Anti-immigrant posturing now seems certain to play a significant role in the 2019 national and provincial elections. The ANC government was first off the mark with its 2017 white paper on international migration. The document recognised that skilled migration is essential for economic growth, but its broader message was that high border fences and detention centres for asylum seekers are needed to protect the country from a “flood” of unskilled migrants.

In September the National Council of Provinces and the Gauteng provincial legislature joined forces to present anecdotal evidence about the “swamping” of Gauteng’s health, education and policing systems by an “influx” of irregular cross-border migrants. The DA’s Jacques Julius this week threw himself into the anti-immigrant quagmire, blaming “porous borders” and a “collapse” of the immigration system for cross-border crime, human trafficking, stock theft, drug smuggling and public service delivery failures.

On the face of it, this rise of anti-immigrant sentiment is curious. According to the International Organisation of Migration (IOM), just 3.3% of the world’s population are migrants, up from 2.9% in 1990.

Credible estimates of SA’s migrant population are in line with the global average, and the country stands in stark contrast to high migration countries such as the US (15%) or Australia (28%).

It is difficult to model the impact of migration on destination countries. Particular groups, such as local business owners, will suffer from competition. Migrants concentrate in cities, and insufficient resources are often provided to improve urban migration governance. But most current research suggests the overall impact of in-migration on employment and wages tends to be positive.

Why, then, are ANC and DA politicians turning to the apartheid-era rhetoric of “swamping” and “influxes”? A first factor is the government confusion. Treasury and the department of trade & industry doubtless understand the importance of skilled immigration for growth, and the wide-ranging benefits brought by young and entrepreneurial foreigners. Home affairs, in contrast, has a “Fortress SA” mentality, while labour department officials view themselves as the guardians of local workers.

Second, poor planning has created educational and public health shortfalls in some of the urban areas in which migrants are concentrated. Corruption and inefficiency at home affairs  has resulted in an absence of reliable data about migrants’ locations.

Third, EU migration flows have polarised and destabilised political competition on that continent, fuelling anti-immigrant parties and resurgent nationalism.

The EU has thrown more than €10bn at tackling the “root causes” of migrant flows in countries such as Nigeria, Mali and Ethiopia, and billions more paying border states to stop refugee transit.

“Fortress Europe” has also beefed up border protection, pursued traffickers, strengthened screening systems and aggressively returned economic migrants. Many of home affairs minister Malusi Gigaba’s policy initiatives from 2016 and early 2017 merely mimicked the EU ideas that were designed for a dramatically different context.

There is legitimate uncertainty about future patterns of south-south migration. Migration flows are already unstable within Africa because of a high incidence of conflict and relatively extreme economic cycles. Now demographers predict that more than half of global population growth over the next three decades will occur in sub-Saharan Africa. Meanwhile, the anticipated fallout from global climate change will include negative repercussions for farming and economic development on the continent.

The World Bank reported earlier in 2018 that there could be as many as 86-million “climate migrants” in sub-Saharan Africa by 2050. But most such impacts will occur in countries a long way from SA’s borders, and four fifths of south-south migration currently takes place between neighbouring countries.

In the end, much of the growing climate of hostility towards immigrants is probably best explained politically. After all, we can expect a close electoral competition in Gauteng in 2019, where migrant numbers are largest and where citizens inevitably interpret foreign arrivals as immediate competitors for jobs and services.

Around the world, citizens of host countries suffer from misconceptions about the scale of migrant flows. Economic downturns stoke anti-immigrant sentiment, and so too does avoidable competition for public services, brought about by poor planning and weak governance.

It is perhaps not surprising that the politicians responsible for governance shortfalls in Gauteng and its cities have decided to blame immigrants for their own failings.

• Butler teaches public policy at the University of Cape Town.