EDITORS NOTE: THIS POST CONTAINS GRAPHIC IMAGES

From Bosnia to West Africa, she has witnessed tragedy. But the photo of two drowned Salvadoran refugees this week still left Corinne Dufka in shock.

“It’s horrific,” Dufka, an associate director at Human Rights Watch, says of the picture, which shows a father and his 23-month old daughter dead, face down in the Rio Grande. “Photojournalism is full of images which have illuminated the gravity of a situation, made it less possible to ignore it or spurred both ordinary people and policy makers to action.”

In a world of unremitting information and video-driven chaos, the still photograph is an older and perhaps seemingly limited medium. But a solitary, silent shot can make remote news feel urgent and personal.

The deaths of Óscar Alberto Martínez Ramírez and his daughter Valeria, documented in an image made by journalist Julia Le Duc and distributed by The Associated Press this week, became an instant, singular moment in the immigration debate.

Pope Francis expressed “profound sadness.” The UN Refugee Agency called it “powerful visual evidence of people dying during their dangerous journeys across borders.” Senate Minority Leader Charles Schumer stood by a blown-up copy of the photo Wednesday as he called for the passage of a $4.6 billion border funding bill.

“Images have a way of piercing through indifference and unlocking empathy and shame that can be catalytic drivers of policy,” Suzanne Nossel, CEO of the literary and human rights organization PEN America, said in an email Wednesday.

She said that goes for everything from “the first photos of emaciated survivors of the Holocaust” to “the haunting images of men behind barbed wire in war-torn Bosnia” to “the sight of the corpse of a Syrian refugee toddler washed up on a beach.”

Inmates of the German KZ Buchenwald are seen inside their barracks a few days after U.S troops liberated the concentration camp near Weimar, Germany, April 16, 1945. An estimated 56,000 perished at Buchenwald, most Jews worked to death, shot or hang… — Inmates of the German KZ Buchenwald are seen inside their barracks a few days after U.S troops liberated the concentration camp near Weimar, Germany, April 16, 1945. An estimated 56,000 perished at Buchenwald, most Jews worked to death, shot or hanged by Nazi guards. (AP Photo)

“You can have statistics about a given issue, like how many children are being held in refugee camps. But then you have an image and it makes it all human,” says Mark Lubell, executive director of the International Center for Photography.

“It’s that unique way of bringing something to a scale we can comprehend,” Lubell says. “Photos give you the space and time to really think about something.”

The still photograph has crystallized some of modern history’s most joyous and traumatic occasions, whether it’s Joe Rosenthal’s iconic image of the flag-raising on Iwo Jima, which became a renowned memorial; Alfred Eisenstaedt’s photo of a sailor kissing a woman in Times Square as the country celebrated the end of World War II; or Nick Ut’s AP image of a young Vietnamese girl, naked and screaming after a South Vietnamese napalm attack.

Defiance was never more memorably dramatized than by Jeff Widener’s widely distributed AP picture of a single man standing before a procession of tanks in China’s Tiananmen Square. Thousands died in the Sept. 11 terrorist attacks, but the day’s lonely doom was viscerally captured by Richard Drew’s iconic “Falling Man” photo for the AP, which has inspired a documentary and Don DeLillo novel of the same name.

The Life magazine picture by John Filo from 1970 of a teen-age girl looking up in horror as she knelt by a classmate shot by the National Guard was so jarring that James Michener shaped his book “Kent State” around it, and Neil Young wrote the protest song “Ohio,” which he and bandmates David Crosby, Graham Nash and Stephen Stills recorded and released within days.

Some pictures become embedded in our minds but don’t necessarily change them. Polls taken at the time of the Kent State shootings showed the majority of the public siding with the National Guard over the students protesting the Vietnam War. President Donald Trump’s response to the picture of Salvadoran refugees was to blame the deaths on Democrats.

Mary Ann Vecchio cries out as she kneels next to the body of student Jeffrey Miller lying face down on the campus of Kent State University, Kent, Ohio, May 4, 1970. National Guardsmen killed four when they fired into a crowd of demonstrators protest… — Mary Ann Vecchio cries out as she kneels next to the body of student Jeffrey Miller lying face down on the campus of Kent State University, Kent, Ohio, May 4, 1970. National Guardsmen killed four when they fired into a crowd of demonstrators protesting the U.S. bombing of Cambodia. (AP Photo/John Filo)

Other images not only recorded history, but helped make it.

Karen Irvine, curator of Chicago’s Museum of Contemporary Photography, cites pictures of police tear-gassing civil rights protesters. Timothy B. Tyson, author of “The Blood of Emmett Till,” says the grotesque image of the black teenager murdered in 1955 by whites in Mississippi was a crucial part of the civil rights movement. Rosa Parks would see the picture in Jet Magazine and cite it as a factor in refusing to give up her seat on a segregated bus in Montgomery, Alabama — leading to her arrest and the beginning of an historic boycott. Julian Bond and John Lewis were among the future activists driven in part by the Till murder.

“That photo was both local and global. It nationalized and even globalized the violence of America’s race relations,” Tyson says. “The photograph tied North and South together and convened black America as one congregation, into a kind of church where horror was transfigured into resolve.”

The greatest photographs never lose their power to bring us back to the time and place they were taken. Lubell wonders if, one day, a photograph will help make climate change an issue that even deniers can’t avoid. He notes that for all of the climate-related disasters, from fires in California to famine in Africa, there is still no singular still image with the impact of “Falling Man” or the Salvadoran refugees.

“We’re all trying to understand climate change on a macro level, but we’re also looking for those individual moments,” he says. “The picture of the Salvadorans is that kind of moment.”