With COP26 at the center of current news, we all know there’s a climate crisis. You’ve probably heard percentages of diversity we’re going to lose if global temperatures increase by various °C but it's rare people get connected with the science and research behind those numbers. A couple of weeks ago I watched a seminar by Melody Clark from the British Antarctic Survey, she spoke about polar adaptations to the cold and responses to a warming world. Her research has been bouncing around my head ever since so I thought I’d share it on here.
Melody investigates organisms' tolerance to climate change by seeing whether the temperature is right for processes inside cells to work properly. Every process that happens in the cell has a bit of DNA that switches on for the process to occur, Melody can tell how many processes are happening in the cell by how many bits of DNA are turned on. Melody and her team used heat settlement panels which warm up the thin layer of water above the panel to +1°C or +2°C, they left the panels in the sea for 9 months for small animals to settle on them. At the end of the 9 months, she checked the DNA of the animals to see whether lots of it was turned on or off. For the +1°C panel lots of the DNA was turned on, this is because the animals were finding that the temperature was too high for their cells to function quite right so they were throwing everything they had at tackling the problem. In other words, they were stressed about it and they had enough energy to try to fix it. For the +2°C panel hardly any DNA was turned on, this is more worrying as only the very basic cellular processes were working and the animals didn’t have enough energy to try to fix the problem, they were essentially burnt out, and just like us when we’re burnt out they were too tired to reproduce.
The Southern Ocean is a challenging environment to live in. Animals grow slowly, live for longer, have low activity levels; a snail for example might take 20 days to eat one shellfish. The 20,000 species that live there are well adapted to the environment. With temperatures almost permanently below -0°C, many fish produce antifreeze to keep their blood liquid, some rely on oxygen just to diffuse into their blood instead of having haemoglobin (the protein that collects oxygen in our lungs and carries it through our bloodstreams). The clock of evolution ticks to the tempo of generational turnover, since things move slowly in the Southern Ocean an icefish might be 10 years old before it has offspring¹, for comparison Atlantic cod would be 2 years old. This means it would take an icefish 5x the time to adapt to a change in its environment than an Atlantic cod would.
Antarctic organisms may not be able to reproduce after a temperature increase of 2°C, let alone adapt to environmental changes occurring more rapidly than evolution could ever occur. This makes them particularly vulnerable to a warming world. Melody’s research reiterates the urgency world leaders, businesses, and each of us should be moving at to reduce climate change.
This is the link for Melody's paper: https://www.nature.com/articles/s41467-019-11348-w
¹based off Blackfin icefish