儲存那些曾經需要的截圖要付出多少代價？雲端能源與環境成本超出想像

There’s probably a photo on your phone right now that you haven’t looked at in years. Open your gallery, and you’ll find all kinds of things you forgot you saved. You might see recipes you swore you would cook, 50 blurry shots just to get one good picture for Instagram, duplicate documents or screenshots of a random QR you scanned once and never needed again.

You probably think none of it matters. It’s just sitting there, not doing anything, right?

Not quite. It is actually doing something quietly in the background to the environment. That forgotten photo or screenshot hasn’t disappeared. It’s sitting on a server somewhere, saved not just once, but a few times, on machines that never really turn off.

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CNET’s parent company Ziff Davis employs some of the most tech-savvy journalists on the planet, and when surveyed, even they didn’t know what happens to their forgotten media. In a survey conducted across our sister sites and internally at CNET, nearly half of respondents — 47.9% — said they had never thought about how storing files uses real electricity or affects the environment.

Which makes sense. Nobody gets a monthly bill for their old emails or photos the way they do for electricity at home. So, it’s not that people don’t care. It’s just that no one ever told them there was something to care about in the first place.

People aren’t just taking more pictures. Phone companies have actually made your photo files much larger without making it obvious. Most phones automatically record a short 3-second video every time you snap a photo. That turns what used to be a simple 2MB photo into an 8MB file. Videos eat up space even faster because your phone records in high definition by default. Just one minute of video takes up about 55MB, so filming your entire trip can quickly fill up your phone. And if you happen to turn on pro photo settings, a single picture can take up a massive 75MB.

How does one photo turn into a few copies?

Let’s follow a photo from start to finish. Imagine you went out with friends and took a few pictures, maybe your lunch, a selfie or a meme you screenshotted and shared.

The moment you take that picture or screenshot, your phone quietly starts backing it up to iCloud or Google Photos. Within seconds, that photo is no longer just in your gallery. It’s already on its way somewhere else: a data center hundreds or thousands of miles away that you’ll never see or think about.

When it gets there, it’s not saved just once. Storage systems assume hardware can fail at any time, so they make copies of your photo to protect it. There are two main ways to duplicate data: replication and erasure coding.

In replication, the file is copied in full, usually two or three times, onto different drives. This method is simple and fast, but if you copy a file three times, you use three times the storage space. A 1MB photo becomes 3MB of actual storage used. This is often described as a 200% overhead, meaning you use 200% more space than the original file needs just for backups.

In erasure coding, instead of making full copies, the file is broken into “chunks” along with a small number of extra repair chunks. A common setup uses 17 data chunks and three repair chunks. If a drive fails and a couple of chunks are lost, the system rebuilds the missing pieces using the surviving ones. This is similar to solving a Sudoku with some numbers missing, as long as enough clues remain. Because you only add a few extra repair chunks instead of whole copies, the overhead is much smaller, around 15% to 20% instead of 200%.

If erasure coding is more space-efficient, why does the company use the replication method? While erasure coding saves space, it is slightly slower to read from. Rebuilding a file from scattered pieces takes more computing work than simply grabbing one of three ready-made copies. Because of this, companies often use erasure coding for older files that people rarely open.

Cloud providers promise that your file will basically never get lost — the odds of that happening are something like 1 in 100 billion. That’s the main reason your single photo ends up saved in multiple places. It’s not wasteful for no reason; it’s the cost of making sure nothing disappears.

The life of dark data

There’s a difference in where files end up long-term. Companies split storage into “Hot” tiers, which are built for instant access, and “Cold” or “Archive” tiers, built for files nobody’s touching. Amazon Web Services’ version of cold storage is called S3 Glacier; its cheapest tier costs roughly 23 times less per gigabyte than standard storage, but retrieving a file can take anywhere from a few hours to two full days and incurs an extra charge each time. Microsoft and Google often offer nearly identical tiers of their own, prices within a fraction of a cent of each other — meaning this isn’t a quirk of one company; it’s now how the whole industry handles anything kept “just in case.”

