Extreme Weather Events

A huge area of Queensland is under water right now with the region suffering flooding that is described as “of biblical proportions”. They are likely to be the biggest floods on record because all three main rivers flooded simultaneously – the first time that has happened. 500mm (or 20”) of rain fell in just one week [1200mm fell through December after a prolonged drought]. 200,000 people are displaced and 100,000 sq kms of land inundated or as the media say – an area bigger than France and Germany combined. And now a further 300mm has come down. That is one big flood and certainly an extreme weather event, but aren’t there lots of extreme weather events these days? I can possibly already say “yes” as the situation has become a lot worse with an area about 5 times the size of the UK now declared a ‘disaster area’ in Queensland.

But that was last week and now further massive rains have dumped an unbelievable 160mm in just one hour yesterday (9th January 2011) in Southern Queensland; about ¼ of UK’s annual rainfall in just one hour but others put it over 250mm. The Australian Broadcasting Corp. described it as “a complete freak of nature, an extraordinary deluge that came out of nowhere – - – a grim and desperate situation”. “Mother nature has released something shocking” “an inland tsunami”. Low level Toowoomba was almost washed away as a wall of water said originally to be 8M high crashed through the town. Across the region some 30,000 houses have now been inundated or destroyed.

Unbelievably events have moved on again with flooding now in Victoria declared to be “the worst in recorded history” but we need to recognise this is not all one storm. Many have died across Eastern Australia, but is this just Mother Nature or are we partly responsible?

Those who have known me for a long time are used to noting the environmental (and economic) news and have unfortunately watched many predictions become reality. It concerns several, but a colleague recently said “I wonder how long it will take for people to realise that when so many floods and droughts are described as a ‘1 in 100 year event’; ‘a 1 in 200 year event’ or ‘the highest on record, this is telling us that the climate is changing”.

Isn’t it time to consider if the weather patterns are indeed showing us the climate is changing. In 2007 I noticed the greatly increased frequency of natural disasters and decided to keep a diary, but before we consider it might we run through what a warmer climate should involve.

The Hydrological Cycle

So what is this? Water evaporates from the oceans, rivers, lakes and land surface but all living plants and trees absorb water through their roots and ‘transpire’ it out through their leaves. Together they are called ‘evapotranspiration’. You might think there is not much transpiration, but here are the facts. Growing just one ton of wheat requires the wheat plants to breathe out about 1,000 tons of water. I was shocked to learn this but from my basic research I deduced a figure of 870 tons. With the UK producing over 8 tons of wheat per hectare that is more than 8,000 tons of water transpired for each hectare – and fields can be sort of 30 hectares. Or a huge amount of water.

All this water vapour rises into the atmosphere where it condenses into clouds from which it falls as rain -the cycle.

What happens in a warmer World?

A warmer planet evaporates more water, so more goes up and more comes down. It gets wetter and we have more rainfall. FACT. But a warmer atmosphere contains more energy and that will increase wind speeds– and as evaporation also increases with wind speed, the amount of water in the cycle will be more than just the temperature increase suggests. But a more energy charged atmosphere should also take the clouds higher, and higher clouds mean much more water in the vertical column where it is raining.

In a warmer world there will therefore be much heavier rainfall events.

So what is actually happening, and does the reality tell us the climate is warming just like the thermometers do? Let’s look at recent flood events.

‘Recent’ Floods

The ‘mega’ floods are extreme events so we would not expect many of them. After all, by definition, a 1:100 year flood should occur only once every 100 years but there are many places around the world to record such floods. However a ‘worst on record’ should be extremely rare. We start with 2011 which is only 16 days old:

  • TheQueensland floods – of ‘biblical’ proportions. A huge area inundated; so many people displaced, the coal industry almost shut down.
  • Queensland again: There have now been huge rains in southern Queensland with 160 to 250mm in less than 24 hours. Since the record 1974 floods the Wivenhoe dam has been built to protect Brisbane so that must have stopped the floods being even higher now. Even so 18,000 houses have been inundated and the city district full of skyscrapers is becoming an inland sea. This high water level was just below the 1974 floods, but the highest floods before that were back in 1887 – so they are very big indeed. Total cost now put at $13B
  • The heavy rains moved down into New South Wales with more rain predicted.
  • Breaking News’ – Victoria in South Eastern Australia is also now experiencing the “biggest floods in history” or “the worst in 100 years”.
  • Sri Lanka – extreme rainfall in the last week has produced huge floods with another 1M people involved and substantial loss of rice. 300,000 houses have been destroyed.
  • Brazil- continuous rains over the last two weeks have caused many flash floods, huge mud slides and large areas are inundated. One month’s rain fell around Rio in less than 24 hours (144mm) where there have been “the heaviest rains in 40 years”. Over 100,000 are already homeless and many villages and even towns have been “washed off the map”. Substantial damage to roads and railways.

