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Global experts discuss drought risk

A symposium was held in Oxford on 22 September, bringing together global experts on the causes and impacts of droughts. The speakers shared experience and expertise from Australia, America, Europe and the UK, providing interdisciplinary insights into the climatic and socio-economic factors that contribute to drought.

“If you do what you’ve always done, you’ll get what you’ve always got!” said Professor Donald Wilhite, University of Nebraska, stressing the need to change the way droughts are managed. Although drought is a normal part of climate variability, unprepared governments and vulnerable societies often react to droughts with shock and alarm. Professor Wilhite proposed that droughts can act as a window of opportunity to change from post-impact crisis response to a pre-impact drought risk management approach. The cost of preparedness action against drought is insignificant when compared to the cost of inaction, he said.

The speakers at the symposium are members of the International Advisory Board of the Oxford-led MaRIUS project on drought and water scarcity in the UK. Oxford University’s Professor Jim Hall presented the project which was launched earlier this year and adopts a risk-based approach to understanding droughts and water scarcity; analyses the impacts on people, the environment and the economy; and will develop methods to support decision-making and improve drought risk management.

Dr Henny van Lanen from Wageningen University in the Netherlands said that there is medium confidence that droughts will intensify in the 21st Century in some areas and during some seasons in southern and central Europe, central North America, Central America and Mexico, northeast Brazil and southern Africa. Elsewhere in the world inconsistencies in models make it difficult to draw any firm conclusions. The ability of scientists to identify future drought trends is constrained by available data, various definitions of droughts, different ways to quantify or identify a drought, and the inability of models to include all the factors that influence a drought.

Climate change poses a challenge to water planners, as drought risks in the future may be greater than in the past. Professor Casey Brown, University of Massachusetts, argued that the best approach to address these uncertainties is to focus on understanding the project and its vulnerabilities to climate change. By identifying the key climate variables to which the system is sensitive and the magnitude of climate changes that cause unacceptable outcomes, a water planner can incorporate the desired or acceptable level of resilience into the project.

Drawing on research in the Shale Hills / Susquehanna wetland catchments in northeastern United States, Professor Christopher Duffy from Penn State University presented a methodology for assessing the vulnerability of wetlands to climate change and droughts. Early results show that upland catchments are the most vulnerable based on depth to groundwater which acts as a buffer during periods of low rainfall.

Professor Lucia De Stefano stressed that stakeholder input is essential for understanding vulnerability and response to drought. Her research in Spain and on a pan-European scale found that there are inconsistencies in drought perceptions across scales and that improving communication could benefit drought management and address mismatches between policy objectives and implemented measures.

Dr Narendra Kumar Tuteja from the Australian Bureau of Meteorology shared experiences from Australia, a country that has faced around eight major drought events in the last century, with the Millennium drought (1997-2009) radically influencing national water reform. He talked about the need for water availability forecasts at a range of time scales for operational water planning and management, and the challenges in generating these. He underscored the importance of continued and extensive consultation with stakeholders and users in order to deliver useful research, data or tools.

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Report identifies the ‘most vulnerable’ to climate-related disasters

Extreme weather events leave populations with not enough food both in the short- and the long-term, says a new report by the Environmental Change Institute that examines the impacts of climate-related diasters on food security. The authors conclude that better governance could have lessened the impact on the poorest and most vulnerable, and affected populations have been let down by the authorities in past disasters.

The report, commissioned by the charity Oxfam, tracks the effects on four countries: Russia which experienced a heatwave in 2010; flood-hit Pakistan the same year; East Africa during the drought of 2010-2011; and the Philippines after Typhoon Haiyan in 2013. The researchers conclude that the authorities in each of the countries studied were unprepared for extreme weather events, and citizens suffered even more than they needed to.

The report, ‘A Sign of Things to Come?’, says that during the floods in Pakistan ‘coercive landlords’ took advantage of smallholders and people affected by the floods. Overall, the flooding is estimated to have led to an 80% rise in wheat and rice prices in 2010.

