Met Office supercomputers in the pipeline for seasonal forecasting

The Met Office has been providing weather forecasts for the BBC since 1923, and even after 88 years, they can still get the weather wrong. MPs have backed the claim that scientific advances are being held back by insufficient computing capacity, and as a result, new supercomputers for the Met Office could not be too far around the corner.


The new supercomputers would be able to handle more data, and process more complex calculations. Not only would this produce seasonal forecasts on top of the daily and weekly, but also give a much better estimation of the probability of each weather event occurring. One of the great advantages would be improved contingency planning for emergencies. More on this story can be found on the BBC website here.

Climate Change and Cyclone Damage

Satellite Image of Cyclone Yasi from Feb 2011 (Image Source)

A very belated Happy New Year - it's been a while since I last blogged! Earlier today I was kindly pointed in the direction of a new paper which was released in Nature this week (the article can be found here).

The paper ties in nicely with some of the latest cyclone research that I blogged about in December. The purpose of the research was to assess future damages caused by cyclones and climate change. They are clear in their introduction that future scenarios with cyclone models are sketchy at best and that despite increases in cyclone numbers in the past 40 years, they are still well within natural variability. The paper is also quick to note that increasing damages in the last few decades are largely down to the increasing population and more assets in harms way rather than as a result of anthropogenic warming. However, they have taken the scientific viewpoint further by modelling cyclones in separate ocean basins, taking into account frequency, intensity and regional location changes (rather than just wind speeds and sea surface temperatures as seen in previous studies and models). The figure below shows the global storm tracks and their intensity (minimum pressure). It clearly indicates that the storms are more frequent over the warmer equatorial waters, and most occur in the Western Pacific.

The present annual global damage from tropical cyclones is US$26 billion and is used as a baseline for scenario comparisons up to 2100. The results in this paper, reveal (as would be expected) that the distribution of climate-change damage is not even across the world. The figure below shows the estimated projected damage caused by climate change in each region. North America has the highest average damage of US$26 billion yr-1, which is half of the global damage. East Asia and Central America Caribbean average damages of US$15 and US$10 billion yr-1 respectively.

There are some limitations with this study and its projections, which largely revolve around economics and countries GDP and growth rate. Damages vary a great deal if a storm hits a city versus a rural area, but this is not yet captured in this analysis. Moreover, increases in income and population along the coast, relative to the rest of the country, will cause more damage. There is also no account of any adaptation policy that could be put in place. Despite these limitations it is a nice to see an initial attempt at quantifying costs of cyclone damage associated with climate change.

2011 is the second warmest year on record for the UK!

So maybe I lied a little bit in my last post, and I will squeeze another short post in before the New Year. I came across this news article last night on the BBC, where the Met Office data shows that the average temperature for the entire year has been 9.62C in the UK. This makes it the second warmest year on record, only narrowly behind 2006 where the average temperature was 9.73C. The graph below compares this years temperatures to the 30 year average between 1971-2000. The most notable differences are seen in the spring months.

Only two weeks ago the government granted a drought order to South East Water as the dry conditions between September and November have dropped water levels at the Ardingly reservoir in Sussex to just 12%! Nine of the top ten warmest years on record have all actually occurred since 1997, with the seven warmest all occurring in the last decade. In the news article Dr. Huntingford (climate modeller) states:

"As each year passes and we hear that a warming record has been broken, or nearly broken again, it provides further evidence that unfortunately we are not just seeing a natural cycle of global warming, and that instead humans are having an effect on the climate."

Well, I can now officially say that I'm signing off for 2011. Wishing you all a very happy (and mild!) New Year!

2011 - A Year of Extremes, and More To Come...

Firstly, I hope you all had a great Christmas! It is this time of year that makes you really grateful for just the basic things in life. We are now fast approaching 2012 and is a good time to reflect on the past 12 months.

I don't think anyone can doubt that 2011 has had it's fair share of extreme weather events. December has seen the devastating monsoon in the Philippines that killed over 700, Scotland battered by a storm with wind speeds in excess of 165mph, whilst flooding in Kenya displaced thousands. November saw a mounting death toll in Cambodia after thousands were left stranded after monsoon conditions. In October residents fled Bangkok as flooding threatened to overwhelm the capital at the time when Texas was facing a dust cloud 8,000ft high, and the UK was facing it's highest October temperatures on record.  There was also the freak snow storm along the US east coast which killed 11 and left millions without power, only two weeks after hurricane Irene had ripped through the Caribbean and the south-east. September had seen even more destruction for Texas in which huge wildfires destroyed hundreds of homes. Going back to May, the world witnessed one of the most extraordinary tornado sequences ever caught on camera with more than 165 in just 24 hours in the Missouri area. March saw the most devastating natural event of the year in which Japan was hit by a double tsunami leading to 20,000 deaths and millions of pounds of damage. Cyclone Yasi has long been forgotten, but struck the Australian coast only back in February, tearing roofs of houses and bringing power lines to the ground. Going right back to the beginning of the year, January saw 400 killed as a result of torrential rain and mudslides in Brazil, there was flooding in Sri Lanka which forced 300,000 from their homes, as well as flash floods in Queensland.

