It means that sensible people arguing for lower immigration on economic and environmental grounds will now also have to run the gauntlet of being branded as racist.

Meanwhile, property developers, big retail, the banks and others revel in making short-term big profits from high population growth to the long-term detriment of everyone else.

It took just 14 years for the most recent five million to be added from 20 million to 25 million. It took 23 years to add the five million before that from 15 million to 20 million. This is an exponential, unsustainable trajectory. It causes congestion, out-of-reach housing, more pollution, conversion of agricultural land to urban, and more imported food and less exported food.

The population crisis has nothing to do with race. It has nothing to do with what News Ltd columnist Andrew Bolt calls a threat to Australian identity. It is a matter of economics and environment.

If anything, research suggests greater diversity helps companies perform better and that is probably the same for nations. So we should seek greater diversity among immigrants, but there should be a lot fewer of them.

The calls for lower immigration by Bolt, Tony Abbott, Peter Dutton and others mixed with statements about African gangs, loss of identity and calls for white South African farmers to get special treatment is doubly appalling.

First, it makes intelligent discussion about the economics and environmental implications of high population almost impossible. Secondly, it opens the door to racism under the guise of patriotism and nationalism.

In a way they both pose significant threats to some of the best things about the Australian way of life.

One of those things is, of course, Australia’s progress in overcoming racism given our past.

The first British claim over, and settlement of, the Australian continent has based the dispossession of, and violence towards, the Indigenous population.

One of the first Acts of the Australian Federal Parliament – the 17th in fact –was the Immigration Restriction Act which enabled the White Australia Policy by making it virtually impossible for non-whites to emigrate to Australia.

It has been almost 50 years since that policy ended and more than 40 years since the Federal Parliament made racial discrimination illegal.

And still, some people want those things wound back.

The Race Discrimination Commissioner, Tim Soutphommasane, who ends his five-year term this month, said that when he took office he did not anticipate what he described as a rise in “dog-whistling” and “race-baiting” in Australian public debate.

“Race politics is back,” he said. “I wouldn’t have expected that the biggest threats to racial harmony would come from within our parliaments and media.”

They haven’t given up despite the failure to edit or remove Section 18C of the Racial Discrimination Act which makes hate speech that vilifies or offends someone on the basis of their race unlawful.

Overcoming racism, whether perpetrated by laws, institutions or individuals, should be a major national endeavour because it so often leads to violence.

It is one of the lessons of the 20th century in which so much killing, displacement, dispossession and disempowerment was done when people with political and military power asserted that their people were superior to others who were regarded as sub-human, despite the fact that homo sapiens is one species irrespective of skin colour or other attributes.

It was done in the name of ideology and/or empire. In the 21st century, those seeking power or attention are using race again. They can do so because it so often works. Humans are pre-disposed to tribalism and “us” and “them” because that view of the world was necessary for survival in the state of nature.

It no longer is. Indeed, tribalism in developed society does the opposite. It exposes people to violence.

Bolt appealed to the us-and-them mentality. He wrote: “There is no ‘us’ any more as a tidal wave of immigrants sweeps away what is left of our national identity.”

Whoops. Only about half of Australians were born in Australia to Australian-born parents. The other half, however, still regard themselves as Australian, as “us”. As do the 28 per cent of Australian residents who were born overseas.

The threat from any tidal wave of immigrants is not to national identity. People coming here become Australian quickly enough.

No, the threat is to other things that have made Australia one of the best places on the planet to live: high home ownership; high proportion of single-dwelling housing with their own open space; equality of opportunity; a fairly equal society; ease of movement; high standard of living; good working conditions and so on.

All of these things are under threat and high population growth is contributing. The CEOs of companies that profit from high population growth pay themselves ever more money and pay the new pool of under-employed workers ever less.

And the answer is not “better infrastructure” or “decentralisation”. Those things are not happening.

Very few countries have five cities with more than 1 million people, like Australia, not even the UK, Germany, Russia, France, Italy or Brazil. The trend in Australia is for greater centralisation and high immigration is making it worse.

Decentralisation in Australia is about as likely as the states moving their capitals from Sydney to Armidale, from Melbourne to Bendigo, Perth to Bunbury or Adelaide to Whyalla.

As for infrastructure, the equation is too hard. On average, infrastructure lasts 50 years. It means you have to replace two per cent of it every year, just to keep up. If you add a further 2 per cent in population, therefore, you have to double your infrastructure effort. Australia has been falling behind ever since we increased the immigration intake from around 70,000 a year to more than 150,000. The answer is not a fanciful unaffordable wish for more infrastructure, but for fewer people.

www.crispinhull.com.au