The drought-affected people of East Africa did not receive international or domestic aid for six months, partly due to the risks posed by armed groups. Food prices reached record levels in several markets that included the cost of wheat in Ethiopia, maize in Kenya and red sorghum grain in Somalia, says the report. It notes that children under five accounted for over half of all deaths in Somalia.

On a global level, the report warns that climate change is expected to increase the intensity and frequency of heatwaves and floods. It says although there is no scientific evidence to show a specific weather event would not have happened without climate change, scientists can estimate whether it increases the risk of an event. It finds that the Russian heat wave and the East African drought were more likely because of climate change, but there is not yet the evidence to say that climate change played a part in the floods in Pakistan or Typhoon Haiyan.

One of the lead authors Dr John Ingram said: “Weather has always affected food security, particularly for many of the world’s poorest people. Perhaps we think of farmers or fishermen first, but extreme weather will affect many more people in other ways too. While direct measures such as emergency preparedness and the strengthening of response-related institutions is helpful, this study has identified the need for a wider cultural shift to ensure the poorest and most vulnerable are properly protected. This goes beyond mere technical improvements to equipment or redirected funding and gets to the very heart of what ‘climate justice’ should be about.”

Reference

Coghlan, C., Muzammil, M., Ingram, J., Vervoort, J., Otto, F. and James, R. (2014) A sign of things to come? Examining four major climate-related disasters, 2010-2013 and their impacts on food security. Oxfam Research Reports, Oxford. Oxfam.

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Managing coasts under threat from climate change and sea-level rise

Coastal regions under threat from climate change and sea-level rise need to tackle the more immediate threats of human-led and other non-climatic changes, according to a team of international scientists.

The team of 27 scientists from five continents reviewed 24 years of Intergovernmental Panel on Climate Change (IPCC) assessments. They focused on climate change and sea-level rise impacts in the coastal zone, and examined ways of how to better manage and cope with climate change. The research team was led by Dr Sally Brown at the University of Southampton and included Andres Payo at the Environmental Change Institute, Oxford University.

They found that to better understand climate change and its impacts, scientists need to adopt an integrated approach into how coasts are changing. This involves recognising other causes of change, such as population growth, economic development and changes in biodiversity. Dr Brown emphasised that: “Over the last two and half decades, our scientific understanding of climate change and sea-level rise, and how it will affect coastal zones has greatly increased. We now recognise that we need to analyse all parts of our human and natural environments to understand how climate change will affect the world.”

The scientists also acknowledged that long-term adaptation to climate change can greatly reduce impacts, but further research and evaluation is required to realise the potential of adaptation. “Many parts of the coast can, with forward planning, adapt to sea-level rise, but we need to better understand environments that will struggle to adapt, such as developing countries with large low-lying river deltas sensitive to salinisation, or coral reefs and particularly small, remote islands or poorer communities,” said Dr Brown.

For example, in the Maldives, many small, remote low-lying islands are at risk from climate change and will struggle to adapt. But around the densely populated capital city and airport, adaptation has already occurred as land claim is a common practice in order to relive population pressure. Sea-level rise has already been considered into newly claimed land. Thus in decades to come, potential climate change impacts, such as flooding, will be reduced for this island, benefiting both the local population and economy.

Dr Jochen Hinkel from Global Climate Forum in Germany, who is a co-author of this paper and a Lead Author of the coastal chapter for the 2014 IPCC Assessment Report added: “The IPCC has done a great job in bringing together knowledge on climate change, sea-level rise and is potential impacts but now needs to complement this work with a solution-oriented perspective focusing on overcoming barriers to adaptation, mobilising resources, empowering people and discovering opportunities for strengthening coastal resilience in the context of both climate change as well as existing coastal challenges and other issues.”

