20 Before-and-After Photos of Glaciers, Lakes and Forests

Before-and-after photographs are one of the clearest ways to see a changing planet. Pair a picture of a glacier taken a century ago with a modern shot from the same rock, and the loss of ice needs no explanation. The twenty pairs below come from glaciers in Montana and Alaska, shrinking lakes in Central Asia, Iran, the United States and Argentina, a bleached coral reef and cleared forests in Kenya, Brazil and Niger.

They do not all tell the same story. The glacier pairs, most of them from the U.S. Geological Survey's repeat photography work, record warming over the twentieth century. Several of the lake and forest pairs show something different: people diverting rivers, pumping groundwater and clearing land. Drought and heat often make that damage worse, but it would be misleading to label every image "climate change" and leave it there.

So each caption below says what the pair shows, where and when, and what mainly drove the change. At the end you will find what has been measured since the photos first went round, and a few simple checks for judging any before-and-after image you come across.

How repeat photography works

The method is simple and hard work. Researchers dig historic photographs out of archives, work out where the photographer stood, then hike to the same spot at the same time of year and shoot the scene again. The USGS Northern Rocky Mountain Science Center began doing this in Glacier National Park in 1997. Its collection holds about sixty pairs covering more than twenty glaciers, with historic images from 1887 to 1943 and modern ones taken between 1997 and 2019. Grinnell Glacier alone has 23 pairs.

Fieldwork is limited to a short window in late summer, after the winter snow has melted off the ice. Several seasons were lost to wildfire smoke. The satellite pairs further down work on the same principle, using Landsat and other Earth-observing satellites instead of a person with a tripod.

Glaciers in Montana and Alaska

Grinnell Glacier Overlook, Montana, 1920 and 2008

The 1920 view from the overlook shows a broad sheet of ice filling the basin below the Garden Wall. By 2008 the ice had pulled back far enough to leave a meltwater lake and bare, polished rock. Grinnell is the best-documented glacier in the park, which is why it appears more than once here.

Grinnell Glacier, Montana, 1926 and 2008

This pair has a built-in ruler: the large boulder. In 1926 visitors stood beside it on the glacier's surface. In 2008 the same boulder sits on open ground with no ice in sight. Because the rock has not moved, the change cannot be blamed on a different camera angle or a trick of perspective.

Logan Pass, Glacier National Park, 1957 and 2009

Not every change is about ice. At Logan Pass the striking difference is plant life. Trees and shrubs have spread up the slope where lasting snowpack once held them back, a shift the USGS links to warmer, shorter winters. The historic photographer is unknown (Glacier National Park archives); the 2009 image is by Lisa McKeon of the USGS.

Hidden Lake, Glacier National Park, about 1930 and 2009

The earlier view, credited to T.J. Hileman from the park archives, shows thin, patchy vegetation around Hidden Lake. In the 2009 photo by Lisa McKeon, forest has filled in along the shore and at the foot of Bearhat Mountain. Alpine plants and trees moving uphill is one of the quieter signals of a warming climate.

Pedersen Glacier, Alaska, early 1900s and 2005

Pedersen Glacier flows into Aialik Bay in what is now Kenai Fjords National Park. The historic photo is dated 1917 in some collections and to the 1930s in others, but either way the glacier then reached the water's edge, with icebergs crowding the lagoon. In 2005 the same foreground was a green meadow and the ice had retreated far up the valley.

Muir Glacier and Inlet, Alaska, 1880s and 2005

In the 1880s the face of Muir Glacier in Glacier Bay was a tourist attraction: steamships brought visitors who climbed onto the ice, as the people in the old photograph are doing. By 2005 the photographer looked out over open water. Glacier Bay began losing ice after the Little Ice Age ended, before modern warming, and tidewater glaciers can retreat very quickly once they lose their footing, so this pair shows long-term change that recent warming has kept going.

Muir Glacier, Alaska, 1882 and August 2005

A second view of the same place makes the scale clearer. The wall of ice behind the visitors in 1882 has been replaced by a gravel beach, calm water and distant hills. Muir Glacier has retreated tens of kilometres since then and no longer reaches the sea.

