It's been an interesting journey writing this blog so this is just a quick summary of my thoughts on El Niño Southern Oscillation and its importance for water and development in Africa.
Firstly, El Niño Southern Oscillation is a fascinating natural phenomenon, and I've learned so much about how it works and where it impacts in the world. Particularly since El Niño Southern Oscillation occurs in the Pacific Ocean and Africa has no direct connection, it's been interesting for me to learn how something in one part of the world can come to affect regions halfway across the world.
Secondly, recognition of the importance of El Niño Southern Oscillation has been obviously growing; from being closely reported in the news, to even making an appearance on the Ellen Degeneres TV show! I think this is good news for research and for people seeking to understand how climate changes might affect them. The impacts of El Niño and La Niña years can also be used to further understanding of how long-term changes to climate might impact different areas. For example, Epstein (2000) explains how the meteorological changes that occur under El Niño years can simulate changes under warming temperatures and help in assessing the likely impacts. His particular study focuses on health, and how waterborne disease outbreaks are associated with the extreme weather of El Niño that could soon be commonplace due to increasing global temperatures.
Thirdly, with predictions that there will be an increased frequency of El Niño events due to climate change, it is important that research into the potential impacts is further developed. More countries may be affected by future El Niño events, so it is beneficial for all to study the results of historic El Niño events (such as the one just passed/that we're in the middle of this winter) and improve projections of impacts for future El Niño events.
Finally, understanding how El Niño Southern Oscillation events can affect communities is a part of mitigating for future climate changes. As Nick describes in his blog post, building resilience to changing climate is important, particularly for smallholder farmers. Understanding the likely conditions El Niño or La Niña could create is part of this. Therefore, initiatives such as the Gro Futures El Niño Monitoring in Tanzania, are important for mitigation and adaptation to climate change. This initiative looks to measure how heavy rains associated with the El Niño Southern Oscillation replenish groundwater resources in Tanzanian wellfields. As stated, this will bring better understanding to sustainable management of the wellfield, as well as inform "strategies for amplifying replenishment". Studies like these are vital to continuing to measure and understand El Niño effects, particularly as they can be linked to high variability that is unsustainable and unpredictable.
El Niño Southern Oscillation events still remain rather mysterious and hard to predict; each El Niño or La Niña year results in different consequences and patterns and the spatial distribution of effects can be difficult to predict. I hope with further studies we will begin to understand this fascinating phenomenon in more depth, and be better equipped to react and plan for its potentially deadly effects.
Tuesday, December 22, 2015
Friday, December 11, 2015
El Niño effects on water access
Therefore, I think the biggest challenges that ENSO can create for access to water are affecting water quality and the damages to the socio-economic structure of a population. This area may be less researched than the scientific side of ENSO and the direct output of El Niño/La Niña years (particularly rainfall), but it highly important for development and water management.
Last month, Unicef released a statement to emphasise the impact the El Niño winter and potential La Niña year could have on vulnerable communities. They summarised the threat to Africa as follows: "An estimated 11 million children are at risk from hunger, disease and lack of water in eastern and southern Africa as a result of a strengthening El Niño". Hunger, disease and adequate water for living are all linked back to having good access to safe water supplies. Firstly, as the previous blog post mentions, the variability of rainfall under ENSO conditions can cause problems for water availability for both domestic and agricultural use. If we are to expect more and more El Niño years, southern Africa must be prepared for droughts or else suffer a major shortage of water.
Secondly, waterborne diseases can be massively exacerbated by rainfall variability and contamination. The IPCC acknowledges that the frequency and duration of cholera outbreaks
are associated with heavy rainfall in, "with a possible association with the El Niño-Southern Oscillation", in western African and southern African countries. Cann et al. (2013) also studied weather events and waterborne diseases and suggest that "extreme water-related weather events" (such as El Niño) lead to the highest numbers of cases of waterborne illness. ENSO-related outbreaks of cholera were also highly linked to extreme water temperature change due to Vibrio cholerae having an increased growth rate at increased temperatures. In general, they summarised that extreme water-related events (one-off or recurring) represent a risk to public health. Further studies of specific countries and diseases, such as de Magny et al. (2012), Mendelsohn and Dawson (2008), Mabaso et al. (2006) and Kilian et al. (1999), all agree that increased rainfall due to ENSO seemed to result in higher incidence of waterborne diseases like cholera and malaria in Africa. This also seems to ring true in other parts of the world affected by ENSO, such as India and Sri Lanka. However, Patz et al. (2000) astutely reminds us all that ENSO is not responsible for all epidemics, such as the Ethiopian epidemics in 1953 and 1958, neither of which were El Niño years. In fact, Patz and Lindsay (1999) argue that in some cases, heavy rainfall could even wash larvae from breeding sites, thus reducing the incidence of malaria. Regardless of the patterns of disease, it is obvious that when water sources are contaminated (such as with cholera), or when incidence of other diseases are high, it is difficult for that population to have adequate access to safe water for use.
