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April is renowned for its unpredictable time in many regions of the world. In the German tradition, time in bad mood is captured in the saying April, April – that does what he wantsOr “April does what he wants”.
A “false spring” in the northern hemisphere can be followed by snowfall and temperatures below frost – all in a few days.
This rapid swing phenomenon between hot and cold extremes is also often described as a “cervical boost” and according to the latest research – on the contrary, unlike the meteorological tradition – it becomes more common as our planet warms up.
Research published in Nature Communications This week has revealed that more than 60% of the world has experienced more frequent, intense and faster flips between hot and cold extremes between 1961 and 2023.
The study identified striking examples such as cold hot flip in the rocky mountains in September 2020, where areas with a serious heat wave were covered in snow in a few hours because temperatures have dropped by more than 20 ° C.
The researchers analyzed the data over more than six decades to follow hot Flip events in cold when the temperatures went from a standard deviation (SD) above the average temperature to an SD below the average within five days-and vice versa.
They have found vast areas in the average latitude regions of Western Europe, South South and Southeast Asia, South America and the most southern region of Africa have experienced the biggest effects.
Physics behind the effect was “difficult”, a scientist who was not involved in the study, which attributed the increase in wild oscillations to an increased “undulation” of the jet flow that surrounds the globe as well as the evolution of the evaporation model as the planet warms up.
How did we do
To map the frequency of flip events, I downloaded the geospatial data provided by the authors here. They used temperature data from sources, including the European era5 of the fifth generation, Berkeley and American national centers for environmental prediction in their analysis (the three treated sets are available on the link). I only downloaded ERA5 data for mapping purposes.
The file contains all the variables that they have calculated: Flip Event Frequency, Intensity and Flip Transition Duration for cold heat and hot with cold oscillations for each of the four seasons as well as the annual average.
I was mainly interested in visualizing the most affected places for cold and cold hot and hot hot events, and I therefore used the R programming language to open the NetCDF file and extract the appropriate data layers (find my path around the file has taken a minute – too much dimensions!)
(Nerd Note: NetCDF, or Network Common Data Form, is a format that supports the creation, access and sharing of scientific data oriented towards the table.)
Some small multiple maps (using the Open Source GGPLOT package) have enabled a good overview of the data, but it was obvious that trends would be quite difficult to distinguish on this scale.
Instead, I calculated the average frequency of events on all years (1961-2023). After a few final data format adjustments, I styled the final data of the open source geospatial software.
Scientists have also modeled what would happen to return events under various emissions.
On average, FLIP events should increase in frequency and intensity and become faster in their swing transition in the coming years. In other words – temperature drops and even larger points, more of them, and faster swings.
The extent of the change depends largely on the emission scenario used as the multi-line graphic shows.
And finally, I created a simplified version of the explanatory diagram which was included in the newspaper to show the skilled swings as a flip event.
In a scenario of high greenhouse gas emissions which are the cause of climate change, research has revealed that the world population exposed to rapid temperature flips would be more than doubled by the end of the century – with the most affected low -income countries.
Wei Zhang, professor at Utah State University and study co-author, warned that the increased risk of flips can lead to “cascade effects on natural and built environments such as cultivated land, ecological systems and cities”.
Like the term “cervical boost”, this is largely due to very short time for humans and ecosystems to adapt.
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