Last weekend we were out on the balcony grilling fish on the barbecue, wearing T-shirts and enjoying the sun, in temperatures up to 20 degrees. This weekend it is shaping up to be a cold one, dipping below freezing. Snow is expected, and the mountains around Athens will certainly be covered in snow, and it may even get down to Parthenon level, which is a sight to be seen. A cold snap is expected, and it will be sharp.
I mention this extreme range of temperature in part to offset one of the most annoying conversations that can take place these days:
“Cold isn’t it?”
“Freezing! So much for global warming eh?”
I am tempted to reply at length, going into detail about the science, and how weather is not the same as climate, but this is not a pleasant way to pass the day when you are just engaging in small talk. It is however worth examining the causes and effects of the cold weather about to grip not only Greece, but already has most of the Eurasian continental landmass in its grasp.
Firstly the cause: the wonderfully named ‘polar vortex’ has been split. Let me try and explain in simple English. The polar vortex is a large area of low pressure and cold air surrounding the North and South Poles, flowing counterclockwise keeping the colder air close to the poles. Sometimes, it becomes unstable sending cold air south (or nor north), causing outbreaks of cold weather in normally warmer places.
A stable low-pressure system normally keeps the jet stream – a band of reliably strong winds blowing west to east – in place, which in turn keeps colder air towards the poles, and the warmer air towards the temperate, mid-latitude areas. Incidentally, long haul flights ride on the jet stream from west to east, one of the reasons why flights out to Asia from Europe are quicker than those coming back, and also why the flight paths tend to veer north. But when the vortex weakens, parts of the low-pressure system can break off. Without a strong polar low-pressure system, the jet stream loses its power and starts moving around, and when faced with a high-pressure system pushes further away from the polar regions bringing cold air with it.
Our weather occurs in the troposphere, in the air immediately above us. The stratosphere above it, about 15-45 km above, is normally stable. During the winter, when little to no sun can warm the air, the cold air spins, in a much smaller vortex than the one below, but for it to remain stable it has to be much cooler than the air below, and the difference in the temperature has to be wide and distinct.
What’s interesting for me is that the current cold snap in Asia, and now coming for Greece, has been caused by a rise in temperatures in the stratosphere above Siberia, increasing in the first week of this month from -70 degrees centigrade to -13 degrees. This threw the stratospheric vortex off balance, pushing the lower vortex ahead of it, and with it cold weather.
These warming events happen on average every other year, and aren’t well understood, but are caused by warm air funneling up into the stratosphere, typically over Siberia or the North Atlantic. The interaction between the stratosphere and the troposphere is little understood either. Climate change may have a hand in it too. As National Geographic points out:
In the past 30 years, the Arctic has warmed about twice as fast as the rest of the world, a phenomenon known as arctic amplification. The warming has led to retreating glaciers and a loss of sea ice in the region, and it may also make the stratospheric polar vortex less stable, though that connection isn’t yet clear to scientists…. “Losing all that ice allowed a great deal of extra heat from the sun to warm the Arctic waters, which is now being released back into the atmosphere, creating bulges of warm air in those key regions,” [Jennifer Francis, Woodwell Climate Research Center] says. “These bulges can make northward swings in the jet stream larger, stronger, and more persistent, which in turn can disrupt the polar vortex.”
The link between climate change and weather is not clear. The cause of the cold weather could be climate change, where warmer weather in certain areas causes disruption and colder weather in others.
When you consider the many massive physical forces at work in the world – the earth turning on its axis, the tides, the ocean currents, the energy of the sun, the movement of air, the tectonic plates – it makes humankind seem very small indeed. When you consider also how man has changed the chemical makeup of the planet by releasing massive amounts of previous geologically locked-in carbon into the atmosphere, it becomes far more understandable when scientists say “we don’t know what’s going to happened, but something will.”
But it’s an ill wind that blows nobody any good, even if it’s an erratic jet stream. The cold snap in Asia, and now in Europe, has increased demand for energy, and LNG carriers are benefitting, as well as bulk carrier owners in East and South East Asia. Paradoxically of course, the demand for energy means the consumption of more hydrocarbons.
It is even stranger in these COVID times. My friends in Tokyo tell me that restaurants are open only until eight o’clock in the evening due to new lockdown regulations. But they have to keep the windows open to avoid the spread of the virus in closed spaces. The heating (natural gas and coal mostly, either pure or used to generate electricity) is turned up in an effort to keep their customers warm; Korean barbecues are very popular you may imagine.
What can we do? It’s a strange and weirdly interconnected world we live in, economically, politically, physically, and environmentally, but as we are repeatedly reminded, doing nothing is less of an attractive option as time goes on.
I suppose a start would be to acknowledge facts, and trust scientists, especially those that say “we don’t really yet understand…” Reasoned doubt is always preferably to unreasonable certainty, especially when the truth is concerned. There are always people willing to bend, manipulate or distort the facts for their own benefit, and I am sure all of us do it to a greater or lesser extent at some point or other; it’s part of the human condition.
The world is challenging and scary, and changing all the time. The things we held secure, even the weather and the passing of the seasons, feel out of sync. But, to paraphrase the Classical Greek philosopher Heraclitus, the only constant is change. He also – kind of – said, you can choose, and what you think and do is what you become. If we can choose to learn the difference between climate and weather, between facts and opinion, between science and fashionable thinking, then we may yet see a profitable and fairer future for the whole of the planet.