Severe weather, forest fires and mudslides: one country after another is struggling with extreme weather this summer. That raises a lot of questions from our readers. Climate reporter Rolf Schuttenhelm answers the best and most frequently asked questions here.
To what extent does climate change cause this extreme weather?
“The extreme weather in southern Europe is caused by a number of successive heat waves. These heat waves have been studied internationally. They were 2.5 degrees higher due to climate change. With the same air pressure distributions, these temperatures would have been impossible a century ago.”
“The connection with the heat has therefore been demonstrated and is also very strong. Other weather extremes can be the result of that heat. For example, heat leads to stronger evaporation and dehydration, after which forest fires start more quickly.”
“Severe weather due to high precipitation can also be exacerbated by climate change. After a period of higher temperatures, the weather can change with more force. For example, showers are up to 14 percent more intense for every degree of warming. In such more extreme downpours, larger hailstones can form. And in mountain areas also have mudslides.”
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Is the extreme weather this year a coincidence or will we only see more of this in the coming years?
“The climate will warm up even further anyway. This will lead to a further net increase in heat waves, droughts and locally also other forms of extreme weather, such as downpours and floods.”
“Climate scientists are not yet completely sure about all of the weather extremes of 2023, nor about those of the European summers that preceded it. For example, the development of summer droughts and heat waves is in practice faster than models had anticipated.”
“Worldwide, 2023 seems to be a ‘harbinger year’, which is slightly ahead of the future. This is because the global average temperature is temporarily pushed up a bit further by El Niño (warm water in the Pacific Ocean).”
“There are also two major anomalies going on that scientists can’t yet fully explain: very high temperatures in the Atlantic Ocean and a very rapid reduction of sea ice around Antarctica. What that means for the next few years is now unclear.”
Is this extreme weather due to El Nino? How does this relate?
“The extreme summer weather observed in North America, Europe and Asia in recent weeks is virtually unrelated to El Niño. However, there do seem to be somewhat weaker westerly winds on average across the northern hemisphere. As a result, high pressure areas stay in one place longer and heat waves are getting more vicious. This is related to global warming.”
“El Niño will still stir in the second half of 2023, especially in the tropics. Western South America can prepare for torrential rain and mudslides, and Australia and Indonesia for drought and forest fires.”
What can humans do for the climate and thus against this type of extreme weather?
“The cause of global warming is the increase in greenhouse gases in the atmosphere. This is mainly due to the large-scale burning of coal, oil and gas. Only if that concentration does not rise further can the warming stop.”
“There are big differences in CO2 emissions between individuals. On an annual basis, for example, it makes a lot of difference whether someone flies or not. But to stop the global increase in greenhouse gases, it is especially important that countries adhere to international agreements. For example by investing more in sustainable energy.”
Are there still areas in Europe that still have relatively little chance of severe weather?
“Awareness is slowly growing that Southern Europe in particular is in a pinch. That is a region that is warming up strongly above average, and that is also drying out strongly.”
“With a few degrees of warming, Spain, Italy and Greece will have the original climate of North Africa. This not only means that heat waves of more than 40 degrees occur more often in the summer, but also that water is becoming increasingly scarce. For example, forests or common forms of agriculture disappear.”
“The climate also changes relatively quickly in Northern Europe. But in Scandinavia, for example, the annual average precipitation will actually increase. That can cause other problems, but in any case no water shortage. Temperatures further north will also always be lower.”
“The Netherlands is in between: our winters are getting wetter, our summers will probably be drier in the long run. But with more downpours.”
Climate is a complicated interplay. What influence does warm ocean water have, and how does that warm up in the different oceans? How do winds, precipitation patterns, sea level and temperature change as a result?
“With the oceans, many questions have not yet been fully answered. The water warms up from above, via the atmosphere. This can lead to stratification: a layer of warm water that floats on the cooler ocean. If the exchange with the deep sea decreases, that is bad for the oxygen content, for example. Ocean currents can also be disrupted.”
“The warming of the oceans also leads to sea level rise, because warmer water expands. In the long term, the melting of large ice caps is a more important cause of that sea level rise.”
“Indeed, wind patterns can also be strongly influenced by differences in ocean temperature. Those differences can be amplified by changes in ocean currents.”
“For example, if the Gulf Stream in the Atlantic Ocean weakens as a result of climate change, this will lead to more westerly winds, higher temperatures and more rain in the Netherlands in the winter. And in the summer to a decrease in wind and an increase in drought risks.”
Meteorologists say very often that it is such a typical Dutch summer, but I doubt it. How does this work?
“It is clear that the temperature is rising everywhere and that heat waves in particular are increasing strongly. It is much less certain how weather patterns develop in the summer under the influence of climate change.”
“Climate models expect with further warming (after 2050) that our region will more often have to deal with ‘persistent weather’. These are, for example, persistent high-pressure areas or, conversely, lingering rain areas. If a country has the same weather for a long period of time, the harmful consequences can increase sharply.”
“Whether we already see this pattern in the past six summers is now the subject of a scientific discussion. We will have to wait and see.”