Climate change sceptics may suggest that we are just becoming more 'aware' of extreme events since the 'global warming' hype of the 1980s but from research over the past few months, and the experience of extreme weather events in my lifetime I can only come to the one conclusion that anthropogenic climate change is a primary driving factor in the increasing frequency of these extreme events.

An extract from the Scientific American, dating back to June, summarises this nicely through the results of one of the worlds largest insurance companies Munich Re. The company has compiled the world's most comprehensive database of natural disasters, reaching all the way back to the eruption of Mount Vesuvius in A.D. 79. The records are kept with extreme interest by financial companies, in order to successfully evaluate insurance risks. On average 700-1000 natural disasters are added to the database each year. Their data shows a small increase in geologic events such as earthquakes since the 1980s, largely down to better reporting. However, increases in the number of climate disasters is 'far larger'. 

Peter Höppe, head of Munich Re's Geo Risks Research/Corporate Climate Centre:

 "Our figures indicate a trend towards an increase in extreme weather events that can only be fully explained by climate change... It's as if the weather machine had changed up a gear."

In the latest SREX report, we have seen the IPCC state:

"There is evidence that some extremes have changed as a result of anthropogenic influences, including increases in atmospheric concentrations of greenhouse gases."

Direct cause and effect literature has been hard to come by in the past, but this year has seen a significant increase not only in literature suggesting increasing likeliness of climate change on extreme events, but also as direct attribution. This does not mean however that every extreme event is a direct result of anthropogenic climate change. For example, solar forcing causing winter lows which I looked at in a previous post, can be assigned to natural variability. There has always been extreme events, and always will be as a result of natural variability, but the latest findings point to both an intensification and frequency of such events as a result of human impact. Over time with better climate model simulations, greater understanding of the hydrological cycle (specifically with vorticity and wind speed), and an increase in data collaboration and research papers, will I'm sure, only pile on greater evidence that extreme weather is slowly becoming the new normal (unless human anthropogenic impact is significantly minimised or reduced).

All I can conclude with is a warning: Extreme Weather Ahead.

Signing off for 2011.

Monsoons and Climate Change

Image Source

After the devastating effects of Tropical storm Washi in the Phillipines earlier this week, I thought I would look further into any links between monsoons and anthropogenic climate change. It is well acknowledged that land use changes and human impacts through mining and illegal logging were a major cause in the flash floods, but 12 hours of continuous rain, in an area of the Philippines which storm tracks do not normally take is somewhat unusual. In an earlier post where I stated some of the latest finding form SREX, the tropical cyclone statement was one that particularly shocked me:

"It is likely that the global frequency of tropical cyclones will either decrease or remain essentially unchanged."

As a result I have done some digging to try and find other sources to these claims. I have come across two papers: one which looks at the evolution of Monsoons through the Holocene (12,000 years before present to modern day) using climate modelling, and another which assesses monsoon precipitation changes over the past 100 years.

The first paper deals with changes on the millennial time-scale and focuses on insolation forcing and feedbacks. It is found that the responses of the monsoons to the insolation forcing and oceanic feedback differ substantially among regions, because of regional features of ocean - atmosphere interaction. In the Northern Hemisphere, 'the models show a significant enhancement of all of the monsoons in the early Holocene and a gradual weakening toward the present'. The monsoons are enhanced in the Holocene by a positive oceanic feedback in North Africa and North America but are suppressed by a negative overall feedback in Asia.

The more recent second paper (July 2011) deals with changes on the decadal time-scale, over the past 100 years. Changes of global land monsoon precipitation are assessed by using three sets of rain-gauge precipitation data for the period of 1901-2002. It has been found that during 1901–2001, global land monsoon precipitation exhibits multi-decadal variations, with an overall increasing trend from 1901 to 1955, followed by a decreasing trend up to 2001. See the image below for the regional trends and Northern Hemisphere (NH) mean. There is uncertainty over changes in the 2000s.

