The goals of the Paris Climate Agreement are still achievable, suggesting new research

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The Paris Climate Agreement’s goal of limiting global warming in this century to pre-industrial temperatures of 3.6 degrees Fahrenheit (2 degrees Celsius) is still achievable, but the apocalyptic worst-case scenario is no longer valid. New CU boulder analysis suggests.

Get out today Environmental research letterIn a new study, a subset of the Intergovernmental Panel on Climate Change (IPCC) climate scenarios is most in line with recent data and International Energy Agency (IEA) forecasts, with the 2050 project at 3.6-5.4 ° F. It turned out to be (2-3 C). With a median of 3.96 F (2.2 C) degrees, it will warm up by 2100. By comparison, some incredible worst-case scenarios predict warming as high as 7.2 or 9 F (4 or 5 C) by the end of the century.

“This is cautiously optimistic good news about where the world is today compared to where we were thinking,” said lead author Roger Pielke, Jr., Professor of Environmental Studies. .. “The two goals from Paris are still within reach.”

The climate research community uses scenarios to explore and plan for possible futures. Predict how the future will evolve based on factors such as forecasts. Greenhouse gas emissions Various possible climate policies.

The most commonly used scenario, called the Typical Concentration Route (RCP), has been developed by the IPCC since 2005. The Shared Socio-Economic Channel (SSP), which has continued since 2010, was intended as a renewal. Together, the two sets of scenarios inform the IPCC’s fifth and upcoming sixth assessment reports.

For their work, Pielke Jr. and his co-authors began with a total of 1,311 climate scenarios in which the climate research community chose 11 RCPs and SSPs. Pielke et al. Set the scenario with the projected growth rate of fossil fuel and industry carbon dioxide emissions from 2005 to 2050, which most closely matches the actual observations from 2005 to 2020, and the IEA forecast by 2050. I compared. Number of scenarios closest to the data Over the last 15 years and subsequent emission forecasts ranged from less than 100 to nearly 500, depending on the method applied. These scenarios represent what the future looks like if current trends continue and countries adopt the climate policies they have already announced to reduce carbon emissions.

Additional, more optimistic or pessimistic futures may also exist, the authors said.

“Because we haven’t updated [IPCC] scenario [for many years]There are some futures that are plausible but not yet envisioned. “

Route and validity

This analysis adds to the growing consensus of independent groups around the world, showing that the most extreme climate scenarios are unlikely to occur this century and that medium-sized scenarios are likely to occur. The IPCC Sixth Assessment Report (AR6) report, published in 2021, also states that high emission scenarios are considered unlikely.

Why are these worst-case scenarios now less plausible? Mostly, they were all developed over a decade ago and much has happened since then.

For example, renewable energy is becoming more affordable and therefore faster than expected, says Matthew Burgess, co-author and fellow at CU Boulder’s Joint Institute for Environmental Sciences (CIRES). ..

These fast-moving changes are captured in a scenario drafted by the IEA, a Paris-based intergovernmental organization that provides annual updates.

Climate scenarios also tend to overestimate economic growth, especially in poor countries, according to Burgess, an assistant professor of environmental studies.

In addition, the 2010 scenario should serve as an update to the early RCP socio-economic assumptions, but RCP continues to be used frequently by scientists. And the commonly used “worst case” scenario, RCP8.5 (8.5 watts per square meter, named after solar irradiance measurements), was 7.2-9 by 2100. Predict an increase in F (4 to 5 C).

“How hard it is to exaggerate [climate] The study focuses on 4th and 5th scenarios, one of which is RCP8.5. And they seem to be becoming less and less relevant year after year, “says Burgess.

Relying on plausible scenarios, not just outdated ones, has a huge impact on how we think, act and spend money for research and policy. climate The issue of change, the author said.

“We need to update these scenarios more often. Researchers may be using the 2005 scenario, but we need a 2022 perspective,” says Pielke Jr. Says. The question is, whatever the political implications for either side. ”

The authors emphasize that warming at 3.6 degrees Fahrenheit (2 C) still causes dramatic damage to the planet, which is not a time of complacency.

“We’re approaching our two goals, but we still have a lot to do to reach 1.5,” Burgess said.

Justin Ritchie of the Institute for Resources, Environment and Sustainability at the University of British Columbia is a co-author of this publication.

Worst case emissions forecasts are no longer on track

For more information:
Roger Pielke Jr et al, Plausible 2005–2050 Emissions scenario predicts warming from 2 ° C to 3 ° C by 2100. Environmental research letter (2022). DOI: 10.1088 / 1748-9326 / ac4ebf

Quote: The goals of the Paris Agreement are still achievable, a new study (2022) obtained from https: // on February 11, 2022. February 11, 2014) suggests

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The goals of the Paris Climate Agreement are still achievable, suggesting new research

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