Global warming is happening, but it’s not statistically ‘spiking’, new study finds

Example of GMST time series with spurious fit. Credit: Communications Earth & Environmental (2024). DOI: 10.1038/s43247-024-01711-1
With record heatwaves occurring around the world in recent years, an international research team including statisticians from Lancaster University found that the rate of global warming has increased significantly, or “suddenly”, over the past half-century. We investigated whether Statistically detectable proportion.
The new study, published in the journal Communication Earth & Environment on October 14 and led by scientists at the University of California, Santa Cruz, shows that the planet is warming, but not at a statistical rate. temperature, supporting the broad consensus that temperatures are not high enough. An acceleration that can be statistically defined as a sudden increase.
In recent years, the world has seen record temperatures and heatwaves. Data shows that 2023 will be the warmest year by a wide margin since world records began in 1850, and the warmest 10 years in historical record have all occurred in the past 10 years (from 2014 to 2023).
Earth’s average surface temperature, according to NOAA
These record temperatures have spurred debate and debate over whether the rate of global warming is increasing, with some arguing that it has accelerated over the past 15 years. However, the researchers’ findings indicate a lack of statistical evidence for an increase in the rate of warming that could be defined as a surge.
“We’ve been experiencing record temperatures recently, but that’s not necessarily inconsistent with steady global warming,” said lead author Claude Beaulieu, a professor of marine science at the University of California, Santa Cruz.
“Of course, it is still possible that an acceleration of global warming is occurring. But we know that either the magnitude of that acceleration is statistically too small or we don’t yet have enough data to detect it with certainty. I did.”
The research team rigorously analyzed a series of Earth surface temperature averages dating back to 1850 from four major agencies that track average temperatures on the Earth’s surface, including NASA and the National Oceanic and Atmospheric Association (NOAA). I did. According to NOAA, the Earth’s temperature is rising by 0.11 degrees Fahrenheit every 10 years.
Specifically, this study analyzed ‘global mean surface temperature’ (GMST), which is widely studied to monitor climate change, but also presented some challenges. GMST tends to increase over time due to anthropogenic pressures and fluctuates over that period. -Period trends due to natural phenomena that affect global temperatures, such as large volcanic eruptions or El Niño Southern Oscillation. Distinguishing that natural variation from true fundamental changes in the pace of warming is therefore a statistical challenge, the researchers acknowledged.
In their analysis, an increase in warming surge was considered statistically detectable if it remained above a level that exceeded temporary fluctuations for an extended period of time. Imagine a temperature record plotted on a graph. A small change in slope will require more time to be detected as significant, but a large change will become apparent sooner.
The research team takes into account short-term average temperature fluctuations (which can mask long-term trends and make warming appear to be slowing or surging) and uses a variety of statistical techniques to predict global warming. determined the level of increase in global warming required to achieve Number of years specified for detecting surges.
For example, they determined that the rate of warming in 2012 would need to increase by at least 55% for the trajectory to become statistically detectable in 2024 and thus be called a “surge.” Another example shows that a change in the warming rate of about 35% in 2010 will become statistically detectable by about 2035.
The researchers applied that threshold to a statistical analysis of recent records dating back to the 1970s to see if temperature trends exceeded that threshold, but not beyond that threshold. It turns out there is nothing.
“Our concern with the current debate over the existence of a ‘surge’ is that there has been no rigorous statistical treatment or evidence,” said study co-author Rebecca Killick, professor of statistics at Lancaster University. “We decided to tackle this problem head-on by using all commonly used statistical approaches and comparing their results.”
Their study also provides minimum percentages of statistical detectability for the next few years until 2040.
“Along with the results, we provide scientists with a benchmark, a minimum threshold that must be exceeded before a change is detected,” Professor Killik explained. “We hope this will help bring more rigor to future discussions about potential surges and pauses.”
Although their findings show no statistical evidence that we are in the midst of a warming surge, Beaulieu said they do not deny the reality of climate change. emphasized.
“The Earth is the warmest it has ever been since instrumental records began due to human activity. And to be clear, our analysis shows that warming is occurring. “Professor Beaulieu said. “But even if global warming is accelerating, we still cannot statistically detect it.”
Further information: Claudie Beaulieu et al., “The recent surge in global warming is still undetectable,” Communications Earth & Environmental (2024). DOI: 10.1038/s43247-024-01711-1
Provided by Lancaster University
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