Temperature graph misrepresented to deny climate change
CLAIM: A graph from the National Oceanic and Atmospheric Administration displaying land and ocean temperatures over the last eight years shows that the Earth has been cooling, not warming, proving that global warming from carbon emissions is a hoax.
AP’S ASSESSMENT: False. A small portion of the graph showing only the period between 2015 and 2022 has been taken out of context to make the incorrect claim. The larger graph from which it was isolated displays temperature trends over more than 140 years, showing a dramatic upward trend. Experts say El Niño and La Niña cycles have impacted the last eight years, but more reliable climate data must be measured over periods of decades.
THE FACTS: Social media users are misrepresenting a small portion of a graph from NOAA to support the erroneous claim that global temperatures are falling rather than rising, meaning global warming is not real.
“Last 8 years... global cooling... at a rate of 0.11°C/decade.... despite 450+ billion tons of emissions worth 14% of total manmade CO2 in the atmosphere. CO2 warming is a hoax,” wrote one Twitter user in a post that received nearly 10,000 shares and more than 13 million views.
The user shared an image of a graph with NOAA’s logo that displayed eight red bars corresponding with global land and ocean temperatures from 2015 to 2022. While some of the years fluctuate, a black line placed over the top appears to show a slight downward trend. A key on the graph says the overall temperature decreased 0.11 degrees Celsius during that period.
“The 8-year temperature time series shows the annual global mean surface temperatures for the most recent eight years,” said Jeffrey Hicke, a professor at the University of Idaho’s Department of Earth and Spatial Sciences. “It is accurate as shown, but is misleading.”
That’s because while the last eight years trended slightly downward, this small period of time was greatly impacted by El Niño and La Niña cycles, experts explained. Zooming in on just this period does not discredit the overall upward trend of global temperatures over the past century.
The full NOAA graph, which displays temperature trends over a period of 142 years, from 1880 to 2022, shows a dramatic rise in global average temperatures. Hicke said the graph in its full context is “much more appropriate for assessing the influence of human activities on climate.”
NOAA’s National Centers for Environmental Information said in a statement that although the climate is warming, it is also subject to natural variability as it is impacted by weather events such as El Niños and La Niñas.
El Niños are a phenomenon that bring unusually warm temperatures across the central and eastern tropical Pacific Ocean, while La Niñas bring unusually cool temperatures. El Niños and La Niñas affect global weather patterns and temperatures, NOAA scientists explained. During El Niños, global temperatures tend to be warmer than years when La Niñas were present. Global temperatures tend to be slightly cooler, though still above average, during La Niñas.
In its statement, NOAA said that 2015-2016 experienced a strong El Niño, which helped boost global temperatures to record highs. But since then, about three La Niñas have helped slightly cool global temperatures.
“The selected timeframe from 2016-2022 can create the appearance of a cooling trend,” the agency said, adding, “this is why when computing trends we use timescales of at least 10 years.”
John Knox, a professor at the University of Georgia’s Geography Department who studies the dynamics of weather and climate, said the claim in the tweet “is a classic example of cherry-picking the end points of a time series to seemingly prove a false point.”
He similarly pointed out that isolating just the last eight years to claim that global temperatures are cooling does not account for the El Niño and La Niña cycles.
“It’s a very short period of time, which reduces the statistical significance of claims of a trend,” he wrote in an email, adding, “The rising temperature trend over the decades is obvious.”
Despite increasing online misinformation on the topic, overwhelming scientific evidence shows global warming and climate change are real and caused by human activity, including human-caused carbon dioxide emissions, as the AP has previously reported.
This is part of AP’s effort to address widely shared misinformation, including work with outside companies and organizations to add factual context to misleading content that is circulating online. Learn more about fact-checking at AP.