Between July 2011 and July 2012, a series of extreme weather events left many people asking: is there a link with climate change? And what progress are we making in tackling climate change?
This article profiles extremes of weather recently experienced in, amongst other places, the UK, USA and Horn of Africa. We explore how new ground-breaking research into ‘event attribution’ has concluded that the risk of re-occurrence for some of these weather phenomena has significantly increased due to climate change. This article also examines greenhouse gas trends for the world’s biggest polluters (countries whose emissions play a disproportionate role in creating new climate risks, according to prevailing scientific wisdom). Finally, some research suggestions are provided for students interested in finding out more about contemporary climate change mitigation strategies and their progress to date.
Climate change, extreme weather events and the science of ‘event attribution’
Anthropogenic influences on climate change: an emissions update
Researching climate change mitigation (research suggestions for students)
An extreme weather event is defined as the occurrence of a value of a weather or climate variable (such as precipitation, wind strength or temperature) that is above or below a threshold value near to the previously observed maximum or minimum value. Are recent headline-grabbing extreme events, such as wildfires in the USA and torrential summer rain for the UK, symptoms of a changing climate? Or are they within normal probability? Some scientists now believe they have an answer to questions such as these.
The following extreme events made newspaper headlines in 2011-12:
Texan drought, Summer 2011
The state of Texas experienced an extraordinary heat wave and drought. The six-month growing season of March-August 2011 was, by a wide margin, the hottest and driest since records began in 1895.
Thailand floods, Autumn 2011
Following an unusually wet monsoon (July-September) in northern Thailand, rivers in the centre and south of the country burst their banks and inundated large parts of the country, including the capital Bangkok. Large-scale industrial estates were submerged by up to 2.5 m of water for nearly 2 months and the economic damage - both to Thailand and many other countries whose industrial supply networks were interrupted - was considerable (reinsurer SwissRe estimated losses of between 8 and 11 billion US dollars).
UK weather anomalies, 2011-12
November 2011 and February 2012 were unusually warm and dry (leading to a reduction in the water stored in aquifers that contributing to widespread hose pipe bans). However, it was also the coldest December since 1910 and the second coldest December since 1659, according to the Central England Temperature (CET) record, with a –5.3°C anomaly in the monthly average temperature compared with the 1961–90 mean average. The UK subsequently experienced its wettest April-June since records began, triggering floods and landslides.
East African drought, 2011
The United Nations classified large areas of Somalia, Ethiopia, Djibouti and Kenya as being in a crisis or an emergency due to drought-induced food insecurity. Across the whole region - known as the Horn of Africa - up to 10 million people were affected. While many human factors contributed to this crisis (including high global food prices, political instability and poverty), failed rains in both the winter of 2010-11 and the spring of 2011 played a critical role.
US drought and wildfires, 2012
Drought and wildfires in the USA smashed previous intensity records. New Mexico and Colorado were very badly affected by megafires (high-intensity fires covering large areas for a long duration). More than 2,000 heat records were broken around the USA at the start of July. The National Oceanic and Atmospheric Administration (NOAA) reported that the spring of 2012 "marked the largest temperature departure from average of any season on record for the United States". These record temperatures "have been so dramatically different that they establish a new 'neighbourhood' apart from the historical year-to-date temperatures" (Guardian, 05 July 2012).
Russian floods, July 2012
Flash floods caused by torrential rain swept the southern Russian Krasnodar region, killing 144 people. The floods were the worst in living memory (BBC News, 08 July 2012).
Does climate change have a role in these events? Do they have the influence of human fingerprints on them? Or are these events within normal probability after the La Niña phenomenon is accounted for, which was unusually strong in 2011? Some leading scientists think they now have an answer. They have concluded that climate change has "significantly" increased the probability of some unusual recently-occurring weather.
The findings were published in the latest "state of the climate" report in the Bulletin of the American Meteorological Society (AMS). With 348 contributors, the report shows a consensus is emerging amongst leading meteorologists. While they cannot say a particular event was or was not caused by climate change, they say that they can explain how the odds of such events have changed in response to global warming. Particular findings were that:
The Texan heatwave of 2011 is now about 20 times more likely during La Niña years than in the 1960s
The UK’s warm November 2011 temperatures are now about 60 times more likely than in the 1960s
Peter Stott of the UK Met Office told the Financial Times (13 July 2012): "It’s like loaded dice. The chances of throwing a six have gone up a lot and we’re throwing a six in America at the moment." In another article, he was quoted as saying: "This report really is ground-breaking in the sense that we’re applying attribution science to recent extreme weather events. In the past you may have heard: ‘Well it isn’t possible to attribute an individual extreme weather event’, and the science really has moved on now. The way that it’s moved on is the realisation that we can look at how the odds of events have changed ... whether the likelihood of having an extreme weather event has increased or decreased" (Financial Times, 10 July).
