To Conclude

Well, it's already my last post - this has come round extremely quickly! I'd like to use this last post to summarise the things I've been talking about, and to reflect on my blogging experience. I hope that the passion I have for this subject has come across over the last few months, and that it hasn't been too disorientating - I know I've thrown a lot of different information at this blog, but this really reflects the diverse nature of hydrological climate change and the effects it has on humans, both directly and indirectly.  Some of the posts have had very individual themes, so I'd like to conclude the messages I've been conveying. 

1. Climate change caused by humans is altering the hydrological cycle as a whole, with a wide variety of effects - increased rainfall, drought, declines in water quality, a less reliable water supply, reductions in the water available in the tropics - just to name the major ones.

2. Hydrological climate change is intrinsically linked to human health and well being, seeing as we all depend on water. These effects range from the physical (e.g. contaminated drinking water), to the economic (e.g. damage from flooding), to the mental (e.g. risk of extreme weather and associated fear).

3. Though we are pretty sure what the main trends are going to be, we must not forget that their is still great uncertainty associated with attempting the model changes to the hydrological cycle and their potential effects - uncertainty is inherent whenever you try to predict something that has not yet happened.

4. This is not a problem to leave for the future - it is already happening. I hope that it is has run through the blog that my personal opinion is that now is the time for action. I am deeply worried that the scientific community refuses to be as vocal as it should about the potential effects of climate change, largely as a result of the uncertainties involved and a strict adherence to the traditions of the scientific method, feeling that we have to always talk about the uncertainties to be truly scientific. I disagree with this approach. I have long been an admirer of the late Stephen Schenider, a climate scientist who worked with the IPCC and recognised how science has to change its approach when communicating climate change:

On the one hand, as scientists we are ethically bound to the scientific method, in effect promising to tell the truth, the whole truth, and nothing but — which means that we must include all the doubts, the caveats, the ifs, ands, and buts. On the other hand, we are not just scientists but human beings as well.

Source

Schneider did not directly work on climate change and the hydrological cycle, but I agree with his words. We cannot expect the world to make decisions if things are perceived as so uncertain - the science has to be expressed in a way that makes sense to the world as a whole, and not just the climate scientists, if anything is to truly change. 

I hope you've enjoyed reading my blog, and that I've presented the science fairly. Writing about hydrological climate science in non academic casual language has been such a joy - science exists to be communicated and this is the way to do it best, despite academic prose having it's place. It is my great hope that I can come back and read this blog in 10 years and feel happy in the progress we have made in understanding and mitigating against the effects hydrological climate change may have on humans. Here's hoping.

A Price to Pay

As the penultimate post, I thought I'd start to round off the blog by talking about the economics of adaption - just how much is it going to cost to adapt human water systems to the changes to the hydrological cycle that will likely occur over the next 50 years? Calculating such global costs for the water sector is clearly not a simple task, and there is no trace of certainty in any numbers that have been produced. However, they are figures that are hopefully indicative of the scale of the changes the world will face.

Kirshen (2007) estimates the global cost (more than 200 countries) of maintaining water services at current levels through to 2030 under a medium emissions scenario to be US$531 billion. The United Nations Framework Convention on Climate Change (2007) suggest a figure US$225 billion s (approximately US$11 billion per year), for the same emissions scenario. These are incredibly large numbers - US$11 billion is the equivalent of China's 2016 GDP, and this is only the annual cost of adapting the water sector to maintain water services until 2030!

Looking forward to the year 2050, Ward et al. (2010) use suggest average annual costs of US$19.7 billion (in a drier projection of climate) and US$14.4 billion (in a wetter projection of climate) to maintain current global water supply and flood protection. These numbers were derived by using a global climate model (GCM) to make climate projections, and estimating costs based on the projections. Once again, big numbers.

