A Mini Case-Study of Cyclone Lothar

Last post I looked at the science of extra-tropical cyclones, today I will explore the damages that these cyclones can cause through a mini case-study of Cyclone Lothar. 

Cyclone Lothar was one of three extreme storms over Europe in December 1999. In total they claimed more than 130 lives and caused about 13 billion euros worth of total economic losses. Lothar was the second storm event which caused a trail of destruction from north-western France to Southern Germany and Switzerland. The largest damages occurred around Paris' well-known tourist sites with gusts reaching wind speeds of almost 50 ms. Damages to forests, buildings and infrastructure was widespread. In France public life was severely disrupted due to power outages, infrastructural damage caused substantial economic losses and over 10,000 trees were uprooted within hours. The photo below was taken in the area following the storm and hints at the extent of damage caused by countless uprooted trees:

In Switzerland, more than 12 million cubic metres of timber were damaged, approximately 3% of the growing stock of the whole country: that's the equivalent of an entire years supply of wood at Ikea's current usage (they account for 1% of all wood used commercially around the world). The economic costs were sky high, amounting to 1.4 billion euros. Transport facilities, cable cars, telecommunication services and the Swiss electricity network were also heavily affected. In terms of human costs, 14 people were killed during the event, mostly from falling trees or bricks and a further 15 people died during clearance work in the forests. 

Here are a few bullet points to help summarise the key points mentioned above:

• formed on Christmas Day of 1999 
• affected Western Europe 
• highest gust recorded 161 mph 
• 110 fatalities

Make sure you check out this video taken from an apartment block on the coast of Vevey (Switzerland) for footage of the storm in action! For those kill joys who didn't click the link, I'm giving you a second chance. Ready, steady - GO!

Can the occurrence of these storms be taken as fuel for discussions on anthropogenic climate change? How does this compare to St Jude only a few days ago? As the worlds population moves into cities along its coasts are we making ourselves more vulnerable? 'Self-regulating machine'? Is it starting to make sense yet? No? Stay with me. Hold that thought, I will come back to it. Later.

Extra-tropical cyclones: The science

Severe extra-tropical cyclones usually form in the North Atlantic basin and represent the dominant feature of the mid-latitudes (Ulbrich et al, 2009). The graphic below from Risk Management Solutions (RMS, 2006)  documents key historical European windstorm events with their associated economic losses. It is striking that developed, heavily populated countries appear so exposed.  The UK, France, Germany, Poland and other significant European countries have suffered from significant losses in the past, and seem sure to be struck again. Cluster events can be particularly damaging, and the events of 1990 and 1999 provide a reminder of these dangers. But what exactly are extra-tropical cyclones? 

The mechanics of extra-tropical cyclones take a very different form to, for example, tropical cyclones, during the processes of genesis, intensification and propagation. Extratropical windstorms tend to be fast moving and broad reaching storms which result in low level of damage at individual sites. The breath of the storms, which can reach 2,000km in diameter, mean losses have the potential to accumulate to significant sums.  In addition to strong winds, heavy precipitation and sharp temperature changes are associated with these large frontal systems. The extra-tropical transition at the midlatitudes is usually a product of low pressure systems where energy is gained from meridional temperature gradients created by polar air masses and subtropical air masses (Harr et al, 1999; Jones et al, 2003). The gradient is greatest during winter and most sever storms tend to develop over this period. The track of the storms is controlled by the position of the Polar Jet, which has the capacity to shift the track north or south.  Ulbrich et al  (2009) suggest that many studies show overall cyclone frequencies to have decreased over the period ~1980-2000. In contrast, however, the average intensity of such storms is shown to have increased with some illustrating an eastwards extension of deep lows in wintertime over the last 50 years. 

Of chief importance in producing conditions favourable to the development of extra-tropical cyclones is the North Atlantic Oscillation (NAO). The NAO is a 'hemispheric meridional oscillation in atmospheric mass with centers of action near Iceland and over the subtropical Atlantic' (Visbeck et al, 2001). The figure below shows its changes in index between 1860 and 2000. The index is defined as the difference between the polar low and subtropical high from December to March. A positive NAO index reflects a stronger than normal pressure gradient and hence more and stronger winds over the North Atlantic ocean basin. Over the last 30 years the NAO has seen an unprecedented trend towards a more positive phase. Incidentally the big cluster storms of 1990 and 1999 occurred over this period. There is an increasing argument that anthropogenic climate change might be influencing this natural mode of atmospheric variability. GCMs do not yet give an unequivocal answer on this viewpoint however. 

Ulbrich et al (2009) support the view that anthropogenic climate change is taking hold, stating that a major result from an ensemble of different models forced with different greenhouse gas concentrations is that extreme extratropical cyclones increase in number in the winter months (when NAO has been at its peak), whilst the total number is slightly reduced in both the norther and southern Hemispheres. 

Bonazzi et al (2012) comment that the damages associated with the European Windstorm peril are amongst the costliest natural perils in Europe. Knowledge on storm development, spatial structure and future frequency and intensity will be crucial in minimising the risk. 

Now you know a little more about the Windstorm peril, the next post will take a look at the impact they can have on humans and our preparedness in a little more detail. 

European Windstorm

Here's a bit of background for next week's focus on European Windstorms from Willis, one of the World's largest (re)insurance firms. There's some interesting commentary on climate variability and Global Climate Models. 

The Great Storm II ?!

I hope you're looking forward to my next post which will introduce climate hazards in more detail. In the meantime brace yourselves! Hurricane-strength winds are expected to reach the south coast of the UK by Sunday night...

Check out these articles in the Independent and Sky News. 

