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COP27: Extreme weather events in 2022 keep climate change in focus

With COP27 on in Egypt at the moment, I take a look at this year's extreme weather events around the world, including floods, extreme heat and drought. Many of which are likely to be exacerbated by climate change.

COP27: Extreme weather events in 2022 keep climate change in focus
Blog by Nick Finnis
Issued: 9th November 2022 10:54
Updated: 9th November 2022 11:05

This year has seen a variety of extreme climate disasters, from flooding in Pakistan and eastern Australia, extreme heatwaves and wildfires across Europe and North America, to extreme drought in East Africa. Climate change has exacerbated the intensity of these events, as global warming increases the evaporation of surface water into the atmosphere, while drying areas with little rain and increasing rainfall in others.

Warmer air increases the amount of water that the atmosphere can hold, meaning more moisture is taken from the surface. Atmospheric moisture has increased by 5% to 20% in general compared with the pre-1970s.

The rising global temperatures from global warming is likely the main driver behind these extreme weather events, but these events have probably been exacerbated by the natural weather pattern of La Nina too, which is now in its third consecutive year.

Horn of Africa drought

As world leaders converge on Sharm el-Sheikh, Egypt for the UN climate conference COP27, our first port of call to highlight countries hardest hit by drought, floods and storms is the African continent.

The Horn of Africa experiences two rainy seasons per year. The timing varies across the region, but rains broadly fall from March to May and from September to December. The delayed start and then failure of the March to May rains this year has been felt particularly in equatorial parts of the region, where this wet season contributes 70% of the annual total.



The situation is unlikely to improve in the short term. Forecasts suggest that the September to December rainy season could also fail, which may mean an unprecedented five-season drought. For the the last four years, the rainy seasons have failed, with northern Kenya, Somalia and Ethiopia (the Horn of Africa) experiencing the worst drought in over 40 years. The lack of rain has killed millions of livestock, destroyed crops and forced over 7 million people from the homes in search of food and water. Over 10 million people in Ethiopia and 7 million in Somalia face starvation, due to food shortages and some areas are on the brink of famine. The situation has been exacerbated by the global food crisis, bringing rising food prices.

Drought in eastern Africa is often linked to the build-up of La Niña conditions in the Pacific Ocean, when patterns of warmer and cooler water in the Pacific Ocean are shifted, with knock on effects for the adjacent Indian Ocean Dipole and eastern African rainfall. The IOD is currently in negative phase, meaning cooler waters off the coast of East Africa, which leads to air above holding less moisture - bringing persistent dry conditions over the Horn of Africa. When the IOD is positive, it can bring flooding rains. 

 

 

Extreme droughts in the Horn of Africa aren’t a new phenomenon, who can forget the Live Aid global humanitarian effort for the famine triggered by severe drought in Ethiopia from 1983-1986. There were just as worse droughts in the 1920s and 1930s. There is historically a close association between globally warm conditions and drying in the eastern Horn of Africa. If this association holds into the future, global warming will be met with drying and we may anticipate worse droughts.

Meanwhile, deadly floods have swept across West and Central Africa, affecting 5 million people in 19 different countries and deepening an already alarming food crisis. Nigeria was particularly badly hit recently, with floods linked to the deaths of over 600 people and displacement of 1 million, which has in turn led to a major increase in cholera cases and other preventable diseases.

Many of these developing African countries, even combined, contribute only a small percentage of the world’s global emissions but are bearing the brunt in terms of loss of life and humanitarian crisis in a large part caused by a climate crisis they did not cause.

Northern hemisphere summer extremes

Parts of the northern hemisphere have born the brunt of extremes of heat during the summer. It started with record-breaking heatwaves in India and Pakistan in May, with prolonged periods of temperatures in excess of 40C (104F), with Jacobabad in Pakistan exceeding 50C. The prolonged extreme heat accelerated the melting of the Himalayan glaciers, which then combined with the arrival the monsoon, which brought 3 times the normal rainfall in Pakistan starting in June, led to extensive flooding to Pakistan. Thousands of homes were washed away, killing over 1,700 people, submerging over 5 million acres of cropland, and killing 800,000 livestock.

 

Meanwhile, extreme heat and drought built across large parts of Europe through June and July. Wildfires broke out across Spain, Portugal and France due to dry and hot conditions, extensive areas of pine forests and homes within them in SW France were destroyed. Reservoirs and rivers dried up, with barges on the Rhine unable to move while prompting France to reduce electricity from Nuclear Power Plants, as there was a lack of water to cool them. Rivers in northern Italy reached critically low levels, triggering the authorities to implement emergency measures to restrict water use that greatly affected agriculture. Numerous June temperature records were broken across France and Spain, with intense and prolonged heat continuing through July across large parts of western Europe. In mid-July, an area of pressure settled over western Europe, which combined with a cut-off low to the west to pull exceptionally hot air north from North Africa. Temperatures rose above 40°C for at least one day in Spain, France and the United Kingdom. The UK saw a national daily maximum temperature record of 40.3°C, set at Coningsby in Lincolnshire on 19 July – the first time the UK has ever recorded a temperature of over 40°C.

Across the pond, in the United States – the West and Mid-West suffered intense heatwaves and prolonged drought. Crucial reservoirs of Lake Mead and Lake Powell, fed by the Colorado River, which supply southern California and the Desert Cities in Nevada and Arizona with water, hit record lows, forcing water restrictions. Prolonged drought across much of the US Plains has meant low river levels feeding the Mississippi – leading to the US’s largest river falling to record low levels in places. Though some parts of the USA saw extensive flooding too, such as in eastern Kentucky and also Death Valley in the West related to unusually active Monsoon.

In China there was prolonged heatwaves and drought, which led to the drying up of Yangtze River, which reached its lowest level since at least 1865. Though flooding rains affected the same areas in August.

Australia Floods

Eastern Australia again experienced major flooding last month, for the fifth time in 19 months due to record-breaking wet weather that is predicted to stretch into next year.

Across October, heavy downpours flooded large swathes of New South Wales, Victoria and Tasmania, resulting in four people dying, thousands of people being evacuated, homes and shops being inundated, and roads being cut off and damaged.

 

New South Wales was the worst-affected state, with 43 local government areas flooded, mostly in rural areas, with some floods spanning hundreds of miles. The unusually wet conditions and flooding has been affecting Eastern Australia since early 2021 and has been the costliest floods in Australian history. In Sydney, a record-breaking 2.5 metres of rain has fallen this year so far, March was the wettest month, with around 750mm falling.

La Niña is thought to be one of the main contributors to the wet conditions since early 2021, with warm ocean waters pushed towards the western Pacific typically increasing the chance of above average rainfall for northern and eastern Australia during spring and summer. But with three La Niña cycles in a row since late 2020, which has only happened two or three times since records began, it has meant no stop in the wet conditions. But there is another weather system called the Indian Ocean Dipole, which occurs in the Indian Ocean and is currently in its negative phase, which brings more rain to south-eastern Australia too. A strongly positive IOD in 2019 was implicated in creating extremely dry conditions, extreme heat and the unprecedented bushfires which devastated large parts of Australia in 2019-20.

However, climate change may also be contributing, because every extra 1°C of warming in the atmosphere means it can hold an extra 7 per cent of moisture that can then become rain. And this applies globally, climate change is undoubtedly exacerbating the frequency and intensity of the extreme flood events, but decreasing the number of moderate floods. But while a warming atmosphere increases the air’s capacity to hold more moisture and bring heavier precipitation, the climate warming can also increases evaporation on land, which can worsen drought and create conditions more prone to wildfire and a longer wildfire season.

Tags: World Weather  Climate

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