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ICE is a formidable force for change. Even so, it is hard to grasp that it shaped the world we inhabit. Our society owes its existence to the ice ages. We feed ourselves from crops grown on soils made from ancient wind-blown dust and the fine-grained products of glacial erosion. We build with materials mined from the ancient channels of glacial meltwater. Over the past 10,000 years, after the last ice age and in an unusually stable period of Earth鈥檚 climatic history, humans have been able to exploit these glacial resources and develop the world as we see it today.

How do we know this? Our knowledge of the ice ages and their legacy has come to us through the life work of pioneering scientists over the past 200 years. In Frozen Earth Doug Macdougall has assembled their contributions into a remarkable story, revealing how the ice ages came to light.

Until the middle of the 19th century, explains Macdougall, most scientists 鈥� Newton included 鈥� believed that the landscapes we now know to be formed by glacial action were the result of biblical events. Opinions began to change when Louis Agassiz, a Swiss natural scientist, spotted similarities in the landforms of the Alps to other regions that were non-glaciated. He was the first to advocate that a past ice age could explain these formations.

Once Agassiz鈥檚 views gained credence, others began to conjecture what might trigger an ice age. It was twice hypothesised (by geologist James Croll in the late 19th century and by mathematician Milutin Milankovitch in the mid-20th) that changes in Earth鈥檚 orbit around the sun would reduce the level of solar heat reaching the planet, cool it and encourage the growth of glaciers. Both times, the idea, after initial recognition, lost favour. Not until the 1970s was the hypothesis proven, by climate researchers looking at ocean sediments for evidence of past climate shifts.

And events of the last ice age have a message for us today. Ice cores taken in Greenland show that when the world鈥檚 largest ever lake, located in North America and appropriately named Lake Agassiz, burst its shores and flooded into the sea, it reduced the north Atlantic鈥檚 salinity. That slowed the northward flow of warm mid-Atlantic water and lowered the temperature of continental Europe. Macdougall suggests that something similar could happen in the near future. Melting glaciers and increased river run-off could together make the ocean less salty.

鈥淓arly glacial geologists were a huge draw with the public鈥�

Frozen Earth is a very well-constructed book that will appeal to a large academic audience. I for one learned a great deal about the integrated history of palaeoglaciology. The book鈥檚 informal style will appeal to the non-specialist, too.

Early glacial geologists such as William Buckland were a huge draw with the public. People were intrigued by these new explanations for the landscapes in which they lived and worked. Nowadays, with climate change acknowledged in the media, perhaps the causes and consequences of past changes will once again become truly popular issues. This book may help make them so.