Keskiviikko 2.8.2023 klo 19:25 - Mikko Nikinmaa
We have been taught at school how the temperature in Central and Northern Europe is much higher than at similar latitudes elsewhere. The reason for this has been Gulf Stream, which flows northeast from the Gulf of Mexico to the Arctic, North of Norway. The stream moves a lot of heat from tropics to high latitudes. Finally the water cools and sinks to the bottom of the ocean and the cold water flows back south in southwest-directed cold streams. An important part of the dynamic water flow is that the Gulf Stream water sinks to ocean bottom, because that generates the driving force for water circulation. In the absence of water circulation, Central and Northern Europe would be much colder than presently, especially in winter. Gulf Stream water sinks, because when its temperature decreases to four degrees centigrade, the density of water is higher than the water below, which has a lower temperature. The density of water depends also on its salinity, the higher the salinity, the higher the density. Earlier on this has also contributed to the water circulation. The surface water flowing in Gulf stream from tropical areas has traditionally had higher salinity than the bottom water of the Arctic Sea.
Climate change is now threatening to change this warmth-bringing ocean circulation. The melting of Greenland glaciers but also the sea ice of the arctic causes a significant decrease in the density of surface water in the Arctic Sea. As a result, the sinking of Gulf Stream water from the surface to the bottom can be markedly reduced. This decreases the driving force for ocean circulation, and Gulf Stream may stop flowing altogether. The result for Central and North European climate would be that we experience Siberia-like weather patterns. An additional problem associated with presently ongoing freshwater addition is that the global temperature rise observed already seems to be adequate to cause continuing glacier melting in Greenland. This suggests that even if we are able to stop temperature increase to 1.5 degrees centigrade, the weakening of Gulf Stream may occur. There is no way to know, when we reach the tipping point.
So, if climate deniers tell you after three cold winters that clearly there is no climate change, as we have cold winters, you can answer them: “On the contrary, this shows that climate change has reached another tipping point. The heat transfer from tropics to the north in the form of Gulf Stream has stopped.” The real problem with this, and the weather patterns in general, is that what has happened and is happening is increased unpredictability. That is probably the biggest problem with climate change.
Maanantai 2.8.2021 klo 18:22 - Mikko Nikinmaa
Scientists have been trying to alert the public about how the present way of life is not sustainable ever since 1970’s. A very strong message with more than 10000 scientists endorsing the publication of data was written in 2019 indicating that unless strong measures are taken, many tipping points leading to drastic environmental deterioration are reached in the near future. After 2019 the Coronavirus pandemic hit the world, and the lead authors of the 2019 paper thought that it is good time to see, if any measures have been taken to heed the warning. In BioScience this July 28 (https://doi.org/10.1093/biosci/biab079), Ripple et al. estimated what has happened during the pandemic time. For the most part the findings are bleak: the temperature, carbon dioxide, methane and nitrous oxide levels continue to increase, Antarctic, Greenland and overall glacier ice mass continue to decrease at a similar rate as before. What is almost worse is that although many climate-friendly changes took place as a result of the pandemic, almost all have started to revert to pre-pandemic levels. For example, the number of livestock has continued to increase, and all the media are just saying how we need to get the economic growth back to pre-pandemic track.
In the overall gloomy picture there are, however, a couple of bright spots. The first is that the number of births per woman continues to decrease. For ending up with sustainable human population, this is probably the most important trend and should be supported by improving the education of women. The second is the marked decrease in subsidies to fossil fuels. It has been quite funny that the same groups, who have been very vocally against any subsidies to green energy production, have wanted and accepted billions of dollars/euros in subsidies to oil and coal industries.
Stabilizing and reducing the human population by voluntary actions is the key behind making the life sustainable for all citizens of the world. Only with decreasing population can enough environment be kept in natural state to maintain biodiversity and to reduce the risks of new pandemics. Life in the globe with limits requires social justice, not that some superrich burn a lot of money to a few hours space travel.