It could be a key to unlocking a mystery about the world’s climate: a piece of ice so old it formed when ice ages were more frequent, about a million years ago. It may even give scientists insight into what is happening now, as the planet warms. But first they have to find it.

This won’t be as easy as picking up a hammer and knocking a few chips off a block. First, they need an ice core that allows them to see changes in the atmosphere over time. Cores are 4 to 5 inches (10 to 13 centimeters) in diameter and stretch for almost 2 miles (3 kilometers) when all the pieces are laid end to end, said Ed Brook, a professor of earth, ocean and atmospheric sciences at Oregon State University in Corvallis. And the oldest ones retrieved to date are 800,000 years old.

With the stroke of Gov. Kate Brown's signature Friday, Oregon became the first state to eradicate coal from its power supply through legislation and now boasts some of the most stringent demands for renewable energy among its state peers.

The new law will wipe out coal-generated energy in phases through 2030 and requires utilities to provide half of customers' power with renewable sources by 2040, doubling the state's previous standard.

Rising sea levels driven by climate change could upend the lives of more than 13 million Americans by the end of the century, according to a study released Monday.

If global warming lifts oceans 1.8 meters (six feet) by 2100, as some scientists forecast in worst-case scenarios, 13.1 million people living in U.S. coastal areas will become vulnerable to flooding and storm surges, the study said.

One in four deaths worldwide are due to environmental factors like air, water and soil pollution, as well as unsafe roads and workplace stress, the World Health Organization (WHO) said Tuesday.

An estimated 12.6 million people died in 2012 as a result of living and working in unhealthy environments, 23 percent of all deaths reported globally, according to the new study.

Increasing Canada's contribution to international peacekeeping, the fight against climate change and advocacy for women's rights are on the agenda for Prime Minister Justin Trudeau's visit to the United Nations, his office said Monday.

His visit to U.N. headquarters in New York on Wednesday comes one month after Secretary General Ban Ki-moon praised Ottawa's renewed engagement on the world stage.

Climate change could kill more than 500,000 people a year globally by 2050 by making their diets less healthy, according to new research published in the Lancet.

The research is the first to assess how the impacts of global warming could affect the quality of the diets available to people and found fewer fruit and vegetables would be available as a result of climatic changes. These are vital in curbing heart disease, strokes and diet-related cancers, leading the study to conclude that the health risks of climate change are far greater than thought.

Greenland’s vast ice sheet is in the grip of a dramatic “feedback loop” where the surface has been getting darker and less reflective of the sun, helping accelerate the melting of ice and fueling sea level rises, new research has found.

The snowy surface of Greenland started becoming significantly less reflective of solar radiation from around 1996, the analysis found, with the ice absorbing 2% more solar energy per decade from this point. At the same time, summer near-surface temperatures in Greenland have increased at a rate of around 0.74C per decade, causing the ice to melt.

Climate scientists have bad news for governments, energy companies, motorists, passengers and citizens everywhere in the world: to contain global warming to the limits agreed by 195 nations in Paris last December, they will have to cut fossil fuel combustion at an even faster rate than anybody had predicted.

Joeri Rogelj, research scholar at the International Institute for Applied Systems Analysis in Austria, and European and Canadian colleagues propose in Nature Climate Change that all previous estimates of the quantities of carbon dioxide that can be released into the atmosphere before the thermometer rises to potentially catastrophic levels are too generous.

Carbon emissions may have peaked already in China, years earlier than its leaders pledged, according to a study co-authored by the world-renowned economist Lord Stern.

The country’s emissions have fallen, partly as a result of its globally relevant economic slowdown, and partly owing to government policies to pursue a low-carbon path and reduce the rampant air pollution in its major cities.

The prolonged plunge in fossil fuel prices is rippling across the globe. Yet it’s barely put a dent in the booming market for clean energy, heralding perhaps a new era for wind and solar.

Oil prices of less than $30 a barrel—the lowest in 12 years—have shaken stock markets and ravaged the budgets of major producers such as Russia and Saudi Arabia. Along with falling gas prices, they’ve slashed the profits of fossil fuel companies, which are delaying dozens of billion-dollar projects and laying off thousands of workers.