Time was when Africa dominated gatherings of the G7. In the period between two summits held in the UK – Birmingham in 1998 and Gleneagles in 2005 – the talk was of little else. There was public activism and it led to political action.

In part, that was because the big developed countries were enjoying a spell of low-inflationary growth and could look beyond their own problems to see a bigger picture. There was the occasional financial panic, but the G7 thought the problems of economic management had largely been solved and all that was needed was a bit of tinkering by technocratic central bankers.

Once it turned its attention to other parts of the world, the G7 found much that needed attention. There were initiatives to reduce the burden of debt, to increase aid, to improve governance and to free up trade. It helped that the UK at the time had a prime minister and chancellor of the exchequer – Tony Blair and Gordon Brown – who were committed to the cause and prepared to chivvy along the more reluctant members of the G7.

Gleneagles was the culmination of the process. Public awareness was at its height and was marshalled effectively by the development movement. G7 countries talked the talk with a big package of aid and debt relief. Africa, it was thought, was sorted. Time to move on to other issues.

The Observer view on Syria and the west’s shameful failure to act | Observer editorial Read more

As it turned out, the G7 was living in a fool’s paradise. It hadn’t found the secret to trouble-free growth, as the financial crisis that erupted two years after Gleneagles conclusively proved. And it certainly hadn’t sorted all Africa’s problems, even though economic management generally improved and some countries – Ethiopia, for example – grew strongly.

The west took its eyes off Africa as it focused on its own problems. China, hungry for natural resources, moved in to commodity-rich African countries and provided infrastructure on a no-questions-asked basis. Countries that were rich in natural resources borrowed in the expectation that high oil and mineral prices would be sustained but, when they weren’t, growth slowed and debt problems resurfaced.

Since the Gleneagles summit, the west, for the most part, has become more alive to the risks of global heating; fences have put been erected to keep out migrants; a meeting of the G7 never goes by without a commitment to keep fighting terrorism.

Yet it doesn’t take a genius to work out that escaping poverty is the motivation for migrants to travel to the west, or that the failure of poor countries to provide their young adults with decent jobs breeds extremism. Birth rates are higher in poor countries, with the result that rising populations put pressure on the natural environment. All these problems are particularly acute in Africa.

Facebook Twitter Pinterest Migrants fleeing poverty and conflict in Africa are rescued after being stranded in the Mediterranean. Photograph: Anne Chaon/AFP/Getty Images

Even the biggest and longest walls in the world are not going to prevent poor people being lured to the west. No amount of security is going to keep societies safe from the young and angry. And any attempts to reduce carbon emissions in developed nations are going to be irrelevant if – as seems inevitable – Africa’s hunger for energy rises exponentially as its population grows.

And Africa’s demographic trends are truly scary. Of the 2.4 billion increase in the world’s population between 2015 and 2050, it is estimated more than half (1.3 billion) will come from Africa.

New research to be published later this week by the charity Save the Children UK and the Overseas Development Institute thinktank sums up well the risks of ignoring or underplaying Africa’s problems. That, the report says, is precisely what is happening, even though one of the United Nations 2015 sustainable development goals was a collective pledge to eradicate extreme poverty – defined as living on less than $1.90 a day – for all people everywhere.

That promise will nowhere near be met on current trends. In particular, it will be broken for African children, with the SCUK/ODI research estimating that more than 300 million sub-Saharan African children will be living in extreme poverty by 2030.

Birth rates are coming down, but slowly and at a less rapid pace than in other parts of the world. On average, the report notes, mothers in Africa give birth to four to five children, pushing the continent’s share of global births from about 29% today to a projected 36% by 2030. However, at the same time poverty has fallen more slowly in Africa than other regions, with an estimated 40% of the population living on less than $1.90 a day. Last year, African children accounted for 44% of world poverty; by 2030 it will be 55%.

'I fear for the children': the families battling to beat the odds in Kibera – photo essay Read more

As Kevin Watkins, chief executive of SCUK, notes: “Put simply, the world’s population of children is increasing most rapidly in the region where poverty is coming down most slowly. These trends are unfolding in full view of the governments who have pledged to eradicate poverty – yet their response to child poverty has been a case study in inertia.”

The SCUK/ODI study is pretty unsparing in its conclusions. It found little evidence of African governments developing coherent policy responses to growing child poverty. And the paper criticised the IMF, the World Bank and other donors for failing to put child poverty at the top of their agendas.

It’s not hard to see what this agenda should be: pro-poor redistributive growth; higher public spending on health and education; investment in family planning. African child poverty matters. It is an affront to the children who are suffering and it is a time bomb primed to go off under the west. Time to start joining the dots.