And that cheap-to-store, expensive-to-retrieve setup has a side effect worth noting: once data lands in one of these tiers, almost nobody ever bothers to pull it back out or delete it — the “unlock fee” makes companies leave it alone indefinitely. Multiply that across every company doing the same thing, and you get something the storage industry has an actual name for: dark data.

Dark data is information that’s collected and stored, but never used again. The scale of it is enormous: Industry estimates put it at around 55% to 80% of all enterprise data in this category, with nearly 1 in 3 organizations saying 75% or more of what they store is dark or obsolete. One estimate puts dark data’s total footprint at roughly 60 zettabytes (60 trillion gigabytes) worldwide — and around half the average company’s entire storage budget goes toward keeping data nobody will ever look at.

In other words, it’s not just us. Companies do exactly this too — just at a scale that makes our own inboxes look insignificant.

Every one of these copies, hot or cold, sits on hardware that’s switched on all day, every day — it doesn’t power down for one unused file. And keeping all of it from overheating takes real power. In a typical data center, cooling alone can use up nearly 40% of the electricity the building consumes, even before counting the computers doing actual work.

So, while you’ve completely forgotten that photo exists, it is living quite a busy life. It’s copied multiple times, protected against hardware failure and sitting inside a building that spends nearly half its power just to keep it cool.

The real-world cost of data storage

Every piece of forgotten data sits on physical machines that use up vast amounts of resources in three main ways.

It takes a massive amount of electricity just to keep servers from melting down. In most traditional data centers, for every 100 watts of power used to store your files, another 55 watts goes entirely to giant air conditioners and fans. Some modern data centers are fixing this by submerging servers into special, safe liquids that absorb heat better than air. However, most of the internet still relies on old, power-hungry AC systems to stay cool.

All that heat needs water to cool it down. To keep the building from turning into an oven, a single large data center can consume and evaporate between 3 million and 5 million gallons of water every day. That is enough water to keep a small town running. All that water is evaporating into the air to cool down servers full of stuff nobody has looked at in years. While AI gets the blame for these big resource spikes lately, our own daily digital habits, like hoarding thousands of blurry photos and forgotten backups in the cloud, keep these giant facilities packed and running.

Finally, there’ i’s the hardware itself, which doesn’t live forever. Every three to five years, the hard drives inside these servers wear out and are replaced, then hauled off to be shredded and thrown away. Because of this constant cycle, a large share of a server’s carbon footprint comes straight from the factories that built and shipped it long before it ever stored a single byte of your data, proving that our digital clutter leaves a very real mark on the planet.

We didn’t have to look far to find this playing out in real time

When we ran our survey of our colleagues, it turns out a lot of us are sitting on huge forgotten inboxes. Some people didn’t even know how many emails they had; they just called it inbox infinity. Nearly 1 in 4 people have stored more than 50,000 emails, and several people have genuinely lost count.

Nearly a third of those surveyed (32%) store over 500GB of photos and videos, and 1 in 6 stores more than 2TB.

Nearly half the company, 48.6%, is duplicating storage across services, knowingly or not. This multiplies the actual environmental footprint beyond what people realize.

Why don’t people just delete the stuff they never use?

Based on our company survey, the No. 1 reason people keep data isn’t laziness. It’s the “just in case” mindset, followed closely by emotional attachment. A good chunk of people also admitted they are just scared of accidentally deleting something important. About 18% said things back up automatically in the background, so they never think about it at all.

We also can’t completely blame ourselves for these issues. Tech platforms actually make it tricky to remove data by default, because selling extra storage is big business. They don’t have much reason to make cleaning up easy when clutter makes them money.

Here are a few ways apps get in the way:

• Google Photos: When you tap delete, the photo doesn’t vanish. It goes to your trash folder and keeps taking up your space for another 30 days unless you manually empty the trash.
• Apple iCloud: If you use a shared family library and delete photos from your phone, it deletes them from your partner’s and kids’ photos too. This can make people scared to delete anything.
• Dropbox: If a coworker shares a 20GB folder with you, Dropbox counts that entire 20GB against your personal limit, even if you didn’t create any of the files.
• Microsoft OneDrive on Android: If you delete photos from your phone’s main gallery, OneDrive often keeps them saved in the cloud anyway, meaning you’ll have to do the cleanup twice.

