Tag Archives: cities

Cities need to wean off of cars in the future or become endless traffic jams

If we want cities to remain viable in the future, we’ll have to rethink transportation and car use, a new paper warns.

Image via Pixabay.

Researchers at the University College London (UCL) trying to understand the city of the future say it doesn’t mix well with automobiles. If current trends continue, they explain, cities will eventually be swamped by cars. This will drain ever-more resources on infrastructure, and waste ever-more of our time through busy, slow commutes.

Cars will still be used, undoubtedly, but the authors recommend that walking or cycling should be promoted instead of these for short, local trips. Public transport networks should be improved and encouraged for longer journeys, where possible. In order to keep cities livable in the future, the team concludes, cars should only be used for special occasions or emergencies.

Too many

“The city of the future, with millions of people, cannot be constructed around cars and their expensive infrastructure,” explains lead author Dr. Rafael Prieto Curiel. In a few decades, we will have cities with 40 or 50 million inhabitants, and these could resemble car parks with 40 or 50 million cars.”

“The idea that we need cars comes from a very polluting industry and very expensive marketing.”

The results are based on a mathematical framework that models the use of cars in a city. For the purposes of this study, the model assumed that citizens would either use a car on a daily basis or used public transport. What the model tracked was how long (in terms of time) each journey would take, as time was considered to be the main cost individuals consider when deciding on how to travel. The baseline for the model was a city in which there is no personal car traffic, just cycling, walking, and public transport.

On the other extreme, the model considered a city with 50 million inhabitants and 50 million cars, where all residents would commute to work with their own vehicle in order to save up on time. This virtual city, quite understandably, saw much higher levels of congestion and required more spending on infrastructure such as avenues, bridges, and car parks in order to accommodate all that traffic.

Surprisingly however, while the people in this city opted to drive to work to get there sooner, they actually lost more time than those in other scenarios. While driving is the fastest solution for individuals, when everybody opted for it, commuting times were the longest seen in any of the simulated cities. The team explains that this comes down to traffic — all those cars on the road create jams and slow everybody down significantly.

Where to go from here — and how?

The paper offers reliable evidence that better public transport infrastructure would improve the travel time for citizens, as more of them would opt for public transport over personal vehicles. It also shows that even without any improvements in public transport, time costs for commuters and citizens travelling through the city can be reduced by lowering the number of people driving at any single time.

While they don’t advocate for this solution, the authors give a scenario where a group of people is allowed to drive one week, but must use other transportation options the next one, such as ride-sharing or public transport. Average commuting times could be reduced by up to 25% (depending on the size of the group) for all citizens due to reduced car traffic, less congestion, and faster transportation throughout the city on average.

However, the authors underline that decreasing car use in cities hinges on giving people efficient travel alternatives, as well as local shops and services (so as to reduce demand for transport in the first place). Interventions such as congestion charges, tolls, and driving and parking controls can help discourage car use, but unless people have alternatives to pick from, and are informed as to the local costs of car use, we can’t reasonably expect them to give up the use of their cars. Some cities have tried simply banning some vehicles based on their license plate, such as Mexico City, but this backfired as residents purchased older, cheaper, and more polluting cars to get around the ban.

Not making any changes isn’t a viable option, either. They note that car production is fast increasing, and has actually outstripped population growth. In 2019, 80 million cars were produced, while the population increased by 78 million worldwide. Pollution is a big concern: globally, car manufacturing (including electric vehicles) contributes 4% of total carbon dioxide emissions. Energy use, be it petrol, diesel, or electricity, also generates pollution (right under our noses, in the case of combustion engines) and added costs. Material costs related to the construction and maintenance of infrastructure required by these cars, as well as time lost in traffic due to congestion, are also added costs most people don’t consider.

“Currently, much of the land in cities is dedicated to cars. If our goal is to have more liveable and sustainable cities, then we must take part of this land and allocate it to alternative modes of transportation: walking, cycling, and public transport,” says co-author Dr. Humberto González Ramírez from the Université Gustave Eiffel.

Such research is actually very important, as sustainable transportation is a key objective for many large cities as part of one of the UN’s Sustainable Development Goals. This model, the authors explain, can easily be adapted to other cities around the world, although it is particularly useful for locales where the majority of travel (>90%) is done by car, which is most common for cities in the US.

