Environmental and Resource Economics

, Volume 37, Issue 4, pp 681–695

A portfolio approach to climate investments: CAPM and endogenous risk

Original Paper

DOI: 10.1007/s10640-006-9049-4

Cite this article as:
Sandsmark, M. & Vennemo, H. Environ Resource Econ (2007) 37: 681. doi:10.1007/s10640-006-9049-4


Is there a role for investments in climate change mitigation despite low expected return? We use a model of intertemporal expected utility maximisation to analyse this question. Similar to the capital asset pricing model (CAPM) the rate of return depends on the correlation of risk between the return on investments in climate change mitigation and the market portfolio, but in contrast to the classical CAPM we admit the fact that economic and environmental systems are jointly determined, implying that environmental risk is endogenous. Therefore, investments in climate change mitigation may reduce risk via self-protection and self-insurance. If risk reduction is accounted for in cost–benefit evaluations, climate investments may be justified despite low expected return. These aspects of climate investments are not, however, communicated via standard cost–benefit analyses of climate policy. Optimal climate policy may therefore be more ambitious than previously considered.


CAPMclimate changeendogenous riskclimate investmentrisk management

JEL Classification


Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  1. 1.Molde Research InstituteMoldeNorway
  2. 2.ECON AnalysisOsloNorway