Even the United Nations, which released regular reports on the death toll during the first years of the war, gave its last estimate in 2016 — based in part on 2014 data — saying it was virtually impossible to verify how many had died. At that time, a United Nations official said 400,000 people had been killed.
But so many of the biggest moments of the war have happened since then. In the past two years, the government of President Bashar al-Assad, with Russia’s help, laid siege to residential areas of Aleppo, once the country’s second-largest city, and several other areas, leveling entire neighborhoods. Earlier this month, dozens of people died in a suspected chemical attack on a Damascus suburb, prompting the United States, Britain and France to launch retaliatory strikes against Syrian targets on April 14.
American-led forces have bombed the Islamic State in large patches of eastern Syria, in strikes believed to have left thousands dead. And dozens of armed groups, including fighters backed by Iran, have continued to clash, creating a catastrophe that the world is struggling to measure.
Historically, these numbers matter, experts say, because they can have a direct impact on policy, accountability and a global sense of urgency. The legacy of the Holocaust has become inextricably linked with the figure of six million Jews killed in Europe. The staggering death toll of the Rwandan genocide — one million Tutsis killed in 100 days — is seared into that nation’s reconciliation process.
Without a clear tally of the deaths, advocates worry the conflict will simply grind on.
«We know from conflicts around the world that we can’t have any sustainable peace if we don’t have accountability,» said Anna Nolan, director of The Syria Campaign, a human rights advocacy group. «The most critical thing to understand in that situation is who is being killed and who is doing that killing, and without that information we can’t expect the people involved in resolving this conflict to come to the right decisions.»
Until then, local groups keep the best estimates they can.
Fadel Abdul Ghany, the founder of the Syrian Network for Human Rights, said that there were «tens of incidents daily» that raise the death toll, and that monitoring was needed to one day hold perpetrators accountable.
He sees value in the assessment his group makes. «We are doing this mainly for our people, for our community, for history,» Mr. Ghany said. «We are recording these reports in order to say, on this day, in 2018, these people have been killed and because of this, and in this area.»
Mr. Ghany believes figures will be vital in establishing justice. «We don’t want to lose any one life,» he said.
The last comprehensive number widely accepted internationally — 470,000 dead — was issued by the Syrian Center for Policy Research in 2016. The group was long seen as one of the most reliable local sources because it was not affiliated with the government or any opposition group.
The British-based Syrian Observatory for Human Rights said last month that at least 511,000 people had been killed in the war. Many organizations rely on this tally as the best current assessment.
While the numbers vary, all of the groups agree that the Syrian government is responsible for most civilian deaths.
«We often talk about these numbers, whether it’s 400,000 or 500,000, but it’s also about the trauma that is behind each of these numbers,» said Panos Moumtzis, a United Nations assistant secretary general.
He added: «It’s really just a cold figure, but behind it are lives.»
A sense of fatigue sets in as a civil war drags on.