Thirdly, ENSO can also indirectly affect access to water through socio-economic and health issues. For example, severe droughts from ENSO conditions can lead to increased malnutrition and a threat to food security, which results in difficulty accessing safe water (as one can see, this is a vicious loop as little access to safe water can lead to problems that result in a decreased ability to ensure a safe water supply for oneself). Food security is a particularly important aspect that can be adversely affected by ENSO through highly variable rainfall for agricultural production. If water availability for agriculture is reduced, domestic consumption may be sacrificed in order to meet food demands, thus reducing access to safe water. Cane et al. (1994) used sea surface temperature to forecast maize yield in Zimbabwe and found that there was a strong correlation between the El Niño Index and maize yields, so much so that it correlated stronger than the El Niño Index and rainfall did. They found that more than 60% of the variance in maize yield in Zimbabwe was accounted for by sea surface temperatures in the eastern equatorial Pacific Ocean - where El Niño conditions are created.
Other socio-economic impacts of ENSO, other than health and food, include the economy, education and infrastructure. Cashin et al. (2015) conducted a study of the macroeconomics of El Niño, observing that South Africa (among many other countries such as Chile, Indonesia and Australia) see a "short-lived fall in economic activity" as a response to a typical El Niño event. This is mainly due to the increased in temperature and persistent dry conditions of El Niño, which impact agricultural production (which makes up 10% of South Africa's GDP). In addition, after particularly strong El Niño (and to some extent, La Niña) events, there may be other costs, such as the estimated $1.8 billion in damages of infrastructure and property in Kenya following the 1997-1997 El Niño flooding. And it isn't just flooding or droughts that cost money; ENSO can influence storms across Africa that can also contribute to costs. Donnelly and Woodruff (2007) show that while a strong El Niño year can hinder hurricane development through increased vertical wind shear, a strong La Niña year could increase North Atlantic hurricane activity. Damages to the economy can result in reduced access to water, particularly in the users are reliant on paying for water through vendors or kiosks. Infrastructure damage not only hinders access to water through costs but through the potential to damage water supply systems, roads to access water supply/health treatments, and other vital components of having an adequate supply of safe water to live. ENSO can also affect education through damage to infrastructure, limiting the ability of people to access areas, or in the worst cases, transforming school facilities into emergency shelters due to extreme events like floods. Education is not only vital for development, but it can contribute to improving access to water through NGOs like Water Aid, whose educational element is an important part of improving access to safe water in a sustainable manner.
Finally, the threats of ENSO conditions can leave many families crippled through deaths that could be related to floods, mudslides, famine, storms, or through separation due to a need to seek work elsewhere. Unicef emphasises that this could leave children vulnerable, as well as putting pressure on them to source water. Fewer members in a family evidently reduces access to water and further exacerbate all the problems already mentioned.
It can be very disconcerting to think about how ENSO events can impact the real ability of populations to access safe water and lead their everyday lives. Weather and climate are perhaps the most important aspect of water resources and it is therefore incredibly useful to have good prediction and forecasting systems in place to understand the potential impacts of ENSO on different regions around the world. I've really enjoyed learning about this and I think it's a positive sign that El Niño is becoming a more discussed topic in news and mainstream media and not just in the scientific and academic community. Hopefully our understanding of ENSO (not just El Niño but also La Niña!) continues to improve so we can better plan and mitigate for future ENSO events.
Thursday, December 3, 2015
El Niño effects on water availability
So now I hope we all have a better understanding of how El Niño Southern Oscillation can affect weather globally, and the two extremes that are El Niño and La Niña. To tie this in with the theme of water and development in Africa, the next two blogs will be exploring some ways ENSO can affect water resources in Africa.
Water resources can be impacted by ENSO through many different factors (see the table below for a quick summary). There are aspects (conditions) that ENSO affects like sea temperature, droughts, rainfall variability and storms. These natural changes (ENSO is a natural phenomenon after all, but arguably likely to be intensified due to climate change) can exacerbate man-made aspects of water resources such as flooding in poorly drained cities, contamination of water sources (due to flooding or drought) and more. This blog post will focus on water availability, or how ENSO can affect natural variability in water (such as rainfall), and the next blog post will focus on water access, or how ENSO can affect the ability of people to access water resources for use (such as contamination).
Water resources can be impacted by ENSO through many different factors (see the table below for a quick summary). There are aspects (conditions) that ENSO affects like sea temperature, droughts, rainfall variability and storms. These natural changes (ENSO is a natural phenomenon after all, but arguably likely to be intensified due to climate change) can exacerbate man-made aspects of water resources such as flooding in poorly drained cities, contamination of water sources (due to flooding or drought) and more. This blog post will focus on water availability, or how ENSO can affect natural variability in water (such as rainfall), and the next blog post will focus on water access, or how ENSO can affect the ability of people to access water resources for use (such as contamination).
|
Source: Water Quality and Health Council
In Africa, east and southeast Africa are the main areas affected by ENSO. During an El Niño winter, southeast Africa tends to be drier and warmer, and east Africa tends to be wetter. During a La Niña winter, the opposite occurs, with southeast Africa wetter than normal and east Africa drier than normal. These generic changes are by no means easily predicted and vary hugely within El Niño and La Niña years (and one must also remember that El Niño and La Niña years are not easily predicted either, nor does a La Niña year necessarily follow an El Niño year or vice versa). But this general pattern that occurs with ENSO dictates changes in weather that affect water resources.
