Original article by Jane Pendlenton Read about current and expected impacts of weather and climate across the globe and in Oxfordshire, and the action that may be necessary to combat and adapt to climate change. You can also download this article as a PowerPoint file (see Introduction).

Introduction

We often hear on the news of impacts of climatic change being felt across the globe. But what about impacts felt more locally, here in Oxfordshire? This article starts by looking at what has been happening at the global scale, before focusing on the UK, and on our local climate in Oxfordshire. It also looks at ways in which the climate might be expected to change locally, according to these global and regional trends.

** Download this article as a powerpoint presentation here. **

Sections in this article

What's been happening... globally

Global evidence of change

What has been happening...in the UK?

Attributing human influence to climatic change

So what has been happening... in Oxfordshire?

Impacts of climate in Oxfordshire in recent times

Alternative paths into the future

What can we expect for Oxfordshire up to the 2050s?

Impacts of a changing climate, and adaptation responses

What about changes beyond the 2050s?

Where next?

 

What's been happening... globally

According to official records, global surface temperature increased throughout the last century by around 0.6°C. At the same time carbon dioxide levels in the atmosphere rose to over 380ppm, the highest they have been for at least 420,000, and probably 20 million, years. Carbon dioxide levels had maintained a steady cycle of between 180 and 300ppm throughout the ice ages of last 650,000 years and were 270ppm at the start of the industrial revolution.

Carbon dioxide levels over the last 1000 years (top) and throughout the cycles of ice ages over the past 400,000 years. Source: wikipedia; Robert. A Rohde, Global Warming Art project

Eleven of the last twelve years between 1996 and 2005 are among the twelve warmest years ever recorded, in the instrumental record that dates back to 1850. Particularly notable is the rate at which the observed warming has occurred: the Intergovernmental Panel on climate change (IPCC) recently concluded that it is ‘very likely' that the rate of recent warming in the industrial era since 1850 has not been exceeded over the past 10,000 years, which contain the history of human civilisation.

Global average Temperature rise over the 20th century relative to 1900

A 0.6°C rise may not seem like a very big rise, but this is already having profound effects on our world. The increasing heat energy trapped by the increased concentration of greenhouse gases is transferred throughout the climate system, driving change over and above the equilibrium of weather patterns that have been established over the last 10,000 years. Changes to sea level, melting ice, widespread changes to precipitation and wind patterns, and changes to extremes such as heat waves, heavy rainfall and droughts, have all been observed at both continental and regional scales. Ecosystems, which respond directly to climate signals and extremes, are being significantly affected.

Changes are being observed in all earth systems as a result of the observed 0.6 degree C temperature rise

 

Global evidence of change

Sea level

Sea level has risen, in part due to thermal expansion of the oceans, and in part due to melting of continental ice. Observations suggest that there has been a 12-22cm rise over the last century. The rate at which the sea level is rising is also increasing- from 1.8mm per year between 1961 and 2003, to around 3.1mm per year for the more recent period between 1993 and 2003.

Observations in sea level rise from ocean laboratories around the world. A significant and sustained increase can be seen.

Ice melt

It has been estimated that over 90% of the globe's glaciers are now in retreat, with mountain glaciers and snowfall declining on average in both Northern and Southern hemispheres,  Some of this glacial decline has contributed to the sea level rise observed, particularly losses observed from the Antarctic and Greenland ice sheets. Arctic sea ice has been retreating since the 1970s at the rate of around 3% per decade, with serious consequences for the polar bears which depend on chunks of sea ice as their hunting ground.

 Some glaciers have shown dramatic retreat over the last century.

Precipitation: changes to means; droughts and flooding

Numerous stories from around the globe fit with the scientists' growing observational records. The consistent message is that the climate is changing, bringing a greater variability and unpredictability of weather and particularly to precipitation, which is having serious consequences for crop planting and harvesting. Work of aid agencies such as Oxfam is revealing the reality of these climate changes in the lives of those who depend closely on the land for their survival.

Droughts and changed weather patterns have devastating impacts on crop production and livestock

Extreme events

Storm activity and intensity in the Atlantic has also been increasing. 2005 was the most active storm season on record with 27 named storms. Hurricanes Andrew, Rita and Katrina resulted in bills of about $300bn, smashing the previous yearly record of $45bn.

The number of extreme weather events has increased markedly over the past few decades, and with this the amount of insured losses incurred. Source: Swiss Re

These impacts illustrate the significance and consequence of a 0.6°C rise in global average temperature. It is important also to remember that this rise is an average of much greater regional rises in temperature, and that this variation will continue. The greatest warming has been observed in the Northern Latitudes and particularly in the Northern Polar region. This is due to the lower thermal capacity of the larger land mass of the Northern latitudes relative to the Southern Hemisphere, which is largely ocean with greater capacity to absorb heat.

