Extreme Precipitation

As promised, here is my second post of the set treating the different types of extreme events. Today: Extreme precipitation related events.

Warming increases the amount of water vapor in the atmosphere. When this vapor condenses and precipitates => it rains. 

So what?

Storms:

An increase of heavy rains and torrential rains is expected (this tendencypage 201 has already been observed in mid-latitudes for the las 50 years) like strong hurricanes and tropical storms (categories 4 and 5), in which an increase of both in intensity and duration since the 70'spage 213 has already been observed. See: Emanuel et al. 2005, Webster et al. 2005 (even though the total number of hurricanes is NOT expected to increase).

Floods: 

Flood events globally between 1985 and 2008

Naturally, this increase in extreme precipitation, coupled with rising sea levels, lead to more frequent flooding.

For example, Min et al., 2011. about northern hemisphere:

"Here we show that human-induced increases in greenhouse gases have contributed to the observed intensification of heavy precipitation events found over approximately two-thirds of data covered parts of Northern Hemisphere land areas. [...] Changes in extreme precipitation projected by models, and thus the impacts of future changes in extreme precipitation, may be underestimated because models seem to underestimate the observed increase in heavy precipitation with warming".

Drought: 

Although a net increase in precipitation is expected this would occur mainly near the poles and the tropics, while in mid-latitudes precipitation would fall as a result of the expansion of the subtropical high pressure belt (Svoma et al., 2013.)

Still, extreme precipitation would also increase (although less than in places where there is a net increase in precipitation, like the tropics or higher latitudes), since it is expected that the frequency is reduced but the intensity is increased. Warming also increases evaporation, and it is expected that the trend of increase continues in regions affected by drought. 

Spain is also particularly vulnerable to this phenomenon region, since precipitation is expected to be reduced by 15-30% in the second half of the century according to the spanish meteorological agency.

Voigt&Van Minnen 2004:

"The reduction [of precipitation] in southern Europe is expected to have severe effects, e.g. more  frequent droughts, with considerable impacts on agriculture and water resources."

An interesting review about this topic is Dai 2010, which shows that much of the planet is at risk of increasing drought.

WARMING! Heat waves and wildfires

Hey! Welcome back to Extreme Weather and Climate Change. Good that you're still reading :)

According to IPCC Fourth Assessment Report,  an increase in severe events regarding temperature (heat waves, wildfires, cold waves) and precipitation (storms and hurricanes, droughts and floods) is expected. 

On the next set of posts, we will discuss each of these events separately. Today's special:

Heat waves and wildfires

A cooling dog

From a global increase of average temperatures, we can obviously expect more frequent heat waves being these warmer and longer in time. 

An example in this regard is the European heat wave of 2003 (This heat wave deserves a special post. Coming soon.)

My country (Spain) is particularly vulnerable to this phenomenon and I will also devote a full post to this later on (home is home after all). 

Let's check out some references: 

“Climate-change projections suggest that European summer heatwaves will become more frequent and severe during this century consistent with the observed trend of the past decades. The most severe impacts arise from multi-day heatwaves, associated with warm night-time temperatures and high relative humidity. Here we analyse a set of high-resolution regional climate simulations and show that there is a geographically consistent pattern among climate models: we project the most pronounced changes to occur in southernmost Europe for heatwave frequency and duration, further north for heatwave amplitude and in low-altitude southern European regions for health-related indicators. For the Iberian peninsula and the Mediterranean region, the frequency of heatwave days is projected to increase from an average of about two days per summer for the period 1961–1990 to around 13 days for 2021–2050 and 40 days for 2071–2100.” (E.M. Fischer and C. Schär, 2010).

“Under high emission scenarios every second summer in Europe will be as hot or even hotter than 2003 by the end of the twenty-first century. In southern Europe, these changes are projected to occur even earlier (in Spain by the 2020s).” (Perry et al., 2000).

Good! Beach weather! Well... Not really. There are plenty of studies showing the effects that heat waves have in health (not to talk about biodiversity, economy, etc). As an example, Baccini et al., 2008 show the relation between high temperatures and mortality in 15 european cities. And again E.M. Fischer and C. Schär, 2010 :"In terms of health impacts, our projections are most severe for low-altitude river basins in southern Europe and for the Mediterranean coasts, affecting many densely populated urban centres. We find that in these locations, the frequency of dangerous heat conditions also increases significantly faster and more strongly, and that the associated geographical pattern is robust across different models and health indicators."

It is true that in a warming planet, deaths related to cold waves could also be reduced, but even if it is restricted to the USA territory, this paper by Medina-Ramon, M ; Schwartz, J, 2007, shows that heat waves deaths increase by 5.74%, while cold wave-related do only 1.59%. In other words: heat waves kill 3.6 times more than cold waves. 

As they write in their conclusions: 

"These findings suggest that increases in heat-related mortality due to global warming are unlikely to be compensated for by decreases in cold-related mortality and that population acclimatisation to heat is still incomplete."

See also Kalkstein and Greene, 1997 :"We suggest that the combined impacts of these factors will only partially offset the very large increases estimated by the GCMs, and a substantial rise in weather-related mortality is the most likely outcome of a global warming"

Wildfires

The dramatic moment a family fleeing Australia's wildfires shelter in the water to scape the flames, 2009 (The Guardian)

Naturally, an increase in frequency, length and intensity of heat waves will favor wildfires and their expansion. For example, an increase of around 50% is expected for 2050 in USA. 

