Philip Strange asks if the recent extreme winter weather reflects a change in our climate
This winter, the UK experienced an exceptional series of storms. Heavy rain combined with strong winds and high waves led to widespread coastal flooding and coastal damage. There was significant disruption to individuals, businesses and infrastructure. Locally, damage occurred to the coast at Portland and along Chesil Beach and rivers including the Avon and Stour burst their banks. The Somerset Levels were severely and persistently flooded. Transport was badly affected including the destruction of the main railway line into the south west at Dawlish.
This was indeed extreme weather and we now know that in England and Wales this was the wettest winter for almost 250 years. We are not alone, however, in experiencing extreme weather. The eastern side of the US and Canada was unusually cold this winter whereas California suffered a severe drought. Australia and Argentina experienced exceptionally high temperatures whereas Brazil received record rainfall.
The extreme weather has had the interesting effect of finally making politicians speak up about climate change. Here is what David Cameron said recently: “I believe man-made climate change is one of the most serious threats that this country and this world faces.” John Kerry went a step further, placing climate change alongside disease, terrorism, poverty and weapons of mass destruction as global threats.
But before we get carried away by band-wagon jumping politicians, let’s think about what is really going on. What we have been experiencing recently in the UK is extreme weather. Climate change, however, refers to long term changes in weather patterns. The UK weather is notoriously unpredictable so is there really any evidence for changes in weather patterns that would indicate a change in our climate?
A study of UK weather over the last 140 years found evidence for an increase in the intensity of winter storms hitting the southern part of the country. Instances of heavy rain have also increased in frequency, consistent with a warming planet where a warmer atmosphere holds more moisture. Additionally, global warming has caused sea levels to rise by about 12 cm during the 20th century exacerbating the effects of storms at the coast. The climate in the UK is indeed changing and the recent extreme weather is part of this.
If the climate is changing then we come to the biggest and the most contentious question: why is it changing? Here we need to look at a bit of climate science. The earth is warmed by energy from the sun and as the planet heats up it radiates heat outwards. Some of this heat is retained by so-called greenhouse gases, for example water vapour, carbon dioxide, methane in the earth’s atmosphere. As a result the temperature of the earth is maintained at a level compatible with human life. This is the way it had been for many thousands of years, in fact until the industrial revolution. Since the industrial revolution, however, humans have been increasing carbon dioxide levels in the atmosphere, principally in two ways: by burning fossil fuels (those laid down many years ago from decaying plants and animals) and by cutting down forests (reducing carbon dioxide removal by trees). Increased levels of carbon dioxide mean greater heat retention and the earth’s surface temperature is now nearly one degree centigrade warmer. This may not seem very much but there is also a huge reservoir of heat accumulating in the oceans. Taken together these are the processes described as global warming.
It doesn’t stop there: increased warming leads to disturbances in weather patterns. Higher sea temperatures cause melting of ice so that sea levels rise and the effects of storm surges are greater. Reduction in the size and thickness of the Arctic ice cap is also thought by some to lead to changing weather patterns in Europe. Warmer oceans mean that when storms and hurricanes occur they are stronger. A warmer atmosphere holds more moisture so that when a storm arises the rainfall is more intense. An example of these effects is provided by Typhoon Haiyan which killed at least 6000 people in the Philippines in 2013. Haiyan was the strongest tropical cyclone ever to make landfall anywhere in the world and was fuelled by warm water in the Pacific. Weather patterns are shifting and rather than talking about global warming we could speak of global weirding; in the end, however, it all comes down to climate change.
The implications of these observations for human life have led to intense debate about how much of the change in climate can be attributed to human activity. Among climate scientists, there is a strong consensus that climate change is a result of human activity (burning fossil fuels and deforestation). Last year a report from the Intergovernmental Panel on Climate Change recognised the shift in patterns of extreme weather since 1950 and concluded that most of the rise in global temperature since the mid 20th century was due to human activity. They also warned that without substantial and sustained reductions in greenhouse gases, there will be further warming and damaging climate change.
The message could hardly be clearer. Human activity is causing climate change. The sort of extreme weather we have experienced lately will recur. Things can only get worse if we sit on our hands and do nothing as we have been doing so far.
We, therefore, need to reduce carbon dioxide emissions and this means leaving fossil fuels in the ground rather than burning them. We urgently need a second industrial revolution that embraces and implements low carbon technologies. Governments must stimulate investment in these technologies and politicians must show vision and leadership.