Ice in the Ecuadorian Andes, March 1986 and February 2007

These satellite views show the ice cap on a high Andean volcano in Ecuador shrinking over two decades. Tropical glaciers are especially sensitive to warming because they sit close to the melting point all year round. For towns in the Andes, these ice caps also act as water stores that feed rivers in the dry season.

Sea ice, coral reefs and island communities

Arctic sea ice, 1980 and 2012

These are visualisations of Arctic sea ice at its late-summer low. In September 2012 the ice shrank to about 3.4 million square kilometres, the smallest since satellite records began in 1979 and still the record low, roughly half the typical extent around 1980. Melting sea ice does not raise sea levels much, but the dark open water left behind absorbs more sunlight, which speeds up warming in a region already heating several times faster than the global average.

Coral bleaching, labelled the Great Barrier Reef, 2002 and 2014

When the sea stays too warm for too long, corals expel the algae that live in their tissue and give them colour and most of their food. They turn white and, if the heat lasts, die. We could not confirm where these two frames were taken, so treat them as an illustration of bleaching rather than a record of one spot. The Great Barrier Reef itself did suffer mass bleaching in 1998 and 2002, and again in 2016, 2017, 2020, 2022 and 2024.

San Blas (Guna Yala) Islands, Panama, 2002 and 2014

The San Blas archipelago, home to the Indigenous Guna people, has around 365 small, low-lying islands off Panama's Caribbean coast. Flooding from higher seas and storms is a real and growing problem there: in 2024 hundreds of families from the crowded island of Gardi Sugdub moved to a new settlement on the mainland. As with the reef pair, the exact origin of these two photos is not documented.

Shrinking lakes and reservoirs

Lake Oroville, California, 2011 and 2014

The Enterprise Bridge crosses an arm of Lake Oroville, California's second-largest reservoir. In 2011 the water was close to the roadway; by 2014, in the middle of the 2012 to 2016 drought, it had dropped to a thin channel between steep, bare banks. The opening photo at the top of this page shows the same place. Three years later the opposite problem arrived: after a very wet winter, damage to the dam's spillways in February 2017 led to the evacuation of about 188,000 people downstream, a stark example of swings between drought and flood.

Aral Sea, 1989 and 2014

The Aral Sea, on the border of Kazakhstan and Uzbekistan, was once the fourth-largest lake in the world. From the 1960s Soviet planners diverted its two feeder rivers, the Amu Darya and Syr Darya, to irrigate cotton and other crops. By 2014 the eastern basin had dried out completely. This is mainly a story of water management rather than climate, and the exposed seabed now sends salty, polluted dust storms across the region.

Aral Sea, 2000 and 2014

The later pair shows that the damage is not entirely one-way. In 2005 Kazakhstan finished the Kok-Aral dam, built with World Bank support, which keeps the Syr Darya's water in the small northern part of the lake. The North Aral has since risen and fish have returned, while the southern basins, which depend on the overused Amu Darya, kept shrinking.

Elephant Butte Reservoir, New Mexico, 1994 and 2013

Elephant Butte, completed in 1916 on the Rio Grande, is the largest reservoir in New Mexico and supplies farms and cities downstream. These Landsat images show it near full in 1994 and reduced to a narrow ribbon in 2013. Years of drought, lower snowmelt in the mountains and heavy demand for the river's water combined to empty it.

Mar Chiquita, Argentina, 1998 and 2011

Mar Chiquita in Córdoba Province is Argentina's largest salt lake and an important stop for migratory birds; the area became Ansenuza National Park in 2022. Its size has always swung with rainfall, and it grew dramatically after the 1970s. The shrinking between these two images reflects drier years and upstream water use more than a simple climate trend.

Lake Urmia, Iran, July 2000 and June 2013

Lake Urmia in northwestern Iran was once the largest lake in the Middle East and one of the largest salt lakes in the world. Between these dates it lost most of its surface area. Studies attribute the bulk of the loss to dams, rapidly expanding irrigation and groundwater pumping, with drought and heat adding to it. A government restoration programme began in 2013; the lake partly recovered after wet years and then fell sharply again.

