Africa
is more vulnerable than any other region to the world’s changing weather
patterns, explains climate specialist Richard Washington.
African
climate is replete with complexity and marvels. The Sahara is the world’s
largest desert with the deepest layer of intense heating anywhere on Earth.
In
June and July the most extensive and most intense dust storms found anywhere on
the planet fill the air with fine particles that interfere with climate in ways
we don’t quite understand.
No
other region has documented such a long and spatially extensive drought.
Evidence
points to Western industrial aerosol pollution, which cooled parts of the
global ocean, thereby altering the monsoon system, as a cause.
The
currently observed recovery of the rains is projected to continue through the
21st Century, particularly over the central and eastern Sahel.
But
that change seems to depend on exactly where future heating in the central
Sahara peaks, emphasising cruelly the region we least understand.
In
southern Africa we are seeing a delay in the onset and a drying of early summer
rains, which is predicted to worsen in forthcoming decades.
Temperatures
there are predicted to rise by five degrees or more, particularly in the parts
of Namibia, Botswana and Zambia that are already intolerably hot.
This
observed change sits uncomfortably next to predictions of a wetter future in
the same season; a problem scientists have termed the East African Climate
Paradox.
Central
Africa, one of three regions on the planet where thunderstorms drive the rest
of the planet’s tropical and sub-tropical weather systems, lives perilously
close to the rainfall minimum needed to support the world’s second largest
rainforest system.
Even
a little less rainfall in the future could endanger the forest and its massive
carbon store.
Africa’s
complex climate system is, unusually, influenced by all three global ocean
basins.
Emerging
from one of those rapidly warming oceans, tropical cyclones Idai and Kenneth in
March and April 2019 destroyed parts of Mozambique, Zimbabwe and Malawi, with
Kenneth following a particularly unusual path over Tanzania.
Projections
of climate change depend on climate models of which there are dozens, each as
complicated to understand as the real world.
Through
efforts such as the ongoing Future Climate for Africa (FCFA), a programme
funded by the UK’s Department for International Development and Natural
Environment Research Council, the experience and insights of African climate
scientists have led to a discernible jump in our ability to understand and
model African climate.
Each
region and sub-region of Africa is changing differently but an emerging
commonality is a shift towards more intense rainfall - even where there is
observed and projected future drying.
The
rainfall arrives in shorter bursts, causing more runoff and longer dry-spells
in between.
New
models, developed as part of FCFA, are now run at extremely high resolution
with grid spacing of around 4km (2.5 miles) for the entire continent.
Standard
global climate models can only represent these key systems indirectly but the
new models are capable of representing thunderstorms systems adequately for the
first time.
This
is part of the approach we are adopting - to find out exactly how the models
simulate the changing weather.
From
an extremely modestly resourced lab in Cameroon, for example, Wilfried Pokam
and his team of researchers are exposing the way that the central African
climate system and southern Africa are linked, thereby breaking the mould of
our stubborn piecemeal, regional view of the continent’s climate system.
Such
breakthroughs are improbable when you consider that these researchers download
massive data sets through cheap Sim cards in their mobile phones and analyze
the output overnight.
By
day, they keep the first Lidar system in central Africa running. The Lidar
measures winds in the lowest few kilometres of the atmosphere, helping to fill
the vast data void in central Africa.
They
are part of a set of young scientists joining the race to set adaptation to
climate change in motion before Africa is overwhelmed.
It
is a matter of social justice that we succeed. Africa will be hardest hit by
climate change, but has contributed the least to causing that change.
A
Guest Editorial