 Variations in the average global temperature rise. Make your own map at http://data.giss.nasa.gov/gistemp/maps/

What has been happening...in the UK?

Records of temperature in the UK have been kept in Central England since 1659, and are the longest temperature records held anywhere in the world. These records show that temperatures have increased by 0.7°C in the UK since 1659. Of that, a rise of 0.5°C has occurred in the 20th century.

There has been a rise of 0.5 degrees Celsius over the past century in Central England

At the same time, there have been notable changes to precipitation, with marked seasonal trends for drier summers and wetter winters, precipitation decreasing by about 15% over the summer months, and increasing by a similar amount throughout the winter. Despite overall precipitation levels remaining roughly constant, the mantra of water companies may well be ‘too little, too much, wrong place'.

Changes to precipitation in the UK show significant seasonal trends

Extreme weather events in the UK are also thought to be increasing, with evidence of dramatically increased insurance claims for increasing incidences of flooding, drought and subsidence, storm activity, and periods of intense hot weather such as the heat waves of 2003 and 2006.

Attributing human influence to climatic change

It has been estimated that half the risk of the heat wave event of summer 2003, which killed over 30,000 people throughout Europe, and 2,000 in the UK, was due to human-induced changes to greenhouse gas concentrations. That is to say, without the impact of our fossil fuel and deforestation activities to date, this event would have been half as likely to happen. (View the article from Nature which makes these claims here http://www.nature.com/nature/journal/v432/n7017/abs/nature03089.html )

 The summer heat wave of 2003 seen by infra red camera from space. Source: Met Office

Although this kind of attribution is difficult for more localised events, we can examine current weather and its impacts to see if it forms part of an emerging trend which represents a significant departure from the past. We can then begin to imagine what the future may look like if the factors contributing to these trends continue to be augmented.

 

So what has been happening... in Oxfordshire?

Trends in Oxfordshire seem to be following those of the UK, with rising temperatures leading to hotter, drier summers and milder winters, and changes to precipitation leading to more intense rainfall and prolonged periods of drought. Ecosystems, directly responsive to climate means and extremes, are also being affected. We explore some examples of these climate impacts in the next sections.

 

Some comments of Oxfordshire people, January 2007

Impacts of climate in Oxfordshire in recent times

The impacts of weather in Oxfordshire, are already significant, and provide us with a basis for understanding how further changes to our climate may affect us. Over the past decade or so, Oxfordshire has experienced two intense heat waves in 2003 and 2006, over 40 major instances of flooding, mini tornados, storms and strong winds, and periods of drought and subsidence. In general, the trends experienced across the UK of increasing temperature, with milder, wetter winters and warmer, drier summers, have also been felt here, and have found expression in changes to our local ecology and in impacts on people, buildings and infrastructure.

Milder winters have meant that Port Meadow is rarely frozen nowadays

Some of these weather impacts are described in more detail below...and we can bear these in mind when looking at changes we might expect in the future up to the 2050s.

Summer heat waves: 2003 and 2006

The summer 2003 heat wave in Oxfordshire had serious effects on school and office life, impacted travel and resulted in an increase in crime. There was a sharp rise in the number of crimes, particularly of disorder and assault, reported over the hottest weekend of the year. A rise in theft was also reported, as doors and windows were left open in hot weather. Signs of West Nile, Ustutu and Sinibis viruses, indigenous to hotter climates, were detected in UK birds.

Summer 2006 saw many roads closed due to melting tarmac, with gritters sent out in the intense heat to spread gravel and reduce damage. Repair bills were estimated in the region of several billion. Six schools were closed for up to 2 days, affecting over 1000 pupils, and many offices were unfit for work, with internal temperatures reaching 37°C.

The aftermath of melting tarmac on the Banbury Road, North Oxford

Too much rain....Flooding

Flooding is a common feature of Oxfordshire, particularly in the City of Oxford itself. There have been over 40 major incidents due to flooding recorded in Oxfordshire over the past 15 years, from around 14 periods of flooding. This includes over 12 incidents of summer flash flooding, often caused by heavy rain on ground made hard and impermeable through drought.

January floods in Cutteslowe, North Oxford, 2007

Too little rain... drought

The past 3 years saw the south east face its driest period since 1933, with a sustained period of below average rainfall leading to water restrictions and impacts on ecology. Fish were found to be dying due to low oxygen levels, and insect breeding patterns were affected due to low river flows.

Oxford Mail bill boards in April 2006. Water butts were a good investment!

