Question: By what year is the population of Southern Africa expected to double?
About the article "Global warming", section "Food security".

Candidate passages:
Dar es Salaam is the largest city in Tanzania.
With a population increase of 5.6 percent per year from 2002 to 2012, the city is the third fastest growing in Africa (ninth fastest in the world), after Bamako and Lagos.
The metro population is expected to reach 5.12 million by 2020. 
One of the most serious issues to face Africa is not a dispute between nations, but rather the rapid spread of HIV and the AIDS pandemic.
Sub-Saharan Africa, especially southern Africa, is by far the most affected area in the world, and the infection is now starting to claim lives by the millions.
While the measurement of HIV prevalence rates has proved methodologically challenging, more than 20% of the sexually active population of many countries of southern Africa may be infected, with South Africa, Botswana, Kenya, Namibia, and Zimbabwe all expected to have a decrease in life expectancy by an average of 6.5 years.
The effects on South Africa, which constitutes 30% of the AU's economy, threatens to significantly stunt GDP growth, and thus internal and external trade for the continent. 
India occupies 2.4% of the world's land area and supports over 17.5% of the world's population.
Per the 2001 census, 72.2% of the population lives in about 638,000 villages and the remaining 27.8% lives in more than 5,100 towns and over 380 urban agglomerations.
India's population has exceeded that of the entire continent of Africa by 200 million people; however, since Africa's population growth is nearly double that of India, it is expected to surpass both China and India by 2025. 
The story of two dreams.
Marem, a 14 year old dancer from Senegal, dreams of migrating to Europe, while Sonia, a Spanish dancer, feels drawn by the magic of Africa.
Both are linked by Pap Ndiaye, Marem's father and Sonia’s husband.
Africa isn't what Sonia had dreamt of (Pap Ndiaye has two additional wives), nor is Europe what Marem expected (there are no children in the street and poverty is also present).
"Princess of Africa" is a love story, full of music and dance, where nothing is what it seems and women are the main characters. 
Under present trends, by 2030, maize production in Southern Africa could decrease by up to 30%, while rice, millet and maize in South Asia could decrease by up to 10%.
By 2080, yields in developing countries could decrease by 10% to 25% on average while India could see a drop of 30% to 40%.
By 2100, while the population of three billion is expected to double, rice and maize yields in the tropics are expected to decrease by 20–40% because of higher temperatures without accounting for the decrease in yields as a result of soil moisture and water supplies stressed by rising temperatures.
Future warming of around (by 2100, relative to 1990–2000) could result in increased crop yields in mid- and high-latitude areas, but in low-latitude areas, yields could decline, increasing the risk of malnutrition.
A similar regional pattern of net benefits and costs could occur for economic (market-sector) effects.
Warming above could result in crop yields falling in temperate regions, leading to a reduction in global food production.