As the lower atmosphere becomes warmer, evaporation rates will increase, resulting in an increase in the amount of moisture circulating throughout the troposphere (lower atmosphere). An observed consequence of higher water vapor concentrations is the increased frequency of intense precipitation events… — NASA’s Earth Observatory

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Just off the coasts of Colombia, Ecuador and Peru, the Pacific Ocean has been abnormally warm of-late. For the past month, sea surface temperatures have ranged between 3 and 5 degrees Celsius above average. This excess heating of the ocean surface, facilitated by human-forced climate change, has pumped a prodigious volume of moisture into the atmosphere of this coastal region. Southerly winds running along the western edge of South America have drawn this moisture north and eastward — feeding into the prevailing storms that originate on the Atlantic side of South America and track eastwards.

(Sea surface temperature anomaly map from Earth Nullschool shows 4 degree Celsius above average ocean surfaces just off-shore of Ecuadore and Colombia. These extremely warm waters have helped to fuel very severe storms over Peru and Colombia during recent weeks. Such warm ocean waters are not normal and their highest peak temperatures are being increased by a human-forced warming of the Earth, primarily through fossil fuel burning. Image source: Earth Nullschool.)

Lately, these systems have blown up to enormous size as they’ve run across the Andes or collided with pop-up storms along the coast. And the amount of rainfall coming out of the resulting monster thunderstorms has been devastating. In Peru, hundreds of thousands of people have been rendered homeless by these deluges which have caused the tragic loss of 100 souls, destroyed thousands of buildings, 200 bridges, and 2,000 miles of highway. For the state, the estimated damage toll from this ongoing climate disaster is now 6 billion dollars.

Friday night, a member of this new breed of monster thunderstorms, pumped to greater intensity by the moisture bleed off the record warm ocean waters, unloaded a total of a half-month’s worth of rainfall in just a few hours upon the small Colombian city of Mocoa. More than five inches fell in 1-2 hours on a region where three rivers run out of the mountains toward this community of 40,000. The deluge arrived in the darkness. Its ferocious intensity unleashed a massive flood of boulders, mud, and water as the combined rivers leapt their banks and invaded the town. A nearby hillside, unable to retain integrity beneath this merciless assault of the elements, gave way — burying a large section of Macoa in rubble.

(Extremely high atmospheric moisture loading in the thunderstorm system approaching the Macoa region on Friday, March 31 is indicative of global warming’s impact on the Earth’s hydrological cycle. As oceans and lands warm, the rate of evaporation and precipitation increases. This change generates more extreme versions of storms and droughts by increasing the highest peak intensity for such events. Image source: Earth Nullschool.)

Residents caught unawares were forced to immediately flee homes with little more than the clothes on their backs — carrying infants or dragging children in tow as the flood waters swirled around them and as a wall of moving earth, uprooted trees and large rocks tore through town. Many escaped, but an estimated 254 residents were not so lucky and are now counted among those lost to the raging torrent and landslides.

President Juan Manuel Santos declared the city a disaster zone Saturday even as relief workers searched for survivors in the rubble and as make-shift shelters and hospitals were set up to aid the injured and displaced. According to CBC:

Santos blamed climate change for triggering the avalanche, saying that the accumulated rainfall in one night was almost half the amount Mocoa normally receives in the entire month of March. With the rainy season in much of Colombia just beginning, he said local and national authorities need to redouble their efforts to prevent a similar tragedy (emphasis added).

(UPDATED)

Links:

More Than 200 Killed in Colombia Flood — Swept Away as They Slept

Desperation Sets in as Flood Death Toll Tops 200

Damages Mount in Peru Floods

Earth Nullschool

NASA’s Earth Observatory

Hat tip to Colorado Bob

Hat tip to Zeebra Designs