A week at COP23

From the 6th -17th of November the UNFCCC’s (United Nation Framework Convention on Climate Change) annual meeting or “Conference of the Parties” – COP took place. This year was COP23 and was hosted by Bonn in the UN’s world conference centre with Fiji taking the presidency.

IMG_20171106_123155780

Heading into the Bonn Zone on the first day of the COP. The Bonn Zone was the part of the conference for NGO stands and side events.

As part of the Walker Institutes Climate Action Studio another SCENARIO PhD and I attended the first week of the COP while students back in Reading participated remotely via the UNFCCC’s YouTube channel and through interviews with other participants of the COP.

There are many different components to the COP, it is primarily the meeting of a number of different international Climate agreements with lots of work currently being done on the implementation on the Paris Agreement. However it is also a space where many different civil society groups doing work connected to or impacted by climate change come together, to make connections with other NGOs as well as governments. This is done in an official capacity within the “exhibition zone” of the conference and with a vast array of side events taking place throughout the two weeks. Outside of these official events there are also many demonstrations both inside and outside of the conference space.

Demonstrations in the Bonn Zone

As an observer I was able to watch some of the official negotiations. On the Wednesday I attended the SBSTA (Subsidiary Body for Scientific and Technological Advice) informal consultation on research and systematic observations. It was an illuminating experience to see the negotiation process in action. At times it was frustrating to see how picky it feels like the negotiation teams can be, however over the week I did have a newfound appreciation for the complexity of the issues that are having to be resolved. This meeting was based on writing a short summary of the IPCC report and other scientific reports used by the COP, and so was less politically charged than a lot of the other meetings. However this didn’t stop an unexpected amount of debate over whether to include examples such as carbon-dioxide concentrations.

One of the most useful ways to learn about the COP was by talking to the different people and groups who we met at COP. It was interesting to see the different angles with which people were approaching the COP. From researchers who were observing the political process, to environmental and human rights NGO’s trying to get governments to engage with issues that they’re working on.

Interviewing other COP participants at the Walker Institutes stand

A particular highlight was the ex-leader of the Green Party Natalie Bennett, she spoke with us and the students back in Reading about a wide range of topics, from women’s involvement in the climate movement to discussing my PhD.

Kelly Stone from Action Aid provided a great insight into how charities operate at the COP. She spoke of making connections with other charities, often there are areas of overlap between their work but on other issues they had diverging opinions. However these differences have to be put aside to make progress on their shared interests. Kelly also discussed how it always amazes her that people are surprised that everyone who attends COP does not agree on everything, “we’re not deciding if climate change is real”. The issues being dealt with at the COP are complex dealing with human rights, economics, technology as well as climate change. Often serious compromises have to be made and this must be done by reaching a consensus between all 197 Parties to the UNFCCC.

To read more about the student experience of COP and summaries of specific talks and interviews you can view the COP CAS blog here. You can also read about last years COP on this blog here.

Clockwise from top left: The opening on the evening of Monday 6th November showed Fiji leaving its own mark as the President of the conference. The Norwegian Pavilion had a real Scandi feel, while the Fiji Pavilion transported visitors to a tropical island.

 

New Forecast Model Provides First Global Scale Seasonal River Flow Forecasts

new_web_figure2_rivernetwork

Over the past ~decade, extended-range forecasts of river flow have begun to emerge around the globe, combining meteorological forecasts with hydrological models to provide seasonal hydro-meteorological outlooks. Seasonal forecasts of river flow could be useful in providing early indications of potential floods and droughts; information that could be of benefit for disaster risk reduction, resilience and humanitarian aid, alongside applications in agriculture and water resource management.

