There was lots of talking about the polar vortex this week. Even in this tiny country, which wasn’t affected by the freezing temperatures (yet), the media was full of the polar vortex that made the freezing temperatures in Northern America possible. The media was assuring us that this cold snap was the result of global warming (but a lot carefully avoided calling it global warming and diplomatically called it climate change).
This is basically how the media said it works: it is the result of the rapid melting of Arctic sea ice because of climate change. This decreases the albedo of the Arctic region and as a result it heats up faster than other parts of the Earth. The temperature difference between the Arctic and the southern regions determines the strength of the jet stream. If the jet stream is strong, it isolates the cold Arctic from the warmer mid latitudes. But because of this melt the jet stream becomes weaker and more wavy, allowing cold air (usually confined to the poles) to reach further into the mid latitudes. Et voilà, global warming/climate change caused the severe cold snap. John Holdren, the science advisor of President Obama, even went that far to state that because of this process those deep freeze cold snaps will occur more frequent in the future.
But in general, I can agree with the statement that current cold wave doesn’t disprove global warming. Yet, while it is a nice explanation of the assumed mechanism, it doesn’t prove global warming either. It only proves that media and scientists are creative in finding new ways to fit new events into the theory. AFTER the facts, that is. That’s not difficult, that is what humans are good at, finding connections between seemingly unconnected things.
But deep freeze winters due to the weakening of the jet stream is nothing new. In the 1970s it was used to explain the coming of a new ice age. Younger people may think the weather we see now is unprecedented, but it is not that extreme, nor unprecedented when looking at it over a larger time frame. Remove the hype and there is not much of a story left. Holdren, as a crusader of the coming new Ice Age in the 1970s, should at least recognize that.
How much of this is due to anthropogenic causes? The theory seem to rely on polar amplification. That is a real process, but it doesn’t prove anything about the anthropogenic nature of the warming. Any warming would have that effect, whether it is natural, anthropogenic or both. By the way, the outbreak of cold is also part of the negative phase of the Northern Atlantic Oscillation, which is a natural pattern.
To me it seems yet another patch on a wound of a heavily bruised theory that continue to limp further. I didn’t hear anything about having a higher frequency of very cold winters as a result of global warming/climate change until recently. On the contrary. I heard a lot about more heatwaves, higher temperatures at night, more droughts, more storms, less to no snow,… sure, but very cold winters? No. When it started to snow massively in 2010, suddenly snow became a result of global warming or at least not impossible in a warming world. It seems the same with the cold winters due to the melting ice. Just adding to the possible explanations and covering an additional hole without elimination other ones.
I would be more impressed if scientists came with new falsifiable hypotheses/predictions (based on the global warming theory) about these snowy winters. Now we only hear after the facts that this is not impossible in a warming world or doesn’t disprove global warming. Which is not a big deal actually.