The clocks have been turned back once again, ending Daylight Savings Time (DST), or British Summer Time, for 2024 – an annual practice long criticized by politicians, doctors and travellers.
Scientists are also divided on whether changing the weather might have the power to reverse climate change. A study published in Environmental Research Letters last year found that DST reduces the energy needed to cool office buildings in the summer by nearly 6%. When the clocks go forward in the spring, workers arrive at the office an hour earlier “in the cool of the morning,” said Anthropocene Magazine. They also leave earlier, “which is usually when the demand for cooling is greater.”
“Energy use in buildings is a major contributor to carbon emissions, so understanding how to reduce energy demand for heating and cooling is important in combating climate change,” said the independent science journal published by Future Earth.
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But this study’s findings don’t necessarily apply worldwide—other research on DST’s environmental impact has been far less conclusive.
Mixed findings
Daylight saving time became official when Germany adopted the practice (in part, to conserve coal during the war) in 1916, soon followed by the UK, but its potential energy benefits were being considered much earlier.
Benjamin Franklin is credited with the “original concept”, BBC Future said. The US founding father analyzed candle consumption in 1784 and suggested that people “change their general sleeping hours to save money on lighting costs.”
Now, with climate change accelerating, scientists are seriously considering whether an annual time shift helps or hurts the environment.
Arizona is one of the few US states to ditch DST, and it does so specifically to save energy. The hot desert state implemented it in 1967, but removed it the same year after “the clock change caused an increase in energy consumption.” People had to run their air conditioners longer into the evening, driving up costs. (However, the Navajo Nation inside Arizona adjusts its clocks to DST.) As the globe warms, more states and countries “may follow suit.”
But several studies published in the US and Europe conclude that DST has “very little effect on energy conservation”, Euronews said.
A study by researchers at the University of Prague used data from 2010 to 2017 to estimate that DST in Slovakia had led to energy savings of just 0.8% of annual electricity consumption.
Another study by the US Department of Transportation in 1975 had similar findings. DST reduced about 1% of the nation’s energy use because “much of the energy saved by not turning on the lights in the evening was offset by turning them on in the morning.”
When DST doesn’t save
Experts have also questioned the date of the change of hours. In Italy, the Association of Environmental Medicine calculated that €70m (£58.6m) could be saved in fuel bills simply by pushing the date back by a month.
Natural time zones as close as possible to solar time are likely to “better match the diurnal light and temperature curves to our schedules,” Euronews said.
“This can lead to energy savings in industrial and other lighting early in the morning, early morning heating during the colder months as people leave for work an hour later, and less air conditioning needed in the car during the journey after work and in the evening at home.”
“It’s Slowing Down the Whole Earth”
Scientists have long debated whether DST could affect climate change, but talk of whether climate change could affect DST is much quieter.
But a study published in Nature last year suggested that, in fact, climate change could affect the measurement of time in general. Our universally accepted measurement of time, Coordinated Universal Time (UTC), is related to the duration of one complete rotation of the Earth on its axis and the average of 400 atomic clocks.
“Since the 1970s, UTC has added 27 leap seconds at irregular intervals to keep pace with atomic clocks as the Earth’s rotation has gradually slowed,” Heatmap said. Then, in 2016, this rotation began to accelerate.
Timekeepers have now identified the need for negative “leap seconds” to account for this, Duncan Agnew (the geophysicist behind the study) told Heatmap. These are timing adjustments needed to account for the increasing speed of the Earth’s rotation. Climate change has caused the ice to melt in sufficient quantities to change the rate of rotation of “the entire Earth in a way that is visible”.
This makes the DST debate even more complicated. “Just the fact that we can say, ‘Look, this is slowing down the whole Earth,’ seems like another way of saying that climate change is unprecedented and significant,” Agnew said.