For Africa, the biggest effects I would say ENSO has on water availability are affecting rainfall and influencing droughts. However, as I mentioned, this is highly variable even within El Niño years. For example, the 1997-1998 El Niño that is argued to be the last "truly massive" El Niño we've seen globally, had less of a disastrous effect on southern Africa than expected. The 1997-1998 El Niño may have cost an estimated $35 billion in destruction and 23,000 deaths around the world, but areas like southern Africa were surprised when the predicted catastrophic drought failed to materialise and seasonal rainfall was largely near or even above average. This is argued to have been because of a warm sea surface temperature anomaly in the South Atlantic that created upper easterly winds to counteract the ENSO-induced upper westerly winds over the Atlantic, and shielded southeastern Africa from ENSO (Jury, 1998).
In general though, ENSO tends to lead to a decrease in rainfall in southeastern Africa and drought periods. Rouault and Richard (2003) used the Standardised Precipitation Index to quantify intensity and spatial extension of droughts that have occurred in the 93 rainfall "districts" of the South Africa Weather Service. They found that there have been 10 dry years with an average of 44 dry districts since 1962, seven of which were El Niño years (1966, 1970, 1973, 1979, 1983, 1987, 1992 and 1995). This evidently shows that El Niño can play a major role in whether or not there are droughts in southeastern Africa. Available water resources during droughts are diminished as the water table drops, and effective management is crucial. In southeastern Africa, droughts can put pressure on important water sources like rivers, aquifers, dams and boreholes. This region of Africa is also historically dependent on rainfall for agriculture, and more intense and more frequent drought periods have large impacts on agriculture.
Cartoon depicting the unpredictability of El Niño
On the other end of the spectrum, ENSO can also bring bouts of increased rainfall and flooding to Africa. In the news recently, the 2015 El Niño has brought "the worst drought in 30 years" to Ethiopia, at the same time as flooding and landslides to its neighbour Somalia. This variability within the area of eastern Africa shows how harsh and uneven ENSO can be. Eastern Africa in particular is vulnerable to huge variability of rainfall during El Niño years, with coastal countries like Somalia and Kenya facing increased rainfall and areas more inland like Ethiopia and South Sudan facing drought. Have a look at this great snapshot of predicted El Niño impacts on eastern Africa.
Therefore, water availability can be increased during El Niño (and decreased during La Niña) in eastern Africa due to rainfall. This can be highly variable though as more rain does not always mean more water resources that are available for use. For example, flash floods and corresponding mudslides can occur in eastern Africa during the rainy season created by El Niño, thus damaging crops and livestock. Eltahir (1996) studied the natural variability of the flow of the Nile River and suggests that 25% of natural variability is associated with ENSO. This was due to a positive correlation of sea level pressure anomalies in the Ethiopian Plateau (the source of the Nile) and at Darwin, Australia (where surface pressure can be an indicator of the onset of ENSO). A positive anomaly in annual sea level pressure over the Ethiopian Plateau is associated with decreased rainfall and hence a negative anomaly of the annual flow of the Blue Nile. Since the Blue Nile originates in Ethiopia (and contributes most of the inter-annual variability of the Nile), the negative relationship between ENSO and the flood of the Nile can have a strong forcing on water availability in Ethiopia.
This look into southern Africa and eastern Africa and how they respond to ENSO events gives an indication to how something as simple as changing rainfall patterns due to ENSO can have a major effect on water availability. In the future, I think it's vital that countries have plans for potential El Niño and La Niña years. Governments, farmers, development agencies and other interested parties desperately need to have prediction systems, mitigation strategies and continuing research to understand ENSO and to ensure water availability for all. The scary thing is that El Niño and La Niña events are occurring more frequently, so much so that even if one extreme follows the other (such as increased rainfall following drought due to La Niña following El Niño), they cannot compensate for each other. Jennifer Olson sums it up: "Those kinds of shocks to the system, whether it's drought or flooding, are usually just enough that people can’t recover anymore.”
Friday, November 27, 2015
Why La Niña is less talked about than her brother El Niño
A great question I was asked in my previous introduction to El Nico post prompted me to do a little research into La Niña, the cooling extreme phase of the El Niño Southern Oscillation.
Here is a quick post to demonstrate the reasons why climatologists, economists, scientists and anyone else, seem to talk less about La Niña than El Niño.
1) El Niño and El Niño Southern Oscillation are commonly used interchangeably.
I mentioned this in my last post and I believe this is because the name El Niño comes from the observations of fishermen who supposedly named this phenomenon when they observed unusually warm waters in the Pacific Ocean. Therefore, the entire oscillation focuses around the extreme warming phase more so than the cooling phase of La Niña. However, nowadays you can sometimes see the entire phenomenon known simply as the "Southern Oscillation".
2) La Niña occurs less often than El Niño
Although both warm and cold phases occur on average every 3 to 5 years, the interval between events varies from 2 to 7 years. The NOAA report that, since 1975, La Niñas have been only half as frequent as El Niños. However, recent research suggests that the frequency of La Niña could nearly double from the historic record of approximately once every 23 years, to once every 13 years. The cause of this is from the "increased frequency of extreme El Niño events, which are conducive to development of the extreme La Niña events" as La Niña tends to follow El Niño, as the system swings from one extreme to the other.
3) La Niña is arguably less dangerous than El Niño
Roger Pielke Jr. and Christopher Landsea found a significant relationship between the ENSO cycle and US hurricane losses, with La Niña showing higher damages than El Niño. However, aside from this damage, the main argument that La Niña is less dangerous than El Niño is that it displays "typical" weather conditions (e.g. wet where it should be, cold where it should be) but intensified.