While seasonal river flow forecasting systems exist for some regions around the world, such as the U.S., Australia, Africa and Europe, the forecasts are not always accessible, and forecasts in other regions and at the global scale are few and far between.  In order to gain a global overview of the upcoming hydrological situation, other information tends to be used – for example historical probabilities based on past conditions, or seasonal forecasts of precipitation. However, precipitation forecasts may not be the best indicator of floodiness, as the link between precipitation and floodiness is non-linear. A recent paper by Coughlan-de-Perez et al (2017), “should seasonal rainfall forecasts be used for flood preparedness?”, states:

“Ultimately, the most informative forecasts of flood hazard at the seasonal scale are streamflow forecasts using hydrological models calibrated for individual river basins. While this is more computationally and resource intensive, better forecasts of seasonal flood risk could be of immense use to the disaster preparedness community.”

twitter_screenshotOver the past months, researchers in the Water@Reading* research group have been working with the European Centre for Medium-Range Weather Forecasts (ECMWF), to set up a new global scale hydro-meteorological seasonal forecasting system. Last week, on 10th November 2017, the new forecasting system was officially launched as an addition to the Global Flood Awareness System (GloFAS). GloFAS is co-developed by ECMWF and the European Commission’s Joint Research Centre (JRC), as part of the Copernicus Emergency Management Services, and provides flood forecasts for the entire globe up to 30 days in advance. Now, GloFAS also provides seasonal river flow outlooks for the global river network, out to 4 months ahead – meaning that for the first time, operational seasonal river flow forecasts exist at the global scale – providing globally consistent forecasts, and forecasts for countries and regions where no other forecasts are available.

The new seasonal outlook is produced by forcing the Lisflood hydrological river routing model with surface and sub-surface runoff from SEAS5, the latest version of ECMWF’s seasonal forecasting system, (also launched last week), which consists of 51 ensemble members at ~35km horizontal resolution. Lisflood simulates the groundwater and routing processes, producing a probabilistic forecast of river flow at 0.1o horizontal resolution (~10km, the resolution of Lisflood) out to four months, initialised using the latest ERA-5 model reanalysis.

The seasonal outlook is displayed as three new layers in the GloFAS web interface, which is publicly (and freely) available at www.globalfloods.eu. The first of these gives a global overview of the maximum probability of unusually high or low river flow (defined as flow exceeding the 80th or falling below the 20th percentile of the model climatology), during the 4-month forecast horizon, in each of the 306 major world river basins used in GloFAS-Seasonal.

new_web_figure1_basins
The new GloFAS Seasonal Outlook Basin Overview and River Network Layers.

The second layer provides further sub-basin-scale detail, by displaying the global river network (all pixels with an upstream area >1500km2), again coloured according to the maximum probability of unusually high or low river flow during the 4-month forecast horizon. In the third layer, reporting points with global coverage are displayed, where more forecast information is available. At these points, an ensemble hydrograph is provided showing the 4-month forecast of river flow, with thresholds for comparison of the forecast to typical or extreme conditions based on the model climatology. Also displayed is a persistence diagram showing the weekly probability of exceedance for the current and previous three forecasts.

blog_screenshot
The new GloFAS Seasonal Outlook showing the river network and reporting points providing hydrographs and persistence diagrams.

Over the coming months, an evaluation of the system will be completed – for now, users are advised to evaluate the forecasts for their particular application. We welcome any feedback on the forecast visualisations and skill – feel free to contact me at the email address below!

To find out more, you can see the University’s press release here, further information on SEAS5 here, and the user information on the seasonal outlook GloFAS layers here.

*Water@Reading is “a vibrant cross-faculty centre of research excellence at the University of Reading, delivering world class knowledge in water science, policy and societal impacts for the UK and internationally.”

Full list of collaborators: 

Rebecca Emerton1,2, Ervin Zsoter1,2, Louise Arnal1,2, Prof. Hannah Cloke1, Dr. Liz Stephens1, Dr. Florian Pappenberger2, Prof. Christel Prudhomme2, Dr Peter Salamon3, Dr. Davide Muraro3, Dr. Gabriele Mantovani3

1 University of Reading
2 ECMWF
3 European Commission JRC

Contact: r.e.emerton@pgr.reading.ac.uk

Adventures in Modelling – NCAS Climate Modelling Summer School

At the beginning of September 3 PhD students from Reading, including myself, went to Cambridge to attend the NCAS Climate Modelling Summer School. This is an annual event aimed at PhD students and early career scientists who want to develop their understanding of climate models, with topics covering parameterisations to supercomputers.

