[Paper Review] Energy Limits to the Gross Domestic Product on Earth

Andreas M. Hein, Jean-Baptiste Rudelle|arXiv (Cornell University)|May 11, 2020

Global Energy and Sustainability Research79 references4 citations

TL;DR

This paper argues that Earth's global economy faces a hard upper limit due to thermodynamic constraints, even if carbon neutrality is achieved. By modeling both greenhouse gas-induced and energy consumption-induced warming, it shows that sustained 2% annual GDP growth will exhaust planetary energy capacity within centuries, necessitating space-based economic expansion unless energy intensity is drastically reduced.

ABSTRACT

Once carbon emission neutrality and other sustainability goals have been achieved, a widespread assumption is that economic growth at current rates can be sustained beyond the 21st century. However, even if we achieve these goals, this article shows that the overall size of Earth's global economy is facing an upper limit purely due to energy and thermodynamic factors. For that, we break down global warming into two components: the greenhouse gas effect and heat dissipation from energy consumption related to economic activities. For the temperature increase due to greenhouse gas emissions, we take 2 °C and 5 °C as our lower and upper bounds. For the warming effect of heat dissipation related to energy consumption, we use a simplified model for global warming and an extrapolation of the historical correlation between global gross domestic product (GDP) and primary energy production. Combining the two effects, we set the acceptable global warming temperature limit to 7 °C above pre-industrial levels. We develop four scenarios, based on the viability of large-scale deployment of carbon-neutral energy sources. Our results indicate that for a 2% annual GDP growth, the upper limit will be reached at best within a few centuries, even in favorable scenarios where new energy sources such as fusion power are deployed on a massive scale. We conclude that unless GDP can be largely decoupled from energy consumption, thermodynamics will put a hard cap on the size of Earth's economy. Further economic growth would necessarily require expanding economic activities into space.

Motivation & Objective

• To assess whether long-term economic growth is physically sustainable on Earth under energy and thermodynamic constraints.
• To quantify the combined impact of greenhouse gas emissions and waste heat from energy consumption on global warming.
• To evaluate the feasibility of sustaining 2% annual GDP growth under various energy deployment scenarios.
• To determine whether decoupling GDP from energy use is necessary to avoid a hard upper limit on Earth's economy.
• To explore the implications of energy limits for future economic development and the potential role of space-based expansion.

Proposed method

• Modeling global warming as the sum of two components: radiative forcing from greenhouse gases and heat dissipation from energy use.
• Using 2°C and 5°C as bounds for greenhouse gas-induced warming, and extrapolating historical GDP-energy production correlations to estimate heat-induced warming.
• Setting a total acceptable warming limit of 7°C above pre-industrial levels as a conservative threshold.
• Developing four scenarios based on the viability of large-scale carbon-neutral energy sources, including fusion and other advanced technologies.
• Applying a simplified energy-balance model to project cumulative energy use and associated waste heat over time.
• Calculating the upper bound on GDP growth by estimating when energy consumption would exceed Earth's heat-dissipation capacity.

Experimental results

Research questions

• RQ1 What is the maximum sustainable level of global GDP given thermodynamic constraints on heat dissipation and energy use?
• RQ2 How do greenhouse gas emissions and waste heat from economic activity jointly contribute to global warming?
• RQ3 Can 2% annual GDP growth be sustained indefinitely if carbon-neutral energy sources are deployed at scale?
• RQ4 What is the upper limit of Earth's economy under different assumptions about future energy technology deployment?
• RQ5 To what extent must GDP be decoupled from energy consumption to avoid a thermodynamic ceiling on economic size?

Key findings

• Even under optimistic scenarios with large-scale deployment of carbon-neutral energy sources, Earth's economy faces a hard upper limit due to thermodynamic constraints.
• For a 2% annual GDP growth rate, the upper limit on economic size is reached within a few centuries, regardless of technological advances.
• The combined effect of greenhouse gas emissions and waste heat from energy consumption could lead to a 7°C increase in global temperature above pre-industrial levels.
• Energy consumption-related heat dissipation alone contributes significantly to global warming, with a measurable historical correlation between GDP and primary energy production.
• Without substantial decoupling of GDP from energy use, continued economic growth on Earth is physically unsustainable.
• The paper concludes that future economic expansion beyond Earth's limits will likely require the development of space-based economic activities.