After years of bleak projections, countries now have better than even odds of limiting global warming to at or below the Paris Agreement's 2°C temperature target, a new study finds.
Yes, but: This requires all national emissions reduction pledges to be fully met, which countries are not currently on course to do.
- In addition, the study, led by Malte Meinshausen at the University of Melbourne, finds there is only a faint chance, between 6% to 10%, of meeting the agreement's more aggressive 1.5°C target.
- The only way to do so would be for countries to commit to far more stringent emissions cuts prior to 2030, and reach net zero by 2050.
Why it matters: Published in the journal Nature, this is the first peer-reviewed study to show such high odds of holding the global temperature increase to 2°C based on world leaders' existing pledges.
Threat level: Warming beyond 1.5 degrees risks calamitous consequences, including the death of warm water coral reefs and irreversible melting of large portions of polar ice sheets.
- Such warming is especially dangerous for developing nations and low-lying island countries.
- With just 1.1°C of warming so far compared to preindustrial levels, we're already seeing unprecedented heat waves, wildfires, intensifying tropical cyclones and melting glaciers and ice caps.
Driving the news: The study looks at the evolution in country emissions pledges, technically known as "Nationally Determined Contributions" (NDCs), between the Paris summit in 2015 and the summit in Glasgow late last year, and where they would take Earth's climate if they are fulfilled.
- According to the research, by November 2021, 154 countries had submitted either new or updated NDCs. Seventy-six of these had long-term targets such as net zero commitments.
- By studying over 1,400 emissions scenarios from commitments made up to and during the Glasgow summit, the researchers find that if all pledges are met on time, peak warming could be limited to just below 2°C.
- "This is big news because it's the first time that governments have come forward with specific targets that can hold global warming to below the symbolic two degrees level," study co-author Christophe McGlade of the International Energy Agency in Paris told reporters.
But, but, but... Policies are still needed to implement those pledges, and so far they're in short supply.
- In fact, the global energy crunch due to the war in Ukraine may be pushing energy policies in the direction of more fossil fuel extraction for some countries, including the U.S.
Be smart: Near-term cuts would fall far short of where they need to go to stay within the 1.5-degree guard rail.
- Instead of reducing carbon dioxide emissions by 45% below 2010 levels by 2030, as required to be on a 1.5-degree pathway, existing NDCs would actually increase emissions by between 6% to 13% during this period, the study finds.
- The results, the researchers state, "provide a sobering assessment of how far current pledges are from limiting warming to 1.5°C," the study states.
Context: In an accompanying commentary, Zeke Hausfather, climate research lead at Stripe, and climate scientist Frances Moore of U.C. Davis find that near-term commitments are especially important for the 1.5-degree target.
- "Long-term targets should be treated with skepticism if they are not supported by short-term commitments to put countries on a pathway to meet those targets in the next decade," they wrote.
What they're saying: Meinshausen told reporters on a conference call that the study offers a warning about the 1.5-degree target.
- "Our study clearly shows that increased action this decade is necessary for us to have a chance of not shooting past 1.5 degrees by a wide margin," he said.