IMG_3847
Staff and students of the course pose outside the Chemistry department, which played host to morning lectures

The course ran over two weeks with lectures on the components of climate models in the morning, covering fundamental dynamics and thermodynamics, numerical methods and different parameterisations. This was followed by an afternoon of computer practicals and then more topical lectures in the evening, such as “User engagement in climate science” and “The Sun and Earth’s climate system”. The lectures were very fast paced but this was a great opportunity to cover so many topics in a short space of time and get a grounding in lots of different topics that I will definitely be looking over in future. A poster session on the second evening gave us the chance to learn about other people’s work and make connections with other people starting out their careers in climate science, including a few readers of the blog, that will hopefully last throughout our careers.

One of the highlights of the course was the chance to run some (rather interesting) experiments with an earth system model. This involved breaking into groups with each being given a different project. It was exciting to go  through the whole process of having an idea, developing a hypothesis, thinking of specific experiments to answer the hypothesis and then analysing the results in just a week – something that takes much longer when you’re doing a PhD! My group worked on the Flat Earth experiment, which looked at the effect of removing all of the earth’s orography not, to our dismay, turning the earth into a flat disk. I learned a lot about how to run models, something which I have never done even though I use the output. It also developed my understanding of different climate processes that I don’t work with such as the monsoons, and even dynamical vegetation.

monsoons
Flat earth experiment looking at the change in the monsoon winds

Throughout the course we stayed at St Catharine’s College. Right in the centre of Cambridge it quickly felt like a home from home, keeping us well fed to get through the intense science. Although the weekend was rainy, apparently breaking a run of excellent weather for the school, we still had plenty of time to explore beautiful Cambridge. A few people were even brave enough to go punting!

An interesting, hectic and inspiring two weeks later we may have been glad to head back to Reading for a good sleep but having thoroughly enjoyed the summer school.

Buildings2000-®TimRawle-resized-w680px
The beautiful St Catharine’s College, image from http://www.caths.cam.ac.uk/

 

RMetS Impact of Science Conference 2017.

Email – j.f.talib@pgr.reading.ac.uk

“We aim to help people make better decisions than they would if we weren’t here”

Rob Varley CEO of Met Office

This week PhD students from the University of Reading attended the Royal Meteorological Society Impact of Science Conference for Students and Early Career Scientists. Approximately eighty scientists from across the UK and beyond gathered at the UK Met Office to learn new science, share their own work, and develop new communication skills.

image4

Across the two days students presented their work in either a poster or oral format. Jonathan Beverley, Lewis Blunn and I presented posters on our work, whilst Kaja Milczewska, Adam Bateson, Bethan Harris, Armenia Franco-Diaz and Sally Woodhouse gave oral presentations. Honourable mentions for their presentations were given to Bethan Harris and Sally Woodhouse who presented work on the energetics of atmospheric water vapour diffusion and the representation of mass transport over the Arctic in climate models (respectively). Both were invited to write an article for RMetS Weather Magazine (watch this space). Congratulations also to Jonathan Beverley for winning the conference’s photo competition!

IMG_3055
Jonathan Beverley’s Winning Photo.

Alongside student presentations, two keynote speaker sessions took place, with the latter of these sessions titled Science Communication: Lessons from the past, learning for future impact. Speakers in this session included Prof. Ellie Highwood (Professor of Climate Physics and Dean for Diversity and Inclusion at University of Reading), Chris Huhne (Co-chair of ET-index and former Secretary of State for Energy and Climate Change), Leo Hickman (editor for Carbon Brief) and Dr Amanda Maycock (NERC Independent Research Fellow and Associate Professor in Climate Dynamics, University of Leeds). Having a diverse range of speakers encouraged thought-provoking discussion and raised issues in science communication from many angles.

