A self-styled "whimsical scientist" who locked himself in an airtight dome with 200 plants to raise awareness of climate change has ended his experiment.
Canadian Kurtis Baute entered the 3m (10ft) by 3m cube - which was wrapped in heavy-duty plastic - at midnight on Tuesday in British Columbia.
But he was forced to call a halt after 15 hours as CO2 levels rose.
He thanked fans and described the experience as a "huge success".
He tweeted throughout his time in the dome under the hashtag #KurtisInAJar.
The air humans breathe out has more CO2 in it than the air we inhale, which meant that CO2 levels inside the dome rose as the experiment continued. When the level hits 10%, people can suffer brain damage, fall into a coma, or die.
Mr Baute had hoped that the plants, which use sunlight to convert CO2 into oxygen during photosynthesis, would help to regulate levels in the dome.
But he said earlier on Wednesday that cloudy weather meant the plants were not receiving sufficient sunlight. He ended the experiment after CO2 levels reached his "abort values" - the figure at which it was deemed unsafe.
Plants are great at soaking up CO2, they love the stuff.. But they can only handle so much, and since it isn't a bright and sunny day (its overcast) they aren't getting the light they need... Which means CO2 just keeps rising. Will have to abort today if this keeps up.— Kurtis Baute (@kurtisbaute) October 24, 2018
Although he had initially planned to remain in the dome for three days, he later changed his mission to staying inside safely for as long as possible.
"I could probably survive in the jar three days," he wrote on his website last week. "But my goal is not to just 'not die', my goal is to end this project without having turned blue, developed brain damage, gotten heat stroke, or just generally caused lasting harm to my body."
All safe. My goal here was/is to engage people about #climatechange, and seeing the response on twitter I feel like it's been a huge success. Thanks to everyone for your support. Now is just the beginning - it's time to change our lifestyles!— Kurtis Baute (@kurtisbaute) October 24, 2018
While still inside the dome, he explained his mission in a Twitter thread, writing: "#ClimateChange is real, we're causing it, and it's a real big deal.
"The messed up thing about my experiment is that some of my abort values (eg If CO2 is too high I escape) are just everyday experiences for many people on this planet. Everyone deserves clean air, but not everyone has it."
He said that while humanity is pumping CO2 into Earth's atmosphere at a dangerous rate, there are plenty of steps we can take to limit the damage, including:
1. "Eat less meat, it is horribly inefficient and uses tons of fossil fuels. Maybe try giving it up for #MeatlessMonday or go further than that."
2. "Drive less. Cut your commute time. Bike, carpool, take transit, work from home. Your car is suffocating and cooking you and I both. Besides, you've got better things to do than sit in traffic."
3. "Start a conversation about this. Let's be real, and encourage each other to do better. That's the end of the rant for now. Thanks!"