The largest volcanoes on our planet may take as little as a few hundred years to form and erupt. These "supervolcanoes" were thought to exist for as much as 200,000 years before releasing their vast underground pools of molten rock. Researchers reporting in Plos One have sampled the rock at the supervolcano site of Long Valley in California.

World leaders and Somali politicians are due to gather in Istanbul on Thursday for a conference on Somalia. The two-day meeting is being hosted by the Turkish government, which has tried to raise Turkey's profile in Somalia since last year's drought there. Traditional elders, business leaders and civil society groups from Somalia are also due to attend.

Images from northern Italy in the aftermath of an earthquake which caused major damage.

Scientists have identified thousands of sites in the Arctic where methane that has been stored for many millennia is bubbling into the atmosphere. The methane has been trapped by ice, but is able to escape as the ice melts. Writing in the journal Nature Geoscience, the researchers say this ancient gas could have a significant impact on climate change.

Tackling Asia's increasing wealth gap is on the agenda at the Asian Development Bank's annual meeting in Manila.

The Brazilian Chamber of Deputies has approved controversial legislation that eases rules on how much land farmers must preserve as forest. Brazil's powerful farmers' lobby argues that the changes will promote sustainable food production. But environmentalists say the new forest code will be a disaster and lead to further destruction of the Amazon.

Over-consumption in rich countries and rapid population growth in the poorest both need to be tackled to put society on a sustainable path, a report says. An expert group convened by the Royal Society spent nearly two years reading evidence and writing their report.

Bangladesh has one of the highest rates of child marriage in the world, with 20% of girls becoming wives before their 15th birthday, even though 18 is the minimum age allowed by law. Why? "It is the new kind of slavery," says Mirna Ming Ming Evora, who's the country director for the NGO Plan International.

Ngozumpa Glacier in Nepal snakes away from the sixth highest mountain in the world, Cho Oyo. It's not the greatest glacier to look at - far from it. It's smothered in a layer of rocky debris that's fallen from the surrounding cliffs, giving it a very grey, dirty appearance.

Disparities in consumption and resources in relation to the population of the Earth.

In developing nations, where improvements in health care and sanitation are seeing death rates fall, birth rates still remain relatively high. This is leading to rapidly rising populations. In fact, 97 out of every 100 new people on the planet are currently born in developing countries.

How is the changing global population affecting people's daily lives? With the UN set to announce that there are now seven billion people on the planet, BBC News reporters spoke to seven people from around the world to hear their stories. Production: Anna-Marie Lever, Fiona Crack, John Galliver, Emily Jones.