Extreme weather events need looking at on a case-by-case basis. The AMS scientists did not discover a clear human influence on every single extreme event they looked at. Certain weather events are not demonstrably being induced more frequency by climate change and do not carry obvious human fingerprints. For instance, the Thailand floods at the end of 2011, although highly damaging in financial terms, were not found to be linked with especially unusual amounts of rainfall (in the Chao Phraya river catchment area).
Investigating the extreme weather of summer 2012
And what about the events of summer 2012? The AMS report only examined events in 2011 and it is too soon to firmly conclude one way or the other whether Britain’s rainfall and the US drought in 2012 can be attributed to climate change. The wildfires seen in the USA are, however, clearly being influenced by extreme temperatures "which are consistent with IPCC (Inter-governmental Panel on Climate Change) projections" according to Princeton University's Michael Oppenheimer, who has also commented that we are seeing "a window into what global warming looks like... it looks like heat, it looks like fires, it looks like this kind of environmental disaster" (Guardian, 29 June 2012).
The wet early summer weather in the UK in 2012 is actually at odds with IPCC (inter-governmental panel for climate change) climate change scenarios in which the UK is projected to experience, on average, progressively stormier, wetter winters and drier summers. Though of course the 2012 experience is a snap-shot of a single year, not a longer term average. However, the climate system is so complex that unexpected extreme weather events could also be generated in unanticipated ways. The Financial Times (10 July 2012) reports on the work of Professor Jennifer Francis of Rutgers University in the US: "She studies the fast-changing climate in the Arctic, where she says the average thickness of ice floating on the ocean has shrunk from around 3m in the early 1990s to between 1m and 1.5m. Her work suggests this could be affecting the northern polar jet stream – fast-moving rivers of air several miles high that race from west to east around the northern hemisphere and influence the location of the weather systems. The jet stream is driven by the difference in temperature between the colder polar region and warmer latitudes further south. However, with that temperature difference shrinking as the Arctic warms, it may make the jet stream weaker and more meandering, effectively blocking wet or hot weather patterns, and causing extreme weather."
Extreme weather events
According to the American Meteorological Society (2012), the concept of extreme weather is complicated because it has several different meanings:
It refers to rare events that lie in the far tails of the statistical distribution of the phenomenon being studied. Most people would regard these as being truly "extreme", especially record-breaking events
It also refers to events that may not be regarded by many people as being all that "extreme", such as the occurrence of a daily maximum temperature that exceeds the 90th percentile of daily variability as estimated from a climatological base period
Certain phenomena, such as tropical cyclones that have been classified on the Saffir-Simpson scale, or tornadoes that have been classified on the Fujita scale, are automatically considered extreme as an entire class
Can some recently-reported extreme weather events be related to climate change? Many meteorologists believe so. They are investigating event attribution - meaning that they are examining whether individual extreme events can be attributed to a changing climate.
Recent news reports from the UK and USA show both countries have recorded falling carbon emissions in recent years. Per capita and total emissions for both countries are still amongst the highest in the world but the flow of new greenhouse gases into Earth’s atmosphere from these nations is finally falling, rather than rising. Is this a result of successful and deliberate climate change mitigation actions? Or are other factors responsible? And how do trends compare with developing economies and the world as a whole?
Investigating trends for the UK and the USA
The USA and the UK are two of the top ten carbon polluters, responsible for much of the continuing carbon flow into Earth’s atmosphere. Due to their long history of industrialisation, they are also responsible for a disproportionately large amount of the carbon stock (anthropogenic carbon emissions previously released into the atmosphere since industrialisation began around 1750).
The USA generates 18% of world CO2 emissions, despite a population of less than 5% of the global total. However, since 2007 it has recorded a big drop in carbon emissions for the first time in its history. According to the International Energy Agency (IEA), US energy-related emissions of CO2 fell by 450m tonnes over that period, including a 92m tonne fall in 2011 alone.
