My co-authors and I have argued in previous papers that climate cycles on early Mars could have been driven by oscillations in the carbonate - silicate cycle, which would have provided transient warming from the accumulation of greenhouse gases by volcanoes and subsequent loss by weathering. (haqqmisra.net)
Among other things, the author [of the Economist's report] hopelessly confuses transient warming (the warming observed at any particularly time) with committed warming (the total warming that you've committed to, which includes warming in the pipeline due to historical carbon emissions). (robertscribbler.com)
Ramirez, R.M., A warmer and wetter solution for early Mars and the challenges with transient warming, Icarus, 297, pp. 71 - 82, 2017 (carlsaganinstitute.org)