Once, only explorers in search of adventure or scientific discovery braved the icy heart of the Arctic. But the ice is vanishing. August 29, 2008 marked a turning point: For the first time, merchant ships could navigate both the Northeast Passage and Northwest Passage, without icebreakers. This ship-friendly period in summer has been getting longer and longer ever since.

The 6,500-kilometer-long (4,000-mile) Northeast Passage leads from Asia, past Russia and Norway, and connects the Atlantic with the Pacific Ocean. The slightly shorter Northwest Passage runs past Canada toward New York. Both routes cross the Bering Strait and the Arctic Ocean. This is only possible if ice cover does not block the way.

To get from Rotterdam to Tokyo, ships currently pass India and go through the Suez Canal in Egypt. That's about 6,000 kilometers longer than the route through the Northeast Passage. Ships travel to the US East Coast from Asia via the Pacific and through the Panama Canal. Here, too, taking the Northwest Passage cuts over 4,000 kilometers off the journey.

In 2009, the Bremen-based Beluga shipping company sent two German heavy-lift carriers through the Northeast Passage for the first time. Since then, shipping traffic in the region has increased. Still, Burkhard Lemper of the Institute of Shipping Economics and Logistics in Bremen says the Arctic Ocean is not (yet) heavily frequented — if only because the route is only open at certain times of year.

No climate scientist can say for sure how global warming will progress around the North Pole. But, "Everyone agrees the Arctic will be ice-free within the next 30 to 50 years," says sea-ice expert Christian Haas of the Alfred Wegener Institute in Bremerhaven, Germany. Researchers describe the Arctic as ice-free when ice cover falls below 1 million square kilometers in summer.

Biologists fear for the unique wildlife in the Arctic as shipping traffic increases. Beluga whales, Greenland whales and walruses, for example, could be a risk, US researchers say in a study published by the Proceedings of the National Academy of Sciences. They studied 80 populations of marine mammals and found that more than half are resident along the Northeast or Northwest Passage.

Scientists fear that narwhals in particular could suffer from shipping traffic in the Arctic Ocean. The marine mammals stay close to coastal pack ice. The males are easily recognizable by their helical tusk, which can become up to three meters long. This is a life-size replica in the Ozeanum Oceanographic Museum in Stralsund, Germany.

Researchers and environmentalists are calling for guidelines on Arctic shipping. For example, ships should avoid the whales' main hunting grounds, fit sailing schedules around their migration, and keep noise and speed in check. "This does not yet exist in the Arctic — that's the big difference from Antarctica," Greenpeace biologist Christian Bussau says.

According to Greenpeace expert Bussau, only 50 ships pass through the Northeast and Northwest Passage each year. The German Shipowners' Association says the figure is in the double-digit range. But Bussau says time is of the essence: "In the long run, there will be a lot going on in the Arctic." So far, there are no environmental regulations for shipping in the region.

"Breakthrough" insights into atmospheric dynamics are emerging from "high-maths" —scrutiny of satellite data, say scientists. Their Nature magazine article identifies "significant connections" between extreme rain events, often far apart. Their premise: global rainfall distribution stems "probably" from planetary waves named after the late Swedish-born American meteorologist Carl-Gustaf Rossby.

Normally, monsoon rains over northern Queensland last a "few days," says Australia's Bureau of Meteorology. Unprecedented downpours began a week ago, with more forecast and troops sent to a disaster zone. Evacuations have included these residents of Rossela, near Townsville, and German and Swiss tourists plucked from the Diamantina River catchment by a local farmer using his private helicopter.

Wildfires have scorched swaths of Tasmania, offshore from continental Australia's Victoria state, where residents last month faced a record heat wave. Australia's Bureau of Meteorology (BoM) blames the trend partly on record-warm southern Tasman Sea temperatures that have blocked rain-bearing cold weather fronts. These flow normally west-to-east under Australia toward New Zealand.

Its hills denuded by recent drought-induced wildfires, California's central coast braced Saturday for another Pacific storm, with heavy rainfalls forecast. Santa Barbara County ordered evacuations from areas still clogged by past fire debris. Avalanche warnings were in place on the Sierra Nevada, loaded with snow from storms in January.

The US Midwest, including Chicago, is thawing after a sudden two-day arctic vortex chill. At least 18 people died. Normally, the icy air mass swirling over the darkened North Pole during the winter stays ringed by the polar jet stream at about 60 degrees north. Stream weakening was also behind the prolonged 2018 European summer drought, according to Potsdam's PIK climate institute.

Indonesia, like much of Asia, weathers annual monsoon rains. Last Tuesday, the Sulawesi islands counted its toll: at least 70 people were killed as rivers burst their banks and landslides buried village homes. Authorities said a state of emergency would remain in place until February 6.