Climate science (IPCC 2018) and economics (Emmerling et al. 2019; Burke, Hsiang, and Miguel 2015) indicates that achieving far earlier and deeper mitigation than pledged to date is likely now critical to effective climate action – particularly to ensure limits to adaptation are not breached. However, clear and coherent comparisons of national and regional climate action have been lacking. Therefore, here we summarise a benchmarking method (McMullin et al. 2019) to establish a prudent, fair share of the remaining global CO2 budget for any Party to the Paris Agreement. Using Ireland as a case study, we analyse current policy ambition relative to this benchmarked national CO2 quota, demonstrate early emergence of CO2 debt, and show tacit mitigation policy reliance on future large scale carbon dioxide removal (CDR). Toward society-wide scenarios for effective climate action, we further examine the crucial roles of non-CO2 mitigation and safeguarding land carbon stocks.