“No two seasons are completely the same.”
Source: Meteorological Services Department of Zimbabwe
Harare, Zimbabwe – The latest El Niño-Southern Oscillation (ENSO) climate projections indicate that the current El Nino event has reached its peak and is currently declining as we approach June 2024.
This projection, combined with the current rainfall patterns, which show that some areas have received below-normal rainfall while others have received above-normal rainfall, shows that some areas will receive considerable rainfall totals.
This is contrary to the general theory.
However, the season has been marked by considerable dry spells, some lasting for 25 days and others lasting up to 85 days.
Of significance was the one from mid-October to early December 2023, which led most areas to have a false start to the season.
Some farmers planted using these rains, and this led to crop failure for those in rain-fed agriculture.
Crops under irrigation and those planted in December 2023 have been performing very well, as have those under Pfumbudza/Intwasa (climate-sensitive intervention) spearheaded by the Government of Zimbabwe.
Besides the currently good crop status, the Zimbabwe National Water Authority (ZINWA) also indicated that most dams are above 84% capacity, with some even spilling, like Lake Chivero, Arcadia, and Mbembesi Dam.
Meanwhile, Zimbabwe, through the Meteorological Services Department, is holding regular consultations and meetings under the National Framework for Climate Services (NFCS) for early detection of potential risks in sensitive areas.
Further, this will reduce vulnerability and enhance resilience across all climate-sensitive sectors in Zimbabwe, ensuring the nation’s preparedness in the face of impending climatic uncertainties associated with these climate variables, such as El Nino events. .
EFFECTS OF EL NIÑO ON THE WEATHER
Not every ENSO event is the same, and the consequences vary from region to region.
However, scientists have observed some generally consistent patterns based on analysis of historical ENSO events:
Global temperatures typically increase during an El Niño episode and fall during a La Niña.
El Niño means warmer water spreads further and stays closer to the surface.
This releases more heat into the atmosphere, creating wetter and warmer air.
However, the regional effects are complicated, and some places may be both warmer and cooler than expected at different points in the year.
Changes to rainfall:
During El Niño events, the warmer water pushes the Pacific jet stream’s strong air currents further to the south and the east.
This brings drier conditions to tropical regions like Southeast Asia, Australia, and central Africa typically experience. Under La Niña, the opposite is seen.
El Niño also affects atmospheric circulation patterns, which means there are generally more tropical storms in the tropical Pacific but fewer in the Indian Ocean, including in southern Africa. During La Niña, the reverse is typically true.
Carbon dioxide (CO2) levels:
Scientists have also observed that CO2 levels in the atmosphere increase during El Niño events, possibly as a result of warmer and drier conditions in tropical regions. If plants grow less quickly due to drought, they absorb less CO2, while more wildfires in places like Australia mean more CO2 is released.
Historical Impacts of Past El Niño Events
Analysis of historical El Niño impacts reveals that the majority of El Niño events in the past 43 years have had below-normal rainfall over Zimbabwe.
Most parts of Zimbabwe experienced below-average DJFM rainfall at least 60% of the time, suggesting a doubling of the risk of dry conditions during an El Niño event.
An analysis of each El Niño season indicates that El Niño events have had significantly different impacts on rainfall, in part due to differences in the characteristics of the different El Niño events as well as the interaction of various local and regional climate drivers, such as regional SST patterns.
Three very strong El Niño events occurred in 1982–1983, 1997–1998, and 2014–2016.
The 1982–1983 and 2015–2016 El Niño events resulted in severe droughts, while the 1997–1998 season had near-normal rainfall due to the interplay of various local and regional climate drivers.