The paper “A paradox of traffic and extra cars in a city as a collective behaviour” has been published in the journal Royal Society Open Science.

Cities are literally starting to sink under their own weight

Cities have become so big and crowded that they are gradually collapsing under the weight of their own development, according to a new study.

The researchers specifically looked at San Francisco as a case study and found that the city might have already sunk by 8 centimeters (or 3.1 inches) – something that they argue is likely happening in other cities too.

San Francisco. Image credit: Flickr / Peter Miller

The finding is especially concerning as cities (especially coastal cities) are already exposed to sea level rise because of climate change. Sea level has already risen between 21 and 24 centimeters (or 8-9 inches) since 1880 and the rate is accelerating, increasing the risk of floods, extreme weather events, and coastal erosion.

“As global populations move disproportionately toward the coasts, this additional subsidence in combination with expected sea-level rise may exacerbate risk associated with inundation,” Geophysicist Tom Parsons, from the United States Geological Survey (USGS) agency, wrote in his recent paper.

At the same time, a steady migration of Earth’s population from rural to urban centers is occurring in virtually every part of the world. Currently, about 50% of Earth’s population lives in urban settings, and by 2050 it is projected that number will grow to 70%, according to the UN. Along with people, urbanization has caused a redistribution of mass into concentrated areas. In other words, cities are constantly becoming heavier, and it’s not just because of the people moving in.

Nearly everything necessary to sustain a city’s population must be imported. A global network of suppliers ships food, fuel, water, cars, mass transit, pavement, pipes, concrete, and steel from great distances. Every conceivable object that people want or need is brought to and stored within relatively small areas. Researchers wondered whether all this concentrated weight wouldn’t have an effect. Lo and behold, it does.

For his research, Parsons used San Francisco as a case study to understand why and how many cities are sinking. The San Francisco Bay region has over 7.7 million inhabitants and is the cultural, commercial, and financial center of Northern California. He discovered that the city sunk by 80 millimeters (3.1 inches), this being the city’s level of subsidence (sudden or gradual sinking of the ground’s surface).

Parsons calculated the weight of the bay area at 1.6 trillion kilograms or roughly 8.7 million Boeing 747s, taking into account all the buildings in the city and their contents. This would be enough to bend the lithosphere, which is the rigid outer part of the Earth consisting of the crust and upper mantle, causing it to sink, according to Parsons.

The study didn’t consider the weight of things outside buildings, such as transport infrastructure, vehicles, or people. This means the city could have actually sunk more than the estimated 80 millimeters. For the researcher, it’s a clear sign that the same type of sinking is likely to be happening in other parts of the world, depending on the geography of each city.

“The specific results found for the San Francisco Bay Area are likely to apply to any major urban centre, though with varying importance,” Parsons wrote in the study. “Anthropogenic loading effects at tectonically active continental margins are likely greater than more stable continental interiors where the lithosphere tends to be thicker and more rigid.”

While other causes of sinking also have to be taken into account such as tectonic plate shifting and groundwater pumping, these findings are significant. And they could even be improved further, using satellite photos to better analyze the Earth’s surface and predict where likely flood zones might occur, Parsons argued.

The study was published in the journal AGU Advances.

These 30 cities are leading the way in climate action — their emissions are already dropping

Despite the lack of ambition of most countries, cities are showing they can also step up and reduce their greenhouse emissions even further. A new analysis published by a coalition of cities known as C40 concluded at least 30 major cities are on the right climate track.

Copenhagen is one of the cities in the C40 list. Credit: Wikipedia Commons

The latest analysis by C40 identified a group of cities across the global north that have hit their “peak” emissions before 2015, meaning they have since reduced their greenhouse gas emissions by at least 10%. The list includes large cities such as Lisbon, Berlin, and Barcelona.

The 30 cities identified by C40 have curbed emissions by 22% on average. Some of the most significant reductions came from London, Berlin, and Madrid, which averaged around 30% reductions, while Copenhagen lowered emissions by a dramatic 61%.

San Francisco is another positive example, whose emissions continue to go down. Image credits: C40.

Copenhagen expanded its district heating system, which channels waste heat from electricity production through the pipes into homes to meet the demands of an increasing population. At the same time, it invested heavily in its biking infrastructure and public transit.

