Global warming may be occurring at a faster rate than previously believed, according to a recent study by a team of researchers including former NASA scientist James Hansen. Hansen’s testimony before Congress 35 years ago helped raise awareness about climate change.
The study warns that the planet could surpass a warming of 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, in this decade compared to preindustrial temperatures, and that global warming will reach 2 degrees Celsius by 2050. When countries signed the landmark Paris Agreement in 2015, they committed to limit global warming to “well below” 2 degrees Celsius and strive for 1.5 degrees.
During a news conference on Thursday, Dr. Hansen, who is now the director of the Climate Science, Awareness and Solutions Program at Columbia University, stated, “The 1.5 degree limit is deader than a doornail.” He noted that the 2-degree goal could still be achieved, but it would require immediate and decisive action to phase out fossil fuels at a much faster pace than current plans.
The world has already experienced a warming of approximately 1.2 degrees Celsius, resulting in more intense heat waves, wildfires, storms, loss of biodiversity, and other consequences of climate change. If temperatures continue to rise beyond the goals of the Paris Agreement, the effects will worsen and lead to greater extremes and uncertainties.
Experts generally agree that the planet will soon surpass a warming of 1.5 degrees. Another study published by British and Austrian scientists also concluded that, at our current rate of fossil fuel consumption, the world is likely to exceed a warming of 1.5 degrees within six years.
Zeke Hausfather, a research scientist at Berkeley Earth, stated, “I think everyone agrees that 1.5 degrees is in the rearview mirror at this point.” However, there is disagreement among scientists regarding the sensitivity of Earth’s climate to greenhouse gases and the timing of reaching 2 degrees of warming.
The recent study analyzed historical temperatures and carbon dioxide levels over the past 66 million years to establish a relationship between carbon dioxide and temperature. It revealed that if the concentration of carbon dioxide in the atmosphere doubles, the planet’s temperature will rise by approximately 3.6 to 5 degrees Celsius.
Dr. Hausfather expressed that this estimate is on the higher end of current academic literature. A 2021 report from the Intergovernmental Panel on Climate Change (IPCC) estimated that a doubling of carbon dioxide would result in a warming between 2 and 5 degrees Celsius, most likely around 3 degrees. However, Dr. Hansen believes that warming is accelerating.
One contributing factor, according to Dr. Hansen, is the reduction in sulfate aerosols in the atmosphere due to efforts in reducing air pollution, particularly in the shipping industry. Sulfate aerosols, a byproduct of burning fossil fuels, reflect sunlight and have a cooling effect on the planet.
Despite the disagreements, the deadlines of 1.5 and 2 degrees Celsius are quickly approaching. The exact sensitivity of Earth’s climate to future greenhouse gas emissions may not be of utmost importance. Most experts agree that while the 1.5-degree goal has been missed, there is still a chance to limit warming to 2 degrees. However, it will require much more action than what countries are currently undertaking.
Dr. Hansen emphasized the need to reduce emissions as quickly as possible, stating, “We’re also going to pass 2 degrees. That’s clear unless we take action to reduce the energy imbalance.”