These stamps by Finnish studio Berry Creative feature images of birds and snow clouds that turn into skeletons and thunderstorms when heated to send a message about the consequences of climate change.
Commissioned by the Finnish Post, the Climate Change Stamps aim to offer an innovative way of communicating the negative effects that rising temperatures will have on Finland.
The stamps feature three base designs: a snow cloud, a depiction of limited immigration, and a bird. These images are printed as black silhouettes against coloured gradient backgrounds.
Printed in colour-transforming ink that reacts to heat, these symbols change from black to clear when warmed up by being rubbed with a finger, revealing additional designs underneath.
The snow cloud transforms into a thunderstorm to represent the loss of winter snowfall, while the depiction of immigration turns to mass migration as climate refugees are forced to leave their homes and relocate.
The bird is also made to turn into a skeleton, as a representation of the extinction of many of Finland's native species.
These hidden images reveal what the future will look like "if we don't act fast to fight climate change".
"Unlike the effect in the stamp, climate change is not reversible," said the studio.
As the studio explained, the stamps each have jagged edges and eye-catching colour gradients in order to create a sense of urgency.
"I wanted to play on very alarming imagery," creative director of Berry Creative Timo Berry told Dezeen.
"Usually I like to communicate an alternative, a way to go forward, not just point on a particular problem, but here there was no space for that," he continued.
"I dug into different consequences of climate change here in Finland, and chose three – snow turning into water and rain in the winters, massive climate refugee crisis, and the loss of endemic species."
Aiming to reach as many people as possible, the message will be sent – literally – on letters and parcels across the country to encourage the Finnish population to take actions to reduce greenhouse gas emissions.
Berry Creative's stamp designs have been shortlisted for this year's Dezeen Awards in the graphic design category.
Spanish-Italian designer Pablo Dorigo Sempere also aimed to send a message about the environment to the people of Venice with his From Venice with Algae stamps, which were made using algae paper.
The designer extracted algae that was polluting the Venetian canals and used it to make the stamps as a way of showcasing the sustainable material.