It isn’t always the water that frightens me. When the floods lap below George IV Bridge, the Old Town drowning beneath a surging tide of brownish green, I find the water itself quite beautiful, in a majestic sort of way. What scares me is the waste the water leaves behind. The sea salt that settles like snow on pavements and windowsills as the flood recedes. The wash-line of sickly scum  up the sides of buildings. The dead rats, the crabs, the corpses.

I can’t go down into the lower levels of the city anymore. Last time I tried was on an evening out with Càit, my flatmate. We sat in the starkly lit restaurant halfway up a narrow close and I watched the water swirl under the door, up the table legs, into the pockets of Càit’s jacket draped over the chair. Eventually I had to tell her. I remember the way she peered at me, her confusion magnified by the thick lenses she wears. I’ve never told anybody else.

Our flat, thank god, is up a hill at the top of Pentland Terrace. We got the bus back that night, cancelling our plans for the cinema. My teeth chattered as we sloshed through thigh-deep slurry out of the restaurant. At the top of the close I turned and could see the water lapping at the steps. Back at the flat, I explained everything to Càit: the things I see, the horror of knowing that nobody else can see them. I felt ashamed of myself. The evening was supposed to have been a very different conversation, the one I never quite manage to have with her.

Càit frowned and Googled. “Advanced climate anxiety,” she said with willed firmness. “That’s all it is. You can get help for it.”

I call her now, as I sit with my back to the wall above the Grassmarket. I can hear the water slapping on the stones beneath me. Càit’s voice is calmness, an anchor in the depths. She asks how bad it is. Bad, but not the worst, I tell her, and my voice shakes only a little.

The worst attack I’ve had was last summer, when Càit invited me to visit her parents on the little island where she grew up. That island was hell for me. Càit’s parents smiling at us like ghosts through the pearly murk, their whole house underwater, the whole island. I knew I was going mad. I woke each morning with sand crusted on the sheets, limpets clinging to me, the stench of rock pools in my hair.

I remember sitting opposite Càit in the garden with water lapping our necks. Her hair swirled around her in the current as she told me in a small, determined voice of her diagnosis. That was the first time it occurred to me how beautiful she was. She was garlanded with seaweed, her eyes the colour of the waves, filtered like sunlight through glass.

It takes her ten minutes to get to George IV Bridge. By that time I’ve calmed down a bit, the flood receding, although I can still hear and smell it. Càit sits with me on the dirty pavement. Her hands adjust the beanie she’s taken to wearing since she started her treatment. I’ve never told her, but I love how she looks now, love the way her skin flows up the back of her neck and up and over her skull like a perfectly fitted cap. When she tips her head back to laugh, tiny crinkles form over the bones.

My hands clench in my lap. How I feel for Càit, these days, feeds into my other anxieties. I have the constant sense of time running out, of the world ending, of something beautiful facing its last, most vulnerable hours. I take several short breaths.

“Where’s the water now?” Càit asks.

In my head, I want to tell her. In my dysfunctional eyeballs. About four feet down in the slopping gutters of the Grassmarket.

Instead I say, “You know I love you, don’t you?” and my heart pulses in a great wave of exhilaration while the waters sink back down the slope, leaving their seaweed streaks on the walls, their discharge of algae—gone, for now, although they’ll come back, again and again, as they always do.