BEIRUT, Lebanon — Government helicopters rained barrel bombs on villages across Syria last week, killing civilians and demolishing homes. Hundreds of combatants died in battles that failed to move the front lines. And activists spread videos of hungry, war-weary Syrians through social media.

“We can’t move. We can’t walk,” a languid old man says in one video shot near the capital, Damascus. “This situation won’t work.”

But one of the starkest indications of what four years of conflict have done to Syria came from space, with new satellite images showing that mass destruction and displacement have extinguished more than four-fifths of the country’s lights, according to an analysis by Xi Li of Wuhan University in China and the University of Maryland at College Park.

The Syria conflict began four years ago this week with protests calling for political reforms inspired by the Arab Spring uprisings elsewhere in the Middle East.

Since then, it has repeatedly metastasized: President Bashar al-Assad unleashed soldiers and thugs to quell the unrest; the opposition spawned armed rebel groups; foreign powers poured in military aid; and the resulting violence spread chaos in increasingly large expanses of territory, allowing extremist groups to establish footholds and increase their power.

Syria enters its fifth year of conflict with few signs that the war will end soon. International efforts to bring the warring parties together for peace talks have fallen dormant, and the United Nations envoy, Staffan de Mistura, has made little progress on even his modest goal of a short-term cease-fire in only one of Syria’s many battleground cities.

Instead, international attention has shifted to military action against the extremists of the Islamic State, who control parts of Syria and Iraq and have shocked the world by beheading their foes and demolishing historical sites.

Aid organizations say that the rise of the Islamic State, also known as ISIS or ISIL, has not only inflicted deprivation and violence on the communities it conquers, but has also siphoned international attention from a growing humanitarian crisis that is echoing increasingly far from Syria’s borders. Last year, for example, brought a record high for illegal migration across the Mediterranean to Europe. Many of those taking the often-lethal trips were Syrian.

Humanitarian organizations issued a barrage of reports for the anniversary of the war’s beginning that quantify how hard life has become for Syrians.

About half of the country’s prewar population has fled from home, according to the United Nations, and nearly four million people have become refugees abroad, putting large burdens on neighboring countries like Turkey, Jordan and Lebanon.

A report by the Syrian Center for Policy Research said that education was in a “state of collapse”; that 6 percent of Syrians had been killed or wounded; and that life expectancy had dropped by 20 years since 2010.

“The numbers are staggering,” said Valerie Amos, the departing emergency relief coordinator for the United Nations. “They are so staggering that they have become almost meaningless to people.”

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For Syrian civilians in the country, the war has meant a downward spiral of death, uncertainty, poverty and displacement.

Nayef Abdul-Qader, a teacher, fled his home in the village of Qursaya in northern Syria with his wife and six children early in the war because fighting had erupted nearby and the local rebels said they needed time to clear government forces from the area.

The family returned later to find their home damaged, fields burned and government forces shelling continuously. But with nowhere else to go, the family stayed.

Mr. Abdul-Qader’s school had closed, and he then lost his salary because someone had told the government that he had joined the rebels. His family started planting vegetables, he said.

The area came under siege, so his family moved again, living in a cave for a few months and then in the abandoned home of another family who had fled the country.

When the fighting reached there, too, the family members moved to a camp on the Syrian side of the Turkish border, where they survived on money sent by Mr. Abdul-Qader’s brother, who works in Lebanon.

“The aid coming to the camp is rare, but we are still alive,” he said by phone.

Life has become hard even in areas that are not directly threatened by violence.

Residents of Damascus, which is firmly controlled by government forces and associated militias, have grown used to long lines, rising prices and limited supplies of gasoline, heating oil and even bread.Many also say the war has damaged the social order, giving armed men a leg up on everyone else.

One recent evening in Damascus, hundreds of people waited in a long line in the street to buy their government-set allotment of eight loaves of flatbread from a bakery when armed men from a pro-government militia pounded on the door.

“I am security!” one yelled. “Open it, or I will destroy it!”

The men left soon after, their arms full of bags of bread.

Hopes that the situation would improve rose briefly a year ago when the United Nations Security Council passed its first resolution on Syria, calling for free access to humanitarian aid. Another resolution authorized aid shipments across borders not controlled by the Syrian government.

But last week, a coalition of 21 aid groups released a harsh report saying that the resolutions had failed to make much difference.

“There is more death, more displacement, an increase in restrictions by neighboring countries and a more desperate situation for the refugees and for those displaced inside Syria,” said Daniel Gorevan, who handles Syria policy for Oxfam, one of the groups that participated in the report.

In countries bordering Syria, the flood of refugees has put a heavy burden on economies and budgets. In Lebanon, where about one in five residents is a refugee, some communities have been transformed by the human tide.

Since the conflict started, the Lebanese town of Sadnayel has seen its prewar population of about 15,000 more than double as refugees have arrived, said Raed Sawan, the vice president of the City Council.

“It’s all crowded and filthy,” he said, driving through town and pointing to the tent camps that had sprouted all around. “It’s a miserable life.”

The town could barely keep up with the new arrivals, he said, and the municipal budget could not cover trash collection or other services. Most of the camps had not been connected to the sewer system, and their outhouses emptied into pools of green water in nearby irrigation ditches.

On the edge of town, hundreds of refugees were staying in an old cow shed that had been divided into small rooms. Most contained nothing more than blankets and thin mattresses, and the area smelled of burning plastic as the refugees tried to keep warm.

“There is no firewood, so we are burning trash,” said Fayyad Ogla, 47.

Many of the refugees had babies in Lebanon who have not been registered, making them officially stateless and raising the possibility that they will have trouble returning to Syria once the war ends.

While most refugees said they still hoped to go home, some did not expect they would.

“I have cut off hope that I’ll go back,” said Farid Qassim, 29.

He fled the religiously diverse area of Houla in central Syria, where the fighting among communities has so damaged sectarian relations that he did not think he could live again near his former neighbors.

“The fighting there will never end,” he said.