Never in the past 1,000 years there had been such a high frequency of hurricanes in the Atlantic and present the conclusions of a study by the U.S. Penn State University published in the journal Nature.
Scientists from the University, led by Professor Michael Mann, examined sediments from the hurricanes that have crossed the coast of North America and the Caribbean, and found the actual number of hurricanes is historically high.
In the last decade has seen an average of 17 hurricanes and tropical storms, double that in the early twentieth century and a figure only comparable to and even surpassed, according to the study, during the climatic anomaly that occurred during the Middle Ages (the period Medieval Warming) some 1,000 years ago.
The investigation did not evaluate whether there is a relationship between increased episodes of this meteorological phenomenon and climate change and merely provide the empirical data.
In preparing the time series researchers studied sediment left inland, especially in the lagoons near the coast, winds of 300 kilometers per hour of hurricanes reaching impact on the earth.
We analyzed sediments from seven lakes in the U.S. coast and a lagoon in Puerto Rico, and made an estimate of the number of hurricanes occurred in every age from the number of them reached the coast (many are lost in the sea).
Professor Mann’s team also studied computer models of previous generation hurricane and took into account the main factors influencing the virulence of the phenomenon: the surface temperature in the tropical belt of the Atlantic Ocean, the cycles of El Nino and La Niña, which are generated on the east coast of the Pacific Ocean and the North Atlantic Oscillation.
Research suggests that although the frequency and intensity of hurricanes today and 1000 years ago are the same, they have the same causes behind or features.
1000 years ago, said Mann, a lengthy development of La Niña (a circumstance that affects the generation of hurricanes) coincided with a relatively warm weather in the Atlantic, which became the phenomenon into something more random and circumstantial.
In the last decade, however, the high number of hurricanes has only to do with a warming of Atlantic water, which establishes a pattern easier and more dangerous, because everything indicates that increased ocean temperatures in coming decades .
“Although activity levels are similar, between 1000 years ago and now, the factors involved are different,” Mann said. He warned: “This implies that all other things being equal, then the warming of the tropical Atlantic should lead to a growing increase in hurricane activity.”