Here are the common winter weather patterns of La Nina:
In general, during La Niña, the easterly trade winds strengthen and cold upwelling along the equator and the West coast of South America intensifies, leading to lower sea surface temperatures in the equatorial Pacific region. This is caused by a "buildup of cooler-than-normal subsurface waters in the tropical Pacific". Both La Niña and El Niño tend to peak during the Northern Hemisphere winter.
Therefore, depending on where in the world you are, La Niña may be a welcome sight. For example, La Niña can cause the Pacific jet stream to be more variable over the US, and often moves more north than usual, leading to more storms and higher snowfall in the Northwest region of the US, and fewer storms and reduced snowfall in the southern US region. El Niño has the opposite effect, with more storms over the southern US due to a stronger Pacific jet stream and drier northern US.
The familiarity of conditions under La Niña, compared to El Niño, which flips everything on its head, may be why there is less of an emphasis on La Niña's dangerous effects.
However, that's not to say there are none. La Niña is less predictable than El Niño due to its effect on jet streams and storm tracks, and this can cause huge problems for industries such as agriculture and tourism. In addition, the intensity of La Niña can wreak havoc even if the conditions are typical, such as extreme dryness in the southern US and western South America leading to droughts, as well as extreme rainfall in Australia and Indonesia leading to flooding.
Another interesting idea is that La Niña usually follows El Niño, meaning it can undo some of the damages. For example, droughts in countries such as India due to El Niño, could be followed in the next year by higher than normal rainfall, which can offset the problems caused. In my opinion, however, I don't believe that these two extremes can counteract each other. The climate becoming more and more extreme will only lead to extreme changes and force humans to find solutions to problems that are constantly changing. Droughts followed by floods do not necessarily mean the population in the affected areas can survive, and these extremities could easily render many parts of Earth uninhabitable.
Conclusion
I'd like to quickly conclude that I don't believe we should focus more on El Niño than on La Niña. Both phenomena can cause real and significant impacts on a global scale. Luckily, I have noticed an increase in news headlines regarding La Niña, particularly as speculation of 2016 being a La Niña year, following the El Niño year of 2015. It's important that we continue to investigate the impacts of both El Niño and La Niña in the future, and to improve prediction methods to mitigate against damages and losses from them.
Particularly as we continue to change the global climate, it may be more difficult to predict and understand the El Niño Southern Oscillation, and as the World Meteorological Organisation (WMO) secretary general, Michel Jarraud puts it "this naturally occurring El Niño event and human-induced climate change may interact and modify each other in ways which we have never before experienced".
Edit (Dec 23):
An interesting article in The Wall Street Journal today emphasises what this blog post is about, which is to not underestimate La Niña as the effects could greatly impact one of the most volatile markets in the world: agriculture. To summarise, if 2016 is a La Niña year, food prices will likely be pushed up due to droughts in the US, Canada and Brazil. I was also interested to find out that La Niña has followed El Niño 11 times out of the last 15! Have a read if you're interested!
Here are the common winter weather patterns of La Nina:
In general, during La Niña, the easterly trade winds strengthen and cold upwelling along the equator and the West coast of South America intensifies, leading to lower sea surface temperatures in the equatorial Pacific region. This is caused by a "buildup of cooler-than-normal subsurface waters in the tropical Pacific". Both La Niña and El Niño tend to peak during the Northern Hemisphere winter.
Therefore, depending on where in the world you are, La Niña may be a welcome sight. For example, La Niña can cause the Pacific jet stream to be more variable over the US, and often moves more north than usual, leading to more storms and higher snowfall in the Northwest region of the US, and fewer storms and reduced snowfall in the southern US region. El Niño has the opposite effect, with more storms over the southern US due to a stronger Pacific jet stream and drier northern US.
The familiarity of conditions under La Niña, compared to El Niño, which flips everything on its head, may be why there is less of an emphasis on La Niña's dangerous effects.
However, that's not to say there are none. La Niña is less predictable than El Niño due to its effect on jet streams and storm tracks, and this can cause huge problems for industries such as agriculture and tourism. In addition, the intensity of La Niña can wreak havoc even if the conditions are typical, such as extreme dryness in the southern US and western South America leading to droughts, as well as extreme rainfall in Australia and Indonesia leading to flooding.
Another interesting idea is that La Niña usually follows El Niño, meaning it can undo some of the damages. For example, droughts in countries such as India due to El Niño, could be followed in the next year by higher than normal rainfall, which can offset the problems caused. In my opinion, however, I don't believe that these two extremes can counteract each other. The climate becoming more and more extreme will only lead to extreme changes and force humans to find solutions to problems that are constantly changing. Droughts followed by floods do not necessarily mean the population in the affected areas can survive, and these extremities could easily render many parts of Earth uninhabitable.
Conclusion
I'd like to quickly conclude that I don't believe we should focus more on El Niño than on La Niña. Both phenomena can cause real and significant impacts on a global scale. Luckily, I have noticed an increase in news headlines regarding La Niña, particularly as speculation of 2016 being a La Niña year, following the El Niño year of 2015. It's important that we continue to investigate the impacts of both El Niño and La Niña in the future, and to improve prediction methods to mitigate against damages and losses from them.