Perhaps of special interest in addressing the costs of hydrological climate change is sub-Saharan Africa. This is a region that will be particularly affected by climate change, and is a region of the world where many live in poverty. While they are now outdated, having been succeeded with Sustainable Development Goals (SDGs) for 2030, the 2015 Millennium Development Goals have been used to assess the cost of adoption to hydrological climate change in sub-Saharan Africa. Muller (2007) suggests an annual cost for the adaptation of urban water infrastructure of US$1.1 to 2.7 billion to, with an additional $1.0 to 2.5 billion required to upgrade infrastructure to meet the Millennium Development Goals. Clearly these figures are now approaching 10 years out of date, and do not reflect current development targets nor economic changes since then, but they are still useful. The countries of sub-Saharan Africa are amongst the poorest in the world, and will likely struggle to fund such costs. Given the sensitivity and current state of the region, some amount of aid on behalf of the rest of the world is going to be needed here.

I hope this post helps put the financial scale of hydrological climate change in some sort of context, even if it does just address the adaptation of  water infrastructure and makes no reference to the costs of other hydrological changes. While the numbers are very large, please do take them with a pinch of salt; there is obviously no way to be at all sure what the costs will be, and they are very much just estimates. However, they do make a clear point - this is an expensive issue. Humans die without a reliable supply of clean water, so much expense is will have to be paid. Quite as to who will pay is the question, particularly in the case of the poorer area of the world.

Dealing with Uncertainty

Throughout the blog, I've been talking about how we have utilised both climatic and hydrological computer models to make predictions for how the hydrological cycle may change in the future, and the effect it will have on humans. This week, I'd like to focus on the overall methodology and philosophy behind this method, and address the topic of uncertainty. While the scientific community is generally in agreement in what the impacts of climate change on the hydrological cycle may be, note that in previous posts I've mostly used the words 'could' or 'may' when talking about potential changes. Nothing is set in stone, and the process of trying to predict the future is inherently something of a dark art. 

In theory, the study of the effects of climate change on the hydrological cycle is undertaken to allow us as humans to understand why changes may be occurring, and how we can adapt to those changes. However, one of the key challenges in factoring climate change into management of water resources is uncertainty. In England and Wales, a small set of only three climate scenarios (derived from a variety of climate models) has been used to suggest a potential range of impacts, mostly focusing on one central scenario, and using very simple mathematical approaches to apply the scenarios (Arnell, 2011). In contrast, some approaches have used very large numbers of scenarios to assess impact (e.g. Christierson, et al. 2012), and assess the probability of certain impacts occurring, a feature that is very useful in risk assessment. However, it has been suggested that assessing the probability of hydrological changes in this way is impossible due to the considerable scientific uncertainty on how the climate system and hydrological system may change, and how to represent these possible changes. Stainforth, et al. (2007) argue that it is not possible to develop purely quantitative probability distributions of the impacts of climate change on water resources, and that the philosophy of representing uncertainty needs to change, potentially by interpreting the outcome of modelling studies less quantitatively - e.g. looking for a overall patterns and general magnitudes of change, rather than absolute values. 

This really is something of a debate in the scientific community; some feel we can use models to identify the risks of hydrological change and inform adaptation, while some feel they are simply not reliable enough to do this. Koutoyiannis, et al. (2008) compare the hydrological outputs of a variety of climate models to observations around the globe, and argue that global climate models perform very poorly at a both a small and large spatial scale. Wilby (2010) develops this argument further, suggesting a conceptual divide in the hydrological science community between those who advocate a scenario-led approach to water resource adaptation, and those who feel scenarios are better used to assess potential adaptation options. Wilby notes that hydrological processes are incredibly diverse in  in time, and as a result the management questions that need to be answered vary dramatically in time too, spanning minutes for real time flood protection through to multiple decades for provision of water. It is suggested that climate models are not reliable enough to answer the questions required for future adaptation as a result of their inability to accurately reproduce the temporal characteristics found in hydrological records.

