Summer moves forward 11 days in 50 years

Summer is happening 11 days earlier than 50 years ago lending more scientific weight to global warming theories, according to two university academics.

In ‘Is the onset of the English summer advancing?’ two University of Sheffield geographers show warmer temperatures arriving earlier.

Amy Kirbyshire, a former undergraduate and professor Grant Bigg head of the department of geography, compared dates for the first appearance of summer flowers to the start of warm weather over the last 50 years.

The first flowering dates of 385 plant species that flower in early summer (May and June) were used as an indicator of the start of summer.

Research showed summer has come forward by 11 days in the 1990s compared to the period 1954 to 1963.

At the same time early summer flowering has moved forward by three days, but if this analysis is extended to 2007, it reaches 18 days.

Previous research into seasonal change has shown an early spring and a delay in the start of autumn, as opposed to any changes to the summer.

Professor Bigg now hopes to investigate whether or not summer coming forward may have encouraged drought or heatwaves.

He said: “There has been a lot of attention paid to the shift to earlier springs but we’ve shown similar advancement in summer conditions.

“This could have the same implications as the shift to earlier springs for increased ecological divergences, as well as extending the time for summer weather extremes.”

Luke Walsh

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