Brazil floods leave 150,000 homeless, scores dead or missing

Rescuers rushed to evacuate people stranded by devastating floods across the southern Brazilian state of Rio Grande do Sul on Tuesday, with at least 90 dead, thousands left homeless, and desperate survivors seeking food and basic supplies.

On the outskirts of Eldorado do Sul, 17 kilometres from the state capital of Porto Alegre, many people were sleeping on the roadside and told Reuters they were going hungry. Entire families were leaving on foot, carrying belongings in backpacks and shopping carts.

The flooding has hampered rescue efforts, with dozens of people still waiting to be evacuated by boat or helicopter from stricken homes. Small boats crisscrossed the flooded town searching for survivors.

The state's Civil Defense agency said the death toll had risen to 90 with another four deaths being investigated, while 131 people were still unaccounted for and 155,000 homeless.

The heavy rains that began last week have caused rivers to flood, inundating whole towns and destroying roads and bridges.

Rain is forecast to let up on Thursday but then continue through the weekend.

Climate experts attributed the extreme rainfall in Rio Grande do Sul to the confluence of a heatwave caused by this year's El Niño phenomenon, which warms the waters of the Pacific and brings rain to southern Brazil; a weaker cold front with rain and gales coming from the Antarctic; and unusual warmth in the Atlantic also raising humidity.

Global warming exacerbates these phenomena and intensifies the effects between such systems, making weather unpredictable, said Marcelo Schneider, a National Meteorology Institute (Inmet) researcher.