The frigid air that invaded the United States from the Arctic during the past week has tied or broken nearly 400 cold-temperature records, including all-time November records, across a broad swath of the country.
Yet over the long-term, data shows cold outbreaks of this severity are becoming a rarity, as warm-temperature records outpace their cold counterparts by an increasingly large margin. Nationwide, warm records have been outpacing cold by a 2-to-1 margin so far this decade, whereas in a relatively static climate, one would expect that to come out about evenly over the long term.
The findings are consistent with what would be expected in a climate that is warming due to increasing levels of greenhouse gas emissions from burning fossil fuels, such as coal and oil, for energy.
In Washington, the climate is becoming incredibly skewed in the warm direction, even though we can still get cold snaps like the ongoing event. Between 2010 and Nov. 14, 2019, daily temperature records were set for maximum temperatures 96 percent of the time, compared with just 4 percent for daily cold minimums during that period.
That is a huge change from the early part of the instrumental temperature record, when the global climate was much cooler. During the decade from 1900 through 1910, for example, Washington had 45 percent daily record maximums compared with 55 percent daily record minimums, but that became skewed more toward warm records thereafter. For Washington, the ratio became extraordinarily unbalanced, with daily record lows in the single digits percentage-wise starting in 1990, according to NOAA temperature data analyzed and provided to The Washington Post by the climate research and journalism group Climate Central.
Washington is not the only location where these trends are taking place, either.
In Chicago, the period from 2010 to Nov. 14 of this year also shows way more record daily highs compared with record lows, when viewed as raw numbers or as a percentage basis. Percentage-wise, the disparity is 74 percent for record daily highs and 26 percent for record lows. Interestingly, the 1990 to 2000 period in Chicago had more daily record lows compared with record highs.
In Minneapolis, which is often significantly affected by Arctic outbreaks, record highs are beating out record lows by 92 percent to 8 percent since 2010, the NOAA/Climate Central data shows.
And in Houston, which was also affected by the current cold snap, the current decade has a 89 percent to 11 percent split between daily record highs and record lows, through Thursday.
In addition, data shows that since 1970, winter cold streaks are lasting for at least one day shorter in most of the 244 U.S. cities Climate Central analyzed, with an average reduction of nearly five days.
The Climate Central analysis is backed up by the National Climate Assessment, the latest of which was released in 2018 and found that across the United States, “Heatwaves have become more frequent … since the 1960s, while extreme cold temperatures and cold waves are less frequent.” It projected these trends to continue, with an increase in heat-related fatalities likely to outpace any decrease in cold weather fatalities.
New climate realities await
New climate research published this week finds that based on computer model projections, parts of the world may see their seasonal climate conditions “rapidly shift” away from historical conditions dating back to preindustrial times. The study, published in the journal Earth’s Future, examines changes to the variability of daily temperature and precipitation for different levels of surface temperature increase.
One conclusion the researchers, from the Center for International Climate Research in Norway, found was that in parts of Europe and the United States, “wintertime cold days will disappear more rapidly” than hot days will increase. This would have the effect of reducing the variability of the U.S. climate.
Elsewhere, though, including Africa and the Arctic, the study projects that climate conditions will “rapidly transition” out of the range of preindustrial variability “and into a climate state not yet experienced by modern society.”
The study does not provide information at a high-enough resolution to get down to regional or local levels, however, so there may be exceptions to the broad projections the researchers make.