NGFS-GRASFI-INSPIRE exchange – Optimal Climate Change Mitigation through Green Quantitative Easing and Fiscal Policy

Raphael Abiry (Goethe University Frankfurt) will present his research “Optimal Climate Change Mitigation through Green Quantitative Easing and Fiscal Policy”, co-authored by Alexander Ludwig (Goethe University Frankfurt), Marien Ferdinandusse (European Central Bank) and Carolin Nerlich (European Central Bank).

The NGFS-GRASFI-INSPIRE exchange is designed to strengthen the connection, collaboration and research exchange between the central bankers, financial supervisors and the academic community to share and explore new and innovative research that advances the agenda on greening the financial system. New editions occur monthly and are co-organised by the NGFS Secretariat, INSPIRE and GRASFI (the NGFS’ two designated global research stakeholders). This is the 3rd in a five-part series focused on the impacts and limitations of green monetary policy. This 13th edition is hosted by INSPIRE

Optimal Climate Change Mitigation through Green Quantitative Easing and Fiscal Policy

We address the question of how green quantitative easing could complement governments’ toolkit for climate change mitigation. In our setup, green quantitative easing refers to a given outstanding stock of bonds held by the European Central Bank and its portfolio allocation between a clean and dirty sector of production. Our key research question is how the central bank can contribute to an optimal inter-generational sharing of the burden of climate change policies in comparison to, or in combination with, fiscal mitigation policies.

We develop a quantitative overlapping generations model in which households consume and allocate their savings and their work efforts between a clean and dirty production sector. A reallocation of the central bank portfolio toward the clean sector increases the capital stock employed for production in that sector relative to the capital stock in the dirty sector. This triggers a relative increase of labour demand in the clean sector and a relative expansion of output. Through this mechanism, the central bank can thus influence relative production across the two sectors in the economy. We then contrast this policy with fiscal policy measures to mitigate climate change. We will explore whether the central bank can improve the economic allocation beyond what is thus achieved through fiscal policy.

Holding constant the balance sheet of the central bank enables us to focus on the portfolio reallocation mechanism. However, it limits the interaction between fiscal and monetary policy in the model. As a next step, we extend the model by an explicit notion of money and the introduction of a distortion that requires bond purchases by the central bank, which will enable us to study the effects of an expansion of central bank bond holdings and of climate policy interactions.

Climate Change Mitigation: How Effective is Green Quantitative Easing?

We develop a two sector integrated assessment model with incomplete markets to analyze the effectiveness of green quantitative easing in complementing fiscal policies for climate change mitigation. We model green quantitative easing through a given outstanding stock of bonds held by a monetary authority and its portfolio allocation between a clean (green) and a dirty (brown) sector of production. Our key research question is whether the monetary authority can effectively contribute to a reduction of global damages caused by carbon emissions. Our findings show that green quantitative easing does not lead to a perfect crowding out of capital and thus has real effects in the long-run. Since it only indirectly affects the allocation of production to dirty and clean technologies and since its overall economic size is relatively small, green quantitative easing is, however, a less effective climate change mitigating policy instrument than carbon taxes. We conclude that green quantitative easing might be a quantitatively important complement to fiscal policies if governments only insufficiently coordinate on implementing green fiscal policies