Global warming coincides with fewer tropical storms forming around the world each year than in the second half of the 19th century, according to a new study.
The average annual number of hurricanes fell by 13% in the 20th century, with a more sharp decline after 1950, according to new research.
Several studies using climate models have shown that global warming can reduce the total number of storms generated, but more severe and dangerous systems can be reduced.
The authors of the new study, published in the journal Nature Climate Change, said their findings were in line with expectations that the planet will experience fewer storms in general.
Understanding how climate change affects hurricanes has been difficult because the most reliable and complete satellite observations did not begin until the late 1970s, and this relatively short time frame makes it difficult to separate the effects of global warming from natural climate variation.
The report states that areas prone to floods and storms in eastern Australia may be “unsecured” by 2030. Scientists from Australia and the United States have used climate models and historical atmospheric pressure observations to calculate the possible number of hurricanes from 1850 to 2012.
Decreases were seen in all seven oceans where the storms formed. Worldwide, the number of hurricanes was found to have dropped by 23% annually after 1950, from 13% for the entire 20th century.
The only exception to the larger decline in hurricanes after 1950 was in the North Atlantic, where hurricane numbers had increased in recent years, but were still lower than in the second half of the nineteenth century, according to the report. study.
Dr Savin Chand, lead author of the study, from Federation University of Australia, said: ‘As the climate warms, the underlying weather conditions that contribute to the formation of storms are likely to change. Communities were exposed.
The study was set up not to look for different categories of storms, but to calculate which storms could form.
Category 1 storms often cause only minimal damage to buildings and farms, while the most devastating Category 5 storms, with average winds in excess of 200 km/h, cause billions of dollars in damage and widespread destruction of communities.
Chand said storms have intensified in recent years and are approaching the shores.
Co-author Professor Kevin Walsh of the University of Melbourne said the most complete data on storms only came from the 1970s, with some ship records going back to the 1940s before that, but these were incomplete. models by showing that they agree with observed trends. ”
Walsh added that as tropical ocean temperatures rise, warm air rises will decrease, with the difference in wind speed closer to the surface and higher in the atmosphere two less favorable factors for storm formation.
“Extreme tornadoes really do do most of the damage,” he said, “and there are good theoretical reasons to believe that these tornadoes will increase in the future.”
MIT hurricane expert Professor Kerry Emanuel said he disagreed with the study’s findings, which suggested less hurricane propensity in general.
He explained that climate models are still “too crude” to accurately calculate tropical storms, and he also said he has doubts that the methods used in the new study are accurate enough to give a confident picture of the past, and agree that it exists. There is strong consensus that the intensity of tropical hurricanes will increase in conjunction with global warming.
“In practice, severe tropical storms strongly dominate Category 3 and beyond damage, while weak storms dominate the annual population, so trends in total numbers are less significant for social impacts,” he said. said Emanuel.
source: theguardian
Source: Arabic RT
