UNEP’s detailed ‘overshoot, peak and decline’ pathway seeks to hold the peak as low as possible and then bring temperatures back down below the 1.5°C limit; report terms it ‘best remaining option’ UNEP’s detailed ‘overshoot, peak and decline’ pathway seeks to hold the peak as low as possible and then bring temperatures back down below the 1.5°C limit; report terms it ‘best remaining option’