Prof. Ellie Highwood opened the session challenging us all to step beyond the typical methods of scientific communication. Try presenting your science without plots. Try presenting your work with no slides at all! You could step beyond the boundaries even more by creating interesting props (for example, the notorious climate change blanket). Next up Chris Huhne and Leo Hickman gave an overview of the political and media interactions with climate change science (respectively). The Brexit referendum, Trump’s withdrawal from the Paris Accord and the rise of the phrase “fake news” are some of the issues in a society “where trust in the experts is falling”. Finally, Dr Amanda Maycock presented a broad overview of influential science communicators from the past few centuries. Is science relying too heavily on celebrities for successful communication? Should the research community put more effort into scientific outreach?

Communication and collaboration became the two overarching themes of the conference, and conferences such as this one are a valuable way to develop these skills. Thank you to the Royal Meteorology Society and UK Met Office for hosting the conference and good luck to all the young scientists that we met over the two days.

#RMetSImpact

DEkAxGgXkAAmaWE.jpg large

Also thank you to NCAS for funding my conference registration and to all those who provided photos for this post.

Peer review: what lies behind the curtains?

Email: a.w.bateson@pgr.reading.ac.uk

Twitter: @a_w_bateson

For young researchers, one of the most daunting prospects is the publication of their first paper.  A piece of work that somebody has spent months or even years preparing must be submitted for the process of peer review. Unseen gatekeepers cast their judgement and work is returned either accepted, rejected or with required revisions. I attended the Sense about Science workshop entitled ‘Peer review: the nuts and bolts’, targeted at early career researchers (ECRs), with the intention of looking behind these closed doors. How are reviewers selected? Who can become a reviewer? Who makes the final decisions? This workshop provided an opportunity to interact directly with both journal editors and academics involved in the peer review process to obtain answers to such questions.

This workshop was primarily structured around a panel discussion consisting of Dr Amarachukwu Anyogu, a lecturer in microbiology at the University of Westminster; Dr Bahar Mehmani, a reviewer experience lead at Elsevier; Dr Sabina Alam, an editorial director at F1000Research; and Emily Jesper-Mir, the head of partnerships and governance at Sense about Science. In addition, there were also small group discussions amongst fellow attendees regarding advantages and disadvantages of peer review, potential alternatives, and the importance of science communication.

18527387_1077446359022532_4975831821751623706_o
The panel of (L-R) Dr Sabina Alam, Dr Amarachukwu Anyogu, Dr Bahar Mehmani and Emily Jesper-Mir provided a unique insight into the peer review process from the perspective of both editor and reviewer. Photograph credited to Sense about Science.

Recent headlines have highlighted fraud cases where impersonation and deceit have been used to manipulate the peer review process. Furthermore, fears regarding bias and sexism remain high amongst the academic community. It was hence encouraging to see such strong awareness from both participants and panellists regarding the flaws of the peer review. Post-publication review, open (named) reviews, and the submission of methods prior to the experiment are all ways either in use currently or proposed to increase the accountability and transparency of peer review. Each method brings its own problems however; for example, naming reviewers risks the potential for less critical responses, particularly from younger researchers not wanting to alienate more experienced academics with influence over their future career progression.

One key focus of the workshop was to encourage ECRs to become involved in the peer review process. In the first instance this seems counterintuitive; surely the experience of academics further into their career is crucial to provide high quality reviews? However, ECRs do have the knowledge necessary. We work day to day with the same techniques, using the same analysis as the papers we would then review. In addition, a larger body of reviewers reduces the individual workload and will improve the efficiency of the process, particularly as ECRs do not necessarily have the same time pressures. Increased participation ensures diversity of opinion and ensures particular individuals do not become too influential in what ideas are considered relevant or acceptable. There also exist personal benefits to becoming a reviewer, including an improved ability to critically assess research. Dr Anyogu for example found that reviewing the works of others helped her gain a better perspective of criticism received on her own work.

18527133_1077447019022466_6449209230504509579_o
Participants were encouraged to discuss the advantages and disadvantages of peer review and potential changes that could be made to address current weaknesses in the process. Photograph credited to Sense about Science.

