Meeting on so-called chimney effect

Transcript

Dozens of scientists have converged on Guam this week to study a so-called chimney effect given off by the warm waters around the territory, and the influence it has on the global climate.

Ross Salawitch is one of the principal investigators for the project called CONTRAST, or Covective Transport of Active Species in the Tropics.

He told Jamie Tahana that the scientists are trying to understand how this  phenomenon works, and how it methane - one of the main catalysts of climate change - can be dispersed.

ROSS SALAWITCH: Our specific goals are to understand how marine biology, which produces gasses that get released into the atmosphere, how those gasses are moved through the atmosphere by convection - or clouds.

JAMIE TAHANA: So why the waters around Guam in particular?

RS: So in the equatorial regions accessible from Guam we tend to have the warmest sea surface temperature anywhere, anytime on earth. So, meteorologists use a term called CAPE, that stands for convective available potential energy, and we know that, again, looking at data over many years, CAPE tends to maximised [in] January and February to the south of Guam.

JT: What do you hope to understand?

RS: First off, we have multiple goals but one of our primary goals is to understand how organic halogens, so chemicals with a carbon and either chlorine, bromine and iodine, how they are redistributed through the atmosphere. Halogens have a very important effect on ozone, both in the troposphere where we live and in the stratosphere where ozone protects us from ultraviolet light. So one of our goals is to understand how convection and marine biology effects halogens. But our broader goals are to understand how this phenomenon called the atmospheric chimney sets the composition of the entire global troposphere; the clean unpolluted part. So, if you will, humans act on a background. Ironically, we know a lot more about pollution and its effects on background than we do about the precise composition of background or, say, remote, clean marine tropical air. So, we're going after that, one of our partner missions is trying to understand what controls the amount of water vapour in the stratosphere which has major implications for understanding one of the feedback mechanisms of climate change.

JT: The climate change aspect. What can we learn from that?

RS: One of the primary goals of our mission is to understand how pollutants are lost in the atmosphere even though most pollutants are released at mid-latitudes and, I must say, generally in the northern hemisphere because that's where more people live and where more industrialisation is. Many of those pollutants like methane, the second most important greenhouse gas, they're actually lost in the tropics. The loss process for methane in the tropics involves reaction with a chemical called hydroxyl, the hydroxyl radical. So, our mission is designed to probe hydroxyl radical concentrations in the tropical atmosphere - it's very important for controlling atmospheric methane - and this will be very important for us to understand how methane is lost from the atmosphere, so that's one of our climate-related goals. Methane of course the second most important greenhouse gas and the one that can induce major short-term change.