Something very unusual is occurring in the Atlantic, and it has meteorologists worldwide perplexed. Meteorologist Ryan Maue recently provided a straightforward description of the issue, stating that “The Atlantic tropics are completely broken, unable to produce tropical storms, even with [with] off the charts ‘climate fueled’ oceans.”
Maue went even further, mentioning that "Our models no longer work... This is not normal.”
What’s happening in the Atlantic? On one hand, there are some well-known events taking place. For instance, dust from the Sahara is being carried westward, which is a common phenomenon. As some experts explain, more than a hundred million tons of mineral dust are transported from the Sahara Desert to Central America every year.
As surprising as it may seem, this process plays a significant role in fertilizing large areas of the Atlantic and supporting many ocean ecosystems. Additionally, it helps dry and stabilize the air at the ocean surface, increases wind shear, and ultimately inhibits the formation and growth of hurricanes.
But this isn’t all. As Maue pointed out, “the circulation from the Northeast Atlantic over the cold Canary Current has penetrated even more dry air deep into the tropics.” This is something we haven’t seen “in 50 years.”
This is striking because experts had expected a particularly intense hurricane season, but for all we know, this could be a much more serious change than it appears.
All eyes are on the Sahara, and not just because of the dust. In recent days, all weather models point to a near future where the Sahara Desert is going to experience a very abnormal rainfall episode. Some experts speak of a situation not seen in more than 50 years, with accumulated rainfall that will be 1,000% of the amount of water that normally falls in August and September.
The big question that meteorologists are beginning to ask themselves is whether this “rarity” can become a regular occurrence.
What happens if the intertropical convergence zone shifts? Overall, we can consider the northern hemisphere’s atmosphere as a “fringe system.” North of the equator, there exists a convergence zone, which experts describe as a narrow band of low pressure encircling the equator where the trade winds from both hemispheres meet. This description is quite accurate because most of this zone is situated south of the equator during the northern hemisphere’s winter and north of it in summer.
In other words, the zone tilts, largely accounting for the changes in monsoon patterns.
Two Hadley cells form at the edges of the convergence zone, which are high-pressure systems that contribute to atmospheric stability and create the planet’s major desert areas. Experts are now concerned about the potential repercussions of a northward shift in the zone.
It’s already happening. The Intergovernmental Panel on Climate Change’s Sixth Assessment Report indicated that since 1980, experts have observed expansion and displacement towards the north for the particular case of the cell located in the northern hemisphere. This may indicate that tropical cyclones could move towards higher latitudes, something that may already be occurring. Additionally, this could lead to the subtropicalization of the Mediterranean regions.
These changes entail the expansion of aridity zones, which could lead to more droughts, more extreme heat, and more irregular rainfall. While it’s too early to draw any conclusions, these disturbances are significant enough to warrant attention to what’s coming.
Image | Jacob Buller (via Unsplash)
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