Abrupt summer sea ice decline has not affected polar bear numbers as predicted

Written by Dr. Susan J. Crockford

Yes, Arctic sea ice has declined since satellite records began in 1979 but polar bears have adjusted well to this change, especially to the abrupt decline to low summer sea ice levels that have been the norm since 2007.

Some polar bear subpopulations have indeed spent more time on land in summer than in previous decades but this had little negative impact on health or survival and while polar bear attacks on humans appear to have increased in recent years (Wilder et al. 2017), the reasons for this are not clear: reduced summer sea ice is almost certainly not the causal factor (see previous post here).

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Review: Inheritors of the Earth: How Nature is Thriving in an Age of Extinction

Written by Matt Ridley

If human beings were to vanish from the Earth, what would their effect on wildlife have been? A rash of extinctions, a lot of mixing up so that wallabies and parakeets live in England and rabbits and sparrows in Australia, but also — according to Chris Thomas — an eventual doubling in the number of species on the planet: a “sixth genesis”, as he calls it in reference to the five previous times that biodiversity has expanded rapidly after a mass extinction. We are causing a mass speciation.

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Nickel key to Earth’s magnetic field, research shows

Written by Brooks Hays

New research suggests nickel is essential to the Earth’s magnetic field.

Earth’s magnetic field is generated by what’s called the “dynamo effect,” a unique combination of geophysical factors. Of these factors, the convection currents of Earth’s conductive, molten core and Earth’s constant rotation are the most important.

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