Particularly as we continue to change the global climate, it may be more difficult to predict and understand the El Niño Southern Oscillation, and as the World Meteorological Organisation (WMO) secretary general, Michel Jarraud puts it "this naturally occurring El Niño event and human-induced climate change may interact and modify each other in ways which we have never before experienced".
Edit (Dec 23):
An interesting article in The Wall Street Journal today emphasises what this blog post is about, which is to not underestimate La Niña as the effects could greatly impact one of the most volatile markets in the world: agriculture. To summarise, if 2016 is a La Niña year, food prices will likely be pushed up due to droughts in the US, Canada and Brazil. I was also interested to find out that La Niña has followed El Niño 11 times out of the last 15! Have a read if you're interested!
Sunday, November 22, 2015
What is El Niño?
It's been a while and I've been exploring where this blog could head. 'Environmental change' is a very broad topic and I'd like to look into a bit more depth into an aspect of environmental change and how this could be important for the future of water in Africa.
My last blog post looked at whether Africa would be a region worse off due to (human-induced) climate change, and used an IPCC report on different phenomena that causes climate variability. Whilst the blog post was quite broad, one thing that has garnered popular attention in recent weeks is the phenomenon of the El Niño Southern Oscillation (ENSO). I've decided therefore to focus on this particular phenomena for the next few blog posts to see what effects ENSO could really have, particularly for Africa.
This blog post is therefore a quick introduction on the El Niño Southern Oscillation, for both my sake, and also the sake of (any) readers.
What is the El Niño Southern Oscillation?
El Niño Southern Oscillation has two parts: El Niño and La Niña, or the warming and cooling phases. As we're looking at climate changes leading to warming, we'll be focusing on El Niño more than La Niña. In Spanish, el niño means "the little boy", but when capitalised as El Niño, it means the Christ Child, as the phenomenon tended to arrive around Christmas time.
The National Oceanic and Atmospheric Administration (NOAA) defines El Niño Southern Oscillation as "a disruption of the ocean-atmosphere system in the Tropical Pacific having important consequences for weather and climate around the globe". The oscillation, or cycle, describes fluctuations in the temperature between the ocean (specifically the Pacific Ocean) and the atmosphere (sea surface temperature therefore plays a hugely important role). Although ENSO occurs in the Pacific Ocean, it can affect weather around the world and is of large interest regarding future climate.
El Niño is also more well known that La Niña, due to the fact that El Niño and El Niño Southern Oscillation are used almost interchangeably. The "Southern Oscillation" bit refers to the changing in atmospheric pressure that occurs, while El Niño and La Niña refer to the changes in ocean temperature. These two processes of the ocean temperature and atmospheric pressure are highly linked as atmospheric and air pressure changes can be a direct result of changing water temperature, which is why the phenomenon includes both. El Niño is also seen more often that La Niña, probably because the phenomenon is usually associated with warming more than cooling.
ENSO is described as a phenomenon as it isn't the "normal" conditions of the Pacific Ocean. Normally, trade winds blow strongly from east to west across the Tropical Pacific, which pushes warm surface water towards Eastern Asia, particularly areas like Indonesia. This creates upwelling of cold water in the east side of the Pacific, and therefore a temperature gradient. The sea surface is normally about 0.5 m higher and 8°C warmer in Indonesia than Ecuador. Warmer waters will then affect weather such as increased precipitation due to higher air pressure as it warms.
During El Niño, the trade winds aren't as strong as normal, or may even reverse. This means there is less or no upwelling of cold water in the Eastern Pacific and no temperature gradient forms. The effects of El Niño can vary widely but usually, precipitation and temperature changes are expected. For example, unusually warm waters can be found in South America, from the warm winds of El Niño, which can lead to flooding in places such as Peru. Conversely, the western side of the Pacific can face drought. More importantly, the change in atmospheric heat can alter global atmospheric circulation and affect places far beyond the Equatorial Pacific region.
This basic introduction and understanding of El Niño comes from the NOAA. I'd recommend having a look at this easy and clear introduction video to El Niño from the Met Office for a visualisation of the processes I have explained and I'll explore more El Niño effects in my next blog post!
My last blog post looked at whether Africa would be a region worse off due to (human-induced) climate change, and used an IPCC report on different phenomena that causes climate variability. Whilst the blog post was quite broad, one thing that has garnered popular attention in recent weeks is the phenomenon of the El Niño Southern Oscillation (ENSO). I've decided therefore to focus on this particular phenomena for the next few blog posts to see what effects ENSO could really have, particularly for Africa.
This blog post is therefore a quick introduction on the El Niño Southern Oscillation, for both my sake, and also the sake of (any) readers.
What is the El Niño Southern Oscillation?
El Niño Southern Oscillation has two parts: El Niño and La Niña, or the warming and cooling phases. As we're looking at climate changes leading to warming, we'll be focusing on El Niño more than La Niña. In Spanish, el niño means "the little boy", but when capitalised as El Niño, it means the Christ Child, as the phenomenon tended to arrive around Christmas time.
The National Oceanic and Atmospheric Administration (NOAA) defines El Niño Southern Oscillation as "a disruption of the ocean-atmosphere system in the Tropical Pacific having important consequences for weather and climate around the globe". The oscillation, or cycle, describes fluctuations in the temperature between the ocean (specifically the Pacific Ocean) and the atmosphere (sea surface temperature therefore plays a hugely important role). Although ENSO occurs in the Pacific Ocean, it can affect weather around the world and is of large interest regarding future climate.
