And a year ago drought lit the touch paper to old rivalries over who owns what land, triggering a pitched battle between two sides wielding machetes, arrows, spears and clubs.

"It's the first time water was the cause," said Zacharia Igeria, chief administrator in the 50,000-strong community of the Maai Mahiu region some 50 km (30 miles) from Nairobi.

Drought last year shrank the river Ewasu Kidong, which is Masai for "water jug", to exceptionally low levels, Igeria said.

Water and pasture shortages in the past three years have decimated Masai cattle herds by four-fifths, the herdsmen say.

The dwindling of the vital local river coupled with farmers' plans to divert its waters to irrigate cash crops sparked the conflict 12 months ago, Igeria said.

Disrupted rain cycles are the type of weather changes many scientists predict will become more frequent as a result of climate change, as mankind releases heat-trapping gases into the atmosphere.

Deforestation has also been blamed for more frequent droughts in Africa.

Elders of the local Masai had never heard of global warming nor the UN climate change conference less than two hour's drive away in Nairobi, but wanted to give a message to the 70-plus environment ministers descending on the capital.

"We're not educated, we're not aware of climate change," local Masai elder William Sayo told Reuters and local journalists.

"We need help from you to explain how we can live according to the climate. Come and teach us about what is happening."

MASSACRE

Both sides fear for the changes in weather.

"The rain cycles have changed a lot," said Peter Ndung'u, son of the chairman of the 5,900 acre Lare farm, where irrigation plans helped spark the battle.

Outside the farm office is lush pasture and several acres of irrigated cash crops -- green beans and baby corn for export -- destined mostly for Britain, Ndung'u said.

"For the last five years most of the time it's been very hot," he added. "We get very little rains in the rainy season. The temperatures have been so high."

Some 20 minutes drive away, Masai elder Sayo agrees.

"We don't understand how it has become so hot," he said, in a two-room house made of sticks and dung, filled with smoke as branches smouldered in a simple stone hearth.

"We talk a lot about it. Some of us are even worried the world is coming to an end."

Sayo is one of four elders who lead a 200-strong Masai community among more than 4,000 in the region.

For now tensions have eased. Since the bloodshed international donors have dug four bore wells for the Masai, creating a reservoir.

"People now are trying to come back," said the administrator Igeria. "Buildings burnt to ashes are being re-built. The water must benefit both people."

But the number of people on Lare Farm has more than trebled in the past 30 years, and there are many more Masai and cattle.

And the problems may not be over -- Chairman of Lare farm Stephen Ndung'u Njenga said he still wants to step up irrigation, saying there is plenty of water for all.