A series of giant walls – stretching up to 100 miles along the U.S. "Tornado Alley" – could prevent such disasters from happening in the future, according to physicists.
A scene from Judge Dredd (1995). Hollywood Pictures / Buena Vista Pictures.
The idea is vaguely reminiscent of Mega City One, a fictional city-state in the Judge Dredd universe. The outer walls of Mega City One spanned vast distances – protecting residents from potential weather or environmental disasters outside.
Now researchers believe a structure of similar appearance and scale might become a reality in the not-too-distant future. Running from east to west, several 1,000 ft (300 m) high walls – in Kansas, Louisiana, North Dakota, Oklahoma and Texas – could dampen the effects of tornadoes. In the American Midwest, these violent weather events are caused by intensive encounters between northbound warm air flows and southbound colder air flows. By deploying "great walls" at a number of strategic locations (determined by computer modelling), it might be possible to disrupt the formation of twisters and prevent them from gaining momentum.
The concept has been put forth by Prof Rongjia Tao of Temple University, Philadelphia and was discussed this week at the American Physical Society in Denver. Tao claims the project would cost about $16bn (£9.6bn), but in the long term would save many billions of dollars more in terms of protecting buildings and infrastructure. It could prove an especially useful adaptation measure when considering the rapid increase in disasters from climate change. The Moore tornado that struck Oklahoma last year was among the costliest tornadoes in U.S. history (adjusted for inflation), with peak winds of 210 mph (340 km/h) causing $2bn in damage, killing 25 people and injuring 400 others. Some meteorologists estimated that the energy released by the storm was over 600 times greater than the atomic bomb dropped on Hiroshima.
As evidence for his theory, Professor Tao has cited the flat plains of China, which are broken up by east-west hill ranges. Despite being only a few hundred metres high, these have a dampening effect on air currents, with only three tornadoes occurring in the region last year, compared to 803 in the U.S.
A similar effect is seen in parts of America, as Tao explains: "Washington County is a tornado hotspot. But just 60 miles (100 km) away is Gallatin County, where there is almost no risk. Why? Just look at the map – at Gallatin you have the Shawnee Hills."
Like the hills in China, these are only 200-250 m (650-820 ft) in height, but have a major influence on weather patterns. Computer models have already been demonstrated by Tao and his team. The next step is to build physical models for testing in wind tunnels. No government or environmental agencies have yet been contacted, but if this megaproject ever became a reality, he is confident it would be technically and financially viable. Rather than being eyesores – like the monolithic walls of Mega City One – they could also be designed in a visually attractive way.
"I spoke to some architects and they said it's possible," he added. "It would take a few years to finish the walls but we could build them in stages."
With self-sustaining gardens, this new eco-friendly skyscraper in Sri Lanka will give residents a sensation of ground-level living. The 46-storey tower is planned for completion in 2016.
Pictured here is Clear Point Residences, a new high-rise apartment complex in Kotte, Sri Lanka. The $100 million project – the first of its kind in the country – features an innovative design that is highly sustainable. This includes solar panels for electricity generation, planted facades, automated drip irrigation and water recycling systems.
These self-sustaining gardens provide cool and shady terraces, ensuring that no windows are exposed to direct sunlight, which therefore reduces the need for air conditioning units. They offer enhanced privacy and a tranquil environment that absorbs CO2, air and noise pollution. All of the apartments are cross-ventilated to provide further cooling. In addition to lowering energy consumption, the utility systems cut water usage from the grid by 45% – thanks to harvested rainwater, recycled bathroom water and on-site sewage treatment. Moreover, steps have been taken to allow the building to evolve in time with necessary additions from advancements in technology.
As designer Milroy Perera states: "Ultimately, the aim is to create a living space where you can not only feel at one with the environment, but actively contribute towards safeguarding and sustainable use of its resources. We are working very closely with our contractors Maga Engineering to enable the first self-sustaining building in Sri Lanka. The main focus of the apartment will be to provide an atmosphere and sentiment of ground-level living."