“The key thing is that Copenhagen just shows that it is possible to rapidly decarbonize over a short period of time,” said Michael Doust, C40’s program director of measure and planning. “And the innovations they are applying are applicable globally.”

Tokyo was the only non-Western city on the list and had fluctuations in its yearly emission levels. They began falling after 2003, but by 2010 levels rose again, reaching near-peak levels by 2012 and 2013. Yet Doust assures us that Tokyo is an example of a unique success story; emissions began falling again in 2014.

Despite the success, any of the 30 cities could once again see emissions rise beyond its highest levels in the future. So far, none has, and to ensure that there aren’t any “false” peaks in their data, researchers put in that 10 percent reduction threshold as a requirement.

“It is expected that these cities should peak before 2020, and the fact that they’re doing so is encouraging,” Doust said. “You can still grow your economy; you can still grow your cities in size and still peak.”

The 30 cities are: Athens, Austin, Barcelona, Berlin, Boston, Chicago, Copenhagen, Heidelberg, Lisbon, London, Los Angeles, Madrid, Melbourne, Milan, Montréal, New Orleans, New York City, Oslo, Paris, Philadelphia, Portland, Rome, San Francisco, Stockholm, Sydney, Toronto, Vancouver, Venice, Warsaw, and Washington, D.C.

Cities and climate change

Cities are major contributors to climate change. According to UN-Habitat, cities consume 78% of the world’s energy and produce more than 60% of greenhouse gas emissions. Yet, they account for less than 2% of the Earth’s surface.

An added challenge is the projection that another 2.5 billion people will reside in urban areas by 2050. The good news is that cities around the world have already begun to take measures to reduce greenhouse gas emissions and are putting policies in place that encourage the use of alternative energy sources.

However, cities also hold the key to solving climate change. That is where most of the world’s innovation takes place, and as more and more people flock to urban areas, managing cities properly will ensure not only improved living standards, but also reduced emissions. Simply put, if we want to start tackling climate change, we need more leadership from cities — and this is exactly what we are seeing with C40.

The effects of climate change are worse among poor and low-income communities, in part because many live on the margins of society, in unstable structures, and in areas more susceptible to flooding, landslides, earthquakes, but also because of inadequate capacities, inadequate resources and reduced access to emergency response systems.

The C40 initiative actually has 90 participating member cities across seven geographic regions, from all of the world’s continents except for Antarctica.

City smoke.

Prolonged exposure to Los Angeles Bay air induces dangerous mutations in the brains of rats

Mice trials suggest that city air may be even worse for your health than previously thought.

City smoke.

Image credits Johannes Plenio.

Prolonged exposure to fine particulate matter sourced air in the Los Angeles bay area does not do the brains of mice a lot of good. According to a new study published by researchers from the Cedars-Sinai Medical Center, a non-profit hospital in Los Angeles, it triggered inflammation and the appearance of cancer-associated genes in the animal’s neurons.

Brain trouble

The fact that air pollution is linked to a wide range of diseases isn’t exactly news by now — quite on the contrary. The adverse effects air pollution has on health have been widely documented and reported on. However, one new (and not exactly encouraging) discovery the team made is that certain materials in coarse air pollution — particularly nickel — may have a role promoting genetic changes that underpin the development of diseases such as cancer.

“This study, which looked at novel data gathered in the Los Angeles area, has significant implications for the assessment of air quality in the region, particularly as people are exposed to air pollution here for decades,” said lead author Julia Ljubimova, director of the Nanomedicine Research Center at Cedars-Sinai.

The team worked with one hundred mice — separated in groups of 6 to 10 animals. Each group was exposed to coarse (PM2.5–10: 2.5–10 µm in diameter), fine (PM<2.5: <2.5 µm), or ultrafine particles (UFPM: <0.15 µm) sourced from ambiental air in Riverside, California. Each type of particulate matter was analyzed using atomic emission spectroscopy, so the team had an idea of how much nickel, cobalt, and zinc they contained.

PM exposure lasted for 5 hours daily, 4 days per week for either two weeks (short exposure), one to three months (intermediate), or 12 months (long). One cohort of rats served as control and was kept in the same exposure chambers, for the same duration as the rats in the other groups, but was exposed to filtered air.

Afterward, the team analyzed the brains of each group to see how much of each metal had accumulated and whether this build-up had any effect on the organs’ health.

