The ambitious goal of limiting global warming to 1.5 °C seems increasingly far from being achieved, according to a new study carried out by researchers at the University of Washington (USA).
Experts calculated how much warming is already guaranteed based on past emissions of carbon dioxide, methane, nitrogen oxide, and aerosols such as sulfur and soot. Their findings suggest that by 2029 , the Earth has a two-thirds chance of at least temporarily exceeding 1.5°C of warming, even if all emissions cease by that date.
In the research published in the journal Nature Climate Change , the team, led by Michelle Dvorak, used climate modeling to study what would happen to Earth’s temperature if all emissions suddenly stopped every year from 2021 to 2080, at along eight different emission pathways.
The numbers
The study predicted that if humans continue on a moderate emissions path, by 2057 there is only a 33% chance of limiting warming to 2°C. The forecasts are not at all rosy.
“It is important that we analyze how much future global warming can be avoided with our actions and policies, and how much warming is inevitable due to past emissions,” explains Michelle Dvorak, leader of the work. “I think that hasn’t been clearly teased out before: how much future warming will happen just based on what we’ve already emitted.”
The model indicates that there is a 42% chance that the world is already committed to at least 1.5°C of warming relative to pre-industrial temperatures, even if emissions are stopped immediately. However, this probability increases to 66% if emissions are not reduced until 2029.
This is not the first time in recent weeks that researchers have highlighted the importance of limiting pollutants beyond CO2. Late last month, researchers at Georgetown University also warned that reducing CO2 alone is not enough to mitigate the consequences of climate change.
Paris Agreement
The researchers said the findings underscore the ” need for immediate action ” to avoid committing to even higher levels of warming. Under the COP21 Paris Agreement, scientists and governments agreed that the world must limit global warming to 1.5°C above pre-industrial levels to avoid even more destructive impacts of climate change. However, a recent review by think tanks found that none of the highly polluting G20 countries had so far strengthened their plans since COP26. Neither is on the path to heading to 1.5C .
“An understanding of the unrealized warming that will take place due to past emissions is needed to assess the likelihood of limiting global warming to the targets set in the Paris Agreement, ” the study authors said.
While stopping all human-generated emissions is virtually impossible , the researchers say it’s a “best-case scenario.”
Referencia: Dvorak, M.T., Armour, K.C., Frierson, D.M.W. et al. Estimating the timing of geophysical commitment to 1.5 and 2.0 °C of global warming. Nat. Clim. Chang. (2022). https://doi.org/10.1038/s41558-022-01372-y
