Fact check: Short term global temperature fluctuations do not negate climate science, overall warming
The claim: Global temperatures have dropped to "30-year baseline," down significantly since 2016
Average global temperatures have risen by roughly one degree Celsius – about two degrees Fahrenheit – since 1880, according to NASA. Other independent, long-term climate datasets corroborate that finding.
However, some social media users have been disseminating a blog post that claims global temperatures are in decline.
"Earth's average temperature drops to 30-year baseline, down .71 C (a little over one degree Fahrenheit) since 2016 peak," reads the blog link in a March 2 Facebook post.
The blog argues that this finding challenges the idea of a consequential or dangerous global warming trend.
"In other words, it’s get (sic) harder and harder for the politicized ‘catastrophic global heating’ narrative to be maintained," reads the blog.
The blog garnered hundreds of interactions on Facebook, Twitter and Reddit. .
However, the blog is misleading. It cherry-picks data from a short time frame that does not reflect the overall warming trend documented by multiple climate monitoring agencies. It also leaves out key context that explains the downward trend in the last few years.
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USA TODAY reached out to the blog author and social media users who shared the claim for comment.
Blog references warm, recent "baseline"
The blog references data from the University of Alabama in Huntsville (UAH) dataset, which reports temperatures recorded by instruments on a collection of satellites from the National Oceanic and Atmospheric Administration, NASA, and European. UAH houses data dating back to 1978.
The blog says February 2022 temperatures did not exceed that of the UAH dataset's "30-year baseline." This is accurate – with a caveat.
It is common practice for climate data agencies to report global temperatures as variations from a stated baseline, rather than reporting actual temperature values. Different baselines may be used depending on both the agency and the context in which the data is being reported.
The UAH dataset currently reports monthly temperature changes compared to a 1991-2020 baseline.
This timeframe – which itself reflects temperatures demonstrably higher than the pre-industrial era – is currently recommended by World Meteorological Organization as a "standard reference."
Fact check: False claim that Arctic, Antarctic ice reached record highs
Despite the February 2022 result, UAH reports a February warming trend of about 0.16 degrees Celsius per decade since the late 1970s, John Christy, a professor and director of the Earth System Science Center at UAH, told USA TODAY in an email. Overall warming was roughly 0.13 degrees Celsius per decade.
Appearance of "downward trend" due to record-setting 2016 temperatures, El Ni?o-Southern Oscillation
As the blog states, the global average temperature reported by UAH for February 2022 was about 0.7 degrees Celsius lower than in 2016.
However, contrary to the blog's claims, this finding does not contradict the overall warming trend reported by multiple climate science agencies.
This is because, while global temperatures are rising due to human-generated greenhouse gas emissions, the climate is also subject to natural variability, Ahira Sánchez-Lugo, a NOAA climatologist, previously told USA TODAY.
One example of this variability is the El Ni?o-Southern Oscillation – a natural phenomenon that can cause short-term warming or cooling of global temperatures.
These warming and cooling phases are referred to as El Ni?o and La Ni?a, respectively.
In 2016, a very strong El Ni?o contributed to record high global temperatures. Since then, four La Ni?as have contributed to comparatively lower temperatures, Sánchez-Lugo said.
Even though the years since 2016 have been among the warmest on record, the fact that most are not as warm as 2016 itself results in the appearance of a "downward trend."
Similar short-term "downward trends" occurred in global temperatures after the 1998, 2007 and 2010 El Ni?os, Gavin Schmidt, director of NASA Goddard Institute for Space Studies, told USA TODAY. However, these were merely fluctuations in a consistent warming trend that continues to the present.
The existence of a statistically significant warming trend does not require that every month or year be warmer than all previous months or years, he said in an email.
Defending the blog post, author Cap Allon attributed temperature changes to low solar activity.
"Earth's lower tropospheric temperatures have fallen dramatically since their 2016 peak, in line with historically low solar activity, while all the while CO2 levels have been increasing exponentially," Allon told USA TODAY in an email.
Some critics of the human-driven climate change concept say that fluctuations in sun intensity are actually responsible for global warming. However, the sun's irradiance has decreased over the past few decades while temperatures have risen sharply.
According to both NASA and NOAA, solar fluctuation could only account for a small fraction of warming since the pre-industrial era.
USA TODAY has previously addressed other social media posts that attempt to minimize the significance of global climate change by cherry-picking data.
Fact check: Greenland is still losing ice; no reversal in trend
For instance, social media users identified a "downward trend" in NOAA data and claimed that the dangers of climate change were exaggerated. As in this case, the trend was driven by 2016 record high temperatures followed by multiple La Ni?as.
Our rating: Missing context
Based on our research, we rate MISSING CONTEXT the claim that global temperatures have dropped to a "30-year baseline," down significantly since 2016. The "30-year baseline" references a timeframe already impacted by global warming. A massive El Ni?o in 2016, followed by multiple La Ni?as, contributed to the appearance of a short-term "downward trend" even as temperatures continue to rise overall.
Our fact-check sources:
Ahira Sánchez-Lugo, Feb. 24-25, Email exchange and phone interview with USA TODAY
Gavin Schmidt, March 15-22, Email exchange with USA TODAY
John Christy, March 22, Email exchange with USA TODAY
USA TODAY, March 1, Fact check: Japanese Meteorological Agency data shows warming on Japanese island
USA TODAY, March 9, Fact check: Misleading data used in claim alleging a global cooling trend
NASA, accessed March 16, World of Change: Global Temperatures
Met Office Climate dashboard, accessed March 16, Annual global mean temperature difference from pre-industrial conditions
NASA, January 13, 2021 tied for 6th Warmest Year in Continued Trend, NASA Analysis Shows
NASA, January 13, 2021, Six Questions to Help You Understand the 6th Warmest Year on Record
NASA, accessed March 18, Carbon dioxide
University of Alabama in Huntsville, accessed March 18, Global temperature graph
NOAA, accessed March 21, Global Climate Report 2021
NOAA, accessed March 21, Global Surface Temperature Departures (oC), colored by monthly ENSO values
NASA, accessed March 21, Global temperature
University of Alabama in Huntsville, accessed March 21, Global temperature report
NOAA, August 10, 2017, International report confirms 2016 was warmest year on record for the globe
NOAA, May 5, 2014, What is the El Ni?o–Southern Oscillation (ENSO) in a nutshell?
The Washington Post, Jan. 13, The past seven years have been the hottest in recorded history, new data shows
IPCC, accessed March 22, Frequently asked questions
NASA, Sept. 6, 2019, What Is the Sun's Role in Climate Change?
NOAA, Oct. 29, 2020, Couldn't the Sun be the cause of global warming?
NASA, accessed March 23, Temperature vs. solar activity chart
World Meteorological Organization, May 5, 2021, Updated 30-year reference period reflects changing climate
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This article originally appeared on USA TODAY: Fact check: Apparent recent cooling influenced by El Ni?o, La Ni?as
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