The appointment of Bob Rae to become this country's ambassador to the United Nations made sense to most.  As a Canadian statesmen and politician, Rae just happens to be a person of large interests and experience around the world – a quality that suits the post of someone meant not only to represent Canada to the world, but to sensitize this country's governments, institutions and citizens to a larger global narrative that will inevitably affect our domestic agenda.His challenges are many and complex.  An irascible neighbour to the south, the growing belligerence of both Russia and China, trade problems, a likely wave of pandemics, climate change – these files will be on his desk the moment he enters his UN office on the first day.But there is one growingly acute problem that could soon tax the seasoned man's abilities: global migration.  What has been a growing reality is about ready to burst onto the global stage in a way that could alter much of the global narrative.Climate change is now causing millions of individuals and families to consider making the move beyond their traditional homes and borders.  Livable land has been shrinking across the globe for decades.  While only 1 per cent of the world is barely survivable today, that number will increase to almost 20 per cent in 50 years.  And living in those regions are billions of people in the process of rethinking their future and where they will live.Abrahm Lustgarten, senior environmental reporter for ProPublica, has just published a major projection that comes with little hope of change.  Climate change migration is about to explode, as billions in regions like Africa, India, Southeast Asia and Central America begin considering making the move to more prosperous parts of the world.  One insight in particular is jarring:"The world can now expect that with every degree of temperature increase, roughly a billion people will be pushed outside the range of temperature in which humans have lived for thousands of years.  By the end of the century, heat waves and humidity will become so extreme that people without air-conditioning will simply die."And it's about more than just heat.  Crops are failing annually, sea levels, especially in southeast Asia are rising to alarming levels, rainfall has become unpredictable and drought has become a permanent reality.  People in the millions will soon move into cities that are already straining under the load of humanity.That's climate change, but what about COVID'19?  Rae knew this to be an emerging crisis when he took on the job, but he surely, like everyone else, knows little about how it will conclude.  Ten of the top 12 countries most affected by new cases of the virus are in places like Brazil, Peru, Chile, Russia and many of the poorer nations where climate change has already wreaked its havoc.Many experts believed that the developing world had escaped much of the COVID-19 damage, but that was a pipe dream.  Once anchored in a poor country, the coronavirus can, and will, rage like a wildfire.  A tragic lack of healthcare infrastructure, political leaders that really care little about their citizens, no ability to test, trace or even single out the virus from the many other diseases abounding in such regions, the massive movement of internally displaced populations – these are facts of life in a world so ill-prepared for disease or environmental crisis.For a time, some maintained the slow growth of COVID-19 in developing nations was due to the lack of travel among the population, thereby hindering the spread of the virus.  That is now changing dramatically.But what happens when they do travel, when they seek to move to someplace better and with more hope?  We are about to find out, millions of times over.  It is inevitable that millions on the verge of starvation, living on less than $2 a day, will be expandable the moment their government opts to close down their economies to fight the virus.  The only alternative then for the most marginalized is to remain and die or move out and hope.The world's refugee system is desperately endevouring to prepare for the onslaught and that one international institution looked to most by the world to deal with the problem is the very place where Bob Rae is about to take up residence: the United Nations.Global migration and the dramatic rise in the number of refugees have already forced many wealthy nations in Europe and North America to close their borders, or even construct walls.  Should they maintain that approach, millions, perhaps tens of millions, will perish with little hope of Western assistance.This is the brutal modern world this country's newest UN representative must negotiate.  He will require every bit of the knowledge and persuasion he possesses to remind the United Nations that its very foundations were built on hope and inclusion, as were Canada's.Glen Pearson was a career professional firefighter and is a former Member of Parliament from southwestern Ontario. He and his wife adopted three children from South Sudan and reside in London, Ontario. He has been the co-director of the London Food Bank for 32 years. He writes regularly for the London Free Press and also shares his views on a blog entitled “The Parallel Parliament“. Follow him on twitter @GlenPearson.