Bacteria feeding on Arctic algae blooms can seed clouds

Bacteria feeding on Arctic algae blooms can seed clouds
A 2009 phytoplankton bloom in the Bering Sea. Cloud seed bacteria may feed on phytoplankton. Credit: NASA, Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center

New research finds Arctic Ocean currents and storms are moving bacteria from ocean algae blooms into the atmosphere where the particles help clouds form. These particles, which are biological in origin, can affect weather patterns throughout the world, according to the new study in the AGU journal Geophysical Research Letters.

Particles suspended in air called aerosols can sometimes accelerate ice crystal formation in , impacting weather climate and . Such ice-nucleating particles include dust, smoke, pollen, fungi and . Previous research had shown marine bacteria were seeding clouds in the Arctic, but how they got from the ocean to the clouds was a mystery.

In the new study, the researchers took samples of water and air in the Bering Strait, and tested the samples for the presence of biological ice nucleating particles. Bacteria normally found near the sea floor was present in the air above the , suggesting and turmoil help make the bacteria airborne.

Oceanic currents and weather systems brought bacteria feeding off to the sea spray above the ocean's surface, helping to seed clouds in the atmosphere, according to the new research.

"These special types of aerosols can actually 'seed' clouds, kind of similar to how a seed would grow a plant. Some of these seeds are really efficient at forming cloud ice crystals," said Jessie Creamean, an atmospheric scientist at Colorado State University in Fort Collins, Colorado, and lead author on the new study.

Understanding how clouds are seeded can help scientists understand Arctic weather patterns.

Pure water droplets in clouds don't freeze until roughly minus 40 degrees Celsius (minus 40 degrees Fahrenheit). They are supercooled below their freezing point but still liquid. Aerosols raise the base freezing temperature in supercooled clouds to minus five degrees Celsius (23 degrees Fahrenheit), by providing a surface for water to crystalize on, and creating clouds mixed with supercooled droplets and ice crystals. Mixed clouds are the most common type of clouds on the planet and the best for producing rain or snow.

"Cloud seeds," like the bacteria found in algae blooms, can create more clouds with varying amounts of ice and water. An increase in clouds can affect how much heat is trapped in the atmosphere, which can influence climate. The clouds' compositions can affect the Arctic's water cycle, changing the amount of rain and snow that is produced. Increasing the number of clouds and changing the composition of Arctic clouds also affects northern weather systems, potentially affecting weather trends worldwide, the authors of the new study said.

Bacteria feeding on Arctic algae blooms can seed clouds
This illustration shows how cloud seeds may interact with a phytoplankton bloom and weather events, eventually rising to the atmosphere. Credit: Creamean et al/Geophysical Research Letters/AGU.

Without ice nucleating particles, precipitation from clouds is less likely to happen, Heike Wex, an at the Leibniz Institute for Tropospheric Research in Leipzig, Germany, unaffiliated with the new study explained.

From the ocean to the atmosphere

To learn how biological "cloud seeds" travel from ocean depths to the atmosphere, Creamean and her colleagues took samples from 8 meters (26 feet) below the water's surface and air samples roughly 20 meters (66 feet) above the water's surface in the Bering Strait during an algae bloom.

Algae blooms are big increases in photosynthetic plant-like microorganisms that many ocean animals eat, including some kinds of bacteria. The researchers found bacteria known to seed clouds at the bottom of a phytoplankton bloom in the Bering Strait, but not in the surrounding air. The scientists found the same bacteria roughly 250 kilometers (155.3 miles) northwest of the bloom, suggesting a strong current transported the bacteria to a new spot. The bacteria were also in the air above the water. A storm brought the bacteria from the ocean depths to the surface, transporting the bacterial "cloud seeds" into the air in water droplets.

"What existed at the bottom of the was making its way up to the surface waters," Creamean said.

Since the scientists only were able to take samples from 20 meters (66 feet) up, they don't yet know how the ice nucleating particles ascend to cloud elevation, which on average starts at 1.9 kilometers (1.2 miles) above the surface.

The are experiencing rapid warming from climate change. The Arctic's accelerated warming could cause more algae blooms as well as more bacteria of the type found to seed clouds, in turn further affecting its weather systems, according to the authors.

"This is a piece of the puzzle as to how these clouds form in the Arctic and potentially impact weather patterns all over the world," Creamean said.

Explore further

Distortion of water droplet surface may increase the likelihood of the droplet freezing

More information: J. M. Creamean et al, Ice Nucleating Particles Carried From Below a Phytoplankton Bloom to the Arctic Atmosphere, Geophysical Research Letters (2019). DOI: 10.1029/2019GL083039
Journal information: Geophysical Research Letters

Citation: Bacteria feeding on Arctic algae blooms can seed clouds (2019, August 29) retrieved 15 September 2019 from
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Aug 29, 2019
The ocean indices ENSO and Arctic Oscillation are closely related

Probably important to understand the natural variability before anything else

Aug 29, 2019
This beginning to sound like the start of the next ice age. Clouds in the Arctic dropping snow on the adjacent land. When not all the snow melts in one summer, the snow/ice starts to build up - and spread south. This was postulated in Science Journal back in the late 1950's. Of course, by 1970, researchers were talking about global warming - including some of the same researchers.....

Aug 30, 2019
Seems like your understanding of the climate has been tombstoned ;)

Aug 31, 2019
I sure don't claim to 'understand' climate - and how it changed in the last century, of which I saw more than half. Asked a Real Estate Agent one time, about an area I wasn't familiar with, "What's the climate like there?" He answered, "Climate is what you expect, weather is what you get."

All I can do is follow the arguments on the subject. That's 'arguments' in the old fashioned sense - a presentation of facts and opinions, not yelling at one another.

Read a page from NASA earlier. Seems that in a report on a recent temperature anomaly was given as 0.03°C, with an 'error bar' of 0.18°C. Worked for a scale company back in the early 70's. When I looked at those temperature figures I thought - I've put a 50# test weight on a scale - and my reading could be anywhere between +300# and -300# - a factor of six. Since I have no way of knowing just where on the 'error bar' the true reading falls, I'm up the proverbial creek in a chicken-wire canoe, with a crowbar for a paddle.

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