Halloween Special: Speed of Seasons

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Time flies. Yesterday it was still summer, now it is already autumn, and in some regions of the world nature is preparing for winter. From one day to the next leaves turn from green to colorful yellow, red or in-between and overnight they are dead on the ground. It is impressive to see how fast nature is reacting to seasonal changes and preparing for the next chapter. Have you asked yourself how fast this change happens?

But let’s not talk again about end of life let’s focus already on the next iteration. After winter there will be spring and life will be back in full bloom (literally). But how fast is spring?

The blossom of apple trees is well understood. In Europe it unrolls from southwest to northeast, from Portugal to Finland covering a distance of roughly 3,600 km. Apple trees start to bloom in Portugal at the end of February whereas in Finland you have to wait until the end of May! This means that the blossom unrolls with 40 km per day. But this velocity can be only applied to lowlands, for every difference in height of 30 meters an additional day is required.

There is a country well known for its blossom forecast competence: Japan and its cherry trees. It is a scientific side discipline of the meteorology. For that there are official observation trees, which are located at the 58 Japan Meteorological Agency offices across the country. The blossom starts officially with “first bloom” which means that an observation tree has five to six flowers that have bloomed (read here more about the forecasting method and flowering meter of the Japan Meteorological Corporation JMC). It finalizes into “full bloom” which means 80% of the observation tree flowers have bloomed. On average, a tree fully blooms a week after first bloom.

The blossom of the cherry trees starts in the southwest mid of January in Okinawa (which has no official observation trees), reaches the first main island Kyushu end of March and continues to the northeast up to Hokkaido end of April covering a distance of roughly 2,500 km. While looking on the map you also can clearly see the impact of mountainous regions such as the Japanese Alps, which put dents into the contour lines.

The hype about the cherry blossom has already become a branch of tourism. You can find instruction how to plan you trip for Hanami in 2025 but also other cities have taken up the idea of cherishing the cherry trees and providing information where to find proper spots.

But the world is in constant change even if we think that the world rotates faster everyday. In the next 100 years the rotation of earth will slow down by 1.22 milliseconds. Until now we only had a slow down by one millisecond per century (e.g., between 1920 and 1940). Between 1960 and 1980 we already had a slow down of 0.31 milliseconds.

All of this is happening because of the melting of polar ice and the rise of the sea level. The distribution of the mass is changing and decelerates the rotation of earth. But there is also a small counter-measure: Currently the mass of the ice is pressing on Earth’s surface, which is reaching into the semifluid part of Earth. If this brake is released the inner part can flow without disturbance and rotation speeds up again by 0.8 milliseconds per century.

In the worst-case scenario with very tense climate change the battle between speeding up and slowing down will be won by slowing down by up to 2.62 milliseconds per century. In comparison: The tidal caused by the moon is slowing us down by 2.4 milliseconds per century (see this paper for more details). What do you think: Is it curse or treat that we will have a little bit more time to “enjoy” changing seasons? Meanwhile GEONATIVES wishes a happy Halloween!