Secreted Shiptracks

Drifting beside western coasts

of uncovered continents,

metallic leviathans stretch

their sunken limbs.

Hinged jaws spitting

sulphurous seeds that

linger beneath the ether;

clouds condensing to

float through the air

with steady, rhythmic slur.


Hidden from view these

artificial barrels of rain

line up in formation;

secreted shiptracks

that sway the rising heat

with convoluted patterns

of tempestuous intent.


Shadows forming out of sight,

as overheard unblinking eyes

peel back this salted shroud:

a stark glimpse

behind unsettled scenes.

Shiptracks off the coast of the Iberian Peninsula, taken using the Suomi NPP satellite’s VIIRS instrument (Image Credit: NOAA).

This poem is inspired by recent research, which has identified how satellites  can be used to better monitor the emissions from ships and the effect that these emissions have on cloud formation and climate change.

The emissions from ships contain many different chemicals, including sulphate aerosols (small particles of oxygen and sulphur) which act as surfaces (or seeds) on which water droplets can start to accumulate, leading to linear cloud formations, known as shiptracks. How these aerosols affect cloud formation is important because clouds can influence climate change, cooling or warming the Earth’s atmosphere by either reflecting the heat from the sun, or trapping the heat that is emitted from the Earth’s surface. As such, these emissions and subsequent shiptracks need to be accounted for in the various models that aim to predict future climates.

In this study, researchers observed more than 17,000 shiptracks from satellite observations, and matched these to the movements of individual ships using their onboard GPS. By connecting individual shiptracks to these GPS measurements, the researchers have shown that almost half of all shiptracks are currently undetected, masking a significant contribution to the climate impact of shipping. This new research therefore demonstrates how satellites might be used to better monitor ship emissions, and in turn how this might be used to better enforce restrictions on the sulphur content of fuel.

An audio version of this poem can be heard here:

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