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Antarctic sea ice melt favors cloud formation

May 13, 2021

A new study published in Nature Geoscience led by the Institut de Ciències del Mar (ICM) and the University of Birmingham (UK) has revealed that Antarctic sea ice melt enhances the formation of aerosols in the atmosphere which, in turn, favors cloud formation in summer and could help reduce the solar radiation received by the region and have important climate consequences. From data collected during the PI-ICE 2019 Antarctic campaign, led by Manuel Dall'Osto, researchers found that when air masses come from areas around the sea ice margin, aerosol formation episodes are more frequent. According to the study, these air masses contain high concentrations of sulphuric acid and amines, which are compounds of biological origin that interact with each other to transform from gases to particles. Although the role of sulphuric acid in the formation of polar aerosols was already known, this is the first study that demonstrates the key role of amines, nitrogen-containing organic compounds produced by the degradation of organic matter by micro-organisms that inhabit the sea ice. This confirms that emissions from marine plankton and sea ice melt play a crucial role in regulating Antarctic climate.

Brean, J., Dall’Osto, M., Simó, R., Shi, Z., Beddows, D. C. S., and Harrison, R. M. (2021). Open ocean and coastal new particle formation from sulfuric acid and amines around the Antarctic Peninsula. Nature Geoscience, 14, 383–388.

 

Earth's environmental stability allowed marine biodiversity to flourish

July 13, 2022

A diversification model has been developed that allows reconstructing the history of marine animal diversity from the Cambrian explosion, some 540 million years ago, to the present day. The work, published in Nature, indicates that today's biodiversity is the result of long periods of environmental stability on Earth that allowed the development of biodiversity hotspots, regions with a high number of species. The fossil record shows that life on our planet has been hit by at least five great mass extinctions over the past 500 million years. The mass extinction that occurred at the end of the Permian period, the largest of all time, wiped out more than 90% of marine species and brought ecosystems on the verge of collapse. Today, 250 million years later, life in the sea is more diverse than ever. To understand this, and overcome the problem that the fossil record is incomplete, a new computational approach has been developed that allows reconstructing the history of biodiversity. The model is able to recreate the geographical distribution of diversity in today's oceans, especially the hotspots, and reveals the mechanisms that have created them. This model illustrates that the time between one mass extinction event and the next is key to allowing biodiversity hotspots to develop. The new model also sheds light on one of the most controversial questions in evolutionary ecology: whether or not there is a limit to the global diversity that the Earth can support. Ecological theory states that as diversity increases and biological interactions, such as competition, intensify, the process of diversification slows to a halt. At this point, the emergence and establishment of a new species will inevitably lead to the extinction of an old one. However, some scientists have argued that Earth's ecosystems are so heterogeneous that there will always be room for more species. The results from the new model reconcile both views. While most of the oceans have levels of diversity well below their maximum, regions harboring biodiversity hotspots may be close to their limit. This modelling tool is very powerful because it allows to explore many things, including what would have happened if some of the great mass extinctions had never happened, or if they had happened at another time in Earth's history. Human interference in the natural functioning of Earth systems has prompted what experts call the sixth great mass extinction. According to the United Nations, as many species have disappeared in the last century as would have become extinct in 10,000 years assuming a normal scenario. In addition, 25% of the species evaluated by the International Union for Conservation of Nature are today in danger of extinction. This study shows that, if current trends continue, projected loss of biodiversity could take millions of years to recover, arguably beyond our own existence as a species.

Cermeño, P., García-Comas, C., Pohl, A., Williams, S., Benton, M. J., Chaudhary, C., et al. (2022). Post-extinction recovery of the Phanerozoic oceans and biodiversity hotspots. Nature, 607, 507–511.