Cyclic weather patterns a threat to Southern Africa


By Admire Ndhlovu
The Southern African region is facing a recurrent drought and flood challenge due to cyclic weather patterns, made worse by climate variability and change.

The cyclic weather patterns result from the El Niño Southern Oscillation (ENSO), a naturally occurring phenomenon that involves fluctuating ocean temperatures in the  equatorial Pacific Ocean.

El Niño is a term for the warming phase of the ENSO, while the cooling phase, which has global climate impacts opposite to those of El Niño, is referred to as La Niña.

El Niño and La Niña can make extreme weather events such as droughts, floods and storms more likely, as they influence temperature and rainfall patterns.

Strong El Niño events occurred in the years 1957-58, 1965-66, 1972-73, 1982-83, 1987-88, 1991-92, 1997-98, and 2015-16. The latter is the strongest on record.

Strong La Niña events were experienced in 1973-74, 1975-76, 1988-89, 1999-2000, and 2010-11.

In the Southern African Development Community (SADC) region, an El Niño event is characterised by droughts while La Niña is associated with wet conditions and floods.

An analysis of El Niño cyclic events between 1950 and the present shows that they are increasing in intensity.

The impacts of these cyclic weather patterns are made worse by changing global climate.

Irrespective of El Niño events, there is a long-term trend towards the warming of the Earth’s climate because of rising heat-trapping greenhouse gas emissions from human and industrial activities.

A new report titled “The Global Climate” has identified significant changes in climate since 2015.

The report, published by the World Meteorological Organisation (WMO) ahead of the United Nations Climate Summit held in New York in September, revealed that there have been significant changes in climate over the past five years, including dramatic rises in temperature and the sea level and the occurrence and intensity of extreme weather events such as droughts and floods.

According to the report, the period 2015-2019 is the warmest on record, with the year 2016 being the warmest year on record globally.

Temperatures during the period are said to have been over 1°C higher than the pre-industrial period.

Occurrence of an El Niño under an increasingly warming environment as a result of climate change has serious impacts on climate-sensitive sectors such as agriculture, water supply, energy and tourism.

The El Niño-induced drought during the 2015/16 season impacted on the energy sector and left an estimated 40 million people food-insecure, with Botswana, Eswatini, Lesotho, Malawi, Mozambique, Namibia and Zimbabwe declaring a state of national disaster.

The sensitivity of agriculture to climate-induced water stress is likely to deepen the existing challenges of declining agricultural outputs, declining economic productivity, poverty and food insecurity, with smallholder farmers particularly affected.

The region is particularly vulnerable due to its heavy dependence on rain-fed agriculture   and climate-sensitive resources.

The increase in temperatures usually results in a rise in evaporation loses from reservoirs that support urban, rural, industrial and agricultural water needs in the region.

For example, in 2007 evaporation led to extremely low water levels in most dams in Zimbabwe, resulting in many of them being decommissioned.

Declining water levels in Lake Kariba between Zambia and Zimbabwe continues to be a major concern resulting in low hydropower generation.

Lake Kariba is designed to have minimum levels of between 475.5 and 488.5 metres for hydropower generation.

As of 18 November 2019, the lake level was 477.2m, slightly above the minimum threshold required for power generation.

This was equivalent to about 12 percent of usable storage and was much lower than the 483.8m recorded on the same day the previous year.

In October 2015, Tanzania was forced to switch off all its hydropower plants due to low water levels in the major dams.

As a result of the low water levels, hydro-electricity generation fell to 20 percent of capacity, making it difficult for the dams to operate.

Tanzania, which has significant gas reserves, has since converted its infrastructure in key areas to use mainly natural gas.

Increase in intensity of La Niña occurrences, coupled with acceleration of rising sea levels pose a great concern to countries with extensive low-lying coastal areas such as Mozambique.

According to the WMO report, over the period 2014-2019 the rate of global mean sea level rise amounted to five millimetres per year, substantially faster than the average rate since 1993 of 3.2 mm/year.

More than 60 percent of the Mozambican population lives in low-lying coastal areas. As such, the rise in sea level poses great risk to their infrastructure, coastal agriculture, key ecosystems and fisheries.

The country is already prone to tropical storms from the Mozambique Channel.

In light of the increasing intensity of El Niño and La Niña as well as impacts of climate change, the establishment of vibrant disaster risk strategies is a priority for southern Africa.

In order to prepare for future hazards, the 39th SADC Summit called on member states to implement comprehensive multi-year response plans to tackle the recurrent droughts and food insecurity challenges.

In November 2019, SADC and the European Union launched an Intra African, Caribbean and Pacific (ACP) Global Climate Change Alliance Plus (GCCA+) Programme to strengthen capacity of SADC member states to undertake climate change adaptation and mitigation interventions.

The programme, which is an integral part of the implementation of SADC regional integration agenda, will support SADC governments, regional organisations, the private and public sectors to strengthen the capacity of member states to undertake regional and national adaptation and mitigation actions in response to the challenges posed by climate change and climate variability.

In addition, it will assist in the design of pilot projects on adaptation in several member states.

The SADC Secretariat is, in collaboration with member states, developing a strategy for effective coordination of disaster responses.

The proposed SADC Disaster Preparedness and Response Strategy will ensure that mechanisms are put in place and adequate resources are available for the effective management of disasters. – SADC Today.





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