2021's biggest climate moments

Many countries around the world banned the usual New Year's fireworks to relieve pressure on hospitals swamped with COVID-19 cases. For Germany, that meant an estimated 3,500 tons of plastic waste saved. In Amsterdam, the taboo on home pyrotechnics looks set to endure, with the city organizing public displays instead.

Europe and North America saw plunging temperatures, with many regions blanketed in deep snow. Arctic warming caused dips in the polar vortex and a weaker jet stream, conspiring to send chilly Arctic air south. Disruption of the jet stream can also have the reverse effect, sending warm air up from the tropics. We're yet to see which trend will dominate as the planet continues to heat up.

Thousands of people had to leave their homes after heavy rain flooded towns in eastern Australia. Gladys Berejiklian, then the premier of New South Wales, a state that was particularly affected, called the inundation a "one-in-100-year event." Some commentators argued that this kind of flooding is in fact becoming the new normal.

Europe's biggest economy was given a reality check by its Constitutional Court, which declared the German Climate Protection Act unconstitutional for failing to include climate targets beyond 2030. The court said this would place too great a burden on future generations. The Bundestag toughened up the legislation with a commitment to go climate-neutral by 2045.

In another landmark ruling, a district court in The Hague, Netherlands, ordered Shell to cut its CO2 emissions by 45% by 2030, in line with the Paris Agreement on climate change. It was the first time a private company has been legally forced to comply with the global agreement. "This applies to the entire world, so also to Shell," the judge said.

More than 230 people died during a heat wave in Canada, with record temperatures of nearly 50 degrees Celsius (122 F) recorded in Lytton, British Columbia. The following day, forest fires reduced much of the village to ash. This was also a summer of devastating blazes for California, Mediterranean countries such as Greece and Turkey, and Siberia and the Amazon.

In Central Europe, catastrophic heavy rain turned streams into raging rivers that inundated towns and villages as they burst their banks. In Germany's Rhineland, more than 180 people lost their lives. Parts of Belgium, the Netherlands and the southern German state of Baden-Württemberg also suffered extreme floods. Property damage in Germany alone was estimated at several billion euros.

The UN Intergovernmental Panel on Climate Change released a report with an unequivocal message: The climate crisis is worse than we thought and humans are definitely to blame. The IPCC's assessment reports are the most detailed and comprehensive on the topic, in this case drawing on more than 14,000 peer-reviewed studies.

At the UN General Assembly, Premier Xi Jinping announced that China would no longer build coal-fired power plants abroad — putting an end to a construction spree that has already seen hundreds of Chinese-backed coal power projects go up as part of its Belt and Road Initiative through Asia, the Middle East, Africa and Europe. But Beijing continues to build new coal power plants at home.

Concentrations of greenhouse gasses in the atmosphere reached a new record in 2020. According to the report by the World Meteorological Organization, the year-on-year increase was higher than the average increase over the past decade, despite the economic fallout of the pandemic. The WMO announced the figures with the warning that "we are way off track" for the Paris Agreement targets.

After a pandemic hiatus, the UN Climate Change Conference was back in 2021, but it struggled to decide the details of the Glasgow Climate Pact. With India and China resisting a commitment to phase out coal, the final text agreed only to a "phasedown." For many, this was hugely disappointing, though not necessarily surprising. Greta Thunberg had already declared COP26 "a global greenwash festival."

With the year drawing to a close, the US was hit by more extreme weather as 36 tornadoes swept through six states and left devastation in their wake. Homes and businesses were demolished, while dozens of people were killed. President Biden announced an investigation into global heating's impact on the tornadoes. Soonafter, nearly 400 people died in the Philippines after Typhoon Rai hit.