Now, Ramanathan and colleague Chul Eddy Chung of the Scripps Institution of Oceanography in La Jolla, California have an explanation for the anomaly. By combining measurements of sea surface temperatures and pollution in their regional climate models, they found that while sea surface temperatures near the equator have increased around 0.6 °C over the last 50 years, the northern Indian Ocean has not warmed.

In fact, it may even have cooled because sunlight is being absorbed by the "brown cloud" above it. Without the normal summer temperature gradients over the region, the monsoon cycle is suppressed (Journal of Climate, vol 19, p 2036). "It's causing a tendency for the rain systems to move south and not to hit land," Ramanathan says.

From issue 2552 of New Scientist magazine, 20 May 2006, page 6

The Himalayan region has long been recognised as extremely rich in animal and especially plant diversity. For instance, a paper published last year in Science (vol 308, p 405) concluded that Himalayan watersheds harbour more diverse ecosystems than the Amazon. "Himalaya's importance as a biodiversity-rich area and its need for conservation cannot be overemphasised," says Maharaj Pandit of the University of Delhi, India.

Now a team of researchers led by Pandit have revealed evidence of widespread deforestation in the Indian Himalaya region, which threatens tigers, black bears, musk deer, leopards, golden eagles and bearded vultures that depend on the forests. Large-scale conservation efforts are urgently needed to avoid the disappearance of these animals from the region, they say.

Pandit's team analysed high-resolution satellite images of the region dating from 1972-1974, 1980-1983 and 1999-2001. The team also went out into the field to verify ground features that could not easily be identified in the images. They classed regions with more than 40 per cent forest cover as dense forests, and those with between 10 and 40 per cent of cover as open forests.

By 2000, the region had lost 15 per cent of its forest cover compared with the early 1970s. By 2100, it will have lost almost half its forests, the team predicts. Less than one-third of the dense forest on which many native species depend will survive in the western Himalaya, while less than three-quarters in the eastern Himalaya will remain (Biodiversity & Conservation, DOI: 10.1007/s10531-006-9038-5). What's more, the researchers consider these conservative estimates, as they think increases in population and agriculture will increase the deforestation rate.

However, official Indian government statistics from the ministry of agriculture and the Forest Survey of India imply that total forest cover across the Indian Himalaya will expand by more than 40 per cent between 1970 and 2100. The researchers suspect the discrepancy between the official figures and their satellite data may stem from poor sampling, a lack of technical expertise and a lack of resources in the government institutes. The government might also attach too much weight to projects aimed at stopping commercial logging and at replanting trees in more remote regions, while the more serious threat is deforestation by villagers, they suggest.

These "miscalculations" in land-use decisions could have severe repercussions. "More than 80 per cent of proposed hydro-projects in India are located in the Himalaya," says Pandit. "Diversion of forest lands for hydro-irrigation projects is second only to agriculture in India."

From issue 2552 of New Scientist magazine, 18 May 2006, page 20

NASA is using a Twin Otter plane to study ice caps including the Penny and Barnes caps on Baffin Island, the Devon Island ice cap and Agassiz on Ellesmere Island.

"The Canadian Arctic actually has the largest amount of ice on the planet outside of Greenland and Antarctica, so it's an obvious place to try and understand how much water is going from there," said Martin Sharpe, a professor at the University of Alberta.

Scientists are beginning to realize more attention needs to be paid to glaciers and ice sheets in the Canadian Arctic in calculating the global rise in sea level.

The plane is equipped with an ice-penetrating radar to measure its thickness, and a laser altimeter that determines whether the elevation of the ice surface is changing.

"A large amount of our attention is focused on Greenland but the Canadian work was something I got very interested in," said Waleed Abdalati of NASA's Goddard Space Flight Center.

"Because these smaller ice masses are a little more sensitive to climate in the near term, they're no less important."

A study released earlier this year showed the amount of ice dumped into the ocean by glaciers in Greenland has almost doubled in the last five years.

Greenland contains enough ice to raise the world's oceans by seven metres, Abdalati says. But in the short term, he added, smaller ice masses could actually send more water into the ocean.

"The goal is really to figure out how much these ice masses are contributing to sea-level change," he said.

"Sea level has been going up about 1.8 millimetres a year for the last 50 to 100 years, and it's been going up about three millimetres a year for the last 12 or so years. "While that doesn't sound like much, over time it's quite significant."

Change occurring rapidly

NASA will compare this study with other airborne surveys done in 1995 and 2000.

Sharpe said both aerial surveys and research on the ground are needed to find out how much Canada's ice is contributing to the rise in sea level.

He said it's becoming clearer that when it comes to ice sheets and glaciers, things are changing more rapidly than previously believed.

The first half of the field season will be spent in Canada repeating the measurements from the two earlier surveys.

They will then go to Greenland to set up weather stations and global positioning equipment to see how fast ice is moving and to monitor weather conditions.