A LOCAL ENVIRONMENTAL scientist thinks too little attention is being placed on water vapour or H2O gas as a contributing factor to global warming. Mark Harris, professor in the Department of Biology and Chemistry at Northern Caribbean University, has argued that the popular villain - carbon dioxide (CO2) - might be eclipsed by water vapour in contributing to global warming.
"Popular perception links CO2 with the 'bad guys' - the big oil companies with whom many associate greed and insensitivity. On the other hand, pure, clean water is associated normally with life and health," Harris recently told a gathering at the Mandeville-based university while delivering a public lecture on global warming. "It is, therefore, unfashionable, and even inconceivable, in some quarters to think of too much water vapour as a dangerous substance," he continued.
Indeed, Harris asserted that "no other gas, fossil-fuelled or otherwise traps more heat than water vapour." Noting that water vapour had three times the heat-absorbent capacity of carbon dioxide, Harris explained: "In other words, CO2 does not block heat rays having wavelengths anywhere between five and 16 microns, while water vapour, in general, does."
The trapping of heat or radiation from the sun by certain gases in the stratosphere, which then causes an increase in the Earth's temperature, is described by geoscientists as the greenhouse effect. Substances that trap the sun's radiation above the Earth - thus preventing excess radiation from bouncing back into space - are referred to as greenhouse gases. Water vapour is the most abundant of these, followed in decreasing quantity by carbon dioxide, methane, nitrous oxide, ozone and chloro-fluorocarbons.
greenhouse effect
With water vapour causing 36-70 per cent of the greenhouse effect, Harris posited that it is "the most influential natural greenhouse gas in the atmosphere and plays an important role in the context of climate change ..." In questioning conventional wisdom, he argued: "... There is no scientific evidence that increases in CO2 can produce giant storms, while it is known that water vapour provides the energy for hurricanes ... Hence, water vapour requires more study regarding its movements, fluxes and sinks."
Harris, a notable researcher in the field of geoscience, eases some of the culpability from oil producers for the emission of carbon dioxide by pointing out that the combustion of fossil fuel (in the form of gasolene) produces two units more in volume of water vapour than carbon dioxide. He, therefore, deduced that the proliferation of gasolene-based motor vehicles was harmful to the environment by producing two greenhouse gases - carbon dioxide and water vapour.
Harris pointed, anecdotally, to the impact of the multiplying number of motor vehicles on the weather pattern in Mandeville. "During the 1960s and 1970s, all my friends living in the in-land town of Mandeville ... wore sweaters all year," he recounted. "Nowadays, sweaters are rarely seen there, even in winter. With the extra heat and pollutants - some coming from the proliferation of motor vehicles - of recent years comes unprecedented, regular, conventional afternoon showers at any season," the geoscientist added.
atmospheric water vapour
He stated that one litre of petrol burnt in cars added, through water-vapour condensation, nine kilo calories of heat into the environment. When this process is multiplied and influenced by wind patterns, Harris posited, it results in rainfall, which has been on the increase in Mandeville with its elevation of 800 metres.
Speaking subsequently to The Sunday Gleaner, Harris suggested that increases in the quantity of atmospheric water vapour (by up to 20 per cent over the last two decades in the stratosphere) could be minimised by first reducing the level of methane, a greenhouse gas emitted as one of several vehicular-exhaust gases, which reaches into the upper atmosphere.
Water vapour itself is normally rare at such high altitudes, because, by then, condensation by cooling would have increased its density, Harris explained. However, methane never condenses anywhere in the atmosphere, and, therefore, rises higher until it finally breaks down by oxidation, yielding water vapour as a by-product. Thus, whereas accumulated water vapour in the lower atmosphere (troposphere) is removed as clouds and rain, methane-induced water vapour in the stratosphere remains up there for a much longer time. A substantial stratospheric increase of water vapour, Harris argued, could have a significant warming effect through increased absorption of long-wave radiation from the Earth, and could increase global warming.
sources of methane
"Methane itself, therefore, has to be reduced in the atmosphere," said the geoscientist, pointing out that sources of methane are largely natural, arising from the fermentation of organic matters, such as peat bogs and marshes. Other sources of methane, according to Harris, are the release of natural gas during its production and transportation, and as a by-product of oil drilling; the venting of gases from landfills with decomposing waste; and the release of methane from the guts of ruminants, as well as rice paddies.
