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These Arctic fires have been burning for over a month now. This thread takes a closer look at what might have caused these fires, what exactly is burning, & why we should be concerned... [🛰️images are from the same location in the Sakha Republic, Russia🇷🇺, 65–70°N]
[THREAD 1/9]
[THREAD 1/9]
Taking a closer look at these fires, some are clearly preceded by an outbreak of tall cumulonimbus clouds (thunderclouds🌩️). We can tell these are tall cumulonimbus from their bright white tops [image 1], and cold cloud top temperatures (–100°C) [image 2]
[2/9]
[2/9]
Each of these clouds will have been a short-lived thunderstorm providing many lightning strikes & gusty winds (ideal conditions to ignite a fire). Rain will be patchy with some areas wet and others dry. There is evidence of many lightning strikes across Siberia recently.
[3/9]
[3/9]
Astonishingly, June temperatures were 6–10°C higher than the 1981–2010 average in this part of Siberia & land surface temperatures were an incredible 33–36°C before the fires ignited. This heat almost certainly drying fuel on the ground, increasing risk of ignition.
[4/9]
[4/9]
The key question is whether the fires are burning into peat soils. This map shows large expanses of peatlands in the location of many of these Siberian fires. Source: eprints.whiterose.ac.uk/121665/
[5/9]
[5/9]
Evidence from the persistence of the satellite-detected hotspots as well as large burnt areas with persistent elevated surface temperatures indicates a long-lived smouldering phenomenon. The light & brownish colour of the smoke also suggests peat is burning.
[6/9]
[6/9]
Why should we be worried?
Peat shouldn't be available to burn. It only burns when it has been disturbed by some significant environmental change (e.g. drainage/drought). Siberian peatlands should be moist/frozen through summer, but this year's heatwave has dried them out.
[7/9]
Peat shouldn't be available to burn. It only burns when it has been disturbed by some significant environmental change (e.g. drainage/drought). Siberian peatlands should be moist/frozen through summer, but this year's heatwave has dried them out.
[7/9]
Peat fires in the Arctic are part of a number of positive feedback mechanisms in the climate system. They release old carbon in the form of CO2 & methane emissions, exacerbating global heating, and they leave behind a dark charred surface leading to localised heating.
[8/9]
[8/9]
Some tentative conclusions:
- at least some of these fires were ignited by lightning
- ignition made far more likely by heatwave
- fires are burning peat soils
- this is the symptom of a sick Arctic
[9/9]
- at least some of these fires were ignited by lightning
- ignition made far more likely by heatwave
- fires are burning peat soils
- this is the symptom of a sick Arctic
[9/9]
Most images generated using @NASAEarth
Try it yourself here:
worldview.earthdata.nasa.gov/?p=geographic&…
Try it yourself here:
worldview.earthdata.nasa.gov/?p=geographic&…
