Fake and Overused Weather Photos

Just came across THIS on Facebook and couldn't resist the temptation to share it with you.
You have my word: I will never ever use this pictures!!!

The Ridiculously Resilient Ridge

Welcome again to my blog,

as last week's post was talking about the anomalous cold weather in eastern US, I thought that talking about California's drought would make sense. As I said on my last post, US weather is more bipolar than ever!

California is the first US economy and half of the country's fruit is produced in it's central valley. This study by the University of California, Davis (Sacramento) assesses the massive economic impact of the drought (around 2.200 million dollars)

The official state of emergency was declared in January 2014, in order to address the problem and try to find ways to conserve and use water more efficiently. Serious problems related to water use had already begun: farms can not provide water for livestock, thousands of workers in agriculture are loosing their jobs and severe wildfires are taking place, just to name a few.

The gravity of California's drought is so great that it is already changing the geography of the state: one of it's most important rivers is not reaching the Pacific Ocean anymore.

Just look at a couple of pictures: 

Satellite images showing the snow cover over the Rocky Mountains in January 2013 vs January 2014

California's Governor Jerry Brown encourages individuals and companies to put to work strategies to try to save water and reduce consumption to 20% or more. While many of these initial measures are directed to residents, the agricultural sector accounts for up to 80% of total water consumption in California, according to MacDonald, 2010. The restrictions on water use are usually applied voluntarily, but in certain areas they have become mandatory.

In early February 2014, a heavy rainfall fell over Sonoma. 2013 was the driest year on record and because of this, soil was very poor in moisture.

When soils are lacking moisture so severely, they harden and crack, becoming less permeable to water and this results in heavy rainfall not being absorbed, causing flash floods.

As the drought deepens, flash floods may become more frequent, bringing new challenges to farmers in the area (including the cannabis industry).

As if it were not enough with these, Amos et al., 2014 link drought with higher earthquake probability.

This is the third consecutive year of drought in California. Now comes the one thousand dollar question... Can we attribute this to climate change?

Let's first check the science behind the event.

During the last three years, a vast anticyclone hast remained over the northeastern Pacific Ocean (the so called "Ridiculously Resilient Ridge" I love the nickname!) preventing the winter storms from reaching California and as a result, bringing extreme temperatures and massive drought to this area.

This is also a consequence of the Rossby waves we talked about in the last post.

In this report, the Stanford researchers Noah Diffenbaugh and David Swain (the video stars) analyze the impact of climate change in this particular event trough a combination of GCMs (Global Circulation Models) and statistical methods which have allowed them to determine whether the formation and resilience of such an anticyclone had been possible in the absence of the effects of Climate Change.

They concluded that the atmospheric conditions driving to this situation in California are very likely related to human-caused Climate Change. In other words, human-caused climate change has dramatically increased the likelihood of extremely high atmospheric pressure over the North Pacific Ocean which has lead to the drought in California.

U.S anomalous weather

U.S weather is more bi-polar than ever. Eastern U.S shivers from the polar vortex and California struggles in a historic drought.

The "Polar Vortex", one of the buzzwords of 2014, brought news last week by bringing Arctic temperatures to North America and by providing climate skeptics with arguments against Global Warming.
In fact, the scientific explanation behind this blast of cold weather helps to provide a more troubling evidence about the increasing effects of global warming.

What is a Polar Vortex?

These cyclones (vortex) over the two poles of the earth are located in the middle and upper troposphere and stratosphere and move at different speeds. Thanks to them, the cold, dense air over the poles is confined there.

This movement of strong winds is part of the polar front. It is stronger in the winter and decreases or disappears in the summer.

The Antarctic polar vortex is more pronounced and persistent than the Arctic vortex, this is due to the distribution of land masses at high northern latitudes which leads to an increase of Rossby waves in the jet stream (Rossby waves are oscillations that occur in geophysical fluids and are due to the principle of potential vorticity conservation). These waves shape the polar jet stream, while in the southern hemisphere the vortex remains less affected.

Rossby Waves. Source: knmi.nl

When these polar winds decrease significantly, the vortex may be distorted and the result is that the jet stream plunges deep into the southern latitudes.

This video from  Obama's Science and Technology advisor could help:

When this strong cold current moves towards low pressure areas, winter storms with heavy snow, intense cold and freezing winds may develop. A cold air outbreak caused by a polar vortex is much larger in area and length than a single storm and can lead to cold waves at multiple locations, but this doesn't always happen.

What is the link with Global Warming?

Last January, due to a polar vortex, America experienced a deep freeze. Cities like Chicago recorded a wind chill approaching -60 degrees Fahrenheit (-51°C). Even some parts of Canada reported temperatures colder than Mars!

Homes are covered in snow in West Seneca, N.Y.,Wednesday, Nov. 19, 2014. (AP Photo/The Buffalo News, Derek Gee)

However, the international scientific community points out that global warming can play an indirect role in these occasional freezes.

The fact is that, due to global warming, the Arctic is warming faster than the rest of the planet, warming which is accelerated due to the the polar ice melt (change in the albedo). As a result of this, temperatures recorded in the Arctic are around 2º C warmer than they were in the mid-sixties (compared to the overall increase in the average temperature of the atmosphere of Earth which is about 0.7º C, since 1900).

Therefore, the temperature difference between the Arctic and North America is decreasing. This temperature difference causes changes in the air blast around the polar region. The decrease in the temperature gradient that has made the air jet to slow down and develop Rossby Waves, bringing warmer temperatures farther north and more cold Arctic temperatures further south.

Maybe skeptics who take any chance to deny global warming should read about these mechanisms the climate system has to face imbalances.

