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Start Chemistry in the Atmosphere: Key in the Fight Against Climate Change
18 June 2015

Chemistry in the Atmosphere: Key in the Fight Against Climate Change

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The atmosphere and the oceans have become warmer, the volumes of snow and ice have decreased, the sea level has risen and the concentration of greenhouse gases has increased significantly. By the end of the 21st century the surface temperature is likely to be 1.5°C higher than in the period from 1850 to 1900. All this is certain to cause global changes in the climate that will have implications for hundreds of years to come, at the very least. These are some of the findings highlighted by the IPCC in its fifth assessment report published in 2014. This report contains a detailed description of the observations made in the atmosphere, the oceans, the cryosphere and the rest of the Earth’s surface. All these data are incorporated into climate models that reproduce patterns and trends in surface temperature and other parameters at the continental scale observed over a period of many decades. These observation-based studies and combined models uncover trends and offer forecasts on the magnitude of global warming in response to past and future overactivity.

Knowing what’s happening in the atmosphere

Although climate models have improved over the years, all these conclusions entail reasonable uncertainties due to our insufficient knowledge of chemistry and the behavior of our atmosphere. This produces a degree of unreliability in the forecasts, which often leads to a lack of firm consensus regarding the implications of climate change, and the inability to take adequate measures. The analysis of this report reveals that although everyone knows the impact of gases like CO2 on global warming, the greatest uncertainties –both in terms of their role in climate change and in their evolution– concern the behavior of short-lived gases such as ozone, and the formation, presence and evolution of aerosols and their forerunners. Generally speaking, we could say that these uncertainties are constrained by our failure to properly grasp the reactions that these compounds generate, process and eliminate, and their physical and chemical interaction with solar radiation. The atmosphere is a highly reactive medium in which a particular compound is subjected to the influence of a number of factors that can alter its state. To effectively predict the composition and evolution of the atmosphere and the climate, all these chemical and physical processes need to be clearly characterized in the different conditions in which they may occur.

It has recently been demonstrated that in large parts of the planet, the greatest source of destruction of ozone in the troposphere (the lower region of the atmosphere in contact with the Earth’s surface) is its reaction with iodine. Furthermore, in certain conditions these reactions may give rise to the generation of aerosols, which also play a key role in the processes of warming or cooling of the Earth. It is therefore essential to study the processes involving iodine in order to gain a greater understanding of our atmosphere and be able to ensure greater precision in our climate models.

The oceans and iodine

The main sources of emissions of iodine compounds are the oceans. In them, the iodide from the sea water reacts with the ozone on the surface and produces emissions of reactive iodine (I, I2, HOI, etc.) that are responsible for the processes mentioned above. Furthermore, algae in coastal areas, in addition to phytoplankton (aquatic organisms in plankton), are also responsible for the emission of reactive iodine as a result of their biological processes. This reactive iodine can be found all over the planet, and while it tend to be concentrated around the tropics, large concentrations have been detected over the Antarctic, a region that has crucial importance in the climate processes of the planet. It has also been predicted that the increase in tropospheric ozone caused by human emissions in the industrial age has led to a considerable rise in the concentration of iodine in the atmosphere, which underlines the importance of including all these processes in chemical-climate models. Many of the factors affecting these processes are unknown, and particularly those concerning the interaction of the iodine compounds found in aerosols, and the role they play in their evolution and interaction with other pollutants.

The aim of our research group (formed by researchers from the Institute for the Structure of Matter at the CSIC in Madrid and the School of Industrial Engineering at the University of Castile-La Mancha in Toledo) is to determine the mechanism that produces these processes and thus be able to quantify them. We therefore undertake combined studies of laboratory work and theoretical calculations that allow us to recreate, understand and quantify these reactions. By duplicating these reactions under controlled laboratory conditions we can quantify the processes and separate the contributions of the different factors that affect them (pressure, temperature, humidity, solar radiation, presence of other substances, and so on). In addition the theoretical calculations (through quantum chemistry calculation programs) allow us to predict the behavior of the different species that interest us based on their reactivity to other molecules or to solar radiation. These calculations are particularly important when there is no experimental data available, or when the measurement of these variables involves sophisticated and complex laboratory experiments which would be costly to carry out.

We have recently also launched a crowdfunding campaign through the Precipita project of the Spanish Science and Technology Foundation, FECYT. The aim is to raise awareness of our project and obtain funds to help us develop this research and continue contributing to the knowledge and understanding of the atmosphere and climate.

Go to the original Spanish  version of this article in madri+d, here.

Óscar Gálvez

Department of Molecular Physics, Institute for the Structure of Matter, CSIC

Maria Teresa Romero Baeza

University of Castilla-La Mancha, School of Industrial Engineering.

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