Sandy and Climate Change

Two years ago, hurricane Sandy terrified the United States. More than 110 dead in the world's first economy and in the same area that one year earlier suffered the consequences of Irene (8 deaths then). Flooding in streets, tunnels and subway, and blackouts paralyzed New York and parts of New Jersey, affecting 24 American states on that fateful October 29th. It even paralyzed Mitt Romney and Barack Obama campaigns.
Beyond the first world, Sandy devastated some parts of the Caribbean before landing on the US: Haiti (54 dead), Guatemala (52 dead and 20 missing, coinciding with an earthquake), Cuba, Dominican Republic (2 deaths), Jamaica and Bahamas (here without any dead fortunately).
The presidential campaign itself (Obama and Romney mentioned it) and the press in general (it's global warming, stupid) suggested the relationship between Sandy and global warming. But is there really a relation in this kind of events?

First of all, why was Sandy so devastating? For the simple reason that it was a huge hurricane. It started as a tropical storm originated in the warm Caribbean in front of Venezuela. As it moved northward, Sandy was fed by the unusually warm waters of the Atlantic. Gradually, it was increasing the intensity of showers and thunderstorms until Sandy ran into a very cold front coming from Canada and became a hurricane superstorm with 1900 km in diameter and winds over 120 km / h (up to 280 km / h in the storm center).
But is this normal? Well... Normally these storms dissipate on the Atlantic Ocean but in this case, a rare high pressure system over Greenland (due to an abnormal warming), lead Sandy to the east coast of the US. This way, due to the collision between a warm storm with a cold system over the US, Sandy became a very strange monster: a snowing tropical hurricane. If we add the contribution of the full moon during those days (nothing to do with werewolves), which raises tides above average, we already have our extreme scenario.

Destruction caused by Hurricane Sandy in Breezy Point, New York. Photograph: Julie Hau

Great, but ... this is related or not to global warming? For me, the answer is somewhere between "something" and "pretty much". It is very difficult to establish cause-effect relationships in meteorology. The climate is a chaotic system by definition; multivariable, nonlinear and interdependent. Applying a mechanistic reasoning "A implies B" in meteorology is not correct.
Although, basically, that would not matter if we believe what George Lakoff (the famous linguist author of "Do not think of an elephant" (what are you thinking now?)) points: Through the term "systemic causality" Lakoff explains how sometimes we put the entire guilt on elements affecting something only partially, like if they were totally responsible for its whole. For example, Lakoff cites "smoking causes lung cancer". Well, it's smoking and more things right? It doesn't matter: smoking systemically causes lung cancer. For Lakoff, the same happens with climate change and Sandy and I think it makes sense.

Being objective, in meteorology, frequency is even more important than intensity. So will there be more extreme weather events due to climate change? The answer is "YES, definitely". On a previous post, we already discussed this expected increase in extreme weather frequencies. Andrew Cuomo, the Governor of New York: "We have a 100-year flood every two years now". And studies seem to prove him right. Grinsted et al. 2012 published in Nature an article where it was shown that the number of major storms has increased in frequency since 1923; indeed, they detected that extreme events are about twice more likely during warm years than during cold ones.
Now think about this 2012 summer and the episode of abnormal Arctic Ice loss. In principle, these warmer freshwater could alter the flow of the jet stream around the northern hemisphere leading to an increase of water temperature in the North Atlantic water. Will this have any relation with Irene, Sandy and the massive winter storms that have been hitting the US Northeast in recent years?

There is also an expected sea level rise due to global warming. Lin et al. 2012 indicated that the combined effects of this new climate and an increase of 1 meter in the sea levels could mean that 100 years ago extreme events occur between every 3 and 20 years ... in New York !!! In other words, we should expect a "Sandy" every 3-20 years and that doesn't mean that the next will come in 19 years...
Besides, the American northwest coast is full of small bays, inlets, lowlands etc which means that it is very vulnerable.