No break in extreme events

Reading around about the so-called "climate change hiatus" I just came across this interesting letter published in Nature on the 26th February 2014 by a group of researchers from several countries led by Sonia Seneviratne (Switzerland) indicating how the term "pause" or "hiatus" being applied to the recent period of slowdown in the increasing trend of average temperatures is "ill-chosen or even misleading in the context of climate change".

To assess whether there really is an evolution on the Earth's climate, analyzing the evolution of all the different elements which compose earth's climate is required.

Extreme Temperature Trend in the US. Source: NOAA

It is true that there' s been a slowdown in the increase of global average temperatures over the past ten years. This slowdown can be linked to several causes such as internal climate variability, a change in the solar energy input, increased stratospheric water vapor or strong La Niña events. But climate is not only composed of mean temperatures.

Source: http://www.tiempo.com/

The authors point out that extremes of warm temperatures haven't stopped growing. In fact, these climatic anomalies have presented the greatest increase over the last decade just like other climate change-related elements such as ice melting, sea level rise and ocean heat content haven't stopped growing. Such rise in the most extreme phenomena indicate without any doubt that there is no such "pause". 

Moreover, particularly this increase in warm extremes has negative effects on health, agriculture, ecosystems and infrastructure.

Extreme Weather is here to stay

Weather is insane. Or worse... Torrential rains in southeastern Spain in late September. Terrible tornadoes in the US in April. Extreme drought in California and Brazil. Wild fires in Europe (btw aggravated by cuts in public services). All this only in 2014 .... Because looking at the past years we still find many more extreme examples. Remember: In 2012, Hurricane Sandy was visiting New York. Tremendous flooding in Pakistan in 2010 that left hundreds of dead. Cyclone Nargis left more than 130,000 dead after passing through Birmania. The 2003 heatwave killed tens of thousands in Europe: in France alone almost 15,000 were calculated. Among others. (Not to mention earthquakes and tsunamis).

What's wrong with the weather? Is it really changing or is it just a coincidence? What does the climate change have to do in this? In 2014, which will probably be the warmest year on record, there is little doubt left about the existence of climate change. The question is whether climate events in the short term (such as extreme weather) can relate cause and effect via a complex phenomenon and, in the end, of long-term consequences such as global warming. 

The Mexican Mario Molina, who shared the 1995 Nobel Prize in Chemistry for his work on CFCs and their effects on the ozone depletion, is very clear: "important changes have occurred in the scientific understanding of the extreme weather events [...]. They are now more clearly connected to human activities, such as the release of carbon dioxide ― the main greenhouse gas ― from burning coal and other fossil fuels "

Temperature Anomaly Distribution. Hansen et al. 2012

Hansen's article entitled "Perception of climate change" follows the same logic. Dr. James Hansen is the man who popularized the climate change in the political level, in 1988. He was in this period working in NASA and had enough outreach to talk to the US Congress (to an amazed Al Gore, who was in this period a congressman from Tennessee) about his conclusions on the subject: "the Global warming is now large enough that we can ascribe with a high degree of confidence a cause-and-effect relationship to the greenhouse effect." It was the start of a new era. 

Hansen, as Molina, affirm we can see climate change modify our weather. 

Hansen shows in this paper how the probability of unusually warm seasons has increased, specially in summer.

Hansen has studied the temperature anomalies in the period 1951-1980: a period when the global temperature was very stable, and is useful to compare. Their results show that the probability distribution (frequency of occurrence of temperatures) of local anomalies of the average temperature in the summer were following a normal distribution in the years 1950, 1960 and 1970 in both hemispheres. But each new decade, the distribution would have been flattened and shifted to positive anomalies, ie the zone of higher temperatures (he calls them "hot outliers").

When looking at standard deviations greater than 3, he observes that in 1950 there were 0.1% of the episodes of extreme heat and in 1980 there where 10%. This is 100 times more extreme heat events in 1980 than in 1950. The planet is heating and when it's warm, it is much much warmer.

The same occurs with cold events even if warm events are more frequent than cold ones.

In my opinion, the interesting thing here is that Hansen doesn't use a computer model of climate simulation. He statistically studied empirical data and explained what happened. 

He explains successive heat waves that have occurred in recent years, specially in the northern hemisphere. The question is, why did that happen? It is clear that there is a correlation between global warming and increased presence of extreme events, but establishing a cause-effect relation is difficult and Hansen gets his feet wet. He literally says: “[...] we can state, with a high degree of confidence, that extreme anomalies such as those in Texas and Oklahoma in 2011 and Moscow in 2010 were a consequence of global warming because their likelihood in the absence of global warming was exceedingly small“. Perhaps too categorical... and of course, many scientists have disputed that statement.

This happened because it is very difficult to prove this relation. Weber established in 2010 these barriers to understanding climate change. There relation seems obvious, but ... Does that mean that if we successfully attack climate change, episodes of extreme weather will be reduced? 

Maybe we just have to be more pragmatic... Munich Re, the biggest insurance company in the world speaks openly about the subject (advantages of not being a scientist).

Their NatCatSERVICE collects data from up to 1,000 natural disasters per year, which it studies and analyzes (worth to take a look). The chart below, shows that extreme natural phenomena have been almost tripled in 30 years.

At the end of 2011, Munich Re was talking about the report "Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation", or SREX. They said pretty much the same as Hansen but earlier: “It would seem that the growing number of weather- related catastrophes can only be explained by climate change. The view that weather extremes are more frequent and intense due to global warming is in keeping with current scientific findings“. And nobody complained. 

Whether Hansen is wrong or not, there is something called the "precautionary principle" which is included in the Maastricht Treaty. It is simple: 

"If a threat of serious or irreversible damage to the environment or human heath exists, a lack of full scientific knowledge about the situation should not be allowed to delay containment or remedial steps"

According to this principle, action needs to be taken.

Acting or not, that is the question...