Time series of precipitation anomalies for Northern Hemisphere land monsoon mean. (a) NH Mean (b) North African Monsoon (c) Indian Monsoon (d) East Asian Monsoon.

What does this all mean in brief?

The papers describe an overall weakening of monsoons on the millennial and decadal time scales, suggesting that anthropogenic warming of the past 200 years has not intensified them. I have looked in previous posts about how the intensification of the hydrological system can lead to more precipitation in some areas and decline in others, but I was not expecting such a significant downward trend of monsoons in the Northern Hemisphere over the past 40 years. It is a gentle reminder that ocean-atmosphere interactions are far more complex than we can imagine, and that despite SREX stating that heavy precipitation events will become more likely, it is unlikely that they will come through more extreme monsoon and tropical storm events. 

Moreover, it shows all the more clearly that land use changes can have such devastating effects on our planet, even without significant changes in weather patterns. The removal of the natural environmental buffer in the case of the Philippines has played a major role in the devastating effects and death toll, rather than an intensification of weather patterns.

In the News: Death toll from monsoon in the Philippines rises past 700

Tropical Storm Washi caused widespread flash floods throughout the Philippines 

The typhoon in south-east Asia dumped a month's worth of rain in just 12 hours on Friday, smashing homes and bridges, uprooting trees and carrying vehicles off in the torrent. The storm moved slowly out to sea yesterday, but more than 35,000 people flocked to hastily erected evacuation centres. An entire army division - some 10,000 soldiers - are involved in the rescue efforts around Cagayan de Oro, and many people are still missing.

During the peak of the rain, the water rose to about 11 feet (3.3m) in just a single hour. The Philippines are struck by about 20 major storms every year but most of them take a more northerly track, hitting Luzon island.

What was the real cause?

Lack of flood warning combined with darkness are partly to blame for the high death toll. Officials have also acknowledged that illegal logging and mining contributed to the storm's damage since there were fewer trees to hold water and prevent erosion.

Philippine Federal Environmental Official Nereus Acosta stated:

"We can really see how vulnerable we are. When you tamper with the watersheds and the forests, we become vulnerable."

This is an all to clear reminder that anthropogenic change of not just the atmosphere, but land can have devastating effects. More on the story can be found here.

2011 US Precipitation Record

It's getting to the time of year, where we can look back on events of the last 12 months and make comparisons to previous years on record. Thanks to the NOAA National Weather Service page you can create and plot precipitation maps and compare to yearly means with relative ease. I was able to create this image below within a few seconds, and if you have some time, why not try it out yourself:

The image displays 2011 mean precipitation (in mm) as departure from normal across the US. There are two key things to note: firstly, the extremely high rates of precipitation in the north-east US, and secondly, the extremely low-rates of precipitation in the south (500mm above and 500mm below respectively). I have touched on precipitation extremes in previous posts, but Philadelphia is now the wettest it's been since 1867 and there are 20 other cities who have broken long-term records or are close to. The increase in precipitation in 2011 has largely been down to the tornado outbreak in April/May combined with hurricane Irene and other heavy summer thunderstorm rains.

Now the heavy rains are only half the picture, sections of 16 states have precipitation rates 500mm below normal this year. It has been a significant year of contrast with many places being washed away with heavy rain and floods or whilst other areas have faced and suffered from significant dry conditions.

I have yet to really touch upon droughts in any of my posts, and now would probably be a good time to do so. Arnell (who's based at the Walker Institute for Climate System Research in Reading) in 2004 published this paper on climate change and drought, which has been recently built upon in the SREX report. Essentially droughts are likely to become more frequent and intensify with the intensification in the hydrological system. Precipitation in large parts of southern Europe, north Africa, central Asia and southern Africa (which are often subject to frequent dry conditions), are likely to experience even less rainfall, increasing drought risk. Moreover, the climate change risk is super-imposed on top of things such as land cover changes which could exacerbate the problem even further. It is well agreed upon that there will be an increased (physical) drought risk, but there is still considerable uncertainty over the magnitude of this change. 

The variability in climate change and precipitation is also displayed in a study released last month in which regional climate models were developed for Cyprus in order to project weather extremes. Despite, increases in temperature across the entire country (of 1-2 degrees Celsius in both summer and winter), some areas are expected to experience less frequent precipitation events of lower magnitude (inland places such as Nicosia) whilst other areas such as Saittas and Limassol may experience more precipitation events, with increased rainfall.

Climate change science predicts that if the Earth continues to warm as expected, wet areas will tend to get wetter, and dry areas will tend to get drier. Therefore you would expect this year's side-by-side extremes of very wet and very dry conditions in the US should become increasingly common in the coming decades.