El Niño is also more well known that La Niña, due to the fact that El Niño and El Niño Southern Oscillation are used almost interchangeably. The "Southern Oscillation" bit refers to the changing in atmospheric pressure that occurs, while El Niño and La Niña refer to the changes in ocean temperature. These two processes of the ocean temperature and atmospheric pressure are highly linked as atmospheric and air pressure changes can be a direct result of changing water temperature, which is why the phenomenon includes both. El Niño is also seen more often that La Niña, probably because the phenomenon is usually associated with warming more than cooling.
ENSO is described as a phenomenon as it isn't the "normal" conditions of the Pacific Ocean. Normally, trade winds blow strongly from east to west across the Tropical Pacific, which pushes warm surface water towards Eastern Asia, particularly areas like Indonesia. This creates upwelling of cold water in the east side of the Pacific, and therefore a temperature gradient. The sea surface is normally about 0.5 m higher and 8°C warmer in Indonesia than Ecuador. Warmer waters will then affect weather such as increased precipitation due to higher air pressure as it warms.
During El Niño, the trade winds aren't as strong as normal, or may even reverse. This means there is less or no upwelling of cold water in the Eastern Pacific and no temperature gradient forms. The effects of El Niño can vary widely but usually, precipitation and temperature changes are expected. For example, unusually warm waters can be found in South America, from the warm winds of El Niño, which can lead to flooding in places such as Peru. Conversely, the western side of the Pacific can face drought. More importantly, the change in atmospheric heat can alter global atmospheric circulation and affect places far beyond the Equatorial Pacific region.
This basic introduction and understanding of El Niño comes from the NOAA. I'd recommend having a look at this easy and clear introduction video to El Niño from the Met Office for a visualisation of the processes I have explained and I'll explore more El Niño effects in my next blog post!
Thursday, November 5, 2015
Is Africa worse off than the rest of the world?
Hello!
This week I want to explore the effects of climate change on water resources and whether or not Africa is worse off than other regions in the world. Last week's post about water availability largely focused on Africa, but today I'll be looking explicitly at comparing different regions. One of the reasons I've decided to do this is the recent article from NASA that has people everywhere discussing climate change impacts, as their study indicates that Antarctic ice (in East Antarctica) is in fact growing, not shrinking. What irked me the most was the rush of climate deniers (is there a type of person worse than this to a geographer?!) jumping in to exclaim that "global warming isn't real" or that it's a hoax. This reaction exemplifies the ignorance of those who don't understand how complex climate change is, and how "global warming" is an inappropriate phrase to use to describe it. While Earth may be warming on average, the changes occurring are not equally or evenly distributed and this is what I'll be exploring.
Let's start with the IPCC's Fifth Assessment Report, particularly it's chapter Climate Phenomena and their Relevance for Future Regional Climate Change. This chapter begins with an emphasis that "regional climates are the complex result of processes that vary strongly with location and so respond differently to changes in global-scale influences". The chapter explores various phenomena that could affect climate variability, such as monsoon systems and the El Niño-Southern Oscillation, and specifies the modelled changes by different regions. A crucial reason why climate change does not affect each region equally is due to these phenomena, and the influencing strength of the phenomena. For example, the North Atlantic Oscillation is known to have a high influence on the Arctic region, but is not relevant as an influencing phenomena on Africa.
The report therefore states that Africa is very likely to experience warming. Within Africa they examine regions such as the Sahara, and conclude that the Sahara is very likely to remain dry. In contrast, Western Africa yielded low confidence results for drying and wetting and therefore has a more uncertain future. Additionally, the models they used had the ability to capture the effect of monsoonal behaviour and therefore have a medium confidence in projections of small delays in the rainy season with an increase at the end of the season. For Eastern Africa, there was a medium confidence in projections of little change in mean precipitation. The report shows the complexity of climate variability, even within regions, and therefore consequences could vary hugely.
Another huge factor that impacts whether Africa will be worse off in terms of meeting water demands is how vulnerable they are to change. The Climate Change Vulnerability Index for 2015 looks at the sensitivity of populations, the physical exposure of countries, and governmental capacity to adapt to climate change over the next 30 year, in order to determine vulnerability. Out of the top 10 countries at risk, 7 are in Africa. Verisk Maplecroft, creator of the index, emphasise that a unifying characteristic of the most vulnerable countries is the dependence on agriculture, which is affected by temperature, weather patterns and of course water resources.
Social factors also play a large role, particularly governance and urbanisation, which is so rapid in parts of Africa that it is outpacing public service provisions. The UN World Water Development Report 2015 emphasises that the context of Africa's water challenges is unique as not only is rainfall-dependent agriculture "the backbone of African economies", but demand for water for food, health and energy is growing due to population growth that is not seen at such high levels elsewhere in the world. The UN stress that regional cooperation of transboundary water resources, which relies on good management.
Just to demonstrate this point further, some more different maps showing water risk (based on purely physical factors) show that, as a region, Africa is no more worse off than the Middle East, or on average, North America. A report by Growing Blue (2011) indicates the many different ways to look at sustainability of water through different maps, such as Population and Regional Water Stress, or Groundwater Withdrawal as a Percentage of Recharge, or Net Virtual-Water Import Due to Trade in Industrial Goods.