Changes to ecology

Across the UK, changes are being observed in the flowering and leafing dates for plant life and in the behaviour of wildlife. Ecosystems are complex and interdependent, and climatic change can disrupt this interdependency. Studies in a wood in Oxfordshire have shown that the hatching date for blue tits no longer coincides with the peak in caterpillars on which they feed. Migrating birds are arriving later as temperatures remain warmer for longer at southern latitudes. Trees are coming into leaf earlier, particularly sycamore, hawthorn and hornbeam. Autumn 2006 was a particularly mild season, and a local farm found January King cabbage sprouting in November!

Should the January King be renamed?

Extreme events

In addition to heat wave periods, other extreme events have also been felt across Oxfordshire. Mini tornados affected some parts of the county in 1992, 1997 and 2003, causing damage to buildings, and strong winds have led to deaths, damage to trees and to buildings.

Aftermath of 2003 mini-tornado, Filkins, Oxfordshire  Photo: David Clifton (BBC)

Alternative paths into the future

So what can we expect of the future, given observations both globally and here in Oxfordshire? While the vision of climate change in the press is often apocalyptic, can we realise a more hopeful future?

It has been established with ‘very high confidence' in the Fourth Assessment Report of the IPCC global consensus of scientists that the globally averaged net effect of human activities since 1750 has been one of warming; due to increases in greenhouse gas emissions, and through land use change. Annual fossil fuel carbon dioxide emissions have increased from an average of 6.4 GtC per year in the 1990s, to 7.2 GtC per year in the period 2000 to 2005. It is clear that if emissions continue to rise, we can expect a continued increase in temperature. Latest estimates project a range of 1.8-4°C by the period 2090-2099, but of course, what we see will depend on our emissions today and from now on. Various scenarios of emissions, describing different futures, are shown in the graph below and result in different temperature rises by 2100.

Emissions paths from the IPCC showing projected temperature rises. The black line indicates a 'high emissions' path, the green line lower emissions; the blue and orange paths lie between these.

However, it is important to recognise that, regardless of collective global action to reduce emissions, there will be a certain amount of unavoidable warming over the next 30-40 years, largely due to the slow response of the oceans which take time to release the additional heat that they take up from the atmosphere. The IPCC Fourth Assessment reports an expected rise of at least 0.2°C per decade for all of the ‘emissions scenarios' that they describe in the graph above. This means that we can expect a further temperature increase of around 1°C by the 2050s in addition to the 0.7° we have already experienced in the UK to date. We can see that this is the case by looking at the temperature rises projected for this period (circled on the graph) under the four scenarios shown- until the 2040s we can see that the projected rise is consistent between all of the scenarios, regardless of emissions.

So this graph gives us two important messages:

• It is imperative that we act now, as local communities and globally, to shift to an emissions path which limits and stabilises global temperature rise.
• Regardless of our endeavours to cut emissions, we are committed to a certain amount of unavoidable warming over the next 3 or 4 decades, and will have to prepare for and adapt to this.

If we manage to limit our global emissions, we can stay on a ‘2 degree' path, hopefully limiting global warming to below 2°C and avoiding dangerous climate change. However, if we continue on a ‘business as usual' path, we risk following a path towards a temperature rise of up to 5°C or more. (See What about changes beyond the 2050s?).

What can we expect for Oxfordshire up to the 2050s?

Given the expectation we have of a further 1-1.5°C of ‘unavoidable climate change', current trends in the county and in the UK appear to suggest that we face the following key changes to our climate in Oxfordshire over coming decades:

• Hotter, drier summers
• Milder, wetter winters
• More extreme events: heat waves, more intense storm activity, heavier downpours.

UKCIP02 scenarios of climate change for the South East. The '2020s' refers to the period between 2011 and 2040.

We therefore expect to see an increase in the types of weather events experienced in the recent past: more flooding, both in winter and summer; increased summer drought; increases in heat waves and temperature extremes; and milder winters. Natural variability will always play a part, but trends will become more pronounced and greater in magnitude. Continued changes to our ecology may threaten local species, with species close to their southern limits migrating northwards and those more common in the south migrating northwards. It will be essential for wildlife corridors to be provided to allow these movements to take place.

While we make a transition towards a society which uses energy more wisely, and employs increasing proportions of energy from renewable sources, we need to prepare for the changes we expect to face and adequately adapt.

 

Impacts of a changing climate, and adaptation responses

Based on the key trends we expect, we can begin to explore the implications and look at ways in which we might respond through adaptations. Below are some suggestions of key considerations for certain sectors. Obviously impacts will be diverse and complex and are best examined by those with an in depth knowledge of the sector.

Gardens

• Gardeners will need to employ water conservation techniques such as mulching and rainfall harvesting to manage summer water shortages. New drought resistant plants may become more popular.
• Pests and diseases from southerly regions and mainland Europe will become more common.

Drought resistant echinacea: a new cottage garden plant?