The serious wildfires in southeastern Australia on 2009, in Rusia, or Israel, in 2010 are clear examples of something that seems more and more usual due to global warming.

International Day for Disaster Reduction

Hi there!

On my last (and very first post) on the 13th October I overlooked that it was the UN International Day for Disaster Reduction. Sorry about that!
In order to make up for this, we will discuss about the topic on today's post. But first things first:

What' s a natural disaster?

An extreme natural event (either geological, hydrological or atmospheric) is not always necessarily a disaster. The event becomes a disaster when it affects populations in any ways.
To put an example, I don't thing nobody would care about an earthquake taking place in the middle of nowhere, right? But the Haiti earthquake in 2010 who killed more than 315.000 people, that was a natural disaster.
In this sense, are natural disasters man-made? (Ashish Bose)

A study by IDMC (Internal Displacement Monitoring Centre) shows that 22 million people were displaced due to natural disasters in 2013. Storms displaced 14.2 million people (Haiyan typhoon in Phillipines displaced 4.1 million people alone), floods displaced 6.2 million, earthquakes 1.2 million, wildfires and extreme temperature displaced 102.000 people and 51.000 where displaced by landslides.

This chart, created by the portal Statista shows the number of people displaced by natural disasters since 2008. 

United Nations proclaimed in 1989 the International Decade for Natural Disaster Reduction and with it, an agreement on the measures to work on this line were included. After this decade, the ISDR (International Strategy for Disaster Reduction) is created and remains in force today.

"The aim of ISDR is to combine international efforts with actions to avoid the effects of natural disasters."

The ISDR is especially oriented to developing countries to try to mitigate the loss of life and social and economic disruption caused by disasters.

Major international objectives in this area are:

- Improve the capacity of each country to mitigate the effects of natural disasters, using early warning systems.
- Promote scientific and technical knowledge to reduce human and material losses.
- Provide countries with technical assistance based on prevention, evaluation and diagnosis to mitigate natural disasters.
- Promote education and training projects. *Here you have a small example in the form of didactic game for children.


The last international agreement on the way to the reduction of natural disasters is the Hoygo Framework for Action (HFA) which was signed in 2005 in Japan.
168 countries pledged to introduce measures to prevent and risk assessment in public policy, as well as protocols for actions before, during and after natural disasters.

What about the results?

Around 130 national committees were formed in developing countries but less than half performed effectively.
"Some of them were quite successful in promoting new efforts; for example, the Australian National Committee and the federal agency Emergency Management Australia moved ahead in a broad range of mitigation activities in planning, hazards and risk assessment, and assistance to other countries in the southwestern Pacific region."  Mitigation emergencies as major strategy for reducing losses caused by natural disasters. Science 1999

Atmospheric disasters

Lets focus in atmospheric disasters. The most tragic and recent example that comes into our minds is typhoon Haiyan which devastated Philippines almost one year ago on November 8th 2013 with sustained winds of 314km/h and category 6 on the Saffir-Simpson scale (top cathegory).

Typhoon Haiyan over Philippines. BBC

Here you can see two comparing NASA satellite images. One before and one after Haiyan struck on Tacloban (Mindanao):

It is clear that little can be done against such a phenomenon (btw, hurricanes, cyclones and typhoons are the same weather phenomenon. We call them differently depending on where they occur). In this case devastation occurred many kilometers inland.

The early warning systems worked as expected and almost all the population was prepared for the typhoon. In this sense, risk prevention mechanisms were very useful but days after Haiyan,
the damage mitigation system showed serious deficiencies: only one public hospital operating in Tacloban, high infection risk, prevention of water-borne outbreaks resulted insufficient, safety of immunization at risk. (Typhoon Haiyan: Philippines faces long road to recovery. Yu-Tzu Chiu). This was largely due to the fact that Philippines is an archipelago and infrastructure were devastated which made logistic extremely complicated.


There is clearly much work left to do on risk and impact mitigation and October 13th is just a day to stop-by and reflect on it.

*This is kind of a depressing topic I' ve chosen...

"You can' t blame global warming for a single episode of bad weather"

* Vehicles drive along a flooded street in Guangzhou, South China's Guangdong Province August 14, 2007. Image from China Daily.

Whenever a weather event (heat wave, flood, drought, etc) appears in the media, somewhere someone points the finger at climate change caused by humans. These indictments are often answered with the widespread mantra: "You can' t blame global warming for a single episode of bad weather".

Can we say that these particular extreme weather events are caused, or at least are aggravated by global warming?
Has anything changed in the understanding of climate scientists, or about the attribution "the anthropogenic fingerprint" of these phenomena?

Regarding the climate itself, the danger is that we have lost adaptability to changes in climate: We are no longer nomadic society that can rely on migration as an adaptation measure to climate change. We are a sedentary society with great wealth invested in real estate and infrastructure and with borders and sovereignties which impede migration. This is the climate we have adapted to. Any change in the same supposes intrinsic hazards and must be studied.

We will review some of the phenomena supposed to increase in frequency and scope and treat some specific cases from an academic point of view to try to shed some light on the topic.