Accelerated nature-based mitigation can re-open the window to 1.5°C

Cutting carbon emissions in half every decade through 2050 ¹ has become a benchmark for global ² , national and corporate target-setting that delivers the Paris goal of limiting global warming to 1.5°C above pre-industrial levels. However, with a rapidly shrinking remaining carbon budget ³ , here we show that halving fossil emissions every decade alongside scaling negative emissions technologies (NETs) to balance remaining fossil CO ₂ emissions by 2050, is no longer enough to avoid significant and lengthy overshoot past 1.5°C, unless improvements in ecosystem stewardship are also accelerated beyond levels currently assumed in most 1.5°C-aligned climate scenarios. We further show that a decadal acceleration of natural climate solutions, reaching net-zero emissions from agriculture, forestry and land use by 2030 and -7 gigatons CO ₂ e per year of net removals by 2050, is both consistent with sectoral (or “bottom-up”) estimates of cost-effective potential and can keep the window to 1.5°C decisively open, if delivered alongside decadal halvings of fossil-fuel emissions and scaling of NETs. This “Carbon Law for Nature” mitigation pathway can feasibly be achieved through a transformation of humanity’s land and coastal stewardship: protecting remaining intact ecosystems, climate-smart management of agricultural and forestry lands, restoring natural ecosystems where appropriate, and reducing excess demand for land-intensive products. Crucially, following this pathway also minimizes the magnitude and length of time of temperature overshoot, reducing both the chronic impacts of climate change ⁴ and the risk of exceeding tipping points in the earth system ⁵ .