The other side of the debate are those who think models are robust enough to inform hydrological adaptation, and feel that the critique of climate models is unjust. In a particularly strongly worded journal article, Huard (2011) attacks the publication of papers suggesting climate models cannot inform water management, claiming they are based on the misconception that climate models predict natural climate variability in a deterministic way, involving no randomness and always producing the same result given a certain input. Huard notes that this is indeed how hydrological models operate, but that this is not the way global climate models work. They are inherently chaotic and non-deterministic in their nature, with both the natural variability of the climate system and the influence of external factors playing a role. As such, a climate projection is not a deterministic prediction of climate, but 'an experiment probing the model's response to changes in greenhouse gas concentrations'. Assuming this, it is unreasonable to suggest that individual climate models should be able to predict past hydrological observations with supreme accuracy, given that they have to randomly simulate natural climate variability. To properly assess a climate model's performance, it is necessary to extract the response to external anthropogenic forcing from the inherent random natural variability.

Uncertainty in climate modelling is a huge topic, and I've only presented a short introduction to it here, but I think it is an extremely important topic to discuss, seeing as we are making a lot of predictions and decisions based on climate models. While it is a boring and non-controversial opinion, I sit somewhat on the fence on this issue. I certainly feel that climate models are of great value, but that they are experimental sandboxes that should be used to inform adaptation, as opposed to being what we base adaptation on. Quite frankly we do not have enough time to debate how we should interpret uncertainty, and need to actually get on with finding a framework of how to use all the data and projections available to inform adaptation!

Christmas Warmth

It's Christmas Eve, and Santa will be loading up his sleigh. However, he might have quite a sweat on while he does this - news headlines today have included the story that temperatures at the North Pole may be 20°C above average today, which would break all records. I realise this isn't strictly related to hydrological change, but this is so interesting I think it is worth taking a quick festive look at. These sorts of temperature changes will no doubt have an influence on the hydrological cycle; as we know, warm air can hold more water.

Two weeks back, I touched on how 2016 has been a record breaking year for temperatures globally, but this heatwave event in the Arctic really is something else, likely a 1 in 1000 year event. The temperature at the North Pole today is about 0°C, which for Santa is very warm - he prefers the -20°C average. Scientists are confident these anomalous temperatures are a result of the influence of anthropogenic climate change. It's quite pleasing to see this story make the headlines today, as I think it is something the general public were not particularly aware of. Global public awareness of anomalous climate events and their link to anthropogenic warming can only be a positive thing - though I think the story only made the news due to it's link to Santa and Christmas! I don't think a temperature anomaly of 20°C in the Amazon would have been reported today....

I will leave the final words to Dr Thorsten Markus, chief of NASA's Cryospheric Sciences Laboratory, who has discussed what is really the true issue of the day - Santa's sledding attire.:

"Santa is most likely overdressed. Maybe in the future we'll see him in a light jacket or plastic mac."

The Boxing Day sales could prove useful if this is the case. Happy Hydrological Christmas!

A Mental Struggle

Over the past weeks, I've touched on some of the key issues that changes to the hydrological cycle as a result of climate change may cause for human physical health - a lack of  water causing illness and famine, the spread of water-borne diseases through drinking contaminated water, and the threat to health from extreme flood and drought events. However, human health extends beyond physical health issues to mental health issues. It isn't something that is talked about very much, but climate change and its resultant effects on the hydrological cycle pose a risk to mental health, a key aspect of human well-being. Dealing with problems of this scale and complexity is not easy, and this can take its toll on the human brain.

Changes in the hydrological cycle can cause changes to the environments with which people feel familiar, whether through flooding, drought, storm surges, or pollution of water resources. Humans complex brains are able to develop strong bonds between other people and the physical environmental that surrounds them - the 'sociophysical' environment. The disruption that hydrological climate change can cause to the environment so cherished by humans can cause grief, a sense of loss, and great anxiety. This has been coined 'solastalgia' - the distress caused by environmental change (Albrecht, et al. 2007). 

