Iceland's Eyjafjallajoekull volcano began spewing ash into the sky in March. A month later, air traffic in Europe ground to a halt. Some 100,000 commercial flights across the continent were grounded amid concerns that the ash posed a hazard to aircraft engines. Some 8 million people were affected by travel disruptions. But train and ferry services reported a boost in revenue as passengers made alternative travel arrangements. The volcano, located about 120 kilometers (75 miles) east of Iceland’s capital Reykjavik, had been dormant since 1821.

BP oil spill

An explosion on BP’s Deepwater Horizon drilling rig in April killed 11 workers and spilled millions of barrels of oil into the Gulf of Mexico. For almost three months, an estimated 5,000 barrels (210,000 gallons) of oil rushed into the Gulf each day, choking marine life and threatening fishing communities along the coast. After capping the leak, US officials announced in September that the ruptured well posed no further risk to the environment.

Massive ice sheet breaks away from Greenland glacier

A 260-square kilometer ice sheet tore away from Petermann Glacier on Greenland's northwest coast in early August. The incident triggered fears that the massive floating ice sheet would enter shipping lanes or run into oil platforms while drifting south. The floating ice island was the biggest formation of its kind since 1962. While Greenland has experienced massive glacial loss in the recent decades, it remains unclear whether this particular ice split was connected to climate change.

The results of the first ever global marine life census were published in London after a decade of research conducted by thousands of scientists. The Census of Marine Life, which cost 470 million euros ($650 million) provides a point of reference from which it will be possible to continue monitoring change throughout the 21st century.

Nuclear power debate reignites in Germany

A transport of nuclear waste finally reached its storage site in Germany, after its journey was dogged by some of the country's biggest anti-nuclear protests in years. Thousands of protestors blocked the travel routes for hours, and were eventually removed by police so that the 123 tonnes of waste could be delivered to the depot in Gorleben.

Germany’s Green Party members participated in the protests. Observers say the party soared in popularity, boosted by mounting support for the anti-nuclear movement. Meanwhile, German Chancellor Angela Merkel's pushed to prolong the life span of the country's 17 nuclear power plants. In September, thousands of demonstrators took to the streets of Berlin to protest the legislation.

Cancun climate talks

Climate talks in Cancun failed to see agreement on a new treaty to extend the Kyoto Protocol. But delegates did agree to raise $100 billion (76 billion euros) for a "Green Climate Fund" intended to help poor countries battle climate change. The meeting did not establish a new global, legally binding treaty to tackle climate change, but it provided some of the essential building blocks for bringing that goal closer.

Author: Sarah Steffen

Editor: Saroja Coelho