To be sure, the Smithsonian has a lot of photographs. Millions of them in hundreds of collections spread out across the museums, libraries, and research centers of the institution. And, each day we add more to the pile. We make them and use them everyday for all kinds of reasons and very often re-purpose old photographs for new reasons. But do we use them all; do we need them all? The University College of London is currently posing that very question in an exhibition titled, Disposal?. Disposal? includes objects—among them a collection of glass lantern slides made for illustrating scientific lectures—that wouldn’t normally be on display, and therefore of questionable value to the museum that has to pay for the ongoing upkeep. The New Scientist Magazine also asks its audience the opportunity to vote on five objects earmarked for disposal. Which one goes? Let’s try another version of that game. Gather photography curators around a table and ask them to select the most important photograph. Those who deal with historical and empirical collections shrug off the question as meaningless. They rarely look at one photograph; their work comes measured in groups of thousands, organized, if at all, by subject. Ask a curator of fishes like Jeff Williams, who collects fish by collecting photographs of them, and you might get a photograph of the most important fish, rather than the best technical photograph of a fish. Born digital, his “fish collection” resides on thousands of CD’s or on the hard drive of his computer. On the other hand, curators in art museums who look at individual, masterpiece photographs that function best when matted, framed, and hung on the wall, are more indifferent to the business of the archive. However, facing crucial choices for their collections, institutions may soon have no choice but to ask “which is the most important picture.” If there is only space enough to store, or money enough to conserve the most significant, what criteria will we use to decide which box to open and which photograph to pull out first?  The rarest? Oldest? Most damaged? Most beautiful? The one for which we paid the highest price? Or, once catalogued, digitized, and published is it likely to produce revenue? While it is true that many photographs that are valuable for the subjects they represent—whether fishes, bridges, or portraits of famous Americans—can be copied to a digital form, many photographs have survived to become valuable as objects in their own right. So, what criteria best describes the value of photographic purpose and meaning?

Not to worry. No one is talking about throwing any images out yet. As the University of London suggests, disposing of objects by museums is controversial and conjures up images of collections thrown into dumpsters or valuable objects and the knowledge they contain lost to the nation through private sales. With ever-decreasing resources and ever-expanding collections, however, museums are under serious pressure. Why an image, a collection, or an archive of millions is valuable is worth pondering. Does every image need to be digitized and go online? How many images does it take to describe the character and nature of the archive in which they live? As the Smithsonian Archives goes about sorting through collections in preparation for creating larger online access to the Smithsonian’s image collections, I hope that we will come up with more and better answers to that question. And probably even more questions. For more thoughts on the making, use, and disuse of archives see click! photography changes everything! and hear Jonathan Coddington talk about the digital archive of spiders he’s building; Marvin Heiferman discuss how few snapshots ever survive to become an archive; Kenneth Libbrect talk about whether or not it’s important to have a photo of every snowflake, even if everyone is different; and perhaps most of all, Jennifer Sharpe who writes about pictures abandoned in a dumpster.

Merry Foresta is the Former Director of the Smithsonian Photography Initiative.

Photography is valued for, among other things, seeing what the human eye cannot. From medical scans to red light cameras to artworks made by image makers offering up new perspectives, photography reminds us that there’s always more to observe than we’re physically able to take in. Last week, an article in the New York Times reported on one more instance of this, a new and rapidly spreading use of photography that, experts believe, will play a significant role in blunting climate change.

It turns out that infrared cameras, used to photograph oil and natural gas wells, pipelines, and storage tanks, can “see” methane leaking out through bad seals, joints and cracks that would be invisible to the naked eye. And once that methane—the major component of natural gas—is released into the air, it traps heat in the atmosphere. While ton for ton, methane poses less of a long-term problem than carbon dioxide emissions, it traps 25 times as much heat, and it accounts for one-third of human contribution to global warming.

So, as oil and gasoline prices fluctuate and threaten to soar, and as new underground sources of methane are sought and tapped around the world, photography is becoming an indispensable tool to yet another industry. “People are very surprised,” said Ben Shepperd, an executive of a consortium of 1,200 oil and gas businesses in West Texas, “when they shoot their equipment with these cameras and they see that there are releases in places they wouldn’t have expected.” Within the next year, infrared images from a Japanese satellite will become available to pinpoint the location of methane leaks and hot spots around the globe.

Sealing up the leaks is a win-win situation; researchers say that it will slow the course of global warming and businessmen, like Reid Smith, an environmental adviser for BP, sees another motivating benefit. “We spend a lot of money to get gas to the surface,” he said. “It makes a huge amount of sense to get all of it through the sales meter.”