The last two weeks has registered extreme heat waves in the Northern hemisphere where countries like Spain, Italy, Greece and USA [Arizona] have recorded temperatures above 40 degree Centigrade. According to the World Meteorological Organization [WMO] Europe is the fastest warming region with recorded hottest Summers in the last two years where temperature have hit 48 degrees Centigrade. This has affected thousands of people with increased health risks and death. Reuters News Agency has reported an estimated 61,000 heat waves related death in Europe in the last year alone. Scientists have for long warmed that climate change caused by Greenhouse Gas [GHG] emissions will make heat waves more frequent, severe and deadly.
Climate change refers to the long-term shifts in temperatures and weather patterns, mainly attributed to human activities, especially the burning of fossil fuels. Shifts in climate can be natural, but since the 1800s human activities have been the main triggers of climate change due to burning of Oil, Coal or Gas that release heat trapping gases into the atmosphere. The heat trapping gases are what we refer to as GHGs. Most of these gases naturally occur in the earth’s atmosphere.
How do the GHGs affect weather and the climate? During day, the Sun shines through the atmosphere, warming the earth’s surface. The shining Sun generates solar radiation part of which is reflected back on hitting the surface. At night the earth’s surface cools, releasing heat back into the air. However, some of the heat is trapped by the GHGs that envelop the earth in the atmosphere. This trapping is a natural phenomenon that keeps the earth’s temperature at an average 14 degrees Centigrade.
Without this natural GHG effect, temperature would drop well below minus 18 degrees Centigrade as the heat reflected from the earth surface would escape to outer space. The GHGs act “as a natural blanket around the earth” making the earth habitable. Hence, the GHGs are like a “glass ceiling” trapping and reflecting heat back to the earth’s surface.
Which are the major GHGs? These are Carbon dioxide [CO2], Methane [CH4], Nitrous Oxide [N2O] and Water Vapour. There are also the less prevalent so-called F-gases. These are industrial fluorinated gases like Sulphur Hexafluoride [SF6], Perfluorocarbons [PFC14] and Hydrofluorocarbons [HFC]. Whereas the major gases do occur naturally, the F-gases are man-made during industrial processes. These F-gases appear in small concentrations in the atmosphere but are highly potent in trapping heat compared to the naturally occurring gases.
Due to human activities, the Carbon dioxide concentration has increased by at least 50% since Industrial Revolution began over two hundred years ago. Methane produced through decomposition, has had it’s natural balance disrupted by human activity as large amounts are released through Cattle farming, Landfills or Gas and Oil production. Large scale use of commercial fertilizers or biomass burning is contributing to increased Nitrous Oxide. Water Vapour, the most abundant GHG, is increasing as the earth’s atmosphere warms up.
According to Intergovernmental Penal on Climate Change, a UN body to advance scientific knowledge about climate change, not all GHGs have the same global warming potential as measured by the ability to trap heat. The man-made F-gases have, though small in quantities, a much greater warming effect. For instance, Sulphur Hexafluoride is 23,000 times and Perfluorocarbons 6,600 times more potency compared to Carbon dioxide.
Furthermore, the longer the gases stay in the atmosphere the more the warming effect. For example, Carbon dioxide stays much longer in the atmosphere compared to water vapour. Also, the F-gases stay in the atmosphere much longer compared to other gases. Even if we stopped emitting GHGs today, it would take several hundred years before most man-made emissions are removed from the atmosphere.
The heat waves in the Northern hemisphere have been attributed to the changing climate. Sometimes these heat waves coincide with wild fires which in turn affect livelihoods like Tourism with Tourists choosing cooler destinations and changing the season of travel.
Francis Nakomolo Ojambo
Executive Director, Action for Safe Livelihood
fnakomolo@yahoo.com