One key message that I took away from the workshop is that peer review isn’t mechanical. Humans are at the heart of decisions. Dr Alam was particularly keen to stress that editors will listen to grievances and reconsider decisions if strong arguments are put forward. However, it also then follows that peer review is only as effective as those who participate in the process.  If the quality of reviewers is poor, then the quality of the review process will be poor. Hence it can be argued that we as members of the academic community have an obligation to maintain high standards, not least so that the public can be reassured the information we provide has been through a thorough quality control process. In a time when phrases such as ‘fake news’ are proliferating, it is crucial more than ever to maintain public trust in the scientific process.

I would like to thank all the panellists for giving up their time to contribute to this workshop; the organisations* who provided sponsorship and sent representatives; Informa for hosting the event; and Sense about Science for organising this unique opportunity to learn more about peer review.

*Cambridge University Press, Peer Review Evaluation, Hindawi, F1000Research, Medical Research Council, Portland Press, Sage Publishing, Publons, Elsevier, Publons Academy, Taylor and Francis Group, Wiley. 

A PhD Student’s Guide to EGU 2017

Email: r.frew@pgr.reading.ac.uk

EGU2017logo

Science is a community effort, requiring collaboration and lots of different people providing different parts of the jigsaw to try to understand more and more of the full picture. Despite a lot of research being carried out individually in a lab, or at a desk, no one individual can do everything themselves, no matter how much of a genius they are. Sharing, discussing and debating are key to the progression of scientific ideas, and this ethos is something large scientific conferences like EGU cultivates.

Attending EGU for the first time as a PhD student was both an exciting and overwhelming experience due to its shear size and number of people. This year 14,496 people from 107 countries participated, giving 4,849 talks, 11,312 posters and 1,238 PICO presentations throughout the week!  

With 649 scientific sessions running throughout the week, deciding how to spend your day was a significant challenge in itself! The EGU website and app allowed you to create a personal programme, cutting down the number of entire printed programmes being printed, aiming to try to make EGU slightly more environmentally friendly.

IMG_2541
Vienna international conference centre, image courtesy of Matt Priestley.

A ‘typical’ day at EGU consisted of something like… 

7-8am: Wake up, shower and breakfast and then hop on the U-bahn to the conference centre. Pick up a EGU Today newsletter on the way into the centre, highlighting a few sessions happening that day that may be of general interest

8.30-10am: Division session of your choice consisting of six 15min talks. People also pick out specific talks in different sessions and hop between, especially if their work is more interdisciplinary and covers a few different sessions.

10-10.30am: Recharge with a much needed coffee break!

10.30am-12pm: Go to a debate on ‘Make Facts Great Again: how can scientists stand up for science?‘ There were a number of other topical debates throughout the week, including ‘Arctic environmental change: global opportunities and threats‘ and ‘Great Debate on Great Extinctions‘. This consisted of a short introduction from members of a panel, then questions from the floor.

12-1.30pm: Pick up something for lunch from one of the nearby bakeries or cafes around the conference centre, and sit in the nearby park and enjoy the sunshine (hopefully).

1.30-3pm: Explore the many information stands in the exhibition areas. These included publishing houses, geoscience companies, NGOs etc. Next go and vote in the EGU photograph competition: https://imaggeo.egu.eu/photo-contest/2017/, before stopping to listen to some PICO (Presenting Interactive COntent) presentations. These are very interactive sessions where speakers give a 2min overview of their work, after which people have the opportunity to go and question speakers further afterwards by a poster/couple of slides.

3-3.30pm: Tea/coffee break with cookies in the Early Career Scientists lounge.

3.30-5pm: Polar Science Career Session aimed at Early Career Scientists (there were also sessions for other divisions), consisting of an informal Q&A with a panel covering a variety of different career paths.

5-7pm: Poster sessions in the big halls with beer/juice and nibbles. These were a great opportunity for in depth discussion, and meeting other people in your field.

7-8.30pm: Early career scientist (ECS) reception with drinks and canapes, meet other ECS from all fields and chat with division leaders. This year 53% of EGU participants were ECSs, and there was a definite effort to cater for them throughout the week.