To conclude, yes Africa is likely to be worse off in terms of having sustainable water, than the rest of the world. But this isn't solely due to the physical limitations of climate change, but rather the combination of climate change with socio-economic and political circumstances that already put Africa at a disadvantage. The pressure is also on Africa to develop economically in a sustainable way to prevent contributing to climate change as other nations have while developing, which could prove to be tricky in the face of extreme climate changes.
This week I want to explore the effects of climate change on water resources and whether or not Africa is worse off than other regions in the world. Last week's post about water availability largely focused on Africa, but today I'll be looking explicitly at comparing different regions. One of the reasons I've decided to do this is the recent article from NASA that has people everywhere discussing climate change impacts, as their study indicates that Antarctic ice (in East Antarctica) is in fact growing, not shrinking. What irked me the most was the rush of climate deniers (is there a type of person worse than this to a geographer?!) jumping in to exclaim that "global warming isn't real" or that it's a hoax. This reaction exemplifies the ignorance of those who don't understand how complex climate change is, and how "global warming" is an inappropriate phrase to use to describe it. While Earth may be warming on average, the changes occurring are not equally or evenly distributed and this is what I'll be exploring.
Let's start with the IPCC's Fifth Assessment Report, particularly it's chapter Climate Phenomena and their Relevance for Future Regional Climate Change. This chapter begins with an emphasis that "regional climates are the complex result of processes that vary strongly with location and so respond differently to changes in global-scale influences". The chapter explores various phenomena that could affect climate variability, such as monsoon systems and the El Niño-Southern Oscillation, and specifies the modelled changes by different regions. A crucial reason why climate change does not affect each region equally is due to these phenomena, and the influencing strength of the phenomena. For example, the North Atlantic Oscillation is known to have a high influence on the Arctic region, but is not relevant as an influencing phenomena on Africa.
The report therefore states that Africa is very likely to experience warming. Within Africa they examine regions such as the Sahara, and conclude that the Sahara is very likely to remain dry. In contrast, Western Africa yielded low confidence results for drying and wetting and therefore has a more uncertain future. Additionally, the models they used had the ability to capture the effect of monsoonal behaviour and therefore have a medium confidence in projections of small delays in the rainy season with an increase at the end of the season. For Eastern Africa, there was a medium confidence in projections of little change in mean precipitation. The report shows the complexity of climate variability, even within regions, and therefore consequences could vary hugely.
Another huge factor that impacts whether Africa will be worse off in terms of meeting water demands is how vulnerable they are to change. The Climate Change Vulnerability Index for 2015 looks at the sensitivity of populations, the physical exposure of countries, and governmental capacity to adapt to climate change over the next 30 year, in order to determine vulnerability. Out of the top 10 countries at risk, 7 are in Africa. Verisk Maplecroft, creator of the index, emphasise that a unifying characteristic of the most vulnerable countries is the dependence on agriculture, which is affected by temperature, weather patterns and of course water resources.
Just to demonstrate this point further, some more different maps showing water risk (based on purely physical factors) show that, as a region, Africa is no more worse off than the Middle East, or on average, North America. A report by Growing Blue (2011) indicates the many different ways to look at sustainability of water through different maps, such as Population and Regional Water Stress, or Groundwater Withdrawal as a Percentage of Recharge, or Net Virtual-Water Import Due to Trade in Industrial Goods.
To conclude, yes Africa is likely to be worse off in terms of having sustainable water, than the rest of the world. But this isn't solely due to the physical limitations of climate change, but rather the combination of climate change with socio-economic and political circumstances that already put Africa at a disadvantage. The pressure is also on Africa to develop economically in a sustainable way to prevent contributing to climate change as other nations have while developing, which could prove to be tricky in the face of extreme climate changes.
Tuesday, October 27, 2015
Climate Change and Water Availability
Today's post is focused on the theme of water availability, and more precisely, how climate change will likely affect it.
To begin, let's define water availability as the amount of water a country or region has, for use (domestic, agricultural and industrial). This is related to water scarcity, and the Falkenmark Water Stress Index stipulates that when a country falls below 1000 m3 of freshwater per person per year it experiences water scarcity and below 500 m3, absolute scarcity. Climate change and many other factors can influence whether a country experiences water scarcity, as the ability of its population to access and use water is dependent (at least in part) on its physical water resources.
So how do changes in climate affect the real availability of water?
Kusangaya et al. (2013) reviewed the many potential impacts of climate change on water resources in southern Africa, encompassing both physical and human consequences. There is a general consensus that increasing atmospheric greenhouse gases as a result of human activity will have widespread effects on the environment, mostly due to increased temperatures. For example, climate change is likely to cause an increased frequency of occurrence of extreme events such as droughts and intense storms. Temperature rises can also intensify the hydrological cycle (as I mentioned in my last blog post!) and may lead to increased evaporation but also increased rainfall. However, it is important to note that regional patterns differ from global patterns, so areas that experience a greater increase in evaporation, relative to increase in rainfall, would experience a real loss in available water. In Matondo et al. (2004), they claim the UN Environmental Programme study in 1989 predicts that greenhouse gases will elevate average precipitation by 5–15% and evapotranspiration by 10–20%; hence, real water available will decrease. Kusangaya et al. focused on southern Africa, and emphasise that southern Africa is likely to experience significant temperature rises, with more rapid increases in maximum temperature than minimum temperature extremes. At the same time, dry periods in southern Africa have become longer and more intense.
