The research, published in Geophysical Research Letters, concludes that the planet has been warming at its fastest rate since modern temperature records began.
The pace of human-driven global warming has nearly doubled over the past decade, raising concerns that the Paris Agreement’s 1.5°C threshold could be breached within the next few years, according to a new scientific study.
The research, published in Geophysical Research Letters, concludes that the planet has been warming at its fastest rate since modern temperature records began. Scientists found that while global temperatures had been rising at about 0.2°C per decade since the 1970s, the rate has accelerated to around 0.35°C per decade since 2015.
If this trend continues, the study suggests the internationally recognized warming limit could be crossed between 2026 and 2029. “The essential result of this paper isn’t how fast we’re warming, but that warming is now happening faster than before and that the difference isn’t negligible,”
RELEVANT SUSTAINABLE GOALS
Removing Natural “Noise” Reveals the Warming Signal
To identify the underlying warming trend, researchers separated human-caused temperature increases from natural climate variability.
Short-term temperature fluctuations are influenced by several natural factors, including:
- El Niño and La Niña cycles, known collectively as the El Niño–Southern Oscillation (ENSO)
- Volcanic eruptions
- Changes in solar activity
Study author Dr Grant Foster, formerly of Tempo Analytics, described these influences as “random noise” that can obscure the long-term warming signal.
Using a statistical technique first developed in a 2011 study, researchers removed the effects of these natural drivers from global temperature records. The analysis was applied to five major datasets, including those from NASA, NOAA, the Met Office Hadley Centre and the University of East Anglia’s HadCRUT5, Berkeley Earth and Copernicus ERA5.
After accounting for natural variability, the years 2023 and 2024 remained the two warmest years on record, even though adjusted values appeared slightly cooler.
Evidence of Accelerating Warming With High Confidence
Scientists used two statistical methods to determine whether global warming is accelerating.
Both approaches indicated that warming is accelerating with more than 98 percent statistical confidence across all five datasets. When the same tests were conducted using unadjusted data that included natural variability, the confidence level failed to reach even 95 percent, highlighting the importance of isolating human-driven warming trends.
The first method applied a quadratic trend line to detect long-term acceleration. The second identified the period when warming rates began to increase noticeably.
Across datasets, this shift was estimated to have occurred between February 2013 and February 2014.
Since then, warming rates have risen to 0.34°C to 0.42°C per decade, significantly higher than the long-term average. The study concludes that the last decade has experienced the highest warming rate in the instrumental record.
What Crossing the 1.5°C Threshold Means
The year 2024 was the hottest on record, with global average surface temperatures exceeding 1.5°C above pre-industrial levels for the first time. However, a single year above the threshold does not constitute a breach of the Paris Agreement. The agreement refers to long-term warming, typically measured as an average over 20 years. Scientists therefore focus on identifying when sustained warming could exceed the 1.5°C limit.
According to the study’s methodology, the breach would be defined as the midpoint of a 20-year period during which average temperatures exceed that threshold.
Beyond surface temperatures, other indicators suggest growing climate pressure.
Ocean heat content, a measure of energy stored in the oceans, has been rising steadily, with the largest year-to-year increases recorded since 2020. At the same time, the Earth’s energy imbalance — the difference between incoming solar radiation and outgoing heat — has also increased in recent years.
These trends point to continued accumulation of heat within the climate system.
The study underscores a broader concern among scientists: that the window to limit global warming to 1.5°C may be narrowing faster than previously expected. Human activity — particularly greenhouse gas emissions and land-use change — remains the primary driver of long-term warming.
While natural factors continue to influence year-to-year variability, the underlying trend shows sustained temperature increases. Whether warming continues to accelerate or stabilizes at current rates will depend largely on how quickly global emissions are reduced.
For now, the latest research adds urgency to international climate efforts, suggesting that the timeline for reaching key thresholds may be shorter than once assumed.
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