The reason for this, however, is not due to a switch to renewable energy or less energy consumption. Rather, it is attributable to a shift from coal to gas burning within the US energy mix, the latter producing less carbon emissions.
A gas-fired plant produces half the emissions of a coal-fired one (IEA News, 24 May 2012)
Cheap gas is becoming the fuel of choice in the US energy sector due to advances in the technology of hydraulic fracturing, or "fracking" (see our recent article on shale gas production)
During 2011, coal generation slumped by 19% while gas generation increased by 38%
Across the Atlantic, news reports from the UK also record a fall in emissions. UK emissions of CO2 have plunged to 456m tonnes, their lowest levels in 40 years, according to the Department of Energy and Climate Change (DECC). There are numerous reasons for this, including:
Increased use of nuclear power
A warm winter in 2011 resulting in less energy use
High energy prices coinciding with a period of economic hardship for many families, which may reduce energy consumption
The closure of many factories during a period of deindustrialisation since the 1970s
A shift from coal to cheaper gas power, in common with the USA
DECC reports that the UK has cut its domestic carbon emissions by 23% since 1990. This means the UK is well on its way to meeting a target of reducing GHG emissions by 34% between 1990 and 2020. The government is claiming a victory in the fight against climate change; however some energy experts have pointed out that the fall in emissions has little to do with government initiatives on renewable energy and is in fact rather attributable to other factors instead.
Dieter Helm, professor of energy policy at Oxford University told the Financial Times that the falling domestic emissions mask the fact that the UK now imports much of its food and consumer goods from other countries since deindustrialisation took place. "While we have been reducing our carbon footprint we have been increasing our carbon consumption, importing the energy-intensive goods we used to produce when we had our own energy-intensive industries."
The wider world
Corresponding with Professor Helm’s analysis is the fact that global carbon emissions rose by the largest margin ever recorded in 2011. The total volume was 31.6 gigatonnes, one whole gigatonne higher than in in 2010 and significantly higher than the average increase of around half a gigatonne recorded through the noughties. The world economy has bounced back from the global credit crunch of 2009 (when global emissions actually fell year-on-year).
The IEA identifies fast-growing capita emissions for the BRICS grouping of Brazil, Russia, India, China and South Africa. China now contributes the greatest share of world emissions (24%) while accounting for 20% of the world population. Its emissions rose by 720m tonnes, or 9.3%, in 2011, primarily due to higher coal consumption. However, improvements in energy efficiency and greater use of renewables has meant that the rise has not been as high as it could have been. China’s carbon intensity — the amount of CO2 emitted per unit of GDP — fell by 15% between 2005 and 2011. India, with 17% of world population, contributes more than 5% of global CO2 emissions
Some oil-producing nations, notably the desert state of Qatar, have exceedingly high per capita emissions (with petrodollars funding high energy usage, including significant use of air conditioning)
Japan’s emissions have increased by 28m tonnes, or 2.4%, as a result of a substantial increase in the use of fossil fuels in power generation post-Fukushima (see our recent feature). Meanwhile, Germany is abandoning nuclear power altogether in the near future - will it be able to avoid a similar rise?
Many of the world’s least developed countries (LDCs), such as DR Congo, continue to make a negligible contribution to anthropogenic GHG emissions, although economic changes afoot in some African countries, such as Nigeria and Kenya, mean that energy consumption there is rising
Among the five largest emitters, the levels of per capita emissions are of course very diverse, due to vastly differing population sizes, ranging from 1 tonne of CO2 per capita for India and 5 tonne for China to 17 tonne for the USA
The overall picture is therefore a complex one. In total, in 2011, a 6.1% increase in CO2 emissions in countries outside the OECD group (a grouping of mainly developed countries) was only partly offset by a 0.6% reduction in emissions inside the OECD. As a result, the IEA fears that the window is closing for limiting GHG emission rises to a level that will prevent global temperature rising by no more than 2°C "The new data provide further evidence that the door to a 2°C trajectory is about to close," says IEA Chief Economist Fatih Birol (IEA News, 24 May 2012).
Also in the news: fresh research on the natural causes of climate change
For millennia the earth’s climate has been changing as a result of natural causes - one of which is volcanic eruptions. Brief periods of cooling have been recorded in recent years when global dimming has occurred due to the high levels of particulates ejected into the atmosphere by major eruptions (Krakatoa’s eruption in 1873 led to worldwide cooling of 1°C in 1874).