This new research, published as a commentary in Nature Climate Change, will help in the understanding of the impacts of climate change and how to reduce impacts via adaptation. Its multi-disciplinary approach could be useful if future IPCC assessment reports are commissioned.

Reference

Brown, S. et al. (2014). Shifting perspectives on coastal impacts and adaptation. Nature Climate Change, 4: 752–755. DOI: 10.1038/nclimate2344

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Safe enough? Proportionate climate change adaptation in London’s water supply system

London faces increased risk of water shortages in the future due to climate change and population growth if no actions are taken to increase supply or reduce demand, according to a new study led by Edoardo Borgomeo and Jim Hall at the Environmental Change Institute. The research presents a new methodology for water managers to incorporate climate change uncertainties into water resources planning.

Water resources managers have significant experience in planning and operating their systems in the face of hydrological and weather variability. The reality of climate change, however, poses new challenges for water resources managers. Whilst the precise impacts of climate change for temperature, precipitation and water availability remain uncertain, water managers still need to take into account these uncertainties in their water plans. In the UK water companies are now legally obliged to evaluate the impacts of climate-related risks on their systems.

To help water managers address this challenge, this study develops a methodology for incorporating climate change related uncertainties in water resources planning. The methodology uses a risk-based metric to compare different water management options on the basis of their ability to reduce risks of water shortages under continuously changing climate conditions.

This methodology responds to the need in the UK and worldwide for a way of identifying water management investments which are proportionate to the risks the water systems are facing. Supply-side and demand-side management strategies can be compared based on how cost-effective they are at reducing risks to acceptable levels.

The risk-based methodology was applied to the London water supply area to characterise the most important uncertainties and identify water management options that are capable of reducing the harmful impacts of climate change. Results from the study demonstrate that without further supply or demand interventions, the combined effects of climate change and population growth are projected to increase the risk of water shortages in the future in London.

This research, led by Edoardo Borgomeo and Jim Hall, was carried out in partnership with Thames Water and the Environment Agency. The study contributes to the ongoing discussion in the UK water sector on whether the current approach to water resources planning should change for the next round of water resources management plans in 2019.

Reference

Borgomeo, E., Hall, J.W., Fung, F., Watts, G., Colquhoun, K. and Lambert, C. (2014) Risk-based water resources planning: Incorporating probabilistic nonstationary climate uncertainties. Water Resources Research. DOI: 10.1002/2014WR015558

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Harry Verhoeven speaks about the water-food-energy nexus

Dr Harry Verhoeven was a speaker at the international conference on the water-food-energy nexus in drylands held in Rabat, Morocco on 11-14 June 2014. In a video interview, he highlights the politics behind how the nexus is defined and addressed.

The conference ‘Water-Food-Energy Nexus in Drylands: Bridging Science and Policy‘ gathered international experts to discuss the impacts of climate change and water scarcity and potential solutions in the fields of agriculture, water management, agro-business and energy. Speakers provided analyses and recommendations on how to address the interrelations between water, food and energy in global drylands, particularly in the Middle East and North Africa.

Dr Harry Verhoeven gave a presentation on the nexus and the Nile. Using the example of Egypt, he argued that politically crafted interconnections between water scarcity, food production and energy security have been the foundation of modernist dreams, state-building projects and regime consolidation strategies for generations.

The conference was organised by the OCP Policy Center in partnership with the Barcelona Centre for International Affairs (CIDOB), King’s College London and Texas A&M University.

Dr Harry Verhoeven teaches African Politics at the Department of Politics & International Relations, University of Oxford, and he is a Junior Research Fellow at Wolfson College. He is the Convenor of the Oxford University China-Africa Network and the Oxford Central Africa Forum.

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Citizen science project finds global warming makes very wet winters ‘a bit more likely’

An Oxford University citizen science project to assess the effects of global warming has reported a small but statistically significant increase in the probability of extremely wet winters in southern England.

