|Nature has been sending a strong, chaotic message to many people in the last few months – drought, floods, storms, and very unusual temperatures and weather events.
Public communicators of science have been explaining the underlying phenomena – the ENSO cycle in the Pacific Ocean has been flipping winds and sea surface temperatures from a condition known as La Nina, towards the El Nino configuration; plus, in the northern hemisphere, wind flow high above our heads has been erratic.
|Scientists have been careful not to claim every extreme weather event as proof of climate change theory. After all, any one violent storm or unprecedented high could be just that – freak – never to be repeated. Climatologists instead talk of “loading the climate dice”, a way to explain that extreme weather is more likely in a warming world.
Reticence and restraint are in evidence, however, now is a prime moment to assert, without triumphalism, that all this crazy weather does indeed offer confirmation of climate change theory – everything is happening just the way the atmospheric scientists said it would.
There is no doubt that surface of the Earth is warming up, and the Arctic region of the globe is warming faster than anywhere else. This is to be expected in a world with added Greenhouse Effect from rising carbon dioxide levels in the air. The climatologists projected that this would happen, due to localised additional heating resulting from the side effects of melting ice, snow and permafrost in the northern pole. Antarctica, on the other hand, would not show the same kind of strong “albedo” feedback response as it was still too cold and ice-and-snow bound and surrounded by isolating ocean and wind currents.
Up there, where the air is clear
Scientists predicted that because of Arctic amplification, the profile of the planet’s atmosphere would change under global warming conditions. And so it has. The tropopause – the place where the lower, thicker atmosphere – the troposhere – meets the upper, thinner stratosphere, has shifted, and the temperature change profile or “inversion” at this height has also been modified. While the air close to the Earth’s surface has become warmer, the air in the stratosphere has become colder. All just as the scientists predicted would happen.
Jet stream weaker and loopier
Close to the surface of the planet, wind tracks and the passage of storms, pressure systems and clouds are turbulent and pretty chaotic. But above this zone, winds flow freely. The winds stream because the atmosphere drags whilst the Earth turns. Because of the general patterns of billowing air below them, jet streams are usually centred at particular places – the polar jets at around 30 degrees angle from the poles, the subtropical jets at around 30 degrees from the Equator.
Atmospheric scientists have been monitoring these winds for change, as the models indicated that the northern polar jet, in particular, would shift its position northwards, because of the other climate changes, and weaken. As it weakened, they worked out that the normal wavy kinks in the jet stream would become big loops, and maybe even lock into certain shapes for longer than usual, a situation known as a blocking event.
Because jet streams have an impact on the movement of weather systems further down, the scientists projected that the more meandering jet stream would carry weather systems out of their usual tracks, and also create bubbles of unusual temperature. Normally cold places would see heatwaves, normally hot places would have cold snaps, and everywhere would experience unseasonal and more extreme weather. And this is exactly what we have been seeing.
The number of freak weather events is mounting, along with insurance company manager blood pressure readings. The flooding and drought that would be expected with the periodic Pacific ENSO system flip from La Nina to El Nino have been highly damaging, and when the final accounting is done, probably more damaging than previously.
The food on the table
Climate change scientists have long predicted altered patterns and increased variability of rainfall with global warming. There are real concerns that farmers can no longer predict when, or for how long, it will rain, and this is affecting major food growing regions. The major global rice, wheat and maize corn harvests are at risk, and recent years of failings have dented confidence and ballooned prices.
Strange weather is impacting on fruit and vegetable growing, as seasons are becoming unclear and even swapping their normal order. The weather has gone wrong, and this is exactly what the scientists have been warning us about for several decades in official reports. How much easier would we have accepted changing realities if we had understood the language of the early research papers from the Intergovernmental Panel on Climate Change !