Dr Anjani Ganase considers how earth’s water cycles are changing, affected by global warming.
Currently parts of the world appear to be experiencing a series of severe droughts, while other areas are the suffering from severe floods. Over the last weeks, Pakistan received nearly three times the average monsoonal rain of the past years, wiping away towns and villages resulting in over 1,000 deaths and displacing over 33 million people. Meanwhile Sudan has experienced torrential downpours that destroyed 9,600 homes and damaged 22,000 more with 79 dead. US flash flooding in Texas, New Mexico has seen record amounts of rainfall in just 24 hours.
At the same time, most of Europe has been under severe drought conditions with water reserves low enough to unbury the past. World War II ships full of explosives dumped by the Nazis in the Danube River have resurfaced. A 2,000-year-old Roman Bridge re-emerged in the Tiber River. In Spain the Dolmon of Guadaleral – dubbed the Spanish Stonehenge – has historians abuzz. The last time Britain was under similar drought conditions was in 1935. Back in the US, grizzly reports discovered dumped bodies during the current mega drought (drought occurring for two or more decades) at lake Mead near Las Vegas. Native American artifacts purposely flooded in artificial dams during the 1960s have also resurfaced at Lake Powell in Arizona.
Many droughts are accompanied by wildfires that burn and destroy vegetation and wildlife at epic proportions. Wildfires are occurring across all continents at the moment. Heat waves in European cities are becoming so severe (temperatures beyond 40 degrees and peaking at 47 C in Portugal), they’re being named for the first time in history, starting with Zoe that killed over 2,700 people in Spain, 3,000 deaths in Germany, over 1,000 in Portugal, and in the UK.
[caption id="attachment_972748" align="alignnone" width="1024"] Areas at risk of drought as a result of climate change.Image courtesy IPCC AR6 -[/caption]
Global warming has resulted in warmer oceans and lands. The direct heat on land results in no rainfall, high evaporation from soils, rivers and lakes, but also heat stress in plant life leading to drought conditions occurring over extended periods. Special conditions of drought also include the loss of snow which means less snow melt to supply water as well as less reflection of heat waves from the white surface, known as the albedo effect, all leading to more rapid warming in temperate areas. The threat of drought is also dependent on human activities, and land use and water management in the area, affecting the volume and quality of the groundwater. Drought conditions are likely to impact certain regions more severely, including the Mediterranean, southern Africa, Amazonia, Central America and southern Europe. Between 1983 and 2009, three quarters of all global harvests have been affected by drought conditions, equating to some US$166 billion in loss. Under Business as Usual, it is expected that at least one third of land areas will suffe
