A slowly unfolding catastrophe, told in five charts.

A portion of the Makoko district of Lagos, Nigeria, a vast slum built partly over the Lagos Lagoon. Adekunle Ajayi/NurPhoto, via Getty Images

1. Dire Predictions Were Mostly Right

Humanity has grown as expected since the warnings about global overpopulation of the 1960s. Decades of United Nations projections for the year 2000 came within 3 percent of the actual total, making the U.N.’s 9.7 billion prediction for 2050 both credible and alarming.

YEAR, ESTIMATE FOR 2000 ERROR ’58 6.280 BILLION +3% ’63 6.129 +0.7 ’68 6.493 +7 ’73 6.254 +3 ’78 6.199 +2 ’82 6.127 +0.7 ’88 6.251 +3 ’92 6.228 +2 ACTUAL 2000 POPULATION: 6.084 BILLION YEAR, ESTIMATE FOR 2000 ERROR ’58 6.280 BILLION +3% ’63 6.129 +0.7 ’68 6.493 +7 ’73 6.254 +3 ’78 6.199 +2 ’82 6.127 +0.7 ’88 6.251 +3 ’92 6.228 +2 ACTUAL 2000 POPULATION: 6.084 BILLION

2. The Malthusian Moment Postponed

The Green Revolution and globalization brought food and jobs to soaring populations. Those events, and the declining rate of global population growth, camouflage today’s situation: the rise in absolute numbers of people, with millions more at risk when things go awry. Thomas Malthus, the population theorist of the 18th and 19th centuries, predicted such calamities if the world’s population grew unchecked.

Current growth adds the population equivalent of a new Iran or Germany every year.

GROWTH RATES: GLOBAL POPULATION INCREASE: 2.1% 73 million 1967 1.2% 80 million 2016 GROWTH RATES: GLOBAL POPULATION INCREASE: 2.1% 73 1967 million 1.2% 80 2016 million

3. The Reckoning Arrives

Fast-rising populations degrade economic and agricultural resiliency; add a recession or drought and the human consequences magnify.

In many countries, the population of desperately impoverished has grown to far exceed their total population as of 1970. When conditions worsen, the numbers stricken are staggering, and Malthusian concerns come back with a vengeance.

1970 Madagascar TOTAL POPULATION (MILLIONS) 7 2015 20 MOST IMPOVERISHED 24 TOTAL POPULATION Dem. Congo Niger Zambia 20 4 4 10 10 16 20 60 77 Burkina Faso Mozambique Tanzania 9 14 6 10 19 25 18 28 53 Nigeria 56 97 182 Ivory Coast Uganda Uzbekistan 5 12 9 7 13 20 23 39 30 Ethiopia Haiti 5 28 6 11 33 99 Bangladesh 65 70 161 “Most impoverished”: those living on $1.90 a day or less. 1970 Dem. Congo Madagascar Niger Malawi Burundi Zambia TOTAL POPULATION (MILLIONS) 7 20 3 5 4 4 9 10 12 10 2015 20 MOST IMPOVERISHED 11 16 17 20 24 TOTAL POPULATION 60 77 Burkina Faso Mozambique Benin Rwanda Uzbekistan Tanzania Nigeria 12 9 3 4 14 6 56 6 7 10 19 11 12 20 25 18 28 30 53 Chad 97 4 5 182 14 Ethiopia Mali Ivory Coast Uganda Haiti Bangladesh 6 28 9 5 5 65 6 7 9 13 11 18 23 39 33 70 99 161 “Most impoverished”: those living on $1.90 a day or less. Ranked by ratio of most impoverished in 2015 compared to the 1970 population. Magadascar’s ratio is worst.

4. Facing Down Impossible Economic Math

Curbing poverty in some countries would require unheard of economic growth. Even maintaining the economic status quo, a very low bar, is beyond reach.

To illustrate the burdens of exploding populations, imagine these nations scaled up to the size of the United States, which generated, on average, 129,000 new jobs a month last year. Just to tread water — the dismal status quo — an America-size Tanzania would have to produce 636,000 jobs monthly, without cease.

MONTHLY EQUIVALENT JOB GROWTH NEEDED IN THOUSANDS: 129 (U.S. monthly average, 2016) Honduras 277 319 381 518 521 534 578 588 589 623 636 Nigeria Guatemala Zambia Chad Niger Madagascar Ethiopia Burkina Faso Uganda Tanzania The U.S. has achieved an equivalent level of job creation this robust only twice since 1950. MONTHLY EQUIVALENT JOB GROWTH NEEDED IN THOUSANDS: 129 (U.S. monthly average, 2016) Honduras 277 319 381 518 521 534 578 588 589 623 636 Nigeria Guatemala Zambia The U.S. has achieved an equivalent level of job creation this robust only twice since 1950. Chad Niger Madagascar Ethiopia Burkina Faso Uganda Tanzania

5. Lesotho: A Small Harbinger of Suffering to Come

Drought is devastating a country that also lost one-third of its arable land after 1970. The United Nations says that one-third of Lesotho’s people lack adequate food; the same proportion of its young children are physically stunted.

CHANGE IN ARABLE LAND, 1970-2013 –33% Lesotho –32 Botswana –23 Honduras –13 Bangladesh –9 Guatemala Farmland in these countries has increased, but at a high cost: deforestation and loss of species. Nigeria +7% Dem. Congo +10 Madagascar +70 CHANGE IN ARABLE LAND, 1970-2013 –33% Lesotho –32 Botswana –23 Honduras –13 Bangladesh –9 Guatemala Farmland in these countries has increased, but at a high cost: deforestation and loss of species. Nigeria +7% Dem. Congo +10 Madagascar +70