Ice is the white flag being waved by our planet, under fire from the atmospheric attack being mounted by humanity. From the frosted plains of the Arctic ice pack to the cool blue caverns of the mountain glaciers, the dripping away of frozen water is the most crystal clear of all the Earth's warning signals.

It relies on neither the painstaking compiling of temperature records back through history nor the devilish complexity of predicting the future with supercomputers. Ice on Earth is simply and unambiguously disappearing. Last week saw the annual summer minimum of the Arctic ice cap, which has now shrunk to the lowest level satellites have ever recorded. The ice at the roof of the human world is faring little better: mountain glaciers are diminishing at accelerating and historic rates.

The lower glaciers are doomed. Kilimanjaro may be bare within a decade, with the Pyrenees set to be ice-free by mid-century and three-quarters of the glaciers in the Alps gone by the same date. As you climb higher, and temperatures drop, global warming will take longer to erode the ice into extinction. But at the "third pole", in the Himalayas, the ice is melting as evidenced by dozens of swelling milky blue lakes that threaten to burst down on to villages when their ice dams melt.

The threat posed is far greater than even this terrifying prospect: a quarter of the world's people rely on Himalayan meltwater, which helps feed the great rivers that plunge down into Asia. The Yellow, Yangtze, Mekong, Brahmaputra, Ganges and Indus nourish billions and will eventually lose their spring surges.

Melting ice is the cause of another of the greatest long-term threats posed by climate change: rising sea level. The deep freezes of Greenland and west Antarctica store enough water to raise the oceans by 20 feet. That would flood many of the world's greatest cities from New York to Shanghai, but remains for now a distant prospect.

Perhaps it is because ice is at the cold heart of all our deepest global warming fears that climate change sceptics wield their picks so heavily on it. The error by the publicists and cartographers of the Times Atlas, who stated that Greenland's ice cover had shrunk by 15% since 1999, prompted a renewed sounding of sirens by climate sceptics who saw another example of rampant alarmism by warming fanatics. In fact, it was climate scientists themselves who sounded the alarm, prompting the Atlas publishers to promise a new map would be inserted.

This was not the first time ice had been under the lens of those holding the fringe view that global warming is a fantasy. In the run-up to the Copenhagen climate summit in December 2009, a three-year-old mistake surfaced among 3,000 pages of report by the UN's climate science advisers. The Himalayas would be ice-free by 2035, it claimed, instead of the rather more distant date of 2350 that scientists would recognise. A PR bungle turned this typographic tic into a deeply damaging global story, much to sceptics' delight. As Suzanne Goldenberg discovered in the Himalayas, glaciologists have been deeply chastened by the experience and the UN's Intergovernmental Panel on Climate Change has instituted a swathe of reforms to avoid a repeat.

The Himalayan and Greenland farces did nothing to dent the global scientific consensus on climate change but could not be laughed off given the already weak political will to tackle the crisis. Despite every government and science academy on the planet agreeing that climate change is real and must be addressed, the hot fumes of industry continue their relentless upward trend. As the white flag shrinks yet further, the chance to limit the impact of that melting is dripping through our hands.