Why Europe Is Becoming a Heat Wave Hot Spot

France experienced its hottest May on record in May of this year. Spain, Italy and other countries were hit by a spring heat wave last month. Poland and other parts of Eastern Europe experienced a heat wave this month.

From Spain to the British Isles, temperatures are in the triple digits. Many countries are in the throes of a heat wave and some are in the throes of a long dry spell.

There are still two months to go.

The heat this year is in line with a trend. They claim that heat waves in Europe are increasing in intensity and Frequency at a faster rate than any other part of the world.

In heat waves around the world, global warming plays a role because temperatures are on average 2 degrees hotter than they were in the 19th century, before emissions of carbon dioxide and other heat-trapping gases became common. Extreme heat can take off from a higher point.

There are other factors that could make Europe a hot spot for heat waves.

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There are not exactly the same heat waves. A region of upper level low-pressure air that has been stuck off the coast of Portugal has caused the current hot weather in England and Wales. It was cut off from the mid-latitude jet stream which circles the planet at high altitudes.

Air tends to go toward them in low-pressure zones. The low-pressure zone has been drawing air from North Africa towards it. The hot air is pumping northward, according to a researcher at the observatory.

Changes in the jet stream have been linked to an increase in heat waves in Europe over the past four decades. Many European heat waves occurred when the jet stream split in two, leaving an area of weak winds and high pressure air between the two branches that is favorable to the build up of extreme heat.

The lead author of the study, Efi Rousi, said the current heat wave appeared to be linked to a double jet that had been in place over Europe for the past two weeks. Dr. Rousi said that the creation of the cutoff low could have been caused by this.

She said that it seemed this was favoring the heat wave.

Some of the reasons Europe is seeing more and more heat waves are being debated by scientists. It's hard to tease out specific influences from natural climate variability.

Warming in the northern part of the world, which is occurring much faster than other parts of the world, may be a factor. The temperature differential between it and the Equator decreases as the polar regions warm. The effect of decreasing summertime winds is that weather systems linger for longer. There is an increase in persistence.

Changes in one of the world's major ocean currents could affect Europe's climate. Dr. Rousi published a paper last year that showed that a weakened current would cause a change in atmospheric circulation that would lead to more dry summers in Europe.

In Europe, a heat wave can cause it to be more likely for others to occur in the same area because of the extreme heat.

A small amount of the sun's energy is used in the water to cool it. When a heat wave wipes out most of the soil, there isn't much left to dry. The sun adds to the heat by baking the surface.