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.

Kommentoi kirjoitusta. Avainsanat: climate change, weather, jet streams

IPCC Report - Nothing New But Still Alarming: Immediate Global Climate Actions Are Needed

Tiistai 10.8.2021 klo 12.11 - Mikko Nikinmaa

The IPCC report on the physical science basis of climate change was released yesterday. It is not likely that many people read all its 1300 pages. However, it is enough if the 65-page summary for policymakers is read through. In fact, all of the findings and information are in line with what scientists have been saying for the past 50 years: ever since the book “Limits to Growth” was published in 1972. The scientists’ warning has been repeated twice – or three times, if you take into account the recent addition to the 2019 data. This is now the 6th IPCC report. The scientists’ voices have come louder and more demanding: actions are needed. What was a worst case possibility in 1970’s has become likelihood with high probability, if drastic actions are not done.

 With the wildfires raging throughout the world, many massive heat waves, heavy rains causing floods and droughts in various parts of the world one would think that people accept that climate change is taking place, and demands global action. Hot temperature extremes and heavy precipitation have increased frequency in most places, and there is not a single area in the world where their frequency would have decreased. Similarly, droughts have increased in many parts of the world, but decreased only in one: Northern Australia. Despite this, a significant proportion of people think that climate change is a hoax, and many politicians are of the opinion that one must not do any environmental actions if they interfere with economic growth and decrease the economic competitiveness.

Quite often those, who deny climate change, say that for example last year it snowed in Spain and Texas, and that very high temperatures have been reported earlier, e.g. in 1998. That one year is climate denials’ favourite, since having that as a basis, there has hardly been any change in average global temperature afterwards. However, it is known and repeatedly pointed out by climate scientists that natural variability dampens or accentuates changes in the short term. In fact, the probability of most types of extreme weather increases with climate change: the likelihood of both droughts and heavy precipitation doubles even if the temperature increase can be kept at 1.5oC; if drastic climate actions are not done, droughts become 5x more common, and heavy precipitation occurs 3x more frequently than now.

The climate problem is global. Thus, we cannot say that our country is doing its share, now the other nations should do the same. Combatting climate change in developing countries should be a primary focus of the rich countries, and rich individuals: what is the point of spending billions to military or space flights if the world is in peril. Even if the report is gloomy, we have all the technology and other means to still prevent the climate catastrophe. What is required is that we start to think globally instead of nationalistically.

Kommentoi kirjoitusta. Avainsanat: climate change, temperature, weather