Weather fluctuates. Hot July in 2012 doesn't show climate change is a hoax | Fact check
The claim: US July temperatures show climate change is a hoax
An Aug. 3 Instagram post (direct link, archive link) shows a screenshot of U.S. temperature maps originally posted on X, formerly Twitter, by Steve Milloy, a skeptic of human-driven climate change.
"12 years of emissions down the drain: July 2024 cooler than July 2012 in the US by average and max temperatures," reads text above the temperature maps. "Ask a climate hoaxer to 'splain that."
The Instagram post, which garnered more than 400 likes in a few days, included a caption that also called climate change a "hoax."
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Our rating: False
Multiple lines of evidence show Earth's average temperatures are warming. National Oceanic and Atmospheric Administration data shows average and maximum temperatures were cooler in the U.S. in July 2024 than in 2012, but that is due to weather fluctuation, not a lack of overall global warming.
Climate change doesn't mean every July will be hotter than the previous July
The maps in the post were created by meteorology company WeatherBELL Analytics using data from the PRISM Climate Group, according to Christopher Dickson, a meteorologist at WeatherBELL. Chris Daly, an Oregon State University professor who founded the PRISM Climate Group, told USA TODAY the group's preliminary data does show July 2024 was cooler than July 2012.
He said the preliminary July data needs more quality control work and significantly more data would be added to it in the coming months. He also said PRISM data should not be used to analyze climate trends because it is not adjusted to account for "temporal changes in station data availability, observation time, equipment and sighting, etc., all of which can bias the results."
NOAA data, which accounts for these issues, also reports maximum and average temperatures in July 2012 were warmer than July 2024. But this doesn't show global warming is a "hoax."
Fact check: False claim Earth is 4 degrees cooler than 'medieval times'
Milloy, in a video he sent to USA TODAY, argued that if greenhouse gas emissions from human activity are causing Earth to warm, and humans have continued to produce greenhouse gases since 2012, then July 2024 should be warmer than July 2012. But this reasoning is flawed.
This is because Earth's temperature patterns are influenced by both accumulating greenhouse gases and natural variability – such as weather and cyclical climate patterns like the El Ni?o-Southern Oscillation. This variability means a modern July won't necessarily be hotter than every previous July even though the planet is warming overall.
"Global warming is a long-term trend, but that does not mean that every year will be warmer than the previous one," The Royal Society reports.
While July 2024 was cooler than July 2012, it was still the 11th-warmest July in NOAA's 130-year record. NOAA data also shows a clear long-term warming trend for the month of July in the U.S. and for annual temperatures in the U.S. and globally.
Long-term trends, typically involving decades of data collection, are what scientists are referencing when they talk about climate, according to NOAA.
The post's "comparison between July 2012 and 2024 is not sufficient to draw conclusions about climate trends in the United States nor globally," Dickson said.
Multiple lines of evidence show Earth's climate is changing due to human activity
There are many ways scientists know Earth's climate is changing and that the change is driven by greenhouse gas emissions from human activity. In the mid-1800s, researchers demonstrated that CO2 is a greenhouse gas ? a substance that warms the planet by absorbing and redirecting radiation otherwise destined for space.
Researchers have been documenting rising CO2 levels for decades. They can tell the CO2 is from human activity because a disproportionate amount of it contains the kind of carbon found in fossil fuels and because the excess matches the amount humans have put into the atmosphere once natural processes are accounted for.
Researchers have also been documenting the simultaneous rise in global temperatures and have found "the amount of warming we see matches what we expect based on the increased CO2 we've added," Josh Willis, a NASA climate scientist, previously told USA TODAY. Additionally, "the timing of the warming matches the timing of the CO2 increase caused by people."
Scientists have also documented the consequences of this warming in the U.S. and globally. These include:
Ice sheet melting in Antarctica and Greenland
Earlier ice breakup dates in Alaskan river systems
Changes in the ranges of various marine species
An increase in the frequency of heat waves
Shrinking snowpack in the western U.S.
Changing time frames for the emergence of leaves and flowers in the spring
An increase in flooding events due to sea level rise
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The Instagram user who shared the post did not provide evidence to support the claim.
Our fact-check sources:
Chris Daly, Aug. 7, Email exchange with USA TODAY
Christopher Dickson, Aug. 7, Email exchange with USA TODAY
NASA Vital Signs of the Planet, accessed Aug. 8, Causes
NASA Vital Signs of the Planet, accessed Aug. 8, Ocean warming
NASA Vital Signs of the Planet, accessed Aug. 8, Ice sheets
NASA Vital Signs of the Planet, accessed Aug. 8, Sea level
NASA Vital Signs of the Planet, accessed Aug. 8, Arctic Sea Ice Minimum Extent
NASA Vital Signs of the Planet, accessed Aug. 8, Carbon dioxide
Environmental Protection Agency, July 2022, Climate Change Indicators: Heat Waves
Environmental Protection Agency, February 2023, Climate Change Indicators: Marine Species Distribution
Environmental Protection Agency, July 2022, Climate Change Indicators: Snowpack
Environmental Protection Agency, September 2023, Climate Change Indicators: Coastal Flooding
Environmental Protection Agency, April 2021, Climate Change Indicators: Leaf and Bloom Dates
Environmental Protection Agency, July 2022, Community Connection: Ice Breakup in Three Alaskan Rivers
Environmental Protection Agency, August 2016, Climate Change Indicators: Glaciers
Environmental Protection Agency, May 2014, Climate Change Indicators: Bird Wintering Ranges
Environmental Protection Agency, July 2022, Climate Change Indicators: U.S. and Global Temperature
USA TODAY, March 31, 2022, Fact check: Short-term global temperature fluctuations do not negate climate science, overall warming
USA TODAY, March 1, 2022, Fact check: Japan Meteorological Agency data shows warming on Japanese island
USA TODAY, Dec. 20, 2023, How we know humans are causing warming: A brief history of climate science | Fact check
USA TODAY, Nov. 28, 2022, Fact check: Earth's warming well documented, other planets' climate data limited
USA TODAY, Jan. 20, 2023, Fact check: Global warming caused by greenhouse gas emissions, not mysterious ocean warming
NOAA, March 23, 2018, What’s the Difference Between Weather and Climate?
NOAA, July 17, El Ni?o & La Ni?a (El Ni?o-Southern Oscillation)
NOAA, Aug. 8, Assessing the U.S. Climate in July 2024
NOAA, accessed Aug. 8, National Time Series (July max temperature)
NOAA, accessed Aug. 8, National Time Series (July average temperature)
NOAA, accessed Aug. 8, National Times Series
NOAA, accessed Aug. 8, Global Time Series
NOAA, Oct. 12, 2022, How do we know the build-up of carbon dioxide in the atmosphere is caused by humans?
The Royal Society, March 2020, If the world is warming, why are some winters and summers still very cold?
The Washington Post, June 11, Anatomy of a flood
The Washington Post, Dec. 14, 2022, The surprising reasons parts of Earth are warming more slowly
Carbon Brief, Aug. 11, 2022, The Arctic has warmed ‘nearly four times faster’ than the global average
The Conversation, July 31, 2020, John Tyndall: the forgotten co-founder of climate science
UCAR, accessed Aug. 8, History of Climate Science Research
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This article originally appeared on USA TODAY: Earth's warming. But each July isn't hotter than the last | Fact check
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