Climate
change and extreme weather have been often linked together, an example of this
is the video in the past post. But solid evidence linking specific extreme
weather events is hard to get. It is almost impossible to rule out all other
possibilities and link for example the Texas drought with climate change. But
recently there is a study been published that sort of claims that it has
connected a single extreme weather event
with climate change. The study was part
of a larger study called State of Climate 2011. Here
The research
was done by a large group of scientists from all over Europe and the USA. By six
extreme events they tried to find out if
there was a link with the event and climate change. All the events were separate,
the article consist of six studies. For their
research they used many different models and techniques to determine if there
was a link. They also use a lot of math and sea surface temperature models. Events
which were investigated are the Thailand floods, the drought in East Africa,
the Texas drought , the cold and warm records in Europe and more focused on
central England the very warm November and the extreme cold December. All these events took place in 2011. In the
first part of the paper the authors give a short overview of the latest
research that has been done or is still going on. This research can be really interesting
if you want to know that is going on in the field of metrology and climatology.
It gave me many interesting articles for my blog.
Thailand
By the
Thailand flooding the outcome of the research was that climate change did not
play a role during the flooding although the flooding was severe. La Niña had a statistically significant effect
on the flooding but the effect on the rainfall, which is very important in the
tropics with monsoon season was very small. The rainfall in the catchment area
was not unusual according to the scientists. They flooding had more to do with
poor water management and using the land in the wrong way than climate change.
East Africa
The large
scale drought followed by a deadly famine in East Africa has been linked to
both La Niña and the warming in the Indian-Pacific warm pool (IPWP). Sea water
with a temperature above 28C is called a warm pool. There is still a lot of
research needed on these phenomena’s and
linking La Niña and IPWP to climate
change is controversial. But La Niña did play a large role is the failure of
rain and also the warming of the IPWP has contributed to the increase in the number
of droughts in East Africa.
Texas
The Texas
drought was a drought that was by far
the hottest and driest since 1895. With this research project they wanted to
find out if today such an extreme drought is more likely to happen than in the past. They
compared the years 1964, 1967,1968 with the year 2008, data for 2011 was not
yet ready. With this research they also included the La Niña effect, because that is the main force
behind droughts in Texas. The aim was to find out if droughts are more likely
to occur in 2008 than they were in the sixties. The years 1964,1967 and 1968
were all influenced by La Niña. They used a climate model called Global Climate
Model. The model calculated the likelihood of droughts using the climate of
2008 and that of 1964,1967 and 1968. The result was that with the climate of
2008 the likelihood of a large scale drought is much greater.
Top
is total precipitation and bottom the mean temperature.
High mean
temperature is much more likely to happen in the 2008 climate than it is in a
sixties climate. A Mean temperature of 26C happens in a 2008 climate almost
every 2 years but with a sixties climate only once every 10 years. The same
thing can be said about the total precipitation although the difference smaller
is.
Heat waves
during La Niña are much more likely to
happen in today’s climate than in the sixties.
England
The very
warm November and the cold December in the UK have also been researched. In a
time of global warming is having record low temperatures quite rare and that is
why the researchers asked themselves the question: If the warm November would be more likely to
happen again and a cold December less likely with the present climate. For this
research they used multiple Global Climate Models. And to measure the
difference between with and without climate change they use the 1960’s and the
2000’s.
Blue is
1960-1969
Red is
2000-2009
A warm November
is much more likely to occur with the climate of 2000-2009. A average temperature
of 8C for the month November occurs every 4 year in the 2000-2009 climate but in the sixties only around once every 30 years. For the cold December
it is the other way around. A cold December is less likely to occur under the
2000-2009 climate and more likely in the sixties climate. You can see that an
average temperature of 2C in December
only happens once every 15 years with a
2000-2009 climate but once every 4 years
with a sixties climate. This indicates that
global warming is causing extreme cold events to occur less frequent.
Central England
The last
research was about the cold winter of 2010/11 in Central England. That winter
was one of the coldest ever in England, it was an odd event in English history.
But the researchers wanted to find out if such cold odds occured less often
with climate change. For this research
they used 352 years of weather data and special climate models. But as already seen
with the last research odd cold events turn out to be happening less often. They
authors but is this way:
‘’The winter of 2010/11 was a rare weather event, even in the
context of the 352 years of the central England temperature record. Yet while
the odds of such an event have lengthened as a result of human influence on
climate, such unlikely events can still happen, as the winter of 2010/11
demonstrated. ’’
Conclusion
After
reading this article you could say that a number of extreme weather events will
happen more often in future. Making the connection between climate change and extreme
weather is not uncontroversial. Climate models are still not perfect and there
is a lot of difference between climate models about assumptions which the
models make. Perhaps they should do the same research about the 2010/11 winter
in the Netherlands which was also extremely cold with even in Amsterdam minus
20 degree Celsius and ice skating on the canals but. But with a different model(but designed for
the same task) and them compare with the results from England. Should give
roughly the same answer if the models are correct.
Never
forget that extreme weather is not something that only happens with climate
change. There has always been extreme weather with and without climate change.
The next
post will be about three editorials from the New York Times, the Washington
Post and the USAtoday in which all state, independent from each other that they
don´t (yet)believe in a connection
between climate change and extreme weather. I will look through the arguments
and also give some examples of responses from readers.
Also I will talk about research
that shows no connection between climate change and extreme weather in the near
future.
Used resources
Peterson,T Stott, P Herring, S Editors (2012) Explaining extreme events of
2011 from a climate prospective. Bulletin
American Meteorological Society Volume 93, Issue 7 p.1041-1067 Here
Blunden,
J., and D. S. Arndt, Eds., 2012: State of the Climate in 2011. Bull. Amer.
Meteor. Soc., 93 (7), S1-S264. Here
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