Scientific rambling
The recent cold snap was "really untimely" for some friends, bringing heavy snow and ice that trapped many people on the highway, and the road home became extremely difficult. Many people may ask, isn't it said that global warming, why is there such an annoying cold snap? A new study in the UK may answer that question.
Earlier this year, the UK Met Office announced that the average global temperature in 2023 was 146°c。This made it the hottest year on record, 017°c。
However, shortly after the announcement, the Met Office also said that the cold Arctic air will continue for many days, bringing sub-zero temperatures and snow and ice to many parts of the UK. When the cold snap arrived, the temperature dropped to -14°C in the Scottish Highlands and -11°C in England.
Ten days later, temperatures in a village in the Scottish Highlands climbed to a mild 19At 9°C, it was the hottest January on record in the UK. This seems to be more in line with the trend of global warming. However, just another ten days later, much of the UK was once again hit by unusually cold and snowy weather. It's not just the UK, Canada, the US and China have all seen record low temperatures this winter.
Seventy or eighty-year-old grandfathers and grandmothers may tell you that half a century ago, long ice cubes hung on the eaves every winter, but now there is no such sight. But no one on Earth can really experience the "global average annual temperature" and the extent of global warming over the past century, the researchers say. The change in the winter scene is not necessarily due to warming, but may also be due to changes in factors such as architectural deconstruction.
This means that we often have a hard time feeling or recalling seasonal averages and how they change over time. We can detect climate change in environmental changes such as glacier retreat or early flowering of plants, and we can track changes with instruments, but it is still difficult to "feel" climate change.
Weather phenomena are very rapid and changeable compared to climate characteristics that are defined and changed on longer time scales. The weather may be hot one day and cold the next, but the average annual climate does not suddenly change from warm to cold. Climate is essentially the accumulation of weather over a considerable period of time. For example, weather information may refer to the local temperature at noon or 4 p.m., daily minimum, average or maximum temperature, or weekly average temperature, while the climate is long-term.
For example, climate information might refer to the average temperature of a month, or the average temperature of a season (three months), year, or decades. In climate analysis, we typically look for anomalies related to a "baseline", which may be a long-term average of 30 or 50 years of data.
We can use more than a century of data to discover patterns, such as the close relationship between global atmospheric CO2 in the figure on the left and the temperature close to the surface. Of course, since climate change is not entirely smooth, there are also some 0sChange around 1°C – the oscillation in the red line. That's why 2016 was unusually hot, and the years that followed were slightly cooler.
These changes become more noticeable when we zoom in and examine smaller areas or shorter units of time. For example, the graph above shows data for the Central England temperature record, the longest lasting instrumental temperature record in the world, from 1659. This graph shows the average winter and summer temperatures in the Midlands of England, with a larger variation of around 1°C in both indicators over the same period since 1850. The internal variability of these seasonal instruments essentially obscures such regional-scale long-term climate change until the sixties of the twentieth century.
If you look at the graph on the right – 174 years of data – it's hard to spot recent climate change, but zooming down to the global annual average on the left makes the long-term trend clear.
Zooming out a little bit to see how the weather changes on a daily basis in Oxfordshire, UK. The histogram below shows two 21-year periods of daily minimum temperatures (Figure 2 on the left).a and 2c) and the average daily temperature (Figure 2 on the right.)b and 2d）。
Charts show that even during the recent period 2002-2022, the likelihood of Oxfordshire experiencing sub-zero weather is still high. However, the daily minimum temperature "tail" of the average is thinner, so extremely cold temperatures are less common. In recent times, the average daily minimum temperature has been 059°C (blue number) increased by about 1°C to 16 ° C, while the average daily temperature increased by 129°C – Both of these increases are greater than the global warming during this period.
These signs suggest that Oxfordshire is experiencing a long-term warming trend, with its winters warming slightly faster than the rest of the world. Global climate change makes extreme heat more likely, even in winter. Global warming hasn't completely made the winter cold snap disappear, but it does reduce the likelihood of a cold snap occurring.