March 5th, 2018
The Beast from the East and Storm Emma have come and gone and we can thankfully look forward to the big thaw over the next few days.
Having survived the exceptionally cold temperatures and blizzards not seen on our island in decades, some, understandably, may be confused by all this talk of global warming.
Others may take the opportunity to scoff at scientists and environmentalists. But, what do we know about the relationship between this recent weather and our climate?
The first thing to make clear is the differences between weather and climate.
Weather refers to how our atmosphere is behaving at a given instant while climate, refers to the average weather conditions in a region over an extended period of time – over tens of years at least.
In recent days, Ireland has certainly experienced exceptionally unusual weather, way outside of what is expected of our normally mild climate.
Data shows that while Ireland and the rest of Europe were hit by freezing temperatures and blizzards, the Arctic was experiencing record-breaking warm winter temperatures – as much as 35 degrees Celsius warmer than normal.
At Cape Morris Jesup in northern Greenland – the most northerly land weather station and thousands of miles north of Ireland – temperatures were above freezing for over two days.
We also know that the unusual weather in the Arctic and in Europe was not a coincidence – the cold polar air was transported from the Siberian Arctic to lower latitudes and westward to Europe.
The Polar Vortex
Normally, there is a mass of cold air called the polar vortex circling around the North Pole about eight km high in the atmosphere – a region called the stratosphere. This circulating vortex deflects warmer air from lower latitudes.
In early-to-mid February, a sudden warming of the stratosphere occurred due to intruding warm air from lower latitudes. This disrupted the circulation of the vortex and split it into two.
This disruption had a knock-on effect for circulation patterns at lower altitude and latitude – the most important of which was a reversal of winds in mid-latitudes and put Europe in the path of the so-called Beast from the East.
Can we say conclusively that the Beast from the East (or other recent extreme weather events) was caused by climate change?
The short answer is no, although I should add ‘yet’ for reasons I will explain below.
Variations in daily temperature or precipitation above or below the average are normal – otherwise, we would not bother to calculate averages.
For decades, scientists have been working to fill in knowledge gaps relating to how and why climate has changed in recent years and during Earth’s long history.
Climate scientists use this accumulated knowledge to improve our predictions for the future.
For this work, scientists need time to interpret measured data, repeatedly test hypotheses and build a consensus.
We should, therefore, press pause on any debate that attempts to conclude that the Beast from the East was a freak event or a product of a shifting climate system. We need to wait for more data, more evidence.
The main warnings from scientists are decades old at this stage – our atmosphere is warming, ice caps are melting and sea-level is rising at alarming and unprecedented rates. We know this is due to runaway carbon emissions.
A 2016 study showed evidence that the decline of sea ice in the Arctic is having the knock-on effect of allowing warm low-latitude weather systems to transport heat to the North pole.
As of this January, Arctic sea ice is at its lowest extent on record and the Arctic continues to experience winter heat waves.
In most walks of life – be that legal, business, sporting or otherwise – we rely on people with credentials and experience to make decisions and take actions based on evidence.
When not all evidence is available, experts err on the side of caution and lowest risk.
Why should how we deal with the Earth – our one and only life support system – be treated any different? That is the real conversation we need to be having.