8.30-?: Dinner and drinks in Vienna town centre with peers, followed by an early night if you plan to make it to a 8.30am session tomorrow…

EGU2017photowinners
EGU 2017 photo competition entries, image taken from the GeoLog blog, more information about the entries and results can be found at: http://blogs.egu.eu/geolog/2017/04/28/at-the-assembly-2017-friday-highlights/

In addition to events highlighted, there were also a variety short courses running, for example ‘Tips and Tricks: How to Navigate EGU‘, ‘How to write a research grant‘ or ‘Rhyme your Research‘! EGU had its own official blog GeoLog, highlighting some of the events from each day: http://blogs.egu.eu/geolog/.

However, EGU is 5 days long, and despite the impressive offering of sessions being put on it would be a shame to go to Vienna and only see the conference centre… The odd extended lunch break to take the U-bahn (included as part of the entrance to the conference) to walk around the centre, or an afternoon off to explore a gallery or museum, or simply sit in one of the beautiful parks or cafes to enjoy some coffee and Sachertorte is definitely a must to recharge and finish off the week!

Can we really use El Niño to predict flooding?

R. Emerton, H. Cloke, E. Stephens, E. Zsoter, S. Woolnough, F. Pappenberger (2017). Complex picture for likelihood of ENSO-driven flood hazard. Nature Communications. doi: 10.1038/NCOMMS14796

Email: r.e.emerton@pgr.reading.ac.uk

When an El Niño is declared, or even forecast, we think back to memorable past El Niños (such as 1997/98), and begin to ask whether we will see the same impacts. Will California receive a lot of rainfall? Will we see droughts in tropical Asia and Australia? Will Peru experience the same devastating floods as in 1997/98, and 1982/83?

news_headlines_elnino

El Niño and La Niña, which see changes in the ocean temperatures in the tropical Pacific, are well known to affect weather, and indeed river flow and flooding, around the globe. But how well can we estimate the potential impacts of El Niño and La Niña, and how likely flooding is to occur?

This question is what some of us in the Water@Reading research group at the University of Reading have been looking to answer in our recent publication in Nature Communications. As part of our multi- and inter-disciplinary research, we work closely with the Red Cross / Red Crescent Climate Centre (RCCC), who are working on an initiative called Forecast-based Financing (FbF, Coughlan de Perez et al.). FbF aims to distribute aid (for example providing water purification tablets to prevent spread of disease, or digging trenches to divert flood water) ahead of a flood, based on forecasts. This approach helps to reduce the impact of the flood in the first place, rather than working to undo the damage once the flood has already occurred.

Photo credit: Red Cross / Red Crescent Climate Centre

In Peru, previous strong El Niños in 1982/83 and 1997/98 had resulted in devastating floods in several regions. As such, when forecasts in early 2015 began to indicate a very strong El Niño was developing, the RCCC and forecasters at the Peruvian national hydrological and meteorology agency (SENAMHI) began to look into the likelihood of flooding, and what FbF actions might need to be taken.

Typically, statistical products indicating the historical probability (likelihood [%] based on what happened during past El Niños) of extreme precipitation are used as a proxy for whether a region will experience flooding during an El Niño (or La Niña), such as these maps produced by the IRI (International Research Institute for Climate and Society). You may also have seen maps which circle regions of the globe that will be drier / warmer / wetter / cooler – we’ll come back to these shortly.

These rainfall maps show that Peru, alongside several other regions of the world, is likely to see more rainfall than usual during an El Niño. But does this necessarily mean there will be floods? And what products are out there indicating the effect of El Niño on rivers across the globe?

For organisations working at the global scale, such as the RCCC and other humanitarian aid agencies, global overviews of potential impacts are key in taking decisions on where to focus resources during an El Niño or La Niña. While these maps are useful for looking at the likely changes in precipitation, it has been shown that the link between precipitation and flood magnitude is nonlinear (Stephens et al.),  – more rain does not necessarily equal floods – so how does this transfer to the potential for flooding?