Cleared forests in Africa and the Amazon

Mount Kenya forest, Kenya, 1976 and 2007

The dark ring of forest around Mount Kenya has thinned and broken up between these two satellite images. Logging, farming and charcoal production cleared much of the lower slopes. These forests matter far beyond the mountain: they catch rain and feed rivers that supply water and hydropower to much of Kenya.

Rondônia, Brazil, 1975 and 2009

The "fishbone" pattern in the 2009 image is typical of Amazon deforestation. From the 1970s, settlement programmes and new roads such as the BR-364 highway opened Rondônia to farming and cattle ranching, and side roads spread from the main route like ribs. Forest clearing is a cause of climate change rather than a result of it: it releases stored carbon and can reduce rainfall across the region.

Baban Rafi forest, Niger, 1976 and 2007

Baban Rafi in southern Niger, near the border with Nigeria, lost much of its tree cover to farmland and fuelwood cutting over these three decades. There is a hopeful counterpoint elsewhere in the country: since the 1980s, farmers in parts of Niger have regrown millions of trees by protecting and pruning the stumps and roots already in their fields, a method known as farmer-managed natural regeneration.

Climate change makes so much more sense when illustrated with a Domino's Pizza Tracker https://t.co/TW1gslBYrs pic.twitter.com/lhz7VUV7lz

— Huffington Post (@HuffingtonPost) 2 Νοεμβρίου 2015

In November 2015 HuffPost shared a lighter take on the same subject, comparing warming to a pizza-delivery tracker. The joke works because the trend has only gone one way.

What the measurements show since

When these photos first went viral, they often came with a quote from USGS research ecologist Daniel Fagre, who said the park's glaciers had shrunk quickly since Glacier National Park was created in 1910, and with a forecast that they could be gone by 2030. That forecast came from early computer models and has since been dropped. Newer work showed that the glaciers are shrinking more unevenly than expected; the park has since updated signs that once said the glaciers would be gone by 2020.

The measured losses are still large. In 2017 the USGS and Portland State University reported that 39 glaciers in and around the park had lost an average of 39% of their area since 1966, some as much as 85%. Only 26 were still larger than 25 acres, the usual size threshold for calling a mass of ice a glacier. Portland State geologist Andrew Fountain said the trend was "in line with trends that have been happening on a global scale."

The same quote listed the five warmest years then on record, all from the late 1990s and early 2000s. That list is long out of date. Every year from 2015 onwards has ranked among the warmest ever measured, and 2024 was the warmest year on record. Satellite measurements show global sea level has risen by roughly 10 centimetres since 1993, and the rise is speeding up.

How to read a before-and-after photo

Pictures like these spread widely, and a few habits help you separate solid evidence from weak examples:

• Check the season. Snow cover and lake levels change through the year. Good pairs, like the USGS glacier photos, are taken at the same time of year.
• Look for a fixed reference. A boulder, a ridge line or a bridge proves the camera is in the same place.
• Ask what drove the change. Dams, irrigation and logging can empty a lake or clear a forest without any help from the climate, though heat and drought often make things worse.
• Find the source. Captions on viral images are often wrong or missing. Agencies such as the USGS, NASA and national parks publish their pairs with dates and photographers.
• Remember that one pair is not a trend. The strongest evidence comes from many sites measured the same way over decades, which is exactly what the glacier surveys provide.

Two common objections are worth answering. "Glaciers have always come and gone" is true over thousands of years, but the speed and near-global reach of today's retreat is unusual, and it matches the measured rise in temperature. "The photos are cherry-picked" is a fair question for any single image, which is why the measured data matter more than any single picture.

Sources: USGS Northern Rocky Mountain Science Center, Repeat Photography Project; National Park Service, Glacier Repeat Photos; ScienceDaily (USGS), Glaciers rapidly shrinking and disappearing: 50 years of glacier change in Montana (2017); PetaPixel, USGS repeat photographs of US glaciers (2015); Business Insider, before-and-after image collection (2015); earlier compilation by Vandita for AnonHQ.