Why Australia’s fires are linked to floods in Africa

Downright apocalyptic images coming out of
Australia right now. There are now six fires burning at emergency
levels. The smoke is so intense and so thick it can
be seen from space. 2,000 homes have been destroyed. Six million hectares of land charred. Staggering toll on the nation’s wildlife. This is just heartbreaking. These record-breaking bushfires in Australia
have been kicked off by things like lightning strikes, a few cases of arson and winds. But one of the biggest reasons they’ve become
so extreme, is the same reason East Africa is flooding. Bushfires in Australia are a natural part
of the country’s ecosystem. Their “fire season” varies across regions. Even New South Wales, the most populous state, is used to blazes breaking out. In 1974, fires burned 3.5 million hectares,
and in 2003, another 2 million hectares were lost to fire. But the fires that started in 2019 are even
worse: 4.9 million hectares in New South Wales have burned already — and it’s only going
to grow. So why is this fire season so awful? For starters, as the world is getting warmer
from climate change, so is Australia. 2019 was it’s hottest year on record, with
parts of the country reaching 45 degrees Celsius in December. 2019 was also it’s driest — the places
here in gray have seen historic droughts. Together, that provides the perfect conditions
for bushfires to start and spread quickly. Throughout the year, other large-scale climate
drivers affect Australia’s weather, and its likeliness to burn. But one of the most influential is the Indian
Ocean Dipole, or the IOD. The IOD is a big temperature gradient that
affects the surface water in the Indian Ocean, from the edge of Africa to the edge of Australia. Meteorologists have been measuring these temperature
shifts for decades in three phases: Positive, neutral and negative. When the IOD is neutral, the surface water
in the Indian Ocean is evenly warm. A negative phase is when winds come in from
the east and shift the warm water toward Australia. Warmer water means more evaporation which
means more rain. So Australia gets more rain than usual, sometimes
even floods. But the colder water near East Africa means
they get less rain and even drought. A positive phase is what’s happening now. It’s when the winds come from the west and
shift the warm water towards Africa. Which causes flooding there, and drought in
Australia. The entire process of shifting water temperatures
is natural. But 2019’s was extreme. The positive IOD was one of the strongest
on record, with the water temperature difference between Africa and Australia being unusually
high. Hence, extreme weather in Australia, but also
in Africa. The worst flooding in two decades. More than three times their annual rainfall
in only four days. Scientists believe it’s linked to record
temperatures in the Indian Ocean. The good news is the IOD is already shifting
to neutral which should bring some much needed relief to Australia and Africa in early 2020. But as the planet continues to warm, some
scientists are concerned about how that might affect weather phenomenons like the IOD. One study predicts positive IODs, like what
we’re seeing now, could happen more frequently as global temperatures rise and warm the Indian
Ocean. Combine that with the rising overall temperature
of Australia, and these kinds of devastating fires, fueled by unusually dry vegetation,
could become the new normal.


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