New Analysis Confirms Acceleration in Global Warming Since 2015
Recent research conducted by the Potsdam Institute for Climate Impact Research (PIK) reveals a significant acceleration in global warming rates since around 2015. This finding, which accounts for natural temperature fluctuations, offers the first statistically significant evidence of an increased long-term warming trend.
Analyses indicate that global temperatures have surged at a rate of approximately 0.35°C per decade over the last ten years. This contrasts sharply with the warming rate from 1970 to 2015, which was just under 0.2°C per decade. Such acceleration surpasses any previous decade since the commencement of instrumental temperature records in 1880.
Distinguishing the Long-Term Warming Signal
Grant Foster, a US statistics expert and co-author of the study published in Geophysical Research Letters, stated, “We can now demonstrate a strong and statistically significant acceleration of global warming since around 2015.” He explained that the research aimed to isolate the long-term warming signal by filtering out known natural influences, thus reducing “noise” in the data.
The term “noise” in climate data refers to temporary variations in temperature that might obscure or exaggerate the underlying trend. Phenomena like El Niño can temporarily inflate global temperatures, while volcanic eruptions or changes in solar activity can lead to temporary cooling.
To disentangle these short-term effects from the overall warming trend, the study examined measurements from five widely recognized global temperature datasets: NASA, NOAA, HadCRUT, Berkeley Earth, and ERA5.
Consistent Findings Across Multiple Datasets
Stefan Rahmstorf, a researcher at PIK and lead author of the study, noted, “The adjusted data show an acceleration of global warming since 2015 with a statistical certainty of over 98 percent, consistent across all data sets examined and independent of the analysis method chosen.”
This high level of statistical certainty underscores the robustness of the findings, which were consistent across all five temperature records, despite the differing methodologies employed by the various scientific organizations.
After adjusting for factors like El Niño and the solar maximum, the analysis slightly reduced the extreme warmth recorded in 2023 and 2024. Despite these adjustments, both years remained the hottest on record since the inception of instrumental data.
Signs of the warming acceleration became apparent as early as 2013 or 2014, with clearer evidence emerging around 2015.
Two Analytical Approaches Confirm Acceleration
The research team utilized two statistical methods to evaluate changes in the warming rate since the 1970s. The first method, a quadratic trend analysis, assessed whether the temperature curve was increasingly steep. The second, a piecewise linear model, divided the temperature record into distinct periods to objectively identify shifts in warming rates. Both methods corroborated the acceleration of global warming.
Uncovering, Not Explaining the Cause
While the study successfully detected and quantified the acceleration, it did not delve into the underlying causes. Nevertheless, the authors mentioned that climate models can simulate scenarios where warming speeds up, aligning with current climate modeling predictions.
Climate models, which leverage physics principles to simulate interactions between the atmosphere, oceans, ice, and land, provide insights into long-term climate patterns and potential future changes.
Implications for the 1.5°C Threshold
Stefan Rahmstorf warned, “If the warming rate of the past 10 years continues, it would lead to a long-term exceedance of the 1.5°C limit of the Paris Agreement before 2030.” Achieving the 1.5°C limit involves maintaining global temperatures within 1.5°C above preindustrial levels over the long term. A single year surpassing this threshold does not equate to a breach of the Paris Agreement; continuous warming over an extended period is the focus.
The study’s results suggest a potentially faster warming of the Earth compared to the late 20th century. The continuation of this trend heavily depends on future carbon dioxide emissions from fossil fuels like coal, oil, and natural gas.
Original Story at www.sciencedaily.com