Climate hoax?

Sunnuntai 3.11.2024 klo 11.12 - Mikko Nikinmaa

The most devastating hurricanes ever in Florida and neighbouring states. The strongest typhoons ever in East Asia. Fourteen hottest months in recorded history. The devastating flash floods in Spain. La Nina has not appeared in Pacific when expected. Floods in South-East Europe. It appears that the jet stream affecting weather in Northern Hemisphere has generally moved northward, causing high temperatures in the Arctic. There are signs of increasing undulations of the jet stream, pushing cold Arctic weather further south than earlier. Atlantic oscillations may be weakening because of Greenland ice melting, as a consequence the mild weather of Western and Northern Europe can be changing to one like that in Siberia and Yukon.

The climate hoax is manifesting in various forms throughout the world. It is already apparent that the costs of weather-related catastrophes are exceeding the costs of really starting to combat climate change. The conservatives are always saying that we cannot leave the monetary debt to future generations. However, monetary debt is only numbers whereas healthy environment is needed for future generations to be able to live.

Ice is melting in Greenland - so what, it is far away from Europe

Lauantai 2.3.2024 klo 15.06 - Mikko Nikinmaa

Heat waves, drought, heavy rain, floods, no snow in winter, extreme cold – weather in Europe has been extreme for many years now. And the weather pattern differs markedly spatially. When the British Isles had very warm November 2023, Scandinavia was freezing. Major things affecting weather are the location, direction and strength of tropospheric jet streams. Knowing how the jet streams are what they are would significantly help in predicting weather effects of climate change.

Oltmanns et al. (Weather and Climate Dynamics 5, 109-132, 2024) have now evaluated what changes in the melting of Greenland’s glaciers does to summer weather in Europe in the following years. They evaluated statistically what the relationship between freshwater flow to the Arctic sea and distinct aspects of weather, like temperature and rain, is. The links between freshwater flow to ocean and European weather were statistically significant for several years, and showed that significant spatial variation will also occur.

Why would there be a significant effect of melting water in East coast of North America? The reason appears to be that the cold meltwater increases the temperature difference between the subpolar and subtropical ocean water. The latitudinal boundary between the southern warm and northern cold water depends on the amount of melted water. This affects where the jet stream is located and if cold or hot air will be moving in the stream. Consequently, the temperature in European continent will be affected. The changes of freshwater melt have been such that heat waves in Europe have been favoured in summer, and the increase of summer temperatures has been greater than expected.

The article elegantly describes why and how the overall climate change can influence weather, often in conflicting ways. If I have read the figures right, the data used also show that ice-melt can cause the observed cold spells in Scandinavia, or, in any case, that weather variability increases. That is bad news for agriculture.

Extreme heat in Europe - a new normal together with cold spells in winter, if climate change is not stopped

Tiistai 20.9.2022 klo 11.29 - Mikko Nikinmaa

The climate models predict that the circulation of warm water towards north and cold water to the south can radically decrease in near future. This is mainly the result of the melting of Greenland ice sheath, which liberates a lot of fresh water to the Arctic Ocean/North Atlantic. Because of this, the surface water becomes less dense than earlier and will not sink in the water column. The downward movement of surface water is the main driver of northward current of warm water in Gulf Stream. Since Gulf Stream keeps the European climate temperate increasing especially winter temperatures, its weakening may change the climate towards Siberian-like.

Other major effectors of European climate are the jet streams at high altitude. Their movements to a large extent determine the movement and stability of low and high pressure zones, and depending of the location of the zones if tropical or arctic air is moving towards Europe. The jet stream has recently started to split more often than earlier, and between the split any weather pattern becomes more stationary that earlier. Although there is no conclusive evidence that the increased splitting of jet stream would be caused by climate change, it has only started to occur recently, more or less at the same time as the global average temperature has increased more than one degree centigrade.

The two factors, weakened Gulf stream and jet stream function, predict that Europe can expect extended heat spells in summer and cold winters. The cold winter weather may occur even though the global temperature increases markedly. So, the truth value of the following is zero. “Look, it is cold now, there is no climate change”, as climate sceptics certainly shall say. But scorching heat in future summers becomes even worse than in 2022