Following preliminary assessments from the Met Office, Oxford University researchers undertook the first scientific experiment to analyse whether the risk of extreme rainfall has changed due to climate change after the winter deluge between December 2013 and February 2014. Total rainfall in Oxford over the three months was the highest ever recorded by the University’s Radcliffe Observatory since it set up 200 years ago.

Scientists used the spare capacity on volunteers’ home computers to compare tens of thousands of simulations of possible weather in our present-day climate with tens of thousands of simulations of a hypothetical world without the influence of past greenhouse gas emissions in the atmosphere using the same climate model. Comparing numbers of extremely wet winters between these two groups provides estimates of the influence of climate change on the UK weather. They found a 1-in-100-year winter rainfall event (ie. 1% risk of extreme rainfall in the winter of any given year) is now estimated to be a 1-in-80 year event (i.e. 1.25% risk of extreme rainfall in any given winter) so the risk of a very wet winter has increased by around 25%.

The researchers say this change is statistically significant thanks to the number of computer simulations they were able to run– over 33,000 computer models run in the experiment. However, the researchers say that while their finding is statistically robust the result depends on how man-made climate change is represented in the experiment. They used different climate models to estimate the pattern of global warming which provided a range of possible changes in risk. In several cases, the models gave no change or even a reduction in risk, but overall the simulations showed a small increase in the likelihood of extremely wet winters in the south of England.

The experiment for the weather@home project, based at the University’s School of Geography and the Environment, started in March 2014. The winter deluge affected large parts of south England and Wales and as a consequence, large areas were flooded, some more than once during the three-month period. This led to a good deal of public debate, which at one point involved Prime Minister David Cameron, about whether the extreme rainfall and resulting floods could be linked to climate change.

Researcher Dr Friederike Otto, from the weather@home project based in the University’s School of Geography and the Environment, said: “It will never be possible to say that any specific flood was caused by human-induced climate change. We have shown, however, that the odds of getting an extremely wet winter are changing due to man-made climate change. Past greenhouse gas emissions and other forms of pollution have ‘loaded the weather dice’ so the probability of the south of England experiencing extremely wet winters again has slightly increased.”

She added: “Total winter rainfall, although useful as a benchmark, is not the direct cause of flood damage, so we are working with collaborators, such as the Centre for Ecology and Hydrology, to explore the implications of our results for river flows, flooding and ultimately property damage.”

Anyone who wants to join the project or volunteer spare time on their home computer should visit the weather@home website.

Graphs displaying the results of the weather@home project can be viewed here.

Watch Professor Myles Allen speaking about these results at a press conference at the EGU General Assembly [Myles speaks at 23 minutes into the video].

Read coverage of this story in the Guardian, the BBC and on the University of Oxford news site.

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Vulnerable substations serving millions still at risk from flooding

An article in the Independent online highlights the significant threat UK power supplies face from flooding, with comment from Professor Jim Hall.

The National Grid has revealed that seven of the country’s biggest electricity substations could be affected by flooding, putting up to 1.1 million households at risk of losing power.

Jim Hall, Professor of Climate and Environmental Risks at the University of Oxford, said: “The 2007 floods were a wake-up call in terms of vulnerability and some very significant steps have been taken since then.

“But we are not there yet and in a changing climate we need to make sure that we are able to deal with past hazards and the increasing risks we face in the future.”

Read the full article in The Independent online

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UK faces more extreme events and floods with climate change

Professor Jim Hall says the UK will see an increase in temperatures, extreme events and floods as a result of climate change.

Jim Hall, Professor of Climate and Environmental Risks and Director of the Environmental Change Institute, speaks to the Telegraph about the impacts of climate change in the UK in light of the newly released report by the Intergovernmental Panel on Climate Change on Impacts, Adaptation and Vulnerability.

“What we’ve seen this winter is consistent with what we would expect to see in a changing climate,” he said. He warned that that the UK needs to think about the long term when making decisions today if we are going to be able to cope with a changed climate.