Metal build-up

They report that all three metals accumulated following intermediate-or-longer exposure. RNA sequencing revealed that intermediate exposure to PM2.5–10, which also correlated to nickel accumulation in the brain, triggered the expression of EGR2 — the early growth response gene 2 which regulates inflammatory processes — and of RAC1 — a gene that has the potential to cause cancer. The team believes the observed effects are a cumulative effect of exposure to the metals and certain toxins present in the air recovered from the Los Angeles Basin.

Furthermore, they report that coarse particulate matter from air pollution entered the body via two mechanisms. Trace metals and other pollutants could pass into the bloodstream from air inhaled through the lungs, later making their way to the brain. Alternatively, some of them could pass directly through mucosa in the nose, from where they had a much more direct pathway to the brain.

The study’s main limitations are that it only involved animal models — so the observed effects may carry over identically to humans — and that it only used a local ‘blend’ of pollutants — so the results may not be universally valid. Ljubimova notes that while the results may be unique to the Los Angeles Basin area, they do reinforce previous findings regarding the health consequences of exposure to air pollution in major cities.

Considering that most of humanity today lives with “unsafe” levels of air pollution, the findings are even more troubling.

“Our modern society is becoming increasingly urbanized and exposed to air pollution,” she says. “This trend underscores the need for additional research on the biology of air-pollution-induced organ damage, along with a concerted effort aimed at reducing ambient air pollution levels.”

The paper “Coarse particulate matter (PM2.5–10) in Los Angeles Basin air induces expression of inflammation and cancer biomarkers in rat brains” has been published in the journal Scientific Reports.

Urban Forest.

As cities grow, we must bring the forest into our midst — or pay up

Urbanisation and urban forests are likely to become some of the defining elements of the 21st century, according to research from the USDA Forest Service.

Urban Forest.

Image in Public Domain.

By 2100, forests will likely move from the wild outdoors to a block near you, says the USDA Forest Service. According to a new study, published by researchers at the governmental organization, urban land surface in the Lower 48 states will more than double between 2010 and 2060. That space, as our attractive, well-informed readers already suspect, must come from somewhere — mainly, the surrounding forests and farmland. Along with the fact that size tends to amplify cities’ innate drawbacks, this will have a negative impact on the environmental quality and general well-being of residents.

The big get bigger

Between 2000 and 2010, urban land increased from 2.6 percent of the overall land surface to 3 percent (from 58 million acres to 68 million acres). The states that saw the greatest urban growth were in the South and Southeast: Texas, Florida, North Carolina, Georgia, and South Carolina. The authors anticipate that between 2010 and 2060, that area will increase by a whopping 95.5 million acres, reaching a total of 163 million acres (8.6% of land area). To put that into perspective, the projected increase of 95.5 million acres represents an area larger than the whole state of Montana.

In addition to estimating how urban areas will evolve, the research also freshened up previous assessments on the size of the US’ urban forests. Overall, they contain roughly 5.5 billion trees (39.4% of tree cover) shelling out in excess of $18 billion in benefits to society. That estimated sum includes health benefits associated with better air quality, negative costs from cities’ higher climate change resilience, and savings on energy use. In a previous study, lead author David Nowak of the USDA Forest Service‘s Forest Inventory and Analysis Program found that (among other benefits) urban forests across the US save 670 human lives each year, and help nip 575,000 incidents of acute respiratory symptoms in the bud.

“Urbanization and urban forests are likely to be one the most important forest influences and influential forests of the 21st Century,” said Nowak.

“A healthy and well-managed urban forest can help reduce some of the environmental issues associated with urbanization such as increased air temperatures and energy use, reduced air and water quality, and increased human stress, and ultimately help people living within and around urban areas.”

It’s not just the body either. Spending time in nature simply makes us feel better, and such urban forests could soothe the weary, dreary urban soul.

Greening up the place

So which Americans stand to gain most from trees moving into the big city? One way to find out is by looking at which states have the largest percentage of urban land (and by extension, have the least forests and other wild areas). These states are all along the Atlantic coast and have relatively small total areas: New Jersey, Rhode Island, Massachusetts, Connecticut, and Delaware.

States that have the greatest amount of projected land growth (California, Texas, Florida, North Carolina and Pennsylvania) would also stand to benefit a lot from weaving forest into their to-be-developed areas — especially since the projected increase in each state over the next 50 years is greater than the size of Connecticut (3 million acres).

