Table 1. Model results for both the carbon cycle (primary production, carbon burial, carbon remineralization, and methane production) and the iron cycle (iron recycling and iron deposition) at 2.5 Ga.

Low, Middle, and High represent the model outputs from the low, middle, and high parts of the ranges depicted by the gray boxes in Fig. 5 and fig. S8. For reference, modern rates of primary production (PP) range from 2760 to 3510 Tmol C year⁻¹ (60).

	C PP	C burial	C remineralization	C to Fe reduction	C to CH4 production	Fe recycling	Fe deposition (upwelling province)	Global Fe deposition	Global CH4
	Tmol C/year	% of PP	% of PP	% of remineralization	% of remineralization	Tmol Fe/year	Tmol Fe/year	Tmol Fe/year	Tmol CH4/year
2.5 Ga Low	4.5	14.8	85.2	72.6	27.4	11.1	1.0	17.9	0.5
2.5 Ga Middle	14.8	14.7	85.3	49.1	50.9	24.8	9.9	59.1	3.2
2.5 Ga High	22.5	14.6	85.4	41.0	59.0	31.4	17.5	89.9	5.7