The world's newest nation, South Sudan, appealed Thursday for help in healing a land ravaged by war and disruptive weather as it made its maiden appearance at the UN climate talks.

"Climate change in Southern Sudan has very, very serious negative effects. In terms of agriculture, this is really catastrophic," its environment minister, Alfred Lado Gore, told AFP.

Independent from Sudan since only July, the country has been crippled by nearly four decades of conflict that left an estimated two million dead.

It has almost no infrastructure, a third of its population is threatened with famine and only four percent of its arable land is under cultivation, by some estimates.

Global warming would seem to be far down the list of South Sudan's priorities but is in fact a pressing concern, Gore said.

"It's a drastic climatic change, and this is manifest in the pattern of rain," he said, speaking before he delivered his country's first address before the 194-nation UN Framework Convention on Climate Change (UNFCCC).

"Nobody can actually predict when rains come, and this is causing a lot of concerns," Gore said.

"People want to cultivate but no longer know when rains come. And when they come, sometimes they are even floods and they destroy the crops."

During South Sudan's war of secession from Khartoum, its land was "carpet-bombed" and sown with mines, Gore said.

Tens of thousands of refugees are on the move, fleeing conflict, searching for food, or both.

Diplomats from Western nations have expressed growing concern of fresh bloodletting, for the two countries still have no fixed border.

At the UN Security Council on Thursday, Sudan and South Sudan staked rival claims to the disputed border region of Jau, which the north's troops attacked last week. They have also clashed over the nearby region of Abyei.

Adding to the infant nation's toll is profound disruption in weather, Gore said.

In areas such Equatoria, historically a bread basket because of its fertile soils and regular rainfall, once-predictable precipitation patterns have become erratic.

"If the crops fail, people have no food. Food security now becomes a threat," Gore said.

During his speech before the world's nations, the ex-general said South Sudan was "ready to join the human family" in the fight against global warming, which he called the "greatest challenge of all the nations in the world."

But his country needed help to get onto its feet.

"South Sudan is only five months old, and one cannot expect a child of that age to do much without the assistance of others."

A planned Green Climate Fund that should help disburse 100 billion dollars a year by 2020 to help poorer countries fight climate change and adapt to it consequences would be critical, he said.

Only when South Sudan's people can meet their basic needs, could they be expected to curtail actions that damage the environment, Gore told AFP.

"You cannot tell us to stop cutting trees because this will affect climate change. For you in Europe, you have everything -- electricity, water, cookers in your kitchen."

He added: "This problem is not yours, it is not mine, it is ours."