Modeling study reveals that Arctic warming accelerates 2-degree Celsius increase by eight years

November 13, 2023

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A recent modeling study conducted by researchers from UCL reveals that a global 2 C temperature rise could occur eight years earlier than predicted if the Arctic continues to warm faster than the average global rate.

The Arctic is currently experiencing a warming rate almost four times faster than the global average. The study, published in Earth System Dynamics, sought to determine the influence of this accelerated Arctic warming on the timeline for breaching the global temperature thresholds of 1.5 C and 2 C, as detailed in the Paris Agreement.

The researchers proposed alternative projections for climate change without the occurrence of rapid Arctic warming. By comparing these hypothetical models with real-world models, they were able to determine when the critical thresholds as outlined in the Paris Agreement would be reached. The study found that without accelerated Arctic warming, these thresholds would be breached five and eight years later than their projected real-world dates of 2031 and 2051, respectively.

In addition to these findings, the study also uncovered that Arctic amplification, or the phenomenon of unproportionately rapid Arctic warming, significantly contributes to the uncertainty of climate change forecasts because the model projections for this region exhibit greater variability compared to the rest of the world.

Alistair Duffey, a Ph.D. candidate at UCL Earth Sciences and the study's lead author, stated, "The global significance of rapid Arctic warming is highlighted in our study by estimating its substantial impact on when we are likely to exceed critical climate thresholds."

While the study does not examine the global effects of Arctic warming such as sea ice retreat and permafrost thawing that lead to more carbon emissions, it estimates the direct influence of Arctic warming on global temperature increases.

Co-author Professor Julienne Stroeve from UCL Earth Sciences, the University of Manitoba, Canada, and the U.S. National Snow and Ice Data Center, pointed out that local impacts such as severe temperature rises should not be overlooked while studying global temperature changes.

Furthermore, co-author Dr. Robbie Mallett of University of Manitoba and Honorary Research Fellow at UCL Earth Sciences highlighted the need for political attention on Arctic climate change due to its significant impact on global targets like the Paris Agreement.

The study explains that Arctic amplification, predominantly occurring in winter, is due to a number of factors including sea ice retreat and less vertical air mixing in polar regions compared to the tropics, which keeps warmer air near the Earth's surface.

The research team relied on a set of 40 climate models used in the UN's 2021 climate change report for this study. They created an alternative projection by modifying these models to exclude rapid Arctic warming and investigated the effect on temperature forecasts under a plausible intermediate emissions scenario.

In addition, they looked at how removing rapid Arctic warming from the models would affect more pessimistic or optimistic scenarios. For example, in a more optimistic scenario, where emissions are cut sharply and net zero is reached shortly after 2050, Arctic amplification causes a seven-year difference in the time of passing 1.5°C.

Temperature projections for the Arctic varied more substantially between the models than for other parts of the globe, accounting for 15% of the uncertainty in projections, despite the region only making up 4% of the global surface area.

The 1.5 C and 2 C limits are regarded as having been breached when average global temperatures over a 20-year period are 1.5 C or 2 C higher than in pre-industrial times.

The goal of the Paris Agreement, an international treaty, is to keep the global average temperature to 'well below 2° C above pre-industrial levels' and pursue efforts 'to limit the temperature increase to 1.5° C.'

The Arctic is thought to have warmed by 2.7 C since the pre-industrial era, and this warming is believed to have accelerated since the start of the 21st century.

Journal information: Earth System Dynamics

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