Fact check – Weather map twisted to claim global temperatures have only risen 0.1 degrees and climate change is a ‘hoax’
A weather mapping tool from the University of Maine’s Climate Change Institute has been used to misleadingly claim that global temperatures have only risen 0.1 degrees Celsius and therefore climate change is a hoax , but the climatologist who runs the tool says that is not the case. .
Screenshots from the University of Maine’s Climate Reanalyzer, which describes itself as “a platform for visualizing climate and weather datasets”, (climatereanalyzer.org/about/) were posted with captions and comments posted alongside the screenshots say this shows it’s not much warmer now than the period between 1979 and 2000, and therefore climate change is a “hoax “. (here), (here),
A tweet read: “Global warming cancelled…again. Today, two days in a row, the estimated global temperature is 0.1°C below the 1979-2000 average. What melts is the climate hoax.
Aside from the fact that 0.1°C is a valid measure for change, there are multiple errors in the analysis of the weather maps provided in these articles.
Although the images appear to be actual screenshots from the Climate Reanalyzer (here), the conclusions drawn are inaccurate, according to Maine state climatologist Sean Birkel (here), which codes and maintains the tool (climatereanalyzer.org/about/).
“The temperature anomaly maps depict average conditions predicted for a single day compared to the 1979-2000 average for the same day of the year,” he told Reuters by email. “Daily temperature anomalies can vary significantly from day to day and week to week depending on prevailing weather conditions.”
Birkel directed Reuters to additional information included on the same web page the screenshots were taken from which reads: “The daily temperature anomaly values displayed on these maps reflect current weather conditions, and therefore global and regional averages can vary significantly from day to day and week to week. Climate trends should only be inferred from long-term data sets.
“The global 1-day average temperature anomaly can fluctuate on the order of 0.1°C from day to day depending on weather conditions,” Birkel explained. “The CR temperature anomaly map for Friday August 19, 2022 shows the Arctic at +1.1°C and the Northern Hemisphere at +0.7°C – these values are well above the 1979-2000 climate average On the same day, there are pronounced cold anomalies over Antarctica (-2.7°C), implying that the global average temperature anomaly on that day was strongly influenced by the particular weather pattern over Antarctica, but to determine a climate trend, it is necessary to examine several decades of temperature data.
Long-term measurements, such as those provided by the US National Oceanic and Atmospheric Administration (NOAA), show that between 1979 and 2021, average global temperature has increased by about 0.17 degrees Celsius per decade (here), many times higher than the 0.1 degree figure quoted in social media posts.
“The average global temperature on Earth has increased by at least 1.1° Celsius (1.9° Fahrenheit) since 1880,” according to NASA’s Earth Observatory website. “Most of the warming has occurred since 1975, at a rate of about 0.15 to 0.20°C per decade.” (go.nasa.gov/3AP7TkI).
Misleading. Screenshots of a weather map showing that a particular day was 0.1 degrees Celsius warmer than the 1979-2000 average do not reflect long-term temperature trends. Climatologists estimate that global temperatures have increased by 0.15 to 0.20°C per decade.
This article was produced by the Reuters Fact Check team. Learn more about our fact-checking work here.