Why La Niña is less talked about than her brother El Niño

Cartoon about El Niño or La Niña

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!

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!

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.