Undertaking a program of action against climate change ten years from now is almost as expensive as getting started on a more ambitious effort to stop climate change today, according to a new study.
The results emerge from the first large-scale, comprehensive effort to simulate climate futures that also takes uncertainty into account.
Climate change itself as well as the political, economic, technological measures might deploy against it are highly uncertain. We don’t know exactly when certain green technologies will become available, what they will cost, how sensitive the global climate will be to a given change in greenhouse gas emissions, or the backdrop of global population growth and economic development against which this will all play out.
Most studies of future climate change and decarbonization efforts compare a small number of scenarios across several different computer models, with each scenario representing the average of an array of possibilities – which can lead to a false sense of precision.
In the new study, researchers instead analyzed a large number of scenarios within one massive model of the global climate, economy, and energy system. They used a supercomputer to crunch 700 gigabytes of data and simulated 4,000 different scenarios for 10 regions of the world through the year 2100. The analysis took into account 18 different sources of uncertainty and involved adjusting 72,000 different variables for each scenario.
“This study does not predict the future,” says study team member Evangelos Panos, an energy systems modeller at the Paul Scherrer Institute in Switzerland. “It creates a data map made up of what-if decision pathways based on understanding existing uncertainties to help stakeholders and policymakers make decisions on climate action.”
Some of the scenarios assumed that current social, economic, and technological trends will continue more or less as usual. Some envisioned a major push to decarbonize the global economy in line with limiting warming to 1.5 °C in the year 2100, others a slightly less ambitious push that would result in 2 °C of warming in 2100. The remaining scenarios explored what might happen if the push to limit warming to 2 °C was delayed for a decade.
Of the 4,000 scenarios, 70% suggest that the global temperature increase will exceed 1.5 °C in the next 5 years, the researchers report in the journal Energy Policy. (Many of the scenarios involve an “overshoot” of global temperature benchmarks – but emissions cuts and carbon removal technologies would bring the temperature back down by the end of the century.)
“The study highlights the urgency for immediate policy action for mitigation and adaptation,” Panos says.
Decarbonizing the global economy is likely to be very expensive: on average, the 1.5 °C scenarios require an investment of $8 trillion in 2030 and $26 trillion in 2050.
Delaying climate action is cheaper in the short term – but the costs of limiting warming to 2 °C with action starting ten years from now are similar to the costs of limiting warming to 1.5 °C with action starting today, the researchers found.
Delay also “would risk higher stranded assets in energy supply and use and irreversible climate change damages as in more than 55% of those scenarios with delayed action the temperature increases by more than 2 °C in 2050,” Panos adds.
The study suggests that policymakers need to put more emphasis on electrifying technologies throughout the economy – cooking, heating of buildings, industrial processes, transportation – rather than just focusing on greening the electric grid.
Yet none of the 4,000 scenarios relies on one singular technology or approach to tackling climate change. “It suggests that we need a portfolio approach in energy supply and use, with all low- and zero-carbon options, as well as adaptation measures, being developed together,” Panos says.
Source: Panos E. et al. “Deep decarbonisation pathways of the energy system in times of unprecedented uncertainty in the energy sector.” Energy Policy 2023.