Fact check: Human activity, not temperature cycles, responsible for recent global warming – USA TODAY
The claim: Post implies climate change is ‘cyclical,’ not caused by humans
A graph featured in a Jan. 26 Instagram post (direct link, archive link) appears to show a pattern in historical global temperatures.
“Earth is on a 100,000 year Time/Temp clock, and we’re right on time,” the post’s caption reads. “Yep, climate change is a thing, but it’s boringly predictable.”
The graph, which is purportedly based on data from the National Oceanic and Atmospheric Administration, is titled “Changes in Temperature and CO2 Concentrations over the Past 422,000 Years.”
Other social media users interpreted the graph as proof that human activity is not to blame for increasing global temperatures.
“These roughly correspond to ice ages,” wrote one user. “We are coming out of an ice age. Yes, its getting warmer.”
The post was liked more than 800 times in five days.
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Our rating: Missing context
The implied claim here is wrong. The graph omits the most recent data on carbon dioxide and temperatures, according to a NOAA scientist. Climate researchers have ample evidence that greenhouse gas emissions from human activity are causing global temperatures to increase at an unprecedented rate.
Graph missing vital information, according to NOAA scientist
Text included in the graph says it is based on data from the Vostok ice core, a large cylinder of ice extracted from the Antarctic ice sheet in 1998.
Scientists are able to analyze air trapped within the ice to study past changes in the composition of gasses, including carbon dioxide, going back several climate cycles.
Howard Diamond, senior climate scientist at NOAA’s Air Resources Laboratory, confirmed the graph in the post matches the historical data from the Vostok ice core records. However, Diamond said the graph is presented in a misleading way.
“The Instagram post shows that CO2 and temperature are related, which they very much are,” Diamond told USA TODAY in an email. “Unfortunately, what it fails to do is to show the spike in CO2 over the past 100 years.”
According to NOAA data, the global average of atmospheric carbon dioxide hit a new record high in 2021 of 414 parts per million. The highest level shown in the chart is under 300 parts per million.
The unprecedented increase of carbon dioxide emissions from human activity has altered the cyclical nature of Earth’s heating and cooling patterns, according to Diamond.
“Our planet should actually be cooling, not warming as it is now, continuing a long-term cooling trend that began 6,000 years ago,” Diamond said. “Unfortunately, the effects of climate change from the human emission of CO2 are quite real, and the cause is from a scientific standpoint unequivocal.”
Fact check: Global temperatures have steadily risen over the past century, contrary to post
Ample evidence greenhouse gas emissions from human activity behind global warming
Greenhouse gases like carbon dioxide and methane warm the lower atmosphere by slowing the escape of heat into space, according to the Environmental Protection Agency.
As a result, the earth’s temperature has risen by about 0.14 degrees per decade since 1880, according to NOAA data. Since 1981, the rate of warming has more than doubled, rising at a rate of .32 degrees per decade.
There are a myriad of ways that scientists know greenhouse gas emissions related to human activity are causing global temperatures to rise, NASA climate scientist Josh Willis previously told USA TODAY.
“The amount of warming we see matches what we expect based on the increased CO2 we’ve added,” Willis said. “The timing of the warming matches the timing of the CO2 increase caused by people. Not only that, the timing of global sea level rise matches the CO2 increase.”
Fact check: Global warming caused by greenhouse gas emissions, not mysterious ocean warming
Diamond and Willis both noted that researchers were able to match the specific type of carbon found in fossil fuels to the excess carbon dioxide building up in the atmosphere.
The only explanation for global climate change that accommodates all the evidence is the increase in greenhouse gas emissions from human activities, according to Willis.
“Scientists have looked for other sources of heat, cycles of the sun, volcanos on the sea floor and pretty much everything else you can think of,” Willis said. “Nothing besides humans burning fossil fuels can explain all of these things.”
USA TODAY reached out to the social media users who shared the post for comment.
Our fact-check sources:
- USA TODAY, Jan. 20, Fact check: Global warming caused by greenhouse gas emissions, not mysterious ocean warming
- GRID-Ardenal, 2005, Temperature and CO2 concentration in the atmosphere over the past 400 000 years
- Howard Diamond, Jan. 27, Email exchange with USA TODAY
- NASA Vital Signs of the Planet, accessed Jan. 31, Sea level
- NASA Vital Signs of the Planet, accessed Jan. 31, Carbon dioxide
- NASA Vital Signs of the Planet, Aug. 14, 2017, Core questions: An introduction to ice cores
- NASA Vital Signs of the Planet, accessed Jan. 31, Global Temperature
- NASA Vital Signs of the Planet, accessed Jan. 31, Global Warming vs. Climate Change
- NASA Vital Signs of the Planet, accessed Jan. 31, Is the sun causing global warming?
- NOAA, June 23, 2022, Climate Change: Atmospheric Carbon Dioxide
- NOAA, updated Jan. 18, 2023, Climate Change: Global Temperature
- U.S. Environmental Protection Agency, Aug. 1, 2022, Climate Change Indicators: Greenhouse Gases
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