2.1.3 Longer and harsher droughts
internal references to solve:
- part-4 Impacts-on-global-food-production
- part-4 Impacts-on-water-availability.
- part 5 What-will-our-world-look-like-in-2050-if-we-don%E2%80%99t-take-radical-action-now
- part 5 What-will-our-world-look-like-by-the-end-of-the-century
"An estimated 3.6 billion people (nearly half the global population) already live in areas that are potentially water-scarce at least one month per year." United Nations world water development report, 2018
Warmer air is able to hold more water vapour. This means that in areas where the air is already dry, global heating makes it even less likely that water vapour in the air will condense to form clouds, resulting in reductions in rainfall and increasing the chance of droughts. To make matters worse, drier soils caused by increased temperatures exacerbate the impacts of reduced rainfall, leading to longer and deeper droughts - with major impacts on global food production and water availability (see sections on impacts on food production and water availability).
It has been proposed that the severe drought experienced by Syria between 2007-2010, made more likely by global heating, was a key factor that contributed to the outbreak of civil war which started in 2011.
The Western US has been crippled by droughts in recent years. The "exceptional" drought in California between 2010-2014 was made much more likely by climate change.
In 2015 a drought in Southern Africa, made up to three times more likely by climate change, reduced agricultural outputs by 15%, whilst in 2017 a drought in East Africa - made up to twice as likely by climate change - displaced around 800,000 people in Somalia. In 2018 an intense drought in Cape Town, made three times more likely by climate change, led to severe water restrictions being put in place and the city came to within days of turning off its water supply: dubbed ‘Day Zero’. It has been calculated that climate change made the chance of a drought this severe go from a "once in 300 years" event to a "once in 100 years" event.
In 2019, Australia’s Murray-Darling basin saw its most severe drought in 120 years of records and Tasmania had the driest January in 120 years, whilst parts of Zimbabwe had the lowest rainfall since 1981, contributing to making more than 5.5 million people at risk of extreme food insecurity. India experienced a harsh drought followed by a searing heatwave, with Chennai being left nearly out of water as its reservoirs ran dry. Global heating has also been directly linked to the "megadrought" that’s currently gripping the South West United States, the worst in over 500 years.