Smoke haze from bushfires in 2019 during a spell of hot weather
Smoke haze from bushfires blanket Sydney in 2019 during an extended spell of warm weather. Image by Steven Saphore/AAP IMAGES

No, the warmest decade was not nearly 100 years ago

Meghan Williams August 10, 2022
WHAT WAS CLAIMED

The hottest decade on record occurred nearly 100 years ago.

OUR VERDICT

False. The hottest 10-year period was from 2012 to 2021.

A Facebook user who regularly posts about climate science claims the warmest decade on record was nearly 100 years ago.

The viral post by a New Zealand user is accompanied with an image of a US newspaper article about the country’s recent heatwave, drawing comparisons to periods of extreme temperature in the early to mid 20th century.

The post, which has attracted in excess of 10 million views, says “1934 was during the hottest decade on record”. 

But the claim is false.

While it is not clear if the author is referring to temperatures in the US, New Zealand or globally, the claim is false for all three.

The warmest 10-year period since temperature records began was from 2012 to 2021 globally, in the US and in NZ. 

The Facebook user, who regularly shares content regarding climate change, including here, here, and here, posted on August 3: “1934 was during the hottest decade on record but since so few of us were around then its understandable we wouldn’t remember. 1954 I wasn’t even a tap on Mum’s shoulder but this story from then is relevant right now.” 

2019 bushfires in Tahmoor, NSW
 It’s feared scenes like this during the 2019 bushfires will be more common if temps continue to rise 

Accompanying the post is an image of an article by US columnist and community historian, Brad Belk, about the 1954 Midwestern heatwave. The article was published on July 16, 2022 by the Missouri-based Joplin Globe during the July heatwave.

The article has also been shared by climate change sceptics here, here, and here.

The year in question, 1934, was indeed the hottest year of the Dust Bowl era in the US. But that record has been surpassed several times since then, particularly over the last 10 years.

US temperature data from the National Oceanic and Atmospheric Administration (NOAA) demonstrates that any 10-year period covering 1934 (or 1954) does not exceed the 2012 to 2021 period for the hottest decade. 

While the US did see some high maximum yearly temperatures in the 1930s and 1940s, maximum yearly temperatures have trended upwards, and minimum yearly temperatures have been climbing even more rapidly. The result is that average temperatures in the US have been at their warmest during the decade from 2012 to 2021.

Global temperature data from the NOAA also demonstrates the 10-year period from 2012 to 2021 was the warmest decade on record, with nine of the 10 warmest occurring during those years. Global temperature data from NASA varies slightly, but still shows the decade from 2012 to 2021 was the warmest. 

Dr James Renwick, professor of physical geography at Victoria University of Wellington, confirmed to AAP FactCheck that the post’s claim is false.

“Each decade has been getting warmer over the globe as a whole since the middle of last century,” Prof Renwick said in an email.

“When we look more regionally or locally, there’s more variability, and local temperature peaks have happened at various times in the pastÔǪ The bottom line though is that as the climate warms, we are seeing many more high temperature records set, more often and in more places, than we’re seeing low temperature records set.”

According to data from the National Institute of Water and Atmospheric Research (NIWA), New Zealand’s government-owned research institute, the warmest 10-year period on record in the country was also from 2012 to 2021. 

A spokeswoman from NIWA told AAP FactCheck via email that “any decade (10-year period) ending after 2016 was the warmest 10-year period on record.” 

Dr Nicolas Cullen, associate professor in the School of Geography at the University of Otago, said “the evidence for warming in Aotearoa New Zealand continues to build”.

“New Zealand experienced its warmest year on record in 2021, surpassing the previous record set in 2016,” Prof Cullen told AAP FactCheck in an email.

“Seven of the past nine years have been among New Zealand’s warmest on record. The winter in 2021 was also the warmest winter on record in New Zealand, surpassing the record set in winter 2020.”

The Verdict

The claim that 1934 was during the hottest decade on record is false. Data for global, US and New Zealand temperatures show that the 10-year period from 2012 to 2021 was the warmest decade. 

False ÔÇô The claim is inaccurate.

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