“Research by the USDA Forest Service is informing cities and communities as they make decisions about managing urban forests,” said Tony Ferguson, Director of the USDA Forest Service’s Northern Research Station and the Forest Products Laboratory.

“By measuring and monitoring urban forests, society can better understand the value urban forests deliver, and how urban forests and their role in reducing pollution and reducing energy costs changes over time.”

The findings likely extend to other countries beyond the US, especially those with a comparable level of development or those which are expecting a rapid rise in urban populations.

All in all, the study’s results line up surprisingly closely with Professor Alan Marshall’s vision of the future cities: Ecotopia 2121.

The paper “US Urban Forest Statistics, Values, and Projections” has been published in the Journal of Forestry.


Ecotopia 2121 shows what perfectly eco-friendly cities would look like


Greenville, South Carolina, 2121. The distinctive buildings, dubbed Sunflower Homes, are easy to construct, inexpensive, and self-sufficient. Their unique shapes hark back to the rarest and most endangered sunflower on Earth, Schweinitz’s sunflower, n order to both raise awareness and to increase the homes’ energy-capture efficiency.

Adapt or die.

It’s a law that has governed life ever since it first sprang up on the face of the Earth. In many ways, we have managed to make ourselves exempt from it. We’ve out-hunted our predators. We’re no longer at the mercy of seasons for food. We can steel our bodies against disease and fix the parts that break down with time or injury.

The dramatic changes we’re ushering in on the planet, however, are a stark reminder that our fate is still weaved very deeply into that of the Earth. Environmental crises developing over the last decades show that working against nature, trying to twist it in our image, is a recipe for disaster. Our best bet, then, is to become an integral part of natural systems rather than replacing them with artificial ones.

Living within our means

One very eye-catching view of what this paradigm shift might look like comes from Ecotopia 2121. This project, the brainchild of Alan Marshall, an environmental social science professor at Mahidol University, Thailand, tries to imagine future cities that have adapted to fit their environments.

We wanted to know more about this green utopia, so we sat down with the professor to find out how one goes about imagining the cities of the future.


Antalya, Turkey, 2121. Solar cells can be easily printed by this year, pasted, or painted onto various structures in any color. The color scheme shown in the artwork was decided by popular vote and recreated with the panels.

“The project started quite small some time in late 2012 as a classroom activity for my social studies Masters students, to get them to imagine their own city as a perfectly sustainable urban setting, and to get them to workout how it could transform into a ‘Green Utopia’,” Professor Marshall told me.

That day, he joined his students for the exercise and together they reinvented Alan’s hometown of Wellington, New Zealand. Their results, however, were quite good and they had fun working towards them, so the class decided to continue their project.

It started off with a small research group, the professor explained — one that aimed to pool the social study research work and artistic prowess of various years of students. By 2016, it had grown into a loose international collaboration. Alan tells me that his travels across the world (both for work and leisure) gave him ample inspiration.

“I drew on this ‘fieldwork’ to put my ideas, and the ideas of my Masters students, together into a few ‘social studies’ papers and presentations,” he recounts.

“Using contacts from previous ‘ecodesign’ projects across the world, including the fieldwork I conducted in the Transylvanian alps and across the Carpathian mountain countries, a number of designers from around the world also were intrigued by the idea of designing a ‘perfect’ eco-society, and they also sent in some ideas and sketches.”

Just like their surroundings, each city re-imagined for Ecotopia is unique. Adaptation meant they had to tailor themselves to varying conditions, creating the vast diversity seen in the project.

One hundred of these future cities were brought to life in artwork and through narratives that detail each city’s transformation into an eco-friendly utopia in the book Ecotopia 2121.

Are we there yet?


London, UK, 2121. Massive protests over tanking quality of life standards lock down the center of London for months — ironically making it less polluted by blocking traffic. That’s how England’s capital starts down the path towards Ecotopia.

Change in Ecotopia came on through various channels: “sometimes through political revolution, sometimes through some quirky technological innovation, sometimes through gradual social awareness change, and sometimes through grave ecological tragedy,” says Marshall.

