Unprecedented heat waves swept across the globe in 2017, leading to droughts, wildfires and even deaths. Australia started the year with temperatures near 50 degrees Celsius (122 Fahrenheit), the "Lucifer" heat wave brought the mercury above 40 degrees Celsius throughout Southern Europe in July and August and scorching heat hit India's most vulnerable people. Get ready for next summer...

Earlier this year, scientists realized that coral bleaching in Australia's Great Barrier Reef was worse than first thought. In some parts of the UNESCO World Heritage site, up to 70 percent of the coral has already been killed. By 2050, scientists have warned 90 percent of the reef could disappear. Rising sea temperatures and ocean acidification are the main culprits.

Armed conflicts are pushing millions of people to leave their homes or live in terribly precarious situations — and climate change is making it worse. A lack of natural resources increases the risk of conflict and makes life even harder for refugees. South Sudanese families, for instance, are escaping to neighboring countries like Uganda and Kenya — countries already suffering from drought.

From New Zealand to Spain, from California to even Greenland: the world has seen a nonstop year of wildfires. Global warming has been blamed for the increased fire risk, and in some countries that risk has turned into reality. Wildfires engulfed large areas of Europe's Iberian Peninsula, causing death and destruction, while firefighters in California have had no rest for more than six months.

Hurricanes Maria and Irma, which hit the Caribbean region in August and September, were two of the year's most damaging weather events. The list of deadly storms also included Ophelia in Ireland, Harvey and Nate in Central America and the US, and Xavier and Sebastian in Germany. Warming of the ocean surface has led to more evaporation, and that water may help fuel thunderstorms and hurricanes.

In July, one of the largest icebergs ever recorded separated from the Larsen C ice shelf — one of Antarctica's biggest — reducing its area by more than 12 percent. While calving icebergs in the Antarctic are part of a natural cycle, scientists have linked the retreat of several Antarctic ice shelves to global warming and are closely monitoring potential long-term effects.

Deteriorating air quality causes thousands of deaths around the world every year. India's capital, New Delhi, is one of the world's most polluted cities. In November, large parts of northern India and Pakistan were engulfed by a blanket of thick smog carrying harmful particulate matter. Schools were forced to close, and hospitals were full of people with respiratory problems.

The high levels of carbon dioxide in the atmosphere represent a major threat for our oceans, already in danger due to plastic pollution, overfishing and warming waters. Ocean acidification could make these waters — covering more than two-thirds of our planet's surface — a hostile environment for sea creatures. And without marine animals, entire ocean ecosystems are at risk.

Superstorms often trigger flash floods and mudslides. In late December, more than 230 people were killed when a storm hit the Philippines' second-largest island of Mindanao, a tragedy exacerbated by years of deforestation. In 2017, severe floods also hit countries such as Vietnam, Peru and Sierra Leone. European countries, including Greece and Germany, also felt the damaging effects of heavy rain.

The so-called "Gold Finger" Ende Gelände group marches across a field against a backdrop of the Neurath and Frimmersdorf lignite power plants pumping smoke into the atmosphere.

A protester wearing a mock hazmat suit and carrying a bag of hay prepares to set off from the Bedburg base. The march to the coal carrying rail line takes about three hours.

Protesters break through the first police blockade. "Many police behave well, others not so much," said Milan Schwarze, an Ende Gelände organizer. DW witnessed police hitting several protesters with batons at this first road blockade.

On their way to the rail lines, protesters were chanting slogans such as "We are unstoppable, another world is possible" and "Keep it, keep it in the ground, keep it, keep it in the ground."

Protesters came from Germany, the Netherlands, Sweden, Poland, the Czech Republic, Belgium, the United Kingdom and other European countries. Many had joined Ende Gelände protests in previous years.

Protesters from the "Blue finger" Ende Gelände group march towards the Niederaussem coal-fired power plant, seen spewing out smoke in the distance.

Protesters run past a line of police attempting to block them from crossing a potato field leading to the rail tracks.

Protesters scuttle across a potato field to escape police. Minutes later, they are met by a much larger police presence near the rail line.

A protester lies on the ground after being hit by a baton wielding police in the leg. Another man calls for the medic team that accompanied Ende Gelände.

Police corral about 150 protesters who did not make onto the rail tracks. Activists then sat in the baking sun for several hours surrounded by police until they were herded onto buses and taken to a police holding center.

Police carry a protester to a police bus. As an act of civil disobedience, many protesters refusing to go voluntarily to police buses were forcefully dragged away by police.

Three groups of protesters, each of about 70 people, block the rail line carrying lignite. The action lasted six hours until police were able to remove and transport the protesters.

Julia Verlinden, a member of the Bundestag for Green Party, observes protesters and police. The Left Party also sent parliamentary observers.

Protesters on the tracks were taken away by a RWE railcar. Police said the protesters needed to be transported by railcar because it would be too dangerous to drag them down the steep embankment that they had climbed to reach the tracks.

Police carry away a protester who refused to leave voluntarily. Many of the protesters on the tracks had to be carried away. This protester tactic slows down police and keeps the rail line closed longer.