Some 10,500 firefighters were called to tackle forest fires in California in 2015. They were unable to prevent 1,400 homes from destruction. The blaze was fueled by hot and dry weather - as a result of climate change.

The polar bear has become a symbol of climate change, as its habitat is threatened by global warming. The Arctic predator hunts from ice sheets that are fast disappearing. As the ice retreats, they are unable to stalk their prey, and risk starvation. By 2050, scientists warn that the Arctic could be ice-free in summer.

Just visible from the air is a little wood hut on the island of Spitzbergen in Norway. It is home to the Arctic research base where French and German scientists are studying climatic and atmospheric changes in the polar region, including the damage done to permafrost and glacier systems.

A goat watches a mountain expedition on the Swiss Aletsch Glacier, a UNESCO World Heritage site. It was around a kilometer longer in 1860 than it is today. Due to global warming, the glacier is shrinking by up to 50 meters per year. With the rate of retreat increasing, scientists fear Europe's biggest glacier could disappear altogether.

… the landscape looks peaceful, bathed in a mystical light. But the actual situation is far more unsettling. This aerial view shows Central Luzon in the Philippines, completely flooded after it was hit by a typhoon and heavy rain. People were drowned or buried under landslides, and half a million were forced to flee their homes. The country is hit by 20 typhoons each year.

… escape is all that's left. The World Bank warns that if global warming continues unimpeded, another 100 million people will be under threat. Poor people in parts of Africa and South Asia are at particular risk. Drought and flooding threaten crops - leading to hunger, disease and high food prices.

Climate change often hits children the hardest, through no fault of their own. Studies have found that economic problems exacerbated by drought can have profound social impacts, such as in an increase in child marriages, for example. Families may marry off their underage daughters earlier to have fewer mouths they have to feed.

Elephants produce huge quantities of manure. At Munich's Hellabrunn Zoo in Germany, one local utility is turning their waste into electric power. Around 2,000 tons of biowaste provides enough power for a hundred homes. Could this be a model for an African school? In any case, climate change is forcing new ways of thinking in the search for green energy.

The Rhine River is Europe's busiest waterway for shipping - but climate change is affecting business. Ongoing drought means shipping firms would be forced to use shorter vessels that can navigate shallower waters. If ships aren't able to set off, more goods have to be transported by road - which is more expensive.

Healthy coral reefs are like a blooming garden. But global warming is bleaching the life out of them. Corals have a symbiotic relationship with algae, which are vital to their health. But as the water heats up, they expel the algae. If warmer water temperatures persist, a lack of nutrients calcifies the corals, which makes their color fade and causes the organisms to die.

Global warming also has its benefits. In recent years, wine is being produced on Germany's northernmost island, Sylt. Ever more vineyards are being established at higher altitudes and further north - even Scandinavia now has some. Global warming also means earlier harvests and sweeter grapes.

Copenhagen wants to become the world's first carbon-neutral capital by 2025. Since 1995, it has reduced its carbon emissions by half. It stands out for its efforts on sustainable mobility, with large car-free zones, high quality public transport and impressive cycling facilities. District heating and cooling systems – some of which use cold seawater – do their bit to reduce emissions, too.

The Icelandic capital already has a renewable supply of heat and electricity – mainly from hydropower and geothermal. An impressive 95 percent of homes are connected to the district heating network. The city is also aiming to make all public transport fossil-free by 2040 and strongly encourages residents to do without their cars.

In Brazil's eighth biggest city, around 60 percent of the population relies on the urban bus network. They also have 250 kilometers of bike lines at their disposal, as well as the country's first major pedestrianized street, Rua das Flores. Curitiba's green belt provides natural protection against flooding. But its rapid population growth is putting its green ambitions under pressure.

In 2016, San Francisco passed a law that all new buildings must set aside space for rooftop photovoltaic systems – the first major US city to do so. Plastic bags have been banned since 2007, and it introduced an urban food waste program in 2009. Now, it plans to go waste-free by 2020. Plus, the majority of its buses and light rails are zero-emission.

Germany's financial center was one of the first cities to adopt a roadmap towards a 100 percent renewable energy supply by 2050. New buildings must follow strict guidelines on energy efficiency. Controversial materials like PVC are forbidden, and it has drastically reduced its waste, thanks to a modern waste management system. Frankfurt also has ambitious plans for e-mobility.

Vancouver is trying to become the world's greenest city by 2020. By then, it seeks to reduce carbon emissions by 33 percent compared to 2007. The city's electricity comes almost entirely from hydroelectric dams, but it still needs to move away from natural gas and oil for heating and transportation. The goal is to reduce per-capita ecological footprint by 33 percent.

Kigali has been described as Africa's cleanest city. It's planning to develop pedestrian and cycling corridors. Plastic bags are banned and citizens spend a day each month cleaning up the city, where it's rare to find litter. However, human rights groups have denounced the high price of this "cleanliness," which they say is as an excuse to impose a discriminatory control over the population.

The European Green Capital 2016 gets all its electricity from hydropower. It has a strong focus on public transport, pedestrian and cycling networks, and has banned cars from its city center. It was the first European city to aim for zero waste, and already recycles over 60 percent – one of the highest rates in Europe.