Can you imagine the economic and environmental costs of protecting all this area with dikes? They did something similar in Louisiana to try to contain the Bp's oil spill in 2009. Setting up a (terrible) sand dike of around 70 kilometers long costed $360 million. The cost is low to save human lives but ... can we not spend it on something else? Because if you don't care about weather, let's talk about money.

Lightning in a changing climate

When speaking of the possible consequences of climate change,  the increase of the sea level, the intensity and frequency increase of hurricanes, ocean acidification and many other effects (which are enough to worry about) come to our mind. 
However, according to Romps et al, now we have to also worry about an increase of lightnings. On a paper titled "Projected increase in lightning strikes in the United States due to global warming" and published on the November issue of Science, they concluded that global warming will also result in an exponential increase in the production of lightnings during storms, one of the main causes of wildfires. 
These findings are not new: Price et al. 1994, also studied how global warming would increase the number of lightning-caused wildfires finding "a possible increase in lightning-caused fires in the US of 44% [...] with a 78% increase in the area burned by these fires".

Image: wleog.org

According to Romps et al. findings, climate change is causing a warmer atmosphere which holds more moisture, and this is one of the key ingredients to trigger lightnings.
As they explain in their article in Science, current lightning predictions are based essentially on the thickness of the storm clouds (higher clouds generate more lightnings). However, these models do not account other physical factors as the amount of moisture in the air or the potential of a storm cloud to generate air updraft. Therefore, they incorporated these factors in their prediction model.

What does this new study predict?
According to the developed equations, lightnings would increase exponentially, this means that in the next century it is estimated that the frequency of lightning increases by a 50% in the US territory. (combined with the expected longer and more frequent heat waves (Meehl and Tebaldi, 2004), this becomes a ticking time bomb).
Romps et al, explain as well that when lightning occurs a large amounts of ozone (which in excess is a powerful greenhouse gas) is released and this fact becomes a negative feedback for the climate system.
However, if we want to look in the bright side, lightnings also produce nitrogen oxides which indirectly reduce levels of methane, another important greenhouse gas.

Together with the increasing seismic activity, this is one of the oddest climate change effects I have seen. What do you think?
Btw, here you have Bill McGuire's (UCL geologist) book about how climate change could trigger earthquakes, tsunamis and volcanoes.

WELL DONE PHILIPPINES!

Hi there! Sorry for my disappearance, the end of the term was quite stressful! I'm finally back and I will catch up with the latest things that have been going on during the last two weeks.
I will start with very good news (which is kind of unusual in my blog): Filipinos are a great example of how tragedy can deliver great lessons for the future if we are ready to learn from it.

Satellite view of typhoon Hagupit. Image: NOAA

Typhoon Hagupit (known as Ruby in the Philippines), made landfall last December 6th with winds up to 200km/h. 

The balance of this storm was 19 deaths in Philippines. One year after the powerful typhoon Haiyan, which left more than 7,000 dead in November last year, Filipinos have learned many lessons.

It is true that Hagupit was a slightly less intense storm, and, unlike Haiyan, it did not produce the storm surge of 5.2 meters high which devastated the city of Tacloban, but I think thatit is fair to say that this time the government was much better prepared. Early warning systems and preventive evacuations served to greatly minimize human losses.

At least 1.7 million people managed to evacuate their homes and find refuge in over 5000 evacuation centers. Shelter, food, water, sanitation and hygiene, health and logistics were among the main priorities.

According to the United Nations, the typhoon was estimated to affect 2.9 million people in nine different regions of the Philippines. The official death toll rose up to 19 (including at least seven children) and 916 injured.

As floods recede, more than half of the evacuees returned home in the last days. To date, 788,000 people remain in 3,0000 evacuation centers. Packages of food, water and hygiene kits were distributed to more than 95,000 victims. Meanwhile, government officers are planning to meet with NGOs to coordinate reconstruction efforts and humanitarian aid.

One of the evacuation centers. Image: Reuters

Philippine authorities, with the support of NGOs, continue to assess the damage and needs while focusing efforts in the provinces of Northern Samar, Eastern Samar, and Samar. They have also announced their goal to provide shelter assistance to affected communities until January 2015.