There is little consensus on the prediction of rainfall in Africa under different climate projections, but even if rainfall increases in some regions, with (much more certain) projections for population growth showing alarming rates of growth that are distributed unevenly, it is likely that real availability and access to water will fall. Population growth, particularly in urban areas, can put immense amounts of pressure on water resources. For this reason, many studies such as Carter and Parker (2009) stress that urban population growth, and consequent rise in food and fresh water demand and energy costs, are likely to be much more important than the physical impacts of climate change.
In summary, the two main physical areas that can affect water availability due to climate change are temperature and rainfall, which are also interlinked. It is difficult to accurately predict these changes because of this feedback loop, and particularly as rainfall is characterised by high inter-annual variability. On top of this, human changes (perhaps due to climate change, perhaps not) can contribute to changing water availability.
There are already real problems with water availability and access in Africa. UN Water estimates that 85% of the world population lives in the driest half of Earth, and with water availability estimated to decrease in many regions. This, in conjunction with population growth and growth in demand for water and food, represents a potentially deadly situation unless water management and adaptation strategies can mitigate the physical differences in water available to supply and water demanded.
Although climate change presents real concern for the physical availability of water, Mukheibir (2010) states that "the scarcity referred to globally is mostly rooted in power, poverty and inequality and not in the physical availability". UN Water echo this sentiment as they state that "water scarcity is both a natural and a human-made phenomenon. There is enough freshwater on the planet for seven billion people but it is distributed unevenly and too much of it is wasted, polluted and unsustainably managed". And while there is a lot of emphasis on cooperation around water (from the UN Sustainable Development Goals to scientific articles) to help solve the pressing issue of improving water access in a changing climate, more needs to be done to create optimistic scenarios for humans despite dire environmental changes.
To begin, let's define water availability as the amount of water a country or region has, for use (domestic, agricultural and industrial). This is related to water scarcity, and the Falkenmark Water Stress Index stipulates that when a country falls below 1000 m3 of freshwater per person per year it experiences water scarcity and below 500 m3, absolute scarcity. Climate change and many other factors can influence whether a country experiences water scarcity, as the ability of its population to access and use water is dependent (at least in part) on its physical water resources.
So how do changes in climate affect the real availability of water?
Kusangaya et al. (2013) reviewed the many potential impacts of climate change on water resources in southern Africa, encompassing both physical and human consequences. There is a general consensus that increasing atmospheric greenhouse gases as a result of human activity will have widespread effects on the environment, mostly due to increased temperatures. For example, climate change is likely to cause an increased frequency of occurrence of extreme events such as droughts and intense storms. Temperature rises can also intensify the hydrological cycle (as I mentioned in my last blog post!) and may lead to increased evaporation but also increased rainfall. However, it is important to note that regional patterns differ from global patterns, so areas that experience a greater increase in evaporation, relative to increase in rainfall, would experience a real loss in available water. In Matondo et al. (2004), they claim the UN Environmental Programme study in 1989 predicts that greenhouse gases will elevate average precipitation by 5–15% and evapotranspiration by 10–20%; hence, real water available will decrease. Kusangaya et al. focused on southern Africa, and emphasise that southern Africa is likely to experience significant temperature rises, with more rapid increases in maximum temperature than minimum temperature extremes. At the same time, dry periods in southern Africa have become longer and more intense.
There is little consensus on the prediction of rainfall in Africa under different climate projections, but even if rainfall increases in some regions, with (much more certain) projections for population growth showing alarming rates of growth that are distributed unevenly, it is likely that real availability and access to water will fall. Population growth, particularly in urban areas, can put immense amounts of pressure on water resources. For this reason, many studies such as Carter and Parker (2009) stress that urban population growth, and consequent rise in food and fresh water demand and energy costs, are likely to be much more important than the physical impacts of climate change.
In summary, the two main physical areas that can affect water availability due to climate change are temperature and rainfall, which are also interlinked. It is difficult to accurately predict these changes because of this feedback loop, and particularly as rainfall is characterised by high inter-annual variability. On top of this, human changes (perhaps due to climate change, perhaps not) can contribute to changing water availability.
There are already real problems with water availability and access in Africa. UN Water estimates that 85% of the world population lives in the driest half of Earth, and with water availability estimated to decrease in many regions. This, in conjunction with population growth and growth in demand for water and food, represents a potentially deadly situation unless water management and adaptation strategies can mitigate the physical differences in water available to supply and water demanded.
Although climate change presents real concern for the physical availability of water, Mukheibir (2010) states that "the scarcity referred to globally is mostly rooted in power, poverty and inequality and not in the physical availability". UN Water echo this sentiment as they state that "water scarcity is both a natural and a human-made phenomenon. There is enough freshwater on the planet for seven billion people but it is distributed unevenly and too much of it is wasted, polluted and unsustainably managed". And while there is a lot of emphasis on cooperation around water (from the UN Sustainable Development Goals to scientific articles) to help solve the pressing issue of improving water access in a changing climate, more needs to be done to create optimistic scenarios for humans despite dire environmental changes.
Subscribe to:
Posts (Atom)