Uncertain climate thresholds and optimal economic growth

We explore the combined effects of a climate threshold (a potential ocean thermohaline circulation collapse), parameter uncertainty, and learning in an optimal economic growth model. Our analysis shows that significantly reducing carbon dioxide ðCO2Þ emissions may be justified to avoid or delay even small (and arguably realistic) damages from an uncertain and irreversible climate change—even when future learning about the system is considered. Parameter uncertainty about the threshold specific damages and the CO2 level triggering a threshold can act to decrease near-term CO2 abatements that maximize expected utility. r 2003 Elsevier Inc. All rights reserved.