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Are you having trouble with kidney stones? Well, the scientists might have found a fun way to help you. And here’s some updates for our Earth’s climate change!

Hosted by: Hank Green
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[SciShow intro plays]

Hank: If you’re having trouble with kidney stones, maybe you should just plan a trip to an amusement park. Because according to a new study published in The Journal of the American Osteopathic Association this week, riding a moderately intense roller coaster might help you pass small kidney stones

See, the researchers are medical practitioners. And some of their patients reported passing kidney stones after riding one specific roller coaster: Big Thunder Mountain Railroad at Walt Disney World in Orlando. So they did what any curious scientist would do. They made a model kidney, and headed to Florida to put this anecdote to the test.

Your kidneys make urine, which is a mix of water-soluble wastes that you excrete through your bladder and urethra. Kidney stones form when certain chemicals become too concentrated in the urine and start to build up as hard lumps of minerals and salts. Generally, smaller stones can be peed out. But if they’re too big, they can cause blockages, pain, and other problems – and sometimes need more extensive treatments.

To simulate this, the researchers created a silicone model of one patient’s kidney, added three of the patient’s real kidney stones, and filled it up with some urine. Now, you might think a couple of scientists holding a pee-filled fake kidney would look pretty strange hanging out in Disney World. But the park agreed to the experiment so long as the researchers agreed not to freak out the guests.

So the scientists kept their model hidden in a backpack as they rode Big Thunder Mountain Railroad 20 times, resetting the stones in the kidney passageways before every trial. They considered the stones “passed” if they were bumped up to the point at the bottom of the kidney model, where they would enter a tube that connects to the bladder. And the results were surprisingly successful: When they sat in the front of the roller coaster cars, stones passed 17% of the time.

In the back, that rose to 64%. Now, this is not a magic bullet. The researchers caution that large kidney stones could be jostled by the roller coaster and end up blocking the urinary tract. But if a big stone is fragmented, or if you have small stones, they suggest that riding a moderate roller coaster could help pass them before they get bigger.

And it’s also important to remember that these scientists only tested one ride, and only used a kidney model, instead of real patients with complete urinary tracts and kidney stones. So we still don’t really know whether riding other roller coasters will have a similar effect... but they can start by bringing that fake kidney on some more rides. And if they’d like to send it to me, and give me like free tickets, I would totally do that research.

Now, most research doesn’t take place in theme parks, but that does not mean it’s not exciting. So here is the good news: a study published this week in the journal Nature provides the best estimate ever made of the Earth’s average surface temperatures for the last two million years. The bad news is: we probably can’t avoid getting warmer in the next couple millennia.

Here’s the thing. It’s really tricky to understand how the Earth’s temperature is changing over time. We have different methods of estimating temperature – like using Antarctic ice cores – but these kinds of data can mostly tell you about local conditions, not global ones. It’s not easy to stitch together different studies that use different methods, so the records of worldwide temperatures over long time periods have been a bit spotty.

So, researchers have also been looking at ocean sediment cores, which show what’s been piling up on the ocean floor over time, and can be sampled around the globe. From looking at the cores, scientists can tell what kinds of marine organisms were around, and use them to estimate things like temperature and atmospheric CO2 concentration.

In one study from 2012, using mostly ocean cores, researchers showed that global temperatures over the past 22,000 years track closely with carbon dioxide levels – first CO2 increased, then temperatures went up. That research told us a lot, but we wanted to understand similar trends over much more time.

And that’s what this new research did, using data from 59 ocean sediment cores to estimate temperatures over the past two million years, back to the middle of the Pleistocene era. By looking at the pattern of global temperatures and CO2 levels over all this time, we can estimate what the temperature might do in the future based on the CO2 levels right now.

The author found that up until 1.2 million years ago, the planet was getting cooler. But now, it’s getting warmer. And we’re probably committed to an average global temperature increase of between 3 and 7 degrees Celsius over the next few thousand years. Even if we stop all emissions right now, our impact on Earth’s climate is already well underway.

Thanks for watching this episode of SciShow News, and thanks especially to our SciShow President of Space, SR Foxley. If you wanna be President of Space, or sponsor a graphic for a SciShow video, you can go to to help us keep making stuff like this, and if you just wanna keep getting smarter with us, don’t forget to go to and subscribe!