Europe floods July 2021: What caused them and why people were caught out

[Nick F]

The impacts of the catastrophic flooding during the week across parts of western Germany, eastern Belgium and the Netherlands have been shocking to see. This blog looks at the causes.

View the full blog here

[Timmytour]

I guess there were the Pentecost floods back in 1999, but I would imagine they related to melting snow more than a "Rex Block".

Do we know if a Rex block was behind the  1910 flooding?

I imagine it may be a one in a 100 year event in which case it perhaps isn't the greatest surprise to find it happening around this time.  I know the warning always goes out these days that "this may happen more frequently in the future because of climate change" but is there any evidence to suggest that they are actually happening more frequently now from all the years of atmospheric charts we have?

[Derecho]

12 hours ago, Timmytour said:

I guess there were the Pentecost floods back in 1999, but I would imagine they related to melting snow more than a "Rex Block".

Do we know if a Rex block was behind the  1910 flooding?

I imagine it may be a one in a 100 year event in which case it perhaps isn't the greatest surprise to find it happening around this time.  I know the warning always goes out these days that "this may happen more frequently in the future because of climate change" but is there any evidence to suggest that they are actually happening more frequently now from all the years of atmospheric charts we have?

I think there is a strong physical logic behind these events becoming more frequent globally. Global temperatures are becoming warmer and as a result of that, air can hold more moisture. Due to this, the potential for high intensity rainfall events will just keep on increasing.

The question from here is what will the atmospheric circulation do? If in the UK for example, high pressure became dominant, this would locally cancel out any signal as a result of increasing temperatures because of a stable atmosphere being more common. However if atmospheric circulation just keeps behaving as it usually does, then flooding events would indeed become more frequent.

Flooding is in my eyes the biggest danger many of us will face from climate change, especially given so many houses are being built in flood prone areas and this is just the rainfall aspect. In the future, we also have the threat of rising sea levels due to sea ice melt but also the often overlooked thermal expansion - warmer oceans occupy more space.

Edited July 18, 2021 by Quicksilver1989

[East_England_Stormchaser91]

2 hours ago, Quicksilver1989 said:

I think there is a strong physical logic behind these events becoming more frequent globally. Global temperatures are becoming warmer and as a result of that, air can hold more moisture. Due to this, the potential for high intensity rainfall events will just keep on increasing.

The question from here is what will the atmospheric circulation do? If in the UK for example, high pressure became dominant, this would locally cancel out any signal as a result of increasing temperatures because of a stable atmosphere being more common. However if atmospheric circulation just keeps behaving as it usually does, then flooding events would indeed become more frequent.

Flooding is in my eyes the biggest danger many of us will face from climate change, especially given so many houses are being built in flood prone areas and this is just the rainfall aspect. In the future, we also have the threat of rising sea levels due to sea ice melt but also the often overlooked thermal expansion - warmer oceans occupy more space.

I believe that less dredging of rivers, waterways and more vegetation may be playing an even bigger part. Extreme rainfall events have always occurred for centuries, but the distribution and management of the resultant water has to be questioned here. 

The flooding in Peterborough on Bourges Boulevard seldom ever occurred, but has now been occurring quite frequently after a heavy but not too unusual downpour, to my memory ever since they did some resurfacing work a few years back. Whether they have tarmacked over some drains or gulleys, I’m not too sure. But I’ve been alive long enough in that city and have seen some incredible rainfall events such as Easter 1998, and a storm which must’ve been in the mid 90’s flood Oundle Road bridge under the East coast mainline. I have not seen that happen since. So I don’t believe it’s just a case of hopping on the climate change bandwagon. 

Edited July 18, 2021 by East_England_Stormchaser91

[Derecho]

2 hours ago, East_England_Stormchaser91 said:

I believe that less dredging of rivers, waterways and more vegetation may be playing an even bigger part. Extreme rainfall events have always occurred for centuries, but the distribution and management of the resultant water has to be questioned here. 

The flooding in Peterborough on Bourges Boulevard seldom ever occurred, but has now been occurring quite frequently after a heavy but not too unusual downpour, to my memory ever since they did some resurfacing work a few years back. Whether they have tarmacked over some drains or gulleys, I’m not too sure. But I’ve been alive long enough in that city and have seen some incredible rainfall events such as Easter 1998, and a storm which must’ve been in the mid 90’s flood Oundle Road bridge under the East coast mainline. I have not seen that happen since. So I don’t believe it’s just a case of hopping on the climate change bandwagon. 

There is no question that land use changes have also increased the risk of flooding but the role of climate change is also there, for the reasons highlighted above. It's a combination of both.