Floods in Brazil spark conspiracy theories over the cause, including toxic jet vapor trails and antennas in Alaska

• Floods in Brazil's Rio Grande do Sul have sparked a number of online conspiracy theories. 
• Some say the High-frequency Active Auroral Research Program has caused the extreme weather.
• Scientists have dismissed such theories.

The state of Rio Grande do Sul in southern Brazil has been facing heavy rains since last week, with 143 people confirmed to have lost their lives in the resulting floods so far, the local civil defense agency has said.

Eduardo Leite, the governor of Rio Grande do Sul, described the weather on X as "unprecedented" in the state's history, adding that it would need "a kind of 'Marshall Plan' to be rebuilt."

The state is prone to periods of severe rain and droughts due to its position at a meeting point of tropical and polar climates.

Brazil's National Institute of Meteorology has said the current extreme conditions have likely been influenced by El Niño — the warming of sea surface temperature.

Nevertheless, a number of bizarre online conspiracy theories have cropped up over what's behind it.

"What's happening in Rio Grande do Sul is definitely not natural," one user wrote on X. "Let's open our eyes!"

The user said they believed that the cause of the heavy rains was HAARP, the High-frequency Active Auroral Research Program, a North American scientific project that uses antennas to study a part of the Earth's upper atmosphere known as the ionosphere.

The program has long faced unfounded rumors that it was designed to control the weather, with former Venezuelan leader Hugo Chavez even claiming it caused the 2010 Haiti earthquake.

Some now claim that the rains in Brazil have been caused by toxic jet vapor trails, or "chemtrails," spread by the government and then activated by HAARP antennas in Alaska to alter the weather, AFP reported.

Vapor trails are condensation trails that occur when water vapor produced by jet fuel combustion turns into ice crystals at high altitudes where the air is cooler. The trails pose no risk to public health, per the Arizona Department of Environmental Quality.

Carlos Nobre, who heads Brazil's National Institute of Science and Technology for Climate Change (INCT), told AFP that scientists believed climate change had certainly played a key role in Rio Grande do Sul's weather crisis.

"The warmer atmosphere can store much more water vapor, fueling more frequent and intense episodes of rainfall that lead to disasters like this," he said, while also dismissing the HAARP theory.

"There's no way an instrument in the ionosphere could make weather events more extreme," he said.

It comes after recent heavy flooding in Dubai.

Dubai's media office said in April that the city experienced the heaviest downpour in the United Arab Emirates since records began.

Once again, social media was abuzz with claims about geoengineering — the idea that technologies could be used to alter the weather — with some suggesting that cloud seeding, where clouds are manipulated to produce more rain, had led to the heavy rainfall in the city.

But scientists said the storms behind the floods in the city were likely made worse by the climate crisis, adding that the El Niño pattern also helped intensify the weather.