The map, presented at London's Science Museum, shows graphically how climate change could lead to water and food shortages, mass migration and conflict if action is not taken at a landmark summit in Copenhagen in December.
"The reason for publishing this map is that for many people, not only in our own country but around the world, the penny hasn't yet dropped that this climate change challenge is real, it's happening now," Miliband said.
The effects of climate change are not in "some far flung future" but would affect hundreds of millions of people within his lifetime, he added, unveiling the map with his brother Ed, Britain's climate change minister.
A four-degree Celsius increase could happen in his children's lifetime, Miliband warned. "The penny hasn't dropped that Copenhagen is the chance to address -- on a global scale -- the challenge," he said.
The map shows sea level rises and storm surges with temperatures rising up to 15 degrees, bringing increased risks of forest fires and droughts in Europe, and slashing harvests by up to 40 percent in southeast Asia and Africa.
Vicky Carroll of the Science Museum said: "We thought it was important for visitors to understand the whole picture.
"There's so much information about climate change but many people are still confused, so this gives them the evidence in a clear and accessible way."
British Prime Minister Gordon Brown warned on Monday that the world faces "catastrophe" if action is not agreed to curb the greenhouse gases held responsible for global warming at the UN talks in Copenhagen.