This blog started off
considering how ocean temperatures have been rising, specifically since the
start of the Industrial Revolution, when El Niño started hitting the news
headlines. El Niño
led the direction of this blog, as it is something we are all experiencing and
can all relate to, no matter your previously knowledge. Together we’ve learnt
about just what El Niño is, and considered the forecasts made for the winter of 2015 and
into the spring of 2016. We’ve looked at El Niño in relation to global warming, considering
both the cases that El Niño is causing global warming (don’t worry, we
quickly put that theory to rest!), and the effect that global warming is having
on El Niño
events. We looked at the different types of models used in relation to ENSO,
specifically statistical and dynamical forms, and discussed the advantages and
disadvantages of each of them. We’ve looked at how you can contribute to the
bigger picture, and why it is that sometimes models just don’t quite get it
right. If you’ve missed any of this, catch up with my previous posts!
So, what is next for the current ‘monster’ El Niño?
The latest satellite images
have been released from NASA showing that the current El Niño event
is showing no signs of weakening just yet...
Source: Jet Propulsion Lab, NASA.
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Since I last posted the
NASA satellite images from 16th October 2015, the area of unusually
high sea surface temperatures across the Pacific Ocean has increased. As can be
seen in the latest images from 27th December 2015 above, there is a
large expanse of red-white spreading from the Chilean coast up to the north of
the Mexico’s west coast, and reaching far into the centre of the Pacific. As
you may remember from an earlier post, these images show sea surface height anomalies,
which are highly correlated to temperatures and the heat stored within the
ocean below. The areas of white highlight sea surface that is between 15 and 25
centimetres above normal. Conversely,
the region of blue-purple showing sea levels up to 25 centimetres below average
has decreased since my October post.
The movie below shows the
evolution of sea surface height anomalies since the beginning of 2015 alongside
the corresponding ones from 1997, when the previous immense El Niño was felt
around the world.
The 1997 El Niño was recorded
by the NASA/Centre
National d'Etudes Spatiales (CNES) Topex/Poseidon mission, whilst the current
event is captured by the Jason-2 satellite. It can be seen that there
is a remarkable likeness between the two, which both display the typical development of an
intense El Niño. Given an El
Niño on the same scale as that of 1997/98, what does this mean for the planet
and society?
El Niño:
The Good
I stumbled across this really interesting project that one of our own UCL
Geographers (PhD student David Seddon), supervised by Professor
Richard Taylor, is currently researching. A small wellfield in a semi-arid
basin called Makutapora in Tanzania, supplies the countries
capital city, Dodoma, with safe water. Replenishment of this vital source of freshwater
for hundreds of thousands of people has shown to occur in conjunction with El Niño events. The immense El Niño that we are
currently experiencing will no doubt have an effect on these resources, and the
GroFutures team have
set up instruments to monitor it. This blog has largely focussed on the
negative impacts of El Niño, but this project highlights that episodes are also of crucial
importance in some parts of the world that desperately need groundwater levels
replenished.
El Niño:
The Bad
A recent study by Chretien et al.,
(2015) shows that during
El Niño events the effects not only impact on the
environment, as we’ve seen by flooding and drought, but this incidentally impacts
on global health by possibly increasing the spread of infectious disease. Malaria, chikungunya, and dengue
are all very nasty illnesses that you do not want to catch! They are spread by mosquitoes,
which thrive under the wet conditions El Niño brings to South and Central America, and parts of the US. Conversely, areas
which feel the warm, dry impacts of El Niño may see increases in the transmission of cholera, and other infectious diseases. Powerful El Niños also have a long-term impact on coral
reefs. A 17 year study of coral reefs in Bahia, Brazil, found that for two years after the 1997/98 El Niño there was severe coral bleaching and a significant reduction
in size. In other areas of the world including the Indian Ocean, this was
significantly worse. It took 13 years for the coral in Bahia to fully
recovery.
El Niño:
The Ugly
The shift in temperature and precipitation levels that
coincide with El Niño events impacts on the global yields of major crops. This undoubtedly
has knock-on effects to food prices. Lizumi et al., (2014) considers the global effect of ENSO on
crop yield, and finds that El Niño results in maize, rice and wheat harvest changing
between −4.3% and +0.8%. However, this is not
the case for soybean yield, which actually increases by 2.1% to 5.4%
under El Niño conditions. Lizumi et al., (2014) expects that the global demand for
these crops will increase by 100–110% by 2050 from that in 2005. Close
monitoring of the ENSO cycle is crucial in minimizing the negative impacts and maximizing
the positive impacts that El Niño and La El Niña have on crops. Cashin et al., (2015)
consider not only the countries that
are directly affected by El Niño, but also the
indirect macroeconomic effects filtered through third-markets. 21
country/region-specific models are analysed, from 1972 to 2013, to see how growth,
inflation, energy and non-fuel commodity prices differ under El Niño conditions. The study finds the majority of
countries analysed experience energy and non-fuel commodity price increases in
the short term, however the EU and US actually see a growth effect! Unfortunately
this isn’t the case for Australia, Chile, Indonesia, India, Japan, New
Zealand and South Africa who see a downfall in economic activity.
Whether ‘The Good’, ‘The
Bad’, or ‘The Ugly’, modelling can be used as a tool for preparing for these
situations, either by harnessing the conditions that El Niño brings, or, protecting against it.
What is next for Modelling?
A report published by Rädel et al., only 5 days ago, used the Earth system model,
MPI-ESM-LR, to analyse the
role of clouds in El Niño. The study found that atmospheric circulation is
highly affected by cloud processes, and this contributes to more than half the intensity
of the El Niño. Climate models that didn’t take the interaction of clouds with
atmosphere circulation into account would therefore predict a weaker El Niño
than those which did consider the interaction. Back in 2012, Maslin and Austin discussed whether climate models were
already at their limit. They argued that the complex climate models in use are likely to produce
predictions with more uncertainty due to the increased complex factors such as
interactive carbon cycles, and the role of aerosols in atmospheric chemistry
now included within the models. In relation they express the importance of the
public and policymakers being aware that “climate models may have reached their
limit”. Whilst I agree that the public and policymakers should have an
understanding that a model is not an exact reproduction of the reality, hence
has its limitations and will not always predict exactly as reality turns out to
be, I fear that a statement worded in such a way will in fact decrease public
support of scientific modelling, rather than the intended increase of support. We
should not stop adding further details to current models for fear of them
performing worse. As the study by Rädel et al., (2016) found,
sometimes complex processes do need to be included within models. As our
understanding and technology advances so will the certainty of these models.
Models of all complexity have a role to play; as
Knutti (2010) succinctly put it, “we learn from the
diversity of models, and we will learn from different ways to evaluate and
combine them”.