(CN) – Scientists studying the impact of carbon released into the atmosphere by melting Arctic permafrost and heating up of the Earth’s surface reveal the potential multitrillion-dollar cost to the world economy in a new paper published Tuesday in Nature Communications.
A combination of Arctic permafrost losses and higher solar absorption into the ground due to the melting sea ice and land snow has the potential to increase the long-term economic impact of climate change by close to $70 trillion.
If the Intergovernmental Panel on Climate Change (IPCC) Paris Agreement target of global temperature rises being limited to 2.7 degrees Fahrenheit from pre-industrial levels is achieved, the extra impact drops to $25 trillion. In both cases, permafrost carbon emissions are the primary driver behind the additional costs.
The interdisciplinary research team hope to help guide policymakers towards prudent decisions on emissions reduction targets by providing a better understanding of the socio-economic risks from climate change under different scenarios.
"Our findings support the need for more proactive mitigation measures to keep global temperature rise well below 2 degrees Celsius,” said lead author Dmitry Yumashev, of the Pentland Centre for Sustainability in Business at Lancaster University, in a statement.
"We hope our work will lead to further assessments of multiple nonlinear processes in the Earth's climate system, both those associated with the Arctic and beyond," he said.
Yumashev and his colleagues explored simulations of complex, state-of-the-art, physical models to quantify the strength of the permafrost carbon feedback driven by the additional carbon released from thawing permafrost. They also simulated the surface albedo feedback, caused by the extra solar energy absorbed by the Earth's surface as the white sea ice and land snow cover declines, exposing darker ocean and land.
Nearly all climate policy studies to date have used a constant permafrost carbon feedback and surface albedo feedback for calculations, yet recent observations and computer models show that their strength is changing in nonlinear and more complex ways as climate warms which also alters their impact on both the global climate and economy.
"Arctic sea ice and land snow currently contribute around a third each to the global albedo feedback," Yumashev said.
"These two components are set to peak for global temperatures within the range covered by the Paris Agreement, but if the climate warms further, the summer and spring sea ice and land snow covers will retreat further north and the albedo feedback will actually weaken,” he explained.
The modeling shows disproportional changes in both feedback types. The permafrost feedback, however, grows progressively stronger in scenarios with warmer climates. And both feedbacks have nonlinear responses to warming that include a lag between rising temperatures and permafrost carbon emissions.
Scientists created different scenarios with varying levels of emissions to compare mitigation costs against the overall price of climate change. The low emissions scenarios in the study include meeting the 2.7- and 3-degrees Fahrenheit targets relative to pre-industrial conditions by 2100 versus the medium emissions scenarios that include mitigation levels consistent with current national pledges. The world is set to warm by around 3 degrees Fahrenheit relative to pre-industrial by 2100 under pledges made by the leaders of various nations.
High emissions scenarios, such as the current business as usual trajectory are expected to lead to around 4 degrees Fahrenheit of warming by 2100 and cause by far the greatest impacts on ecosystems and societies. Under these, the strength of the permafrost carbon feedback reaches its peak and does not increase further, while the continued weakening of the surface albedo feedback gradually cancels the warming effect of the permafrost carbon feedback.
Under all scenarios, using the nonlinear Arctic feedbacks rather than previous constant values leads to an increase total cost of climate change. Additional temperature-driven impacts on economy, ecosystems and human health, and additional impacts from sea level rise are what drives the costs up. Based on thousands of simulations, total costs exceed by 10 times the current estimates of long-term economic gains from transit shipping routes and mineral resource extraction in an ice-free Arctic region.
With previous estimates for Arctic feedbacks, the total cost of climate change when warming is held to the levels in the Paris Agreement is essentially the same, around $600 trillion. Nonlinear permafrost carbon feedback and surface albedo feedback add on $25 trillion to the $600 trillion figure, making the more ambitious target marginally more economically attractive.
The estimated cost of business as usual? Around $2 quadrillion.
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