Farming

• Increasing water shortages in summer will mean better irrigation systems and drought resistant crops are needed.
• New crops may be grown and changes to practices needed to manage greater unpredictability and variability of weather.
• Crops that require winter chilling, such as rhubarb and blackcurrants, must develop new varieties.

Water

• Shortages of water in summer will mean careful management of resources is necessary. Rainwater harvesting and better urban drainage will need to be employed to even out water supplies and protect infrastructure.
• Increased rainfall in winter, and greater intensity of rainfall in both winter and summer, will exacerbate flooding problems.

Urban life

• Towns and cities feel hotter than rural areas because of heat trapped by buildings and transport, and less heat removed by greenery. Heat wave effects will be more intense in Oxford.
• Shading and cooling of buildings may be necessary, and new buildings designed to cope with the heat . Trees may need to be planted to create more shade.

 Shutters and blinds, common in the Mediterranean, may be needed to protect us from the heat

Health

• Heat wave impacts for elderly and vulnerable, but fewer winter deaths.
• Increase in tropical diseases such as malaria, and in exposure related illnesses such as skin cancer. Increased summer temperatures often result in an increase in food poisoning.

Transport

• Reduction in travel problems due to snow and ice.
• Increase in disruption due to flooding, melting roads and buckling rail tracks.

Biodiversity

• Species in the south may migrate to the north as climate conditions change. Wildlife corridors will be needed to ensure migration can take place.
• Typical habitats such as the beech woods of the South Oxfordshire Chilterns may suffer as a result of combined heat and drought.

And opportunities...

• New crops adapting to a warmer climate, and new crops for energy use
• Local food initiatives
• Cutting edge technologies for energy efficiency and renewables
• Businesses thriving on low-carbon economy

What about changes beyond the 2050s?

We can see from the IPCC projections of different emission scenarios that there is a marked divergence by the end of the century between the high and lower emissions paths. The amount of unavoidable change we expect up to the 2050s may not push us into dangerous climate change. But our emissions from this point on are already determining the path we choose to take- towards climate stabilisation, or towards a much more uncertain future.

If we take a path of higher emissions, we may see a global temperature rise of 5°C or above. This increase may bring about a tipping point into so called ‘runaway global warming', in which changes to the climate system would rapidly accelerate and have devastating impacts across the globe.

In Oxfordshire, we would expect to see drastic changes to precipitation, with up to a 60% decline in summer months. Summer heat waves like that experienced in 2003 would be a ‘cool summer', and snowfall would be a distant memory. There would be devastating impacts on all living things- some studies suggesting that up to 50% of species could be lost.

How can we respond?

We have the knowledge, the technology and the solutions to take a 'sustainable path' into the future. A combination of using energy more wisely, employing diverse renewable energy sources, and protecting our habitats from destruction can all contribute to a positive future and aversion of the climate catastrophe that could happen if we fail to act. Are we ready to take on this great challenge?

Where next?

On ClimateX.org

Read our overview article ‘Climate Change', and an article about expected UK impacts and adaptation, 'Counting the costs of UK climate change- and the benefits?'. There are also many articles focussing on expected impacts of climate change, such as 'Climate change and health in Europe' and 'Food in a climate of disparity'. There are also plenty of inspiring stories of those taking action in Oxfordshire and beyond- see 'Be Your Own Generator' as an example....

External links

Climate change 2007: The Physical Science Basis Summary for policy makers, from the IPCC (Intergovernmental Panel on Climate Change) Working Group I http://www.ipcc.ch/SPM2feb07.pdf  This is an excellent source for all the official figures and measurements of the changes observed to the global climate, as collated and agreed by a consensus of scientists across the globe; the levels of confidence to which these changes can be attributed to human influence, and for projections of the expected impacts of climate change this century.

An excellent and comprehensive summary of climatic change and global warming and the scientific debate can be found on wikipedia at http://en.wikipedia.org/wiki/Global_warming .

To read about real stories of the impacts of climate change now for people around the world, visit the Oxfam site at http://www.oxfam.org.uk/what_we_do/issues/climate_change/stories.htm

View the Central England Temperature record with monthly data from 1659 to the present day! http://www.metoffice.gov.uk/research/hadleycentre/CR_data/Daily/HadCET_act.txt

Read frequently asked questions about observed climate changes and expected impacts at the UK Climate Impacts Programme http://www.ukcip.org.uk/faqs.shtml#q12 , and browse this site for the latest work in the UK on impacts and adaptation.

Join in to record your observations of ecological change, at http://www.naturescalendar.org.uk/, and view a summary of observed climate impacts and expected changes here: http://www.naturescalendar.org.uk/climate+change/climateimpacts.htm

Look at the weather recorded in Oxford back to 2004 at http://www.bocc.co.uk/weather/. You can look at changes to temperature, wind speed and direction, and pressure; by month, week or quarter.