Josef Sayer and his colleague Nicole Piepenbrink make the trek from the German town of Aachen, on the Belgian border, for Saturday's massive protest march in Copenhagen as the climate change talks, in obvious stalemate, reached the end of their first week. They were wearing plastic blue parkas and carrying "Climate Justice" signs. Thousands of marchers were wearing blue; the colour, they said, represented the rising seas.
Mr. Sayer is the director of the overseas development agency of the German Catholic church, known as Misereor, which has a front-row seat to the harsh effects of climate change in Africa, where rising temperatures are damaging food production and water supplies.
We asked him what impressed him most about the protest march, beyond the numbers - tens of thousands of marchers, 900 of whom were rounded up by the police. "There were a lot of quite young people at the protest," he said. "That's very important because these are the people who will suffer in 2050."
The year refers to the long-term target to reduce greenhouse gas emissions by 80 per cent or more if the planet is to limit its temperature rise to 2 degrees C. It also refers to the most effective slogan of the march. Young people were given orange T-shirts which read: "How old will you be in 2050?"
Mr. Sayer says the slogan is all to do with climate justice. Most of the politicians and industrialists who are making decisions about how much, or how little, carbon will be dumped into the atmosphere won't be alive in 2050. Their children and grandchildren will. "Justice means all the generations living now have the right to a future life," he said. "That means those who are responsible for the emissions and the pollution have to take responsibility for the pollution."
There marchers toted other catchy slogans. "There is no Planet B," said one. Another read "Bla, bla, bla, Act Now!" But there is no doubt the "2050" slogan was the most arresting of the day.
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