A few years ago, a group of Canadian atmospheric scientists and their international colleagues discovered high amounts of ammonia in the summertime air above the Canadian Arctic Archipelago region. Naturally, they wanted to figure out where the ammonia was coming from.
That group published the answer and further findings i. Media coverage that followed summarized it quite succinctly in headlines: bird poop.
鈥淲e identified a fascinating, albeit somewhat comical, connection between Arctic seabirds, atmospheric particles, clouds and climate,鈥� says Betty Croft, first author of the study and research associate with 麻豆传媒鈥檚 Department of Physics and Atmospheric Science.
Together with Dal鈥檚 Randall Martin, Jeff Pierce and colleagues from an NSERC-funded research network called , Dr. Croft used a combination of observations and computer modeling to assess the influence of Arctic seabird droppings on atmospheric particles and cloud formation.
鈥淏ursts鈥� of particles
Every summer, tens of millions of seabirds flock to the Arctic where their nitrogen-rich diets lead to droppings, or guano, that release ammonia into the air.
The molecules of ammonia cluster together with other gas molecules rising from the ocean. This forms small particles that act as 鈥渟eeds鈥� for cloud formation, because they collect, through condensation, enough vapours in the atmosphere to create tiny drops of water. Those droplets form low clouds in the sky.
The observed 鈥渂ursts鈥� of the newly formed atmospheric particles in the summertime sky can lead to changes in clouds, like how bright they can become. This study shows that clouds are getting brighter in the summer, thanks to more 鈥渟eeds鈥� present in the atmosphere. The brighter the cloud, the more solar energy it reflects back into space, cooling the area below.
Dr. Croft explains that clouds play a key role in controlling Arctic temperatures, making factors that influence clouds 鈥� like seabird guano 鈥� a hot topic in climate science.
鈥淭he Arctic, as we know, is experiencing rapid warming,鈥� says Dr. Croft. 鈥淚t鈥檚 very important to understand the set of interconnections that exist within the arctic climate system,鈥� she says.
Connections in the climate puzzle
Dr. Croft鈥檚 study identifies a set of connections that hadn鈥檛 before been recognized as having a role in the Arctic climate system.
鈥淭he findings are surprising, and support the precautionary principle; there are likely [other, similar] interconnections between the living and non-living components of Earth鈥檚 climate system that we don鈥檛 yet understand,鈥� says Dr. Martin, a co-author of the study and head of the at Dal.
While the study now identifies Arctic seabirds as a piece of the complex climate puzzle, both Dr. Croft and Dr. Martin note the magnitude of this modest guano-initiated cooling effect has not been enough to prevent the warming currently observed in the present-day Arctic. The findings point to the importance of connections between ecology, chemistry and climate and highlight the need for further research to better understand such connections.
The study will also be useful momentum for upcoming research activity at the new Ocean Frontier Institute (OFI). The study brings forward the significance of atmosphere-ocean interactions. Dr. Martin, an OFI researcher, explains the same factors influencing atmospheric particles and cloud formation also influence visibility, drizzle and fog. This crucial ocean-atmosphere interaction and its impact on marine safety is one of OFI鈥檚 core areas of research.
鈥淚t鈥檚 exciting to identify a new connection,鈥� says Dr. Croft. 鈥淚 think our findings really highlight and remind us that Earth鈥檚 climate system is characterized by many interconnecting components.鈥�
And sometimes, it just takes a whole lot of bird droppings to help us understand that one by one, and all together, every living thing has a connection to our Earth鈥檚 changing climate.