It is difficult keeping up with events as they are unfolding so fast but here is 2010:

  • Pakistan is still only starting to recover from mega floods in August 2010 which involved at least 20m people which again were ‘the worst in history’ resulting from ‘the biggest rains on record’. In the last big floods in 1956, 222mm of rain fell in one month but 332mm fell in one day this time. 12m people have been made homeless; at least 1,600 died, and the crops (mostly rice) through most of the Indus valley were destroyed, as were all the stocks of food held there. The cost is estimated at $10B to $15B but how do you cost such misery?
  • The Sichuan province in China suffered enormous floods on the upper Yangtze in 2010. They were so severe the authorities feared for the world’s biggest dam – the Three Gorges. 230M people were affected; 1.4m houses destroyed; the cost is about $40B; 97,000 sq km of crops were destroyed = 10% of China’s rice production = 3½% of world production in one go.
  • Victoria South Australia “ I can’t recall a time when Australia had so much severe weather in all four corners” (Australian media quote). 20” of rain fell in 48 hours. Now in 2011 they have more.
  • Haiti had big floods last year, months after the earthquake.
  • California, Arizona and Nevada received 1/3 of their annual rainfall in one week in mid-October last year and flooded accordingly.
  • Eastern Central Europe flooded badly last year with the worst floods for decades.
  • Bangladesh suffered huge flooding.
  • Only 5 years ago we had Hurricane Katrina that devastated New Orleans. The worst natural event in US history and the 6th strongest Atlantic hurricane ever, its cost was put at $80B to $100B and the old New Orleans is gone forever.
  • The Mississippi had a mega flood in 1993 inundating 30,000 sq miles with huge crop losses, and the Redwood River flooded again hugely recently.

And now some big floods that may not have been mega floods – unless you were in them:

  • Coming home to the UK we have had Boscastle (one month’s rain in 2 hours), Cockermouth, Tewkesbury, Hull, Leicester, St Austell, Morpeth, Northern Ireland & Gloucester amongst others. June 2007 was one of the wettest months on record with the May to July period as THE wettest on record. Bridges that had stood for centuries were breaking and flood damage has been severe.
  • Atlanta and Nashville flooded last year.
  • Beirut and Syria flooded recently (truly amazing) after a very extensive drought.
  • Seville, Rio de Janeiro, Venice, Paris, Romania, The Danube and California recently etc.

Not sure what you think about this list but isn’t it exceptional to have so many such big flood events in such a short space of time. Of course if you want to deny the climate may be warming (presumably because you don’t want to contemplate the changes that human society might have to make) you may persuade yourselves that it could happen without a warming climate, and I have to say that is a possibility. Maybe just a possibility, but the likelihood a warming climate isn’t involved or causal is diminishing with time. On the other hand you may think a warming world won’t affect you in which case maybe this Paper will clarify the issue.

But a warmer world will not only produce floods. It will also produce droughts, which make forest fires a greater probability, so what news on these?

Droughts & Fires

We may remember some droughts but they don’t get much media attention unless a real famine is involved, though each drought has an insidious effect. Food is always lost and it has to be supplied from somewhere. Let’s look at a few events:

  • Russia where the prolonged drought and heat wave in 2010 took out 40% of Russia’s arable land and more than 35% of their wheat crop. It caused so many forest fires they couldn’t be contained, and Moscow had a pall of smoke hanging over it for weeks. People died.
  • California, California & California. The State is now bedevilled by drought which is having huge consequences for agriculture, and California is very important for US agriculture. So along with the drought every year there are forest fires – always severe but often very severe.
  • Australia, Australia & Australia. Almost every year now South Eastern Australia suffers drought and forest fires and both seem to be getting steadily worse. Again this region is important for food production, particularly for wheat and beef, and huge losses of both are now regular events.
  • Southern Europe – especially Greece. Greece is now drought stricken. In 1993 it had the worst drought for 100 years and in 2007 fires raged taking out a lot of their forest. Crete was scorched with the temperature said to have reached 47°. In 2008 rainfall in Cyprus slumped to 20% of what used to be normal making it totally dependent on imported water.
  • Arizona & Nevada - the region is suffering prolonged drought with Lake Mead behind the Hoover dam on The Colorado River holding a fraction of what it should. It holds the water for Las Vegas.
  • The Middle East has suffered a prolonged drought through 2010, with Saudi, Syria and Jordan suffering particularly though Israel, Palestine and Lebanon are also in drought. It has been the driest period on record.
  • Israel – a forest fire raged through northern Israel – the worst ever.
  • Turkey suffered a big drought in 2007/8 with wheat and barley production down between 25% and 50%.
  • Niger. Parts of Africa live on the edge of existence and Niger is one of them. Another drought brings 7m people there in dire need of food support.
  • Chad struggles and over the last 40 years droughts have been ever more frequent. Lake Chad was a very large lake but is now just 5% of its recent past size. Permanent food aid is now required but part of the problem is the expanding population.
  • Kenya should be a bountiful country for Africa, but the north east in particular is extremely drought prone with starvation common. While we eat their beans many starve.
  • Sudan, Ethiopia and Somalia now frequently suffer drought and last year was no exception.

