The number of Syrian refugees in Lebanon registered with the United Nations has now passed 1 million, as the organization's refugee agency stresses the urgent need to fund humanitarian aid.

"The extent of the human tragedy is not just the recitation of numbers," United Nations High Commissioner for Refugees representative Ninette Kelley told reporters in Lebanon's second largest city, Tripoli, April 3.

"Each one of these numbers represents a human life who ... have lost their homes, their family members, their sense of future."

The U.N. refugee agency officially registered an 18-year-old student from Homs as its millionth refugee in Tripoli. One year ago, the country was host to 356,000 U.N.-registered refugees.

While the number of registered refugees in Lebanon hit 1 million Thursday, the refugees' full number is much greater.

The Lebanese government estimated 800,000 refugees in early January, and by mid-February had increased its count to 1 million.

"Everybody knows that the real number of Syrian refugees in Lebanon is already well past the million mark," wrote the BBC's Jim Muir, "but the fact that that many have now been officially registered is yet another grim milestone as the conflict grinds on."

David Kenner, Middle East editor at Foreign Policy magazine, tweeted that a graphic showing the sources of the 1 million U.N. refugees from within Syria was "staggering," yet "more staggering when you realize these are only registered ones."

The Melkite Archeparchy of Furzol, Zahle and the Bekaa, on Lebanon's border with Syria, runs its own refugee assistance program – many of the Christians fleeing Syria fear to register with the U.N. for fear of identification and reprisal.

Because of Syria's civil war – now beginning its fourth year – half of the country's population have fled their homes.

Some 6.5 million Syrians are believed to have been internally displaced by the war, and there are 2.6 million Syrian refugees living in nearby countries, most of them in Lebanon, Turkey, and Jordan.

The more than 1 million refugees in Lebanon are straining a country whose population, when its neighbor's war began, was slightly over 4 million.

Now, one in every five residents of Lebanon is a refugee from Syria.

UNHCR chief Antonio Guterres said April 3 that the refugees have had a "staggering" impact on Lebanon.

The Syrian civil war cost Lebanon an estimated $2.5 billion in economic activity in 2013, the World Bank estimates. The presence of refugees has driven down wages for Lebanese and has taxed critical infrastructure like sanitation, water supplies, waste management and health care facilities.

Refugees in Lebanon who cannot afford housing live in tent camps, many not far from the center of the capital, Beirut. The camps are now building housing several stories high in cramped conditions. The sewer system is open and fresh air is scarce, contributing to the spread of disease.

Wadih Daher, an official of the Furzol archeparchy, told CNA last month that the impact on Lebanese has been "huge … in all aspects," including security issues.

The Syrian conflict began March 15, 2011, when demonstrations protesting the rule of president Bashar al-Assad and his Ba'ath Party sprang up nationwide. The following month, the Syrian army began to deploy to put down the uprisings, firing on protesters.

Now an estimated 140,000 persons have died in what has become a civil war. The U.N. quit counting the bodies last July, leaving its estimates at 100,000, saying it could no longer verify its sources.

The civil war is being fought among the Syrian regime and a number of rebel groups. The rebels include moderates, such as the Free Syrian Army; Islamists such as al-Nusra Front and the Islamic State of Iraq and the Levant; and Kurdish separatists.

The millions of refugees created by the war have led to urgent humanitarian need. The UNHCR has appealed for $1.89 billion to fund humanitarian aid in Lebanon in 2014, but has received only $242 million.

"The Lebanese people have shown striking generosity, but are struggling to cope," said Guterres  "Lebanon hosts the highest concentration of refugees in recent history. We cannot let it shoulder this burden alone."

"Support to Lebanon is not only a moral imperative, but it is also badly needed to stop the further erosion of peace and security in this fragile society, and indeed the whole region."