Hopefully, we’ll get there via some of the nicer routes instead of disaster, but the die is yet to be cast. What is encouraging, however, is that Ecotopia is more feasible than you’d initially suspect. The cities depicted in the project mostly use technology which is available today, with some bits and tricks which can be “forecast by anybody with an eye to the near-future,” Marshall told me.

“I’m pretty sure we do not need incredible leaps in technology to propel cities towards the Green Utopias of 2121,” he adds.

One of the most encouraging tidbits I’ve taken away from my bout of emails with the professor, however, is that the shift in our cities will also entail a change in our relationship with nature. The effort to adapt our cities won’t center around pleasing consumers, profit margins, and market-share. It won’t be about the security of military advantage, either.

It will be a collective expression of individual effort and desire to improve, and Marshall believes the “impetus must come from people”. Social agents of change abound in Ecotopia 2121 to reinforce this idea. Beyond just building cities, such a shift in mentality would become the best insurance of sustainability across all areas of human activity.

The project shows us a glimpse of a future where our collective effort — and collective involvement — carried the day. A future made possible by people working together for their own common good and the good of the planet at large. That’s quite an uplifting undertone of community to go with the bright artwork showcased in the project — one that I feel the concrete jungles of today deeply lack.

“Now, if you ask if these cities are proffered as ‘predictions’ or as ‘inspiring urban fantasies’, it’s a bit of both,” Alan confessed.

“Mostly, I believe if the world’s cities are to remain livable for the majority of citizens, then they will have to develop into the forms predicted in the Project. Or else they will grind to a halt through slow eco-collapse, economic decay, or some rapid large-scale disaster.”

On the flipside of the Green Utopias envisaged in the book stands Frankencities, an “evil sister” project that looks at how our cities will turn out in the worst case scenario. It “details the worst-case near-future scenarios for specific real-world cities so that we may graphically identify their risks and dangers” — the artwork is so good, though, that I’d totally visit these dystopian cities.

Ecotopia 2121 and Frankencities effecitvely show us how our communities could adapt to suit the future, and how our choices determine the end result. We can twist the world around us harder and cobble out sprawling Frankencities from the pieces, or we can laze in the sun like sunflowers in our Ecotopias.

The choice is in our hands. Impetus, after all, must come from ourselves.

Trees provide hundreds of millions of dollars in services to cities for free, paper reports

Megacities gain some US$500 million in services from trees each year, a new paper reports. That sum could potentially be increased by up to 85%, simply by planting more trees, the researchers add.

Awesome trees landscape.

Image credits michalhlavac204 / Pixabay.

Trees are good business for cities. They filter air and water pollutants and supply other critters that maintain city ecosystems with room and board. An international team of researchers wanted to quantify how these services translated to avoided costs in the world’s ten largest megacities, which house nearly 10% of the world population. Even better, they also report that these cities can increase that sum by around 85% simply by planting more trees.

Trees — they keep cities running

Trees underpin urban ecosystems and have an annual median value of US$ 505 million, the team reports, equivalent to saving $1.2 million with every square kilometer of trees planted. Crunch those numbers down and it means that everybody living in such a city would have to pay an average of $35 per year for these ecological services if the trees weren’t there, the team estimates. It doesn’t sound like a lot on on a per capita basis, but seeing as a ‘megacity’ is defined as housing in excess of ten million people, that adds up to a huge pile of money overall.

So how can a tree help people save money? We all know they help improve air quality by scrubbing CO2, but they also perform a wide range of often-overlooked services which play a direct role in making our cities livable. For example, their leaves filter harmful airborne particles out of the atmosphere — something your lungs are definitely thankful for. Everybody’s scrambling for the shade they provide during a heatwave, but trees further help mitigate warm weather by transpiring water vapor. Their shade helps keep buildings and pavement cool (meaning lower costs on air conditioning and more comfortable walks outside), prevent soil erosion, and mitigate runoff during storms.

In other words, trees are really good news for cities and the people living there. In their absence, we’d have to find (and pay for) alternate ways to provide these services in our cities or risk them becoming unlivable expanses of concrete. And the simplest way to save even more, according to Dr. Theodore Endreny of the College of Environmental Science and Forestry (ESF) in Syracuse, New York, the study’s lead author, is to plant even more of them.

“Megacities can increase these benefits on average by 85 percent,” Endreny said. “If trees were to be established throughout their potential cover area, they would serve to filter air and water pollutants and reduce building energy use, and improve human well-