In 2011, a record 34 billion cubic tons of carbon dioxide were emitted from man-made sources. Half the emitted CO₂ stays in the atmosphere, about a quarter is absorbed on land (as trees grow, for example), and the remainder is absorbed by the ocean. Unsurprisingly, this incredible amount of carbon dioxide significantly changes the ocean environment. Over time, increased absorption of carbon dioxide in the oceans has led to ocean acidification, and overall warming has also led to warming of ocean waters – both changes impact marine ecosystems and the people who rely on them.

The original version of this article, by Russell Sticklor, appeared at the Stimson Center.

Spend a day in Kathmandu, Nepal’s sprawling capital of four million people, and you’ll quickly notice what has long been a fact of life in this landlocked Himalayan country, and many other South Asian nations – no reliable electricity supply exists. Up to eight times a day, neighborhoods throughout the city suffer rolling power cuts due to load shedding, causing residents and businesses alike to either carry on in the darkness or rely on expensive, diesel-consuming generators to keep the lights on. Although the country’s civil war ended in 2006, carrying the promise of restored domestic stability and accelerated economic development, Nepal’s economy has remained hamstrung by an inconsistent energy supply, with only 40 percent of the population having access to electricity. This situation persists despite the fact that the country sits on top of a virtual goldmine – an estimated 80,000 megawatts (MW) of untapped hydroelectricity, of which it has harnessed a scant 700 MW.

The water-energy-food nexus seems to be garnering more and more attention in the media and elsewhere, and it’s easy to see why: it’s a relatively simple way to illustrate how interconnected the world is today and the kind of domino-like effects that scarcity can have.

On April 1, 2012, a Chinese woman on her way to work suddenly felt the earth beneath her crumble and, in an instant, found herself plunging into an abyss of scalding hot water. The woman had unknowingly stepped into one of the many sinkholes appearing in China’s megacities. The emergence of sinkholes in China is part of a larger set of environmental issues related to rapid urbanization taking place in the Asia-Pacific region overall. [Video Below]

It’s not often that a change in accounting rules could reduce the probability of war. But that’s exactly what happened at the U.S. Securities and Exchange Commission (SEC) last month.

The number of urban slum dwellers worldwide is staggering. According to UN-Habitat, 827.6 million people live in slums around the world. Despite meeting a Millennium Development Goal to significantly improve the lives of at least 100 million slum dwellers by 2020, the total number of people living in these areas still increased by 55 million between 2000 and 2010. By 2020, the world slum population is projected to reach 889 million. With the majority of people now living in cities, urban priorities are synonymous with human security and environmental sustainability and must be accounted for in the global development agenda.

The original version of this article, by Christina Larson, appeared on Yale Environment 360.

Bouncing along bad roads in a jeep through central Mongolia, with bright blue skies and high clouds overhead, we drive for miles through a treeless landscape, passing only dry grasslands dotted with cattle and white yurts. But as we head north – myself, two U.S. scientists, and one Mongolian forestry expert – we begin to notice Siberian pine and larch growing on the northern slopes of rolling hills, but not the southern slopes, and at some elevations, but not others. In water-scarce Mongolia, as my travel companion Neil Pederson of Columbia University’s Lamont-Doherty Earth Observatory explained, the precarious growth of trees is limited by temperature and moisture availability; small variations – northern slopes are slightly cooler and wetter – can make all the difference.

In the “first spatially explicit comparison of groundwater use, availability, and environmental flow for aquifers globally,” a new article in Nature finds that the “size of the global groundwater footprint is currently about 3.5 times the actual area of aquifers.” An aquifer’s footprint is the theoretical size it would need to be to sustainably support use at its current rate, so groundwater footprints being much larger than their corresponding aquifers is a sign of overuse.