The influence of land position, land size and albedo on Mesoarchaean climate
Year: 2026
Type: article
Abstract: Climate change potentially played a pivotal role in the Mesoarchaean gold mega-event, when microbial fixation bound huge amounts of gold in 2.9 Ga siliciclastic sediments. Remnants of this are still preserved in the Witwatersrand gold province (Kaapvaal Craton), where the auriferous 2.90–2.79 Ga Central Rand Group is distinguished from the essentially barren 2.95-2.91 Ga West Rand Group, despite similar sedimentology. This has been explained by intense chemical weathering in Central Rand Group times having facilitated gold leaching from the Archaean hinterland. In this study we investigated the principal drivers behind the suspected climate shift at around 2.9 Ga by performing 140 simulations using Planet Simulator, an Earth system model of intermediate complexity. We assessed the effects of varying land distribution (land concentrated at the equator, at the poles, and dispersed across various latitudes), land surface area, atmospheric CO₂-equivalent concentrations, and surface albedo. In addition to the expected strong dependence of global mean temperature on atmospheric greenhouse gas concentration, our results revealed reduced seasonality at higher atm. CO₂-equivalents. Increasing land area generally leads to cooling, except at low CO2-equivalent concentrations (3-5 %) and low albedo (<0.2). When land exceeds ~13 % of total Earth’s surface, it starts to have a pronounced climatic effect. Among the various spatial land positions, land distribution across different latitudes shows the highest climate sensitivity. The postulated 2.9 Ga climatic shift may be linked to emergence of extensive low-albedo (<0.2) surfaces (e.g., mafic/ultramafic rocks) and/or latitudinal drift of the Kaapvaal Craton to a more radiatively sensitive zone.
Source: Global and Planetary Change
Institution: University of Würzburg
Language: English
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: hybrid
Estimated APC paid: $3,120
OpenAlex ID: W7154125199