Drought in the Amazon

By Geoffrey Lean / from nzherald.co.nz

Deep in the heart of the world's greatest rainforest, a nine-day journey by boat from the sea, Otavio Luz Castello is anxiously watching the soft waters of the Amazon drain away.

Every day they recede further, like water running slowly out of an immense bathtub, threatening a worldwide catastrophe.

Standing on an island in a quiet channel of the giant river, he points out what is happening. A month ago, the island was under water. Now, it juts 5m above it.

It is a sign that severe drought is returning to the Amazon for a second successive year. And that would be ominous. New research suggests that one further dry year beyond that could tip the whole vast forest into a cycle of destruction.

The day before, top scientists delivered much the same message at a remarkable floating symposium on the Rio Negro, on the strange black waters beside which Manaus, the capital city of the Amazon, stands.

They told the meeting - convened on a flotilla of boats by Ecumenical Patriarch Bartholomew of the Greek Orthodox Church, dubbed the "green Pope" for his environmental activism - that global warming and deforestation were pushing the entire enormous area towards a "tipping point", where it would start to die.

The consequences would be awesome. The wet Amazon Basin would turn to dry savannah at best, desert at worst. This would cause much of the world to become hotter and drier.

In the long term, it could send global warming out of control, eventually making the world uninhabitable...

At one point in the western Brazilian state of Acre, the world's biggest river shrank so far that it was possible to walk across it.

Millions of fish died, and thousands of communities whose only transport was by water were stranded.

And the drying forest caught fire; in September, satellite camera images showed 73,000 blazes in the basin.

This year, says Otavio Luz Castello, the water is draining away even faster than last year - and there are still more than three months of the dry season to go.

It is much the same all over Amazonia. In the Jau National Park, 18 hours by boat up the Rio Negro from Manaus, local people who took me out by canoe at dawn found it impossible to get to places they had reached without trouble just the evening before.

Acre received no rain for 40 days recently, and sandbanks are beginning to surface in its rivers.

Flying over the forest - with trees in a thousand shades of green stretching, for hour after hour, as far as the eye can see - it seems inconceivable that anything could endanger its verdant immensity.

Until recently, scientists took the same view, seeing it as one of the world's most stable environments.

Though they condemned the way that, on average, an area roughly the size of Wales is cut down each year, this did not seem to endanger the forest as a whole, much less the planet.

Now they are changing their minds in the face of increasing evidence that deforestation is pushing the Amazon and the world to the brink of disaster.

Dr Antonio Nobre, of Brazil's National Institute of Amazonian Research, told the floating symposium of unpublished research which suggests that the felling was drying up the entire forest and helping to cause the hurricanes that have been battering the United States and the Caribbean.

The hot, wet Amazon, he explained, normally evaporates vast amounts of water, which rise high into the air as if in an invisible chimney, drawing in wet northeast trade winds, which have picked up moisture from the Atlantic.

This, in turn, controls the temperature of the ocean - as the trade winds pick up the moisture, the warm water left gets saltier and sinks.

Deforestation disrupts the cycle by weakening the Amazonian evaporation which drives the whole process.

One result is that the hot water in the Atlantic stays on the surface and fuels the hurricanes.

Another is that less moisture arrives on the trade winds, intensifying the forest drought...

Brazilian politicians say their country has so many other pressing problems that the destruction is unlikely to be brought under control, unless the world helps.

Calculations by Hylton Philipson, a British merchant banker and rainforest campaigner, reckon that doing this would take US$60 billion ($80 billion) a year - less than a third of the cost of the Iraq war.

About a fifth of the Amazonian rainforest has been razed completely. Another 22 per cent has been harmed by logging, allowing the sun to penetrate to the forest floor, drying it out.

Add these two figures together and the total is perilously close to 50 per cent, predicted as the "tipping point" that marks the death of the Amazon...

The Amazon now appears to be entering its second successive year of drought, raising the possibility it could start dying next year. The immense forest contains 90 billion tons of carbon, enough in itself to increase the rate of global warming by 50 per cent.

Nepstead expects "mega-fires" rapidly to sweep across the drying jungle. With the trees gone, the soil will bake in the sun and the rainforest could become desert.

Deborah Clark from the University of Missouri, one of the world's top forest ecologists, says research shows "the lock has broken" on the Amazon ecosystem and the Amazon is "headed in a terrible direction".