New research from the Great Blue Hole in Belize shows that tropical storms have been happening more often over the last 5,700 years, and there has been a big rise in the past 20 years. These storms, known as tropical cyclones, are becoming more common in the Caribbean and may increase even more in the future.
Scientists studied mud and sand collected from the bottom of the Great Blue Hole, which is about 50 miles off the coast of Belize and 410 feet deep. This hole formed around 10,000 years ago after the last ice age, when sea levels rose. They pulled out a long core of sediment, about 98 feet in length, which gave them a detailed history of past storms. This core is the longest continuous storm record in the area.
By looking at the layers in the core, the researchers could tell how many storms had happened over thousands of years. Normally, two layers of calm weather sediment are laid down each year, and any layer with storm debris shows when a cyclone hit. This helped the scientists count the years and match them to storm events, like counting rings in a tree.
They found that storm activity has been slowly increasing over thousands of years, but there’s been a sharp jump in the last two decades. Since the start of the Industrial Revolution, when humans began burning fossil fuels, the number of storms has risen more quickly. For most of the last 5,700 years, there were between four and sixteen storms per century. But in just the last 20 years, they found evidence of nine tropical storms hitting the same region.
Two things seem to be causing this rise. One is a shift in the Intertropical Convergence Zone (ITCZ), a band near the equator where winds from both hemispheres meet. This area has low pressure, high humidity, and lots of thunderstorms. It also includes the Hurricane Main Development Region, where most Atlantic hurricanes form.
Normally, the ITCZ moves slightly north in summer and south in winter. But over thousands of years, it has gradually shifted more to the south. This change may have caused the main area where storms form to move further south as well, bringing more storms to the Caribbean.
The second and more recent cause is human-driven climate change. Warmer oceans, caused by burning fossil fuels, are making it easier for tropical storms to form and grow stronger. This is why there has been a sharp rise in storm activity in just the past 20 years.
Based on the study, extreme weather in the region is expected to become even more common during this century. The researchers predict that up to 45 tropical storms and hurricanes could hit the Caribbean by the year 2100. This is much more than what the region experienced in the past 5,700 years. The scientists believe this is not just due to natural climate changes, but mainly because of rising global temperatures, warmer sea surfaces, and stronger La Niña events — all of which help storms form and become more intense.
