Spring in February? No, it’s not just something you think

In the last 90 years, spring has been moved by two weeks. It’s just the beginning: In 2050, spring starts this week!

March 20 is the vernal equinox in 2023. This is the day when night and day are of equal length. Or when the sun’s path crosses the equator from south to north to be as precise.

With more and more sun in circulation, it is quickly getting warmer and the signs of spring are piling up.

… Crocuses, goslings, outdoor pilchards, birds and things like that. Finally spring!

The spring equinox dividing line may have been fairly precise before, but not now. As a result of global warming, we are seeing major shifts in how the seasons unfold.

The new normal, i.e. the last 30 years, shows that spring is coming much earlier than before.

• Between 1931 and 1960, spring started on March 20.
• Between 1961 and 1990, spring started on March 17.
• Between 1991 and 2020, spring started on March 7.

The figures are from the measuring station at Blindern in Oslo and drawn up by the Meteorological Institute. Time intervals as long as 30 years are used to obtain more robust measurements.

And since these are average measurements over 30 years, one can argue that spring actually starts even earlier than 7 March. The period from 1991 shows an extreme temperature increase in the world.

A spring?

Winter is the loser in climate change. It has so far lost 22 days. Summer has rapped ten of them, while spring and autumn distribute the rest. This means that three out of four seasons have become longer, while winter has also become milder.

We calculate this with seasons climatologicalclimatologicalClimatology, climate science, the science of the climate, the statistical description of the meteorological conditions in the different geographical areas and/or the physical processes that control the climate. Source: snl.no. definitions. Spring is defined here as when the temperature is somewhere between 0 and 10 degrees on average during the day.

It is researcher Helga Therese Tilley Tajet at the Meteorological Institute who has found the data material for Aftenposten. If you look past the hard facts, she summarizes the winter in Oslo in more everyday terms.

– There are several such zero days with slush, ice and rain. Winter is therefore experienced as greyer. The winter has become milder, especially in Oslo, which is in the zone where there are now several days around zero degrees during winter, says Tajet.

This year, with the exception of one day, there have been plus degrees on average every day since 8 February.

You can’t say exactly when spring started last year since weather and climate are two different things. What is known from last year is that the temperature started to rise on 23 February.

Remember this date: 23 February, we will return to it.

Stores will change in the future

Much is known about how climate change will change the seasons in the future. The uncertainty in the calculation depends on how much emissions can be cut.

Therefore, in the climate work, different models are used depending on how much greenhouse gases are released. The calculations in this case were made by Hans-Olav Hygen. He is head of the department for climate services at the Meteorological Institute.

Here he has looked at how the average temperature in June, July and August will be over the next 30-year periods. In the graphs below, we use three scenarios for what will happen in the future.

1. Here, the world manages the Paris Agreement’s goal of a maximum of 2 degrees of warming. That, says Hygen, is “at best”.
2. We manage to stop global warming at three degrees. A “probable” outcome, according to Hygen.
3. If the world’s emissions are not cut, but continue to increase fully in the decades ahead. This is the “worst case”.

To translate the graphic, in 30 years there will be 155 to 160 summer days a year in Oslo. In the 1960s there were 129 summer days. This is almost independent of whether large cuts in emissions are implemented or not. The positive effects of any climate cuts we manage to implement will only come later.

If you continue to emit the same amount of greenhouse gases as before, in 60 years you will have summer temperatures for half the year. During the day, in such a worst-case scenario, you will have average temperatures of 25 degrees in the summer months – including the cold days, which will still come.

There will be more heat waves and the frequency of extreme rainfall will increase.

Then we have a completely different climate than today.

February 23?

In this climate, where summer ends and spring is pushed further towards Christmas, there are good calculations for when the seasons will start and end.

If we look forward in time and use the definitions for this with medium and high emissions as last time, we get the following figures:

• In 2050 with medium emissions, spring will start on 23 February.
• In 2050 with high emissions, spring will start on 17 February.

It is the time after 2050 that the effect of the climate cuts will be decisive. If we extend the time axis further, to the period between 2071 and 2100, spring will start at the turn of January to February and summer will start in mid-April.

If this happens, according to climate scientist Hans Olav Hygen, we will have a climate similar to Nice, in the very south of France.