The United Nations has declared a state of famine in some parts of southern Somalia where the worst drought in over half a century is already being blamed for thousands of deaths.
The announcement on Wednesday signals the need for more aid to the worst affected regions of Southern Bakool and Lower Shabelle.
UN official Mark Bowden said malnutrition rates in Somalia were among the highest in the world, and that they would dangerously spread in the coming months.
"If we don't act now, famine will spread to all eight regions of southern Somalia within two months, due to poor harvests and infectious disease outbreaks," Bowden said.
"One in three children have suffered from severe food shortages, imperilling their lives," he said.
"More than ever, Somali people need and deserve our attention... whether we are donors, members of humanitarian organisations, or parties to the conflict."
A UN statement from earlier in the day said, "Across the country nearly half of the Somali population - 3.7 million people - are now in crisis, of whom an estimated 2.8 million people are in the south."
In all, more than 10 million people are affected and need emergency help, the UN said.
'500,000 children at risk'
"It's extremely serious. We're seeing rates of malnutrition that have pretty much doubled in recent months and weeks," Rozanne Chorlton, UNICEF's coordinator in Somalia told Al Jazeera.
"Almost all of the people who are malnourished are children, but now we're even seeing teenagers who are malnourished," she said, as opposed to what's been seen in recent years where malnutrition has been mostly limited to children under 5 years old.
UNICEF said earlier this week that at least 500,000 children were at risk of death in the Horn of Africa, while the International Committee of the Red Cross has said one in 10 children in parts of Somalia could die from starvation.
Countries affected across the region include parts of Kenya, Uganda, Ethiopia and Djibouti, while the United States on Tuesday also urged secretive Eritrea to reveal how severely it has been hit by the drought.
Famine is officially defined as when two adults or four children per group of 10,000 people are dying of hunger every day and 30 percent of the population is acutely malnourished.
Aid group Oxfam said that some areas in the region have not had such a low rainfall in 60 years.
Fran Equiza, the organisation's regional director, released a statement on Wednesday saying it was "morally indefensible" that countries have pledged only $200m on top of funding for long-running programs.
Equiza singled out Italy, Denmark and France for failing to contribute and said Germany and Spain could do much more.
Chorlton told Al Jazeera, "In UNICEF alone we're asking for $70m, which is double the budget we were expecting to have to spend this year."
On Wednesday, US Secretary of State Hillary Clinton said the US will give another $28m in aid, adding to the $431m in emergency assistance it has given to the Horn of Africa this year.
Britain has pledged $145m in the past two weeks, about 15 percent of what is needed, and the European Union pledged around $8m, with more expected in coming days.
Spain has promised nearly $10m and Germany around $8.5m, but Oxfam said France has so far not pledged any more money and Denmark and Italy have said no significant new sums are available.
"There is no time to waste if we are to avoid massive loss of life," Equiza said in a statement.
"We must not stand by and watch this tragedy unfold before our eyes. The world has been slow to recognize the severity of this crisis, but there is no longer any excuse for inaction."
Aid delivery challenges.
In early 2010, the World Food Programme (WFP) suspended its aid operations across much of southern and central Somalia after al-Shabab ordered aid agencies to halt operations in areas under its control.
Al-Shabab is an armed movement that seeks to overthrow Somalia's Transitional Federal Government and impose sharia law. It controls the majority of the country, including pockets of the capital Mogadishu.
But the group surprised aid workers two weeks ago with a pledge to allow relief agencies "with no hidden agendas" greater access to rebel-held territory.
"What they said, I think, in that statement, was that organisations already there were free to work," Chorlton told Al Jazeera.
She said that in the past two weeks, UNICEF has been allowed to deliver aid unhindered in al-Shabab-controlled areas, but that "it may be more difficult for organisations that were not already in areas affected."
Source: Al Jazeera and agencies