There are many case studies that provide examples of solastalgia. For example, Brubaker, et al. (2011) demonstrate the stress and fear that has been experienced in Alaskan villages that have become increasingly vulnerable to flooding and storm surges during the storm season, with residents reporting sleepless nights and stress during spells of bad weather. Interestingly, residents reported feeling 'safer' and 'happier' after the construction of a 1,000m long sea wall; hard engineering is often perceived by the public to be what will keep them safe from disaster. 

The Lancet Commission report on global health and climate change provides another example, suggesting that  the recent decade-long drought in Australia has caused an increase in depression, anxiety and possibly suicide rates in rural populations. Drought means the livelihoods and key sources of financial income of these rural populations are affected (crop and animal farming), causing great distress. This distress is compounded by feelings of powerlessness in the face of climate change; try putting yourself in their shoes and you can see why the drought has taken such a toll on these populations.

As climate change progresses, some local communities will have to face the task of planning and adapting to environmental change. Mentally, this is not an easy process. Coastal communities that may be suffering from erosion as a result of storm surges and rising sea levels provide an example of how mentally difficult the decision making process might be. In some coastal communities, the only solution is a managed retreat, which can cause great distress associated with place attachment - it is hard to accept that a cherished place to which you are attached may be allowed to erode away, with no attempt at defending it (Ageyman, et al. 2009). Imagine you were told that your seaside cottage will not be defended and left to fall into the sea; this has happened in the UK, and some have taken matters in their own hands and have attempted to engineer their own coastal defences, whether legally or illegally. You can see why.

An example of do it yourself coastal engineering in Suffolk - the darker band of soil is a man-made addition by the homeowner, who was taken to court. Credit: www.geographyphotos.com

Understanding these links between hydrological climate change and mental health is not easy - climate change works in the language of  numbers, and mental health works in the language of emotions. Quantitative (numeric) study of the link has been proposed through an 'Environmental Distress Scale'  (Higginbotham, et al. 2007), which 'combines dimensions of hazard perception, threat appraisal, felt impact of changes, ‘solastalgia’’ (loss of solace), and environmental action'. While this index may potentially be useful in some cases, it is hard to model some climate-mental health relations due to their inherently non quantitative nature, so we may need to develop some innovative qualitative (descriptive, non-numeric) ways of understanding the impacts of climate change on mental health. Climate change is not just about numbers and graphs when we are talking about the effects on humans. 

While I've talked about some serious issues in this post, don't have nightmares, and keep everything about hydrological climate change in perspective! We as humans have caused these changes, and it is within our grasp to mitigate, adapt, and reverse them. However, do remember that climate change is already happening, and for some is causing great mental distress. It really is important to talk about this - just as important as the physical effects of climate change on humans.

COP21 - One Year On

We are currently one year on from the historic COP21 Negotiations in Paris, where some agreement was made between politicians of all nations to attempt to reduce emissions. This is obviously very important with respect to the potential changes to hydrological cycle I have already talked about. The target is to keep the warming of the earth's climate below 2C, but I personally believe that is now impossible. Why? This is a very popular animation of global temperatures that recently became viral, but it indicates an important point - we are coming close to pushing 1.5C of warming already, with 2016 being a year that has broken records temperature wise. Just look at the end of the animation; it will comfortably become the warmest year on record. Admittedly, it is a year with a strong El Nino (a climate phenomenon that leads to warmer temperatures globally), but even accounting for this, it is incredibly warm.

Credit: Ed Hawkins

To celebrate anniversary of COP21 , I thought I'd share a cartoon that amused me. This is a bit of fun and not at all realistic, but behind the cartoon there is an important message - will we ever really do anything major to act internationally as things stand?  Only time will tell if the agreements reached at COP21 will have any impact, particularly given events such as a the recent election of Donald Trump in the USA. I still worry for the changes to the hydrological cycle that are yet to come, but also remain optimistic that humans do have to power to enact change. We just have to give ourselves the chance to enact change - we are so dependent on water. Enjoy the cartoon.