The 186 m (610 ft) structure will consist of 164 three bedroom apartments, four apartments per level, each of 2,300 ft2 with all internal spaces opening into planted terraces. The apartments are designed in a sleek and sophisticated manner. Construction of the tower is now underway and due for completion in early 2016, at which point it will become the world's tallest vertical garden – surpassing the 33-storey, 117 m (384 ft) One Central Park in Sydney, Australia. Given the environmental challenges the world faces, eco-towers like these could be fairly commonplace by 2050.
Despite claims of a recent slowdown in global mean temperature, the number of local temperature extremes has "dramatically and unequivocally increased in number and area", according to researchers at the University of New South Wales. This has also occurred despite the complete absence of a strong El Niño since 1998.
This image shows a time series of temperature anomalies for hot extremes over land (red) and global mean temperature (black, blue). The anomalies are computed with respect to the 1979-2012 time period. The time series are based on the ERA-Interim 95th percentile of the maximum temperature over land (Txp95_Land, red) and the global (ocean + land) mean temperature (Tm_Glob) in ERA-Interim (blue) and HadCRUT4 (black).
Extremely hot temperatures over land have dramatically and unequivocally increased in number and area despite claims that the rise in global average temperatures has slowed over the past 10 to 20 years during what some public commentators have called a global warming hiatus period.
Scientists from the University of New South Wales (UNSW) ARC Centre of Excellence for Climate System Science and international colleagues made the finding when they focused their research on the rise of temperatures at the extreme end of the spectrum, where impacts are felt the most.
“It quickly became clear, the 'hiatus' in global average temperatures did not stop the rise in the number, intensity and area of extremely hot days,” said one of the paper’s authors, Dr Lisa Alexander.
“Our research has found a steep upward tendency in the temperatures and number of extremely hot days over land and the area they impact, despite the complete absence of a strong El Niño since 1998.”
The researchers examined the extreme end of the temperature spectrum because this is where global warming impacts are expected to occur first and are most clearly felt. As Australians saw this summer and the last, extreme temperatures in inhabited areas have major impacts on society. The observations also show that extremely hot events are now affecting, on average, more than twice the area when compared to similar events 30 years ago.
To get their results, which are published in the journal Nature Climate Change, the researchers examined hot days starting from 1979. Temperatures of every day throughout the year were compared against temperatures on that exact same calendar day from 1979-2012. The hottest 10 per cent of all days over that period were classified as hot temperature extremes.
Globally, on average, regions normally expect around 36.5 extremely hot days in a year. The observations showed that during the period from 1997-2012, regions that experienced 10, 30 or 50 extremely hot days above this average saw the greatest upward trends in extreme hot days over time and the area they impacted. The consistently upward trend persisted right through the “hiatus” period from 1998-2012.
“Our analysis shows there has been no pause in the increase of warmest daily extremes over land and the most extreme of the extreme conditions are showing the largest change,” said Dr Markus Donat.
“Another interesting aspect of our research was that those regions that normally saw 50 or more excessive hot days in a year saw the greatest increases in land area impact and the frequency of hot days. In short, the hottest extremes got hotter and the events happened more often.”
While global annual average near-surface temperatures are a widely used measure of climate change, this latest research reinforces that they do not account for all aspects of the climate system. A stagnation in the increase of global annual mean temperatures, over a relatively short period of 10 to 20 years, does not imply that global warming has stopped. Other measures – such as extreme temperatures, ocean heat content and disappearance of land-based ice – all show continuous changes that are consistent with a warming world.
“It is important when we take global warming into account, that we use measures that are useful in determining the impacts on our society,” said Professor Sonia Seneviratne from ETH Zurich, who led the study while on sabbatical at the ARC Centre. “Global average temperatures are a useful measurement for researchers, but it is at the extremes where we will most likely find those impacts that directly affect all of our lives. Clearly, we are seeing more heat extremes over land more often as a result of enhanced greenhouse gas warming.”