Physics Society Talks: The Stratosphere

Why should we care about the stratosphere? Such is the question Simon Clark presented us with at the latest of the Physics society’s weekly talks. Former undergraduate at St Peter’s College Oxford and prominent Youtuber, Clark has made a name for himself as a powerful and effective science communicator and it becomes clear why as he begins to talk. 

The stratosphere is a region in the atmosphere high above the clouds, an outlandish land where it gets hotter the higher you go. There is a strangely sharp edge to the stratosphere, so well-defined that clouds expanding upwards spread out at its lower barrier, forming flat-topped shapes. 

 Air in the stratosphere is stable at its height, so all motion occurs on flat planes, with very little vertical motion. For an example of this, Clark shows us a picture from the Pinatubo volcanic eruption of 1991. Like an enormous explosive needle, it injected ashen clouds directly into the stratosphere. This roof of grey dust stayed at the edge of the stratosphere for years, a burning example of the unique nature of the stratosphere.

However, there is a darker side to the properties of the stratosphere. Clark tells us of a dangerous idea rising to the surface; delaying climate change by pumping megatons of aerosols into the stratosphere. Here they would sit, reflecting short wavelength light that warms the earth back into space. But to Clark, this idea is hazardously reckless. Not only would this require constant replenishment of the aerosols, but it could also change the delicate balance of the biosphere and change the distribution of precipitation, which could even change where on the planet people live. But most of all, it is a solution that simply excuses ever-increasing climate irresponsibility, allowing people and companies to pollute without consequences. The scariest part is, Clark says, is that a well-wishing forward thinking billionaire, a few of which come to mind immediately, could do this as soon as tomorrow, changing our entire climate for years to come.

We finish with questions, which range from the stratospheres of other planets to the pre-industrial abundance of trees in the earth’s atmosphere. The physics society offers pizza at the end, and we chat, before drifting off, like particles on a flat plane wandering away from one another in the starry stratosphere above our heads. 

Physics Society talks are every Thursday in the Martin Wood lecture theatre at 7:30. Find out more at