THE history of the last two centuries is punctuated by the movement of large numbers of people from one country to another.

Examples include the Irish potato famine in the 1840s with over one million leaving, and the eviction of the crofters from the Highlands of Scotland to make way for sheep and English landlords. These movements set the scene for the future, with even Welsh settlements in Patagonia.

Between 1880 and 1920 the USA accepted five million immigrants, with many fleeing persecution in First World War Europe, and more movements continued after the end of the Second World War. In 1945 hundreds of thousands of Europeans left their homelands, with displaced persons, the movement of Soviet peoples, and the establishment of Israel in Palestine evicting one million Arabs.

And then there are the more distant examples, in China, with enormous numbers moving to the cities, and the partition of India following the establishment of Pakistan, and later Bangladesh, with some 15 million moving from where they were born. By 1960 the hundred square mile Mangla dam had flooded Mirpur in Azad-Kashmir, and many made Bradford their new home.

So large numbers moving is nothing new, with war, famine, and religious differences making migration the natural response, even though there were barely three billion people world wide in 1960.

But now future migration will certainly increase remarkably as the world population approaches eight billion. Post colonial struggles, political, religious and sectarian ambitions, plus the search for raw materials, particularly oil, will still unsettle people, but now there's another significant reason that will up-root millions - climate change.

By mid-century there will be noticeable sea level rise, regional flooding, country wide droughts, and food shortages. Internal movement within countries will strain political systems, stress food supplies and threaten stability prompting millions to search for a safer place to live. The Syrian war and exodus has a severe drought background.

By mid-century more than a fifth of Bangladesh will be below sea level, with some 30 million people forced to move, while the current drought and food shortages in southern Africa will be normal in a warmer world.

Border walls and fences cannot provide a peaceful solution, and the biggest test for our species will be learning to live together. Almost instantaneous worldwide communications, widespread and available, will inform the distressed of more settled areas, and they'll keep coming.

We need to stop competing with each other, and treat each individual human life with the respect and support it requires. We are one family, and in future selfishness fostered by national pride and nationhood will need to give way to a sharing humanity.

It's that, or we fight to the death.