Credit: The Economist

There's a Storm a Coming

The UK has just experienced its first named storm of Autumn 2016, Storm Angus, which hit the UK on the 20th November. As a result, there were some quite nasty weather conditions and impacts for the south of the UK - flooding, power cuts, ships running aground, and car accidents causing people to be hurt, though there were thankfully no fatalities. Take a look at this nice summary by the Met Office if you are interested in what happened. It is too early to say how much damage was caused by the storm, but this picture of a street in Bristol indicates the sort of issues that might have occurred:

Credit: Lee Gitsham/PA

In light of this recent storm, and following on from the article about jet stream research I posted a few weeks back, I thought it topical this week to explore the relationship between intense weather events and climate change, with a particular focus on the UK. At a global scale, there is consensus from the IPCC that climate change will lead to more extreme rainfall events in the future, but with a higher number of dry days. This is caused by the fact that in a warming world, air can hold more water vapour before it reaches the point where it must fall as precipitation. As such, there will be less rainfall events as a whole (it takes longer for the amount of water needed for there to be rain to build up), but the rainfall events that do occur will be more extreme in both their intensity and duration. There are obvious implications from this sort of climatic arrangement - an increased risk of flooding, damage, and loss of life during extreme weather events.

The discussion has already begun as to whether the recent Storm Angus has been influenced by climate change. The UK has experienced a succession of strong and destructive winter/autumn storms in the past 5 years, leading to widespread debate as to whether climate change is affecting weather patterns in the UK. During the recent severe floods of 2013/14 in southern England, Prime Minister at the time David Cameron told parliament that he 'very much suspected' anthropogenic climate change was associated with the event.  These floods were quite severe, and caused by continual low pressure storm systems moving in from the Atlantic across southern England, with a consistent amount of high level precipitation leading to flooding.

It is very hard to pin a single extreme weather event to climate change; it is simply one event in a chaotic system, and it is hard to tell whether that one event is due to a change in the boundary conditions of the system, or is simply a natural part of the chaotic system. Despite that, attempts have begun to examine whether anthropogenic climate change may have increased the risk of the occurrence of heavy storms and resultant flooding that have been recently been experienced in the UK.

The first piece of such research was published earlier this year by Schaller, et al. (2016), who examined the potential influence anthropogenic climate change had on the floods of 2013/14 in southern England. They conclude (through the use of a variety of climate model simulations) that along with the atmosphere being able to hold more moisture, anthropogenic warming has likely caused a small increase in the number of January days that have a westerly airflow, and a stronger jet stream. In combination, both of these factors increase the risk of the UK experiencing events of extreme precipitation.

The study then feeds this information into a hydrological model, in an attempt to understand how this event affected the River Thames - the area around the Thames is one of the key places flood damage to property occurred during 2013/4. It is found that under these the conditions experienced in 2013/4, the 30 day average of peak river flow in the Thames increased significantly. Combining these results with flood risk mapping, a small increase is found at the number of properties at risk from riverine flooding, though there is great uncertainty in the true value of the number. Despite this, similar events of a greater intensity could lead to even greater flood damage.

All of the aspects of this study have large bounds of uncertainty - the conclusions that have been drawn are simply the best estimates of the data available, reflecting how anthropogenic climate change has so far only had a subtle impact in increasing the risk of intense precipitation events in the UK. Far more attribution studies of this type are needed to begin to understand how climate change is affecting UK weather patterns. However, it is reasonable to suggest from this study alone that it is likely anthropogenic climate change may be beginning to influence extreme weather events in the UK - keep an eye on the weather forecast this winter! The next named storm we experience in the UK will begin with a B, so guesses for the name in the comments please! I'm going for Storm Bertha.