Extreme events like 1992 drought to fall — study
The Herald
Climate Story Jeffrey Gogo
If the rise in global temperatures is limited to 1.5 degrees Celsius in this Century – the more ambitious target under the Paris Climate Agreement – deadly extreme climate events like heatwaves, tropical cyclones or drought will decline markedly in Zimbabwe and across Africa, a new study suggests.
The study is arguably one of a few to examine the specific impacts of a 1.5°C warmer world on Africa, compared to the 2°C upper limit – perceived by many as insufficient – under the Paris treaty on climate change of 2015.
It shows that the chance of a drought with a severity equal to that of the 1991/92 drought across SADC, both in the sense of excessive heat and record low rain, will reduce by about a quarter, in a world 0.5°C less warmer.
Devastating events like Cyclone Eline in 2000, will become much less frequent, says the study, whose results were published in the journal Nature Climate Change.
And heatwaves, such as the record-breaking one of 2015 in Africa, and the 2009 /10 one in northern Africa, when temperatures soared one to 2,5°C above the 30-year baseline to 1990, will fall by up to 20 percent.
The research indicates that if the 2°C limitation agreed at Paris is pursued, heatwaves, cyclones and droughts in Zimbabwe and elsewhere in Africa will worsen.
It used a combination of different computer models to predict future changes in climates in Africa – until now an area little investigated – under 1.5°C and 2°C global warming scenarios.
The Paris accord promises to hold global temperature increase to “well below 2 degrees above pre-industrial levels” and to pursue “efforts to limit temperature increase to 1.5 degrees.”
But many are concerned whether the two degrees target is enough to prevent dangerous extreme climate events from ravaging Africa’s socio-economic fabric, already struggling to cope with the devastation brought on by climate change so far. Co-author Shingirai Nagombe, a climate scientist from the Meteorological Services Department, said: “ . . . we conclude that limiting global warming to 1.5°C relative to 2°C would have substantial benefits for Africa in terms of reducing occurrences of extreme events similar to historical record- breaking seasonal extremes . . . ”
That would require countries to show greater commitment towards cutting carbon emissions, upgrading their national climate plans under the Paris Agreement, and perhaps refocusing global targets to the 1.5°C threshold.
Dangerous impacts
Even though Zimbabwe accounts for under one percent of the global emissions total – and Africa just about 5 percent – Zimbabweans have seen some of the worst impacts of climate change, largely due to a lack of money and capacity to cope with the changes.
Temperatures have risen by about a degree since the early 1900s and rainfall declined by between 5 percent and 15 percent in the last 60 years, according to Government data.
Droughts and floods have increased in frequency and severity.
Since the 1800s, Zimbabwe has been hit by 16 deadly droughts, Sadc studies show.
The one in 1991 /92, considered the worst in living memory, affected the rest of southern Africa, but Zimbabwe was hardest-hit.
It killed more than one million cattle here, and the maize staple failed completely, leaving millions of people hungry. Only half the average annual rainfall fell at that time.
The devastation of public infrastructure such as roads, bridges, schools and clinics remains unrepaired in parts of rural Zimbabwe to this day, 18 years since Cyclone Eline struck.
The research by Nagombe, and six other scientists from China’s Institute of Atmospheric Physics, typically shows uncertainties over the way the Earth’s system could work in the future – they are simulations of possible futures, after all — particularly as regards precipitation.
It indicates that changes in rainfall might be small under a 1.5°C situation, consistent with previous studies that used different models.
“Regardless of the insignificant seasonal mean precipitation change projection, projected excessive warming alone might increase the probability of drought occurrences in a warmer world, similar to that of 1991 /1992,” the authors say.
But it is El Nino, that periodic weather phenomenon that tends to influence rainfall and temperatures in southern Africa heavily, that will have the greatest undesirable effect.
The study finds that “hot events much stronger than” that of 25 years ago, “are more likely to occur under El Niño conditions in warmer climate scenarios.” It is a sharp reminder.
The El Nino-induced drought of two years ago cut maize harvests to a fraction of national requirements, as four million people went hungry and temperatures set new records.
Incredible outcomes
The new study uses multiple approaches to examine the effects of a 1.5°C or 2°C warmer world on Africa, including a review of different observational data sets and model simulations.
It is incredible that the computer models are at all in line with end-of-century predictions, given the margins of error that accompany similar constructs.
The authors themselves are keen not to be misconstrued.
We asked Nagombe, the Meteorological Services Department scientist, what the results of his study would mean to a grandmother growing maize in rural Chimanimani or Muzarabani.
“The benefits of the paper to a communal farmer are not direct but the overall benefits of the Paris Agreement itself are direct,” he said.
“If the world continues with a business as usual approach, the negative impacts (droughts, heatwaves, floods, dryspells etc) of climate change will be massive. Some coastal regions and small island countries might cease to exist, while other regions will become inhabitable.”
Nagombe said, “Now that there is some form of evidence of the benefit of limiting global warming to 1.5°C, governments can now be strongly motivated to contribute to the reduction of greenhouse gas emissions through the Nationally Determined Contributions.”
God is faithful