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.

Where's the proof?

Tornado makes it way through Baca County, Colorado, May 2010. Source

In the past year the globe has witnessed devastating drought in Africa, unusual tornado clusters in south-eastern USA, and catastrophic floods in Japan and Pakistan. It has always been difficult for climate scientists to provide proof for a direct cause and effect relationship between climate change and these extreme weather events. Predictions can be made how a warming climate can affect evaporation rates over oceans and then try to create links to cloud formation, water vapour and the atmospheric cycle in order to estimate frequency of these extreme events. But it is far from an exact science.

In the past two years groups of researchers from the United States and Britain have forme a loose coalition under the name ‘ACE’ which stands for ‘Attribution of Climate-Related Events’. They are in the process of laying out plans  for a near-real-time attribution system which can assess the changing climate’s influence on weather events as soon as they happen. The paper is being presented at the World Climate Research Programme conference in Denver, Colorado at the end of next week. It will be interesting to hear the scientific communities response to this.

However, one of the major difficulties in the attribution by ACE, and why there are still sceptics about attribution techniques, is the fact that freak weather cycles such as El Niño events have been occurring long before any anthropogenic impact. Each extreme weather event will subsequently have to be analysed as to how much was influenced by anthropogenic greenhouse warming and how much by natural cycles (baseline conditions). The analysis is also dependent upon the type of extreme weather. Temperature based events such as heat waves are far more simplistic and easier to model, but for precipitation events such as droughts and floods , the models don’t just have to take into account precipitation, but soils, natural terrain and human management of rivers and wetlands. Moreover, tornadoes are caused by a balance between moist air convection and wind shear, but it is very difficult to say for certain how climate change affects this balance.

The figure below from an article in nature summarises how attribution research attempts to quantify the effects and frequency of extreme events.

The costs of extreme weather events are substantial – both in terms of livelihoods and economic costs. The death toll from the Japan tsunami in March passed 18,000, and some 40,000 people died as a result of the heat wave across Europe in 2003. Economic costs on top of the death told make a bad situation even worse. The World Bank has estimated that it could cost Japan as much as £145bn to repair the damage from the 2011 tsunami.

As a result the global community should be ever more concerned about whether anthropogenic changes are the direct cause of these extreme events. At a very basic level you could say that humans are killing thousands of people as a result of anthropogenic warming. If these climate models and projects as put forward by ACE can help provide proof of direct links, they may help to provide some form mitigation by outlining the direct quantitative impact humans are having. It could also lead to a greater willingness for the global community to reduce greenhouse gas emissions, and give greater weight to policy decisions on the national and global scale.