Is this a product of our increasing grip on the Earth's climate system? Or is it a regular European windstorm? Find out more when I look at the European Windstorm peril later next week, the first of a series of climate hazard posts. How has this peril evolved through the Holocene? What are scientists expecting in the future? What does this mean for human populations?  

Where do we live?

Hazards involve people. We are only concerned about natural phenomenon like flooding, wind storms and storm surges when they have an impact on people and their possessions. If we understand where people are living, we can start to understand who might be affected. In the map below, the size of each territory shows the relative portions of the world’s population living there.

  

India, China and Japan appear large on the map because they have large populations. Panama, Namibia and Guinea-Bissau have small populations, so are barely visible on the map. So, now we have a rough idea of which countries are heavily populated, let’s find out where exactly the 7 billion of us live.

An urbanising world?

The world is undergoing the largest wave of urban growth in history (UNFRPA). More than two thirds of the world’s population is now in Africa, Asia and Latin America. Since 1950, the urban population of these regions have grown more than fivefold. This rapid urban growth has bought a HUGE increase in the number of large cities. Many cities have reached sizes that are historically unprecedented. Looking back just two centuries ago, London and Beijing were the only two cities with over 1 million inhabitants. By 1950 there were 80; today there are over 300 (Sattherwaite, 2000).

What about mega-cities I hear you ask? Well, they didn't exist until the 1940s. Mega-cities are those with 10 million or more inhabitants and are a relatively new phenomenon. The first city to reach this size was New York. By 1990 there were 12 of them. Although mega-cities have captured much attention they account for fewer than 10% of urban dwellers; most of new growth is projected to occur in smaller towns and cities, particularly in less-developed regions, which have fewer resources to manage the magnitude of change. Hold that thought.

The world is urbanising and FAST, as a result poverty is also urbanising (Ooi and Phua). For the first time ever, the majority of the world’s population lives in a city, and this proportion continues to grow (World Health Organisation). Here are a four bullet points to summarise what has happened, what is happening and what is predicted to happen with world population:

1. 1. 100 years ago 2 out of every 10 people lived in an urban area
2. 1. By 1900 less than 40% of the global population lived in a city
3. 1. As of 2010 more than 50% of us live in an urban area
4. 1. By 2030 6/10 of people will live in a city and by 2050 this will reach 7/10 of us

It is evident that as we move further into the anthropocene, more and more of us are living in cities. We are entering into unprecedented territory.

Opportunities provided by cities

The concentration of people and production in cities can be problematic, but can also provide many opportunities for improving quality of life. This concentration provides economies of proximity which helps reduce unit costs. Let’s list just a few of the opportunities that cities can provide: piped water, sewers, drains, electricity, public transport, health care, emergency services, regulation, waste handling, etc. The provision of such services is part of the reason why the world is undergoing urbanisation on a huge scale.

BUT Cities can also provide an opportunity for disaster. In the absence of good management, they can be particular hazardous as large low income settlements develop in hazardous sites because no other sites are available to them. Poverty is growing faster and faster and faster and faster. 1 billion people live in urban slums which are typically overcrowded, polluted and dangerous. These lack basic services such as clean water and sanitation (UNFPA). Are cities in the developing world therefore particularly vulnerable to disasters? Yeung suggests that this may be the case:

For the scale and speed of urbanization that has been taking place in developing countries of Asia, most municipal governments are unequipped physically, fiscally, politically, and administratively to tackle the problems of providing the basic infrastructure services to their people. In a situation of scarce resource allocation, the urban poor are frequently badly placed to compete for essential services. Biases in investment standards, pricing policy, and administrative procedures, more often than not skew services in favour of the rich, denying the poor shelter, safe water, acceptable sanitation, minimal nutrition, and basic education.

Where do we live? Well, most of us live in cities. What does this mean in relation to climate hazards in the Anthropocene? You'll have to wait and see! My next post will start to look into climate hazards and their evolution  through the Holocene and into the Anthropocene. 

Welcome to the blog!

Welcome to my blog.

Over the coming weeks I hope to bring you a series of commentaries and analyses based on the latest scientific research, as well as providing links to useful and interesting media.

The blog is titled 'Hazards and population in the Anthropocene: A self-regulating machine?'. The aim of the blog is to dig deeper into concepts and processes surrounding the evolution of natural hazards, in particular, climate hazards, as we move deeper into the 21st century, and the impact they have on human societies across the globe. Furthermore, I will explore how human culture and tendencies, coupled with unprecedented expectations impacts upon our risk and vulnerability to such climate hazards.

With life expectancies generally increasing in the developed nations, will natural hazards constitute a more influential population control mechanism than ever before? How have climate hazards evolved over the Holocene? What parameters influence human risk and vulnerability? Are there any coping mechanisms in place to deal with climate hazards in the future? These are just some of the questions I hope to discuss in more detail over the course of the blog.

The growth of an economically and technologically-driven global society has, not without coincidence, developed in a period of relative climatic and geological stability. We have seen recently, however, striking evidence that this is already changing. If we delve back into the Quaternary, it is evident that large scale climatic change can occur as a rapid transition once a threshold or tipping point is crossed or reached. If anthropogenic acumen continues to accrue as such dramatic rates, the consequences will be devastating. Aside from altering the state of the climate system, influencing the nature and creation of certain climate hazards, our actions may also amplify their effects. For example, deforestation increases susceptibility to flooding.

Over the next couple of weeks expect to find posts on the following:

• Changing Earth (Environmental and Human patterns)
• Introduction to climate hazards
• Anthropogenic impact on climate hazards
• Defining hazard and risk. 

I hope you find the blog interesting and thought-provoking. Here's an introductory video to kick things off.