All national roads are already operational, but six bridges remain closed in the affected regions. Power outages continue in 12 provinces, while telecommunications coverage was restored to more than 74%.

The UN Office for Disaster Risk Reduction (UNISDR) congratulated the Philippines and said that this reaction demonstrates the leadership role that Asia plays in reducing mortality and economic losses from natural disasters.

The head of UNISDR Margaretha Wahlström said that the Philippine government has made an excellent job putting into practice the lessons learned from Typhoon Haiyan. 

She added: “We have been telling this story since the Indian Ocean tsunami ten years ago that nations and communities have the power to reduce their losses if they are well-organized, understand the nature of risk and develop the capacity to deliver early warnings and evacuate groups at risk ahead of the disaster event.” Now it is a demonstrated fact.

WELL DONE PHILIPPINES!

Btw, here you can listen to Mary Ann Lucille Sering (commissioner of the Philippines’ Climate Change Commission and lead climate official for the Philippines at the Lima conference) talk about adaptation and mitigation in Philippines

The huge economical cost of coastal flooding in 2050

The effects of climate change are enough now-a-days to start assess the economical cost it will cause to humankind in the future.

Climate change, together with population growth in some areas of the world and economical growth, could lead to a big increase of flooding risk in big coastal cities (up to nine times today's risk by 2050).

A paper published in August 2013 in Nature (Hallegate et al. 2013) titled "Future flood losses in major coastal cities" has estimated this cost and is part of a bigger work carried out by the OECD (Organisation for Economic Co-operation and Development) in order to assess flooding risk (particularly due to storms) as a consequence of climate change and urban development from a social and economic point of view.

The new study has been partially based on previous OECD works, which classified the world's port cities on a scale based on their present and future vulnerability to storms taking into account the number of inhabitants and the value of the goods which could be affected by flooding.

Hallegate et al, have calculated the present and future losses due to flooding in 136 of the biggest coastal cities in the world taking into account the existing flood defenses (the city of Amsterdam is an interesting example with and extremely high exposure but small economic average annual losses due to it's extraordinary defenses).

The average losses in 2005 were quantified to be around 6.000 million dollars and could increase up to the mind-bending number of 52.000 million per year by 2050.

According to this metric, most of the more vulnerable cities in the world  are part of industrialized countries such as: Guangzhou and Shenzhen in China, Miami, Tampa-St. Petersburg, Boston, New York and New Orleans in the US, Bombay in India, Nagoya and Osaka-Kobe in Japan and Vancouver in Canada.

Due to their high wealth and low protection level, three US cities (Miami, New York and New Orleans) explain 31% of total economical losses in the 136 cities. Adding the Chinese city of Guangzhou, the four cities explain 43%.

The economic cost in dollars is a way of assessing the risk but a more complete way of assessing it is to see these economical losses as a percentage of the city's total wealth.

According to this criteria, Guangzhou (China), Guayaquil (Ecuador), Ho Chi Minh (Vietnam) and Abidjan (Ivory Coast) are within the most vulnerable cities in the world.

To estimate future climate change impact, a sea level rise between 0.2m and 0.4m by 2050 is assumed.

In addition to this, about a quarter of these 136 cities are located in river deltas, and therefore more exposed to river floods, as well as decreases of soil on land or promotion of coastal seabed, due to the local subsidence, particularly in cases where overexploitation of groundwater accelerates natural processes.

In my opinion, one of the most important findings of this study is that even a "moderate" sea level rise would cause substantial increases in losses if adaptation measures are not taken because the defenses against flooding are designed to past conditions.

Doing nothing is not an option, as it could cause losses exceeding one trillion or more per year, according to the study. 

Therefore, coastal cities will have to improve its flood action plan, including the construction of good defenses, at an estimated cost of around 50,000 million dollars per year to 136 cities.

The report makes the point that significant increases in the flooding risk in cities which are not vulnerable today may occur.

The five cities with the highest estimated risk increase are Alexandria in Egypt, Barranquilla in Colombia, Naples in Italy, Sapporo in Japan, and Santo Domingo in the Dominican Republic.