In an article in the Guardian online, Professor Hall said that adaptation is difficult, even in a developed country such as the UK. He noted that building still takes place on flood plains, efforts to reduce water use in anticipation of droughts are not working and that infrastructure remains vulnerable.

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Are the UK winter floods linked to climate change?

The general public are being called to take part in an Oxford University research project to find out what role climate change played in the UK’s record-breaking wet winter.

The rainfall from December last year through to February resulted in the wettest winter ever recorded at the Radcliffe Meterological Station in Oxford. The deluge caused widespread flooding across southern England, affecting thousands of people and resulting in an estimated £1bn or more in damage.

The project weather@home, led by Professor Myles Allen, will reveal whether climate change made the extreme rainfall and resulting floods more likely to occur, or not. Anyone can use their home computer to run weather simulations and contribute results to the experiment.

One set of weather model simulations will represent ‘real world’ conditions and possible weather, while another set of will represent the weather in an imagined world where humans have not changed the composition of the atmosphere through greenhouse gas emissions. By comparing the number of extreme rainfall events in the two sets, researchers can work out if the risk of a wet winter has increased, decreased or been unaffected by human influence on climate.

The models have to be run many thousands of times to ensure that the estimated probability of extreme events is robust. That’s why the researchers are asking for the help of the general public who can download the computer software and run the experiment from home. The results should be available within a month and will be published as they come in.

In the video below Nathalie Schaller, a researcher based at the Environmental Change Institute, explains the science behind the project.

Read the Guardian article ‘Home computers to help scientists assess climate role in UK’s wet winter’

Follow Damian Carrington’s blog on the Guardian website which discusses the science and its implications

Visit the weather@home project website and contribute to the experiment

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Action needed to reduce nitrogen and phosphorus pollution in the Thames

In a podcast on the NERC Planet Earth website, Paul Whitehead from Oxford University and Mark Barnett from the Environment Agency comment on the pollution challenge of the river Thames. They explain why the river will fail to meet European Union standards unless action is taken by farmers to reduce fertiliser use and water companies cut the amount of phosphorus being discharged by sewage works.

“Nitrogen and phosphorus come from a range of different sources,” said Paul Whitehead, Professor of Water Science at the School of Geography and the Environment. For example, phosphorus comes through sewage works, from the soap we use in everyday in dishwashers and washing machines, as well as from agricultural and rural diffuse sources.

“They create eutrophic conditions in the river, where you get excessive blooms of algae and growth of unwanted plants” explained Paul. “It is possible to kill a river, meaning the oxygen levels in the river are reduced down to zero and fish and macroinvertebrates can’t survive.”

Mark Barnett, Catchment Coordinator for the Environment Agency said that although a lot of work has been done over the last few decades to reduce nitrates and phosphates, there is still quite a long way to go to meet European Union targets.

Climate change could have significant impacts on river pollution in the future as the distribution of rainfall changes, with more rainfall predicted in the winter and reduced rainfall and river flows in the summer. “This means that in the summer there will be less dilution of pollutants coming into the river system, so that could raise phosphorus levels, and in winter more nitrogen and phosphorus could be flushed out of the catchment into the river system,” warned Paul Whitehead.

Building riparian buffer strips is one measure that could be taken to cut down pollution levels – these are zones of land next to the stream channel which effectively act as a filter for the sediments and nutrients found in water running off the fields. There are also technologies available for removing phosphorus at sewage treatment works, enabling it to be recycled and sold back to farmers rather ending up in the river.

“I’m reasonably confident that things will improve” said Paul Whitehead. “They’ve improved massively over the last 50 years in the Thames so I’m sure that will continue. Technology is improving the whole time, the water companies are quite keen to actually extract phosphorus and sell it back to the farmers, it’s potentially a source of money for them and at the same time farmers want to use less and less fertiliser because it is more expensive.”

Listen to the Planet Earth podcast

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