Background: Carbonate–silicate cycle · Weathering