The motivation behind this work was to provide similar information, but taking into account the hydrology as well as the meteorology. We wanted to answer the question “what is the probability of flooding during El Niño?” not only for Peru, but for the global river network.

To do this, we have taken the new ECMWF ERA-20CM ensemble model reconstruction of the atmosphere, and run this through a hydrological model to produce the first 20th century global hydrological reconstruction of river flow. Using this new dataset, we have for the first time estimated the historical probability of increased or decreased flood hazard (defined as abnormally high or low river flow) during an El Niño (or La Niña), for the global river network.

elnino_flood_hazard_gif_beccalize
Figure 1: The probability of increased (blue) or decreased (red) flood hazard during each month of an El Nino. Based on the ensemble mean of the ERA-20CM-R 20th century river flow reconstruction.

The question – “what is the probability of flooding during El Niño?”, however, remains difficult to answer. We now have maps of the probability of abnormally high or low river flow (see Figure 1), and we see clear differences between the hydrological analysis and precipitation. It is also evident that the probabilities themselves are often lower, and much more uncertain, than might be useful – how do you make a decision on whether to provide aid to an area worried about flooding, when the probability of that flooding is 50%?

blob_floodhazard_comparison_map
Figure 2: Historical probability of increased / decreased flood hazard map for February, with overlay showing the typical impact map for winter during an El Nino. This highlights the complexity of the link between El Nino and flooding compared to the information usually available.

The likely impacts are much more complex than is often perceived and reported – going back to the afore-mentioned maps that circle regions of the globe and what their impact will be (warmer, drier, wetter?) – these maps portray these impacts as a certainty, not a probability, with the same impacts occurring across huge areas. For example, in Figure 2, we take one of the maps from our results, which indicates the probability of increased or decreased flood hazard in one month during an El Niño, and draw over this these oft-seen circles of potential impacts. In doing this, we remove all information on how likely (or unlikely) the impacts are, smaller scale changes within these circles (in some cases our flood hazard map even indicates a different impact), and a lot of the potential impacts outside of these circles – not to mention the likely impacts can change dramatically from one month to the next. For those organisations that take actions based on such information, it is important to be aware of the uncertainties surrounding the likely impacts of El Niño and La Niña.

“We conclude that while it may seem possible to use historical probabilities to evaluate regions across the globe that are more likely to be at risk of flooding during an El Niño / La Niña, and indeed circle large areas of the globe under one banner of wetter or drier, the reality is much more complex.”

PS. During the winter of 2015/16, our results estimated an ~80% likelihood of increased flood hazard in northern coastal Peru, with only ~10% uncertainty surrounding this. The RCCC took FbF actions to protect thousands of families from potentially devastating floods driven by one of the strongest El Niños on records. While flooding did occur, this was not as severe as expected based on the strength of the El Niño. More recently, during the past few months (January – March 2017), anomalously high sea surface temperatures (SSTs) in the far eastern Pacific (known as a “coastal El Niño” in Peru but not widely acknowledged as an El Niño because central Pacific SSTs are not anomalously warm) have led to devastating flooding in several regions and significant loss of life. And Peru wasn’t the only place that didn’t see the impacts it expected in 2015/16; other regions of the world, such as the US, also saw more rainfall than normal in places that were expected to be drier, and California didn’t receive the deluge they were perhaps hoping for. It’s important to remember that no two El Niños are the same, and El Niño will not be the only influence on the weather around the globe. While El Niño and La Niña can provide some added predictability to the atmosphere, the impacts are far from certain.

Presidente Kuczynski recorre zonas afectadas por lluvias e inund
Flooded areas of Trujillo, Peru, March 2017. Photo credit: Presidencia Peru, via Floodlist

Full reference:

R. Emerton, H. Cloke, E. Stephens, E. Zsoter, S. Woolnough, F. Pappenberger (2017). Complex picture for likelihood of ENSO-driven flood hazard. Nature Communications. doi: 10.1038/NCOMMS14796

Press Release: