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Fact check: Misleading claim that high snow cover means no warming – USA TODAY


The claim: Post implies Northern Hemisphere snow cover disproves global warming

Greenhouse gas emissions related to human activity have caused nearly two degrees of warming since the late 1800s, according to NASA

However, some social media users are sharing an article that implies that relatively high November snow cover in the Northern Hemisphere is evidence that the Earth isn’t warming after all.  

The Dec. 3 article is titled “Global Warming? Northern Hemisphere Snow Cover At 56-Year High” and was published on the website Zero Hedge.

The article cited Rutgers University Global Snow Lab snow cover data for November and claimed that “most mainstream media outlets overlooked this data because it is an inconvenient truth for the climate change narrative they’re pushing.” 

A link to the article was shared more than 2,000 times on Facebook, according to Crowdtangle, a social media metrics tool. 

But the article is misleading. While mid-November snow cover did exceed the 56-year record for that specific week in mid-November, cover was not at an overall 56-year high. Further, global warming and climate change are processes that involve multiple Earth systems and are measured on long timescales, so short-term snow cover data is not enough to confirm or negate global warming, according to researchers.

The author of the article could not be reached. 

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Short-term snow cover data inadequate to assess climate change

Mid-November snow cover was higher than the highest total previously recorded for that particular week, according to David Robinson, Rutgers University professor and New Jersey State Climatologist who has operated the Rutgers University Global Snow Lab for decades. 

“In mid-November, the Northern Hemisphere snow cover extent … was at a record high for mid-November,” he told USA TODAY in an email. However, “during the season, we update the data every week.”

The following week, snow cover did not eclipse the record for that week, he said.

Additionally, the “record-breaking” week’s snow cover was simply the record for that specific mid-November week. Several weeks over the past 56 years have had greater snow cover, according to the Rutgers Northern Hemisphere Snow Extent Tracker.

Regardless, a single record-breaking week isn’t enough to assess whether or not Earth’s climate is changing, Robinson said.  

“This is a weekly look based on short-term prevailing weather patterns,” he said. “Time is needed to determine if a trend has become established and then, if so, you can start looking into why such a trend might exist.”

One example of such a long-term trend is the steady decline in springtime snow cover in the Northern Hemisphere over the last 56 years.

“The spring melt is coming sooner due to the warming temperatures,” Walter Meier, a research scientist at National Snow and Ice Data Center, told USA TODAY in an email. However, “even in a warming climate, big snow events and record levels are not surprising.”

At this point, the declining trend isn’t seen year-round, said Robinson. But increased average global temperatures don’t necessarily mean there will be less snow all the time everywhere – at least not right away. 

“Overall, as the Earth warms the trend has been or will be a decline in Earth’s cryosphere” (frozen or snow-covered areas), he said. However, “snow is a variable that is influenced by multiple other climate variables.”

For instance, warmer global temperatures mean that more water evaporates into the atmosphere, which can result in more snowfall.  

“Some areas are likely to get more snow before ultimately temperatures rise more consistently above freezing,” Robinson said. “It is a physical rule that a milder atmosphere has the potential to contain more moisture than a colder one. Thus, if an area warms but still remains below freezing you can potentially produce more snowfall.”

Fact check: Short term global temperature fluctuations do not negate climate science, overall warming

Ample evidence Earth’s climate is changing, temperatures are warming 

Because Earth’s climate systems are complex and subject to variability, researchers have evaluated multiple lines of evidence over long time frames to conclude that global warming is occurring.  

Evidence of global warming includes warming atmospheric temperatures, ocean warming, ice sheet and glacier melt, global sea level rise, the loss of Arctic sea ice, increased heat wave frequency and intensity and springtime snow cover loss in the Northern Hemisphere, according to NASA.

Snow cover loss, like Arctic sea ice loss, exacerbates global warming, according to the National Snow and Ice Data Center

“Where snow cover is disappearing earlier in the spring, the large amounts of energy that would have melted the snow can now directly warm the soil,” reads the center’s website. “With decreased snow cover, the Northern Hemisphere reflects less energy into space (and) absorbs more solar radiation, adding heat to the system and melting more snow.”

Fact check: Climate change measured in decades, day to day temperature fluctuation common

Our rating: Missing context

Based on our research, we rate MISSING CONTEXT a post that implies Northern Hemisphere snow cover disproves global warming. The “56-year high” snow cover referred to a record in mid-November as compared to the same time frame in previous years. It was not the highest snow cover when all data is considered. Furthermore, global climate change and its effects are measured over decades and not negated by specific weather events such as heavy snowfall in one place in one week.

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