In a new study led by the University of Colorado, the cause of the Little Ice Age - a period of global cooling between the late Middle Ages and the 1800s - is argued to have been a series of four huge volcanic eruptions between 1275 and 1300. The vast amounts of ejected sulphates and dust particles reflected solar energy for several years, enough time for a positive feedback loop to set in. Arctic ice expanded, reflecting yet more radiation (due to increased albedo) and causing changes in Atlantic Ocean circulation that prolonged the initial cooling effect for many centuries. Find out more.
What progress is being made towards climate change mitigation? In this section, we provide some contemporary case study suggestions for students to research further.
Climate change mitigation describes any action intended to reduce GHG emissions, such as using less fossil fuel-derived energy, thereby helping to slow down and ultimately stop global warming. Climate change adaptation describes any action designed to protect people from the harmful impacts of climate change however without tackling the underlying problem of rising GHG emissions. For instance, recently, the UK’s Committee on Climate Change adaptation sub-committee recommended that the government needs to invest an additional £20m annually in flood defences (Financial Times, 11 July 2011), which provides an example of adaptation to the impact of climate change.
Here are some mitigation schemes that have been "in the news" recently - and which students can read about further using the links provided. A possible plenary exercise would be to complete the following essay once they have conducted additional research:
Examine the strengths and weaknesses of contrasting climate change mitigation strategies that you have studied. (20 marks)
UK prize competitions for carbon capture and wave power innovation
This first case study looks at government-led incentives in the UK to stimulate research into carbon capture technology and renewable energy. The government has launched a £1bn prize competition for innovation in carbon capture technology alongside a £20m prize for wave power renewable energy innovation. Ministers believe that carbon capture and storage technology could create an industry with 100,000 jobs - and so the government is sponsoring a competition to design the first workable demonstration project. Find out more here and here.
Tesco’s carbon footprint labelling scheme
This case study is an interesting one to evaluate. Large companies have enormous power to bring about change in consumer behaviour. Tesco, however, recently reversed a previous decision made four years ago to introduce carbon footprint labelling because "the message is too complicated". After calculating scores for just 500 of its 50,000 products, Tesco decided to discontinue this work because the task is so complex and its rival retailers are not adopting carbon labelling too. This is a very useful case study for students who are required to examine the difficult decisions individuals and businesses have to take when it comes to engaging with climate change mitigation. Find out more.
EU aviation carbon taxes
This case study engages with climate change mitigation on a very large geographical scale - the EU is pressing ahead with a plan to make foreign airliners pay a carbon tax whenever they touch down at a European airport. For EU ministers, this is seen as an important strand of the trade bloc’s overall GHG mitigation pledges (they aim to reduce emissions by 20% by 2020). But the USA, China, India, Russia and others are unhappy that their TNCs will lose profits if the carbon tax is imposed on their aeroplanes. This case study also shows the importance of people and governments considering how their interactions with other places can increase carbon consumption. Find out more.
China’s new carbon trading scheme
Another very important large-scale mitigation measure is the adoption of carbon trading schemes. Setting a price on carbon is potentially a very important tool for policy makers who want to discourage emissions. Emissions trading, or cap-and-trade as it is also known, was pioneered by the EU, whose seven-year-old carbon market is the world’s largest. Now China has announced plans to start its own pilot carbon emissions trading scheme - and the world is watching with great interest given China’s role as the world’s number one carbon emitter. Find out more.
‘Extreme weather events forecast storm over climate change denial’ Guardian 05 July 2012
‘Russian flash floods’ BBC News 08 July 2012
‘Freak weather raises climate change debate’ Financial Times 13 July 2012
‘Freak weather linked to global warming’ Financial Times 10 July 2012
‘US wildfires are what global warming really looks like, scientists warn’ Guardian 29 June 2012
NOAA ‘State of the climate’ report 2011
‘Global carbon-dioxide emissions increase by 1.0 Gt in 2011 to record high’ IEA News 24 May 2012
Volcanic origin for little Ice age, BBC News, 30 January 2012
‘Climate panel alert on flood defences’ Financial Times 11 July 2012
This report is written by Dr Simon Oakes, a senior A-level examiner and International Baccalaureate Chief Examiner.
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