OK then. Another exceptional list which is surely way beyond anything we could expect. It would therefore be surprising when confronted with these extreme rainfall, drought and fire events if we just ignored them – but so far we have. Are they caused by a warming planet?

Before we look at the historic temperature chart in Part 2 there is a natural and cyclic phenomena that seriously impacts on weather around the world that needs to be introduced:

El Niño and La Niña

First of all what are these? Both involve sea surface temperatures across the Pacific and both are variants from the normal or average conditions. El Niño (means the boy child) involves the warmer temperatures that are normally across the western half of the Pacific. With El Niño they extend right across to the Peruvian coast where they can be very warm. La Niña (means the girl child) is the opposite with the warmer waters retreating to the Western (Australian) end. So El Niño produces higher average surface temperatures and La Niña lower ones with the cycle being called the Southern Oscillation.

 

The image here is of the 1997 El Niño observed by TOPEX/Poseidon. The white areas off the tropical coasts of South and North America indicate the pool of warm water.

The total heat energy in the Pacific doesn’t alter. For El Niño more warm water is at the surface so more water below the surface is cooler, and for La Niña the opposite is true. But changing the ocean surface temperature changes the amount of water vapour rising into the atmosphere, and such big changes at this level can also move the jet streams which are around 35,000 ft up (the level at which we fly) and which drive so many weather patterns around the world.

And as we can all now see, because this paper started by connecting rainfall with temperature, it will alter rainfall. But it does more than that as it alters where the rain falls and it is therefore entirely logical to consider that it couldbe affecting the weather in North Eastern Australia and some of the other places where extreme rainfall events are occurring.

The last El Niño started in June 2009 and ended in April 2010, which was quickly followed by the start of this La Niña in June 2010 – so we are currently in a ‘La Niña’ and close to its peak. La Niña’s keep the warm water local to the western Pacific and tend to cause more rainfall across China, Indonesia and North East Australia! But there is one more interesting thing to consider as not all El Niños are the same ‘size’. Some are stronger than others and conversely some are weaker, so here are those events through the last more than 100 years with the strongest two events in red, and the next strongest in brown (91/92 & 09/10 were equally warm):

El Niño years and event sizes

1902-1903 1905-1906 1911-1912 1914-1915 1918-1919
1923-1924 1925-1926 1930-1931 1932-1933 1939-1940
1941-1942 1951-1952 1953-1954 1957-1958 1965-1966
1969-1970 1972-1973 1976-1977 1982-1983 1986-1987
1991-1992 1994-1995 1997-1998 2002-2003 2006-2007
2009-2010        

Interesting that it seems their strength is growing. After all, the 5 warmest El Niños have all been in the last 10 and the 1997-8 El Nino was the strongest ever which also supports the hypothesis that the world has warmed and is warming.

We have seen that a warmer world has a more energetic atmosphere, and here is a physical system that oscillates and seems to be doing so more extremely as the climate warms. I try to be very careful not to misrepresent anything (I am not trying to prove any point) and it would be possible here as we have a bit of a ‘chicken and egg’ situation – which comes first? Is the strengthening oscillation producing the extreme weather or is the warming planet making the oscillations bigger?

To be sure it isn’t possible for the oscillation to be warming the planet over such a sustained period of time (1850 to 2010) or to be increasing it so much more rapidly now; neither is it likely that it is doing so conveniently as the levels of atmospheric carbon are increasing so rapidly. But stronger Oscillations could and would increase the severity of extreme weather events. If there is no warming climate we would expect extreme events to have the same frequency they had through history – which they are not. So we can at least deduce it is the warming planet that is causing the Southern Oscillation to increase and not the other way around.

We will continue in part 2 which covers temperature signals and our atmosphere.

Interim Conclusion

am a very firm believer that the best way to debate an issue is primarily to present the facts so readers can ask themselves the questions and reach their own conclusions, but it is important that as many facts as sensible are presented and that both sides of the debate are given. I hope to be doing that but it may be appropriate to suggest what is important. In this case we need to ask ourselves if such big weather events coming with this frequency and all over the world can logically be put down to chance – or is it now very likely that a warming climate is involved if not responsible?

The next thing to consider is what is happening to temperatures and the ice around the world – so do they also suggest the climate is warming, after which we will briefly consider Carbon Dioxide and then conclude and work through the implications to all of us if we are changing the climate.

Mike