All of this creates what some call a hoarding tax. The average person spends anywhere between $2 and $10 a month on storage upgrades, which adds up to thousands of dollars over a lifetime spent holding onto duplicate photos and deal files.

Here’s what all that storage actually adds up to

The carbon math is the hardest truth to face. According to Digital Cleanup Day, “If you delete 1GB of unnecessary data, you can prevent about 200 grams of CO₂ emissions per year.” This is not an exact science; different studies land on different numbers, but it does give us a rough way to picture the real-world impact.

Let’s apply that figure to our survey data by working out how many gigabytes of storage the average person from Ziff Davis uses:

That figure of 767GB is a weighted average per person. When we multiply it by the number of people who participated in the survey, it comes to about 55,200GB of data stored in cloud photo or video storage.

Using Digital Cleanup Day’s figure of 200g of CO₂ saved per gigabyte deleted per year, 55,200GB equals roughly 11 million grams, or about 11 metric tons of CO₂ per year. Keep in mind, this is just from the 72 people who participated in the survey.

The average car emits roughly 4.6 metric tons of CO₂ a year. So our 72 people’s storage alone is roughly equivalent to between two and three cars’ worth of annual emissions, just sitting in the cloud. Looking at it like that, it feels like an insurmountable problem.

But here’s the good part: Most people said they’d actually do something about it

When we asked people, “If you had clear data on the energy and water footprint of your cloud storage, would that change how often you clean up old files?” 38.7% of people said yes, and 37.3% said at least maybe. Only a small number said it would not change anything for them.

In other words, this is not a story about people who do not care. It’s a story about people who would care the moment someone actually shows them the numbers. That is good news; it means this is fixable, and it doesn’t take much.

So, if we stop hoarding data, does it actually save the planet?

No, at least not on its own.

The main reason data centers are growing so fast right now isn’t your old selfies. It’s AI. Training and running massive AI models uses far more energy than any of our personal photo libraries ever will. The scale is so massive that some companies are exploring wild fixes, like setting up data centers underwater or even in space.

Deleting your camera roll will not single-handedly fix the climate. But “individual” doesn’t mean “pointless.” One forgotten email doesn’t matter much, but an entire drive full of photos, videos, emails and files starts to add up. Multiply that by a few billion people around the world doing the same thing, and it’s a different story entirely.

Think of it like turning off the light switch when you leave a room. One lightbulb doesn’t save the planet either, but nobody says, “Well, factories use more power than my lightbulb, so why bother?” You still turn it off because it’s easy, costs you nothing and adds up.

Where do we start?

You don’t have to become a digital minimalist or delete your entire camera roll in one sitting. A few small habits go a long way.

Check your phone storage:

• On Android, go to Settings > Storage > Free up space, or use the Files by Google app to automatically find your duplicate photos and screenshots.
• On iPhone, go to Settings > General > iPhone Storage. Look for apps you rarely use and choose Offload App. This removes the app to save space, but keeps your personal data safe if you reinstall it later.

Empty your trash folders:

Deleting a photo or email doesn’t free up space until you clear the trash. Open Google Drive, Gmail, Google Photos, and open Trash or Recently Deleted (on an Apple device), select all and delete them.

Manage your cloud account:

Go to one.google.com/storage/management to see a simple map of large files and heavy email attachments.

Other ways to clean your data:

• Unsubscribe from newsletters you never actually read.
• Turn on autodelete for spam and trash folders.
• Once a month, go through your camera roll and clear out duplicates and unwanted screenshots.
• Check if old devices are still backing up to the cloud even though you no longer use them.

Build these small habits, not because they’ll save the planet on their own, but because they’re easy and cost nothing, and doing nothing is never the better option.