HM Treasury and the economics of climate and nature | EAC evidence submission

news | publications | September 3, 2026

In evidence submitted to the inquiry earlier this year, CUSP co-director Tim Jackson examines the assumptions about economic growth, wellbeing and discounting that underpin the Treasury’s The Green Book guidance. He argues that these assumptions may undervalue long-term investment in climate and nature, particularly where investments are intended to prevent irreversible or catastrophic environmental harms.

Tim Jackson’s submission calls for Treasury appraisal methods to better reflect ecological limits, long-term risks and the importance of ecological stability as a precondition for future prosperity. It recommends reviewing the growth assumptions within the Social Time Preference Rate—used to discount future costs—, testing investments against lower-growth and climate-constrained scenarios, and developing clearer guidance for appraising investments aimed at reducing systemic environmental and climate risks.

Link

The submitted evidence by Tim Jackson and others is available in full via the Parliament website.

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This post also appeared on the CUSP website. Image: courtesy of Joshua Brown / Unsplash.