Richard Harris

On April 11 of this year, an extraordinary cluster of earthquakes struck off Sumatra. The largest shock, magnitude 8.7, produced stronger ground-shaking than any earthquake ever recorded. And it surprised seismologists by triggering more than a dozen moderate earthquakes around the world.

The quakes are also a sign of big changes to come in the Earth's crust.

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Here's some troubling news. Ice covering the Arctic Ocean has melted more dramatically this year than ever before. This year's loss of ice has exceeded the previous record by an area the size of Texas. NPR's Richard Harris reports.

Arctic sea ice has melted dramatically this summer, smashing the previous record. The Arctic has warmed dramatically compared with the rest of the planet, and scientists say that's what's driving this loss of ice.

To be sure, ice on the Arctic Ocean always melts in the summer. Historically, about half of it is gone by mid-September. But this year, three-fourths of the ice has melted away, setting a dramatic new benchmark.

Mitt Romney outlined an energy plan Thursday that would guide his Republican presidency. It focuses heavily on expanding the supply of fossil fuels. The presumptive nominee said the U.S., Mexico and Canada together could reach energy independence by 2020.

But the plan makes no mention of climate change and would end subsidies for cleaner sources of energy, such as wind and solar.

Ten years ago, a piece of ice the size of Rhode Island disintegrated and melted in the waters off Antarctica. Two other massive ice shelves along the Antarctic Peninsula had suffered similar fates a few years before. The events became poster children for the effects of global warming. But a new study finds that the story isn't quite so simple.

There's no question that unusually warm air triggered the final demise of these huge chunks of ice. But a lingering question is whether these events can be attributed to human-induced global warming.

A federal court has rejected a rule that would have regulated air pollution that blows from one state to the next. The ruling puts a damper on the Obama administration's efforts to reduce asthma, heart disease and other ailments related to air pollution. States and utilities asserted that the rules overstepped the EPA's authority under the Clean Air Act.

It may take some time to pinpoint the exact cause of India's massive blackouts last week, but the underlying issue for India and many other parts of the developing world is that supply is struggling to keep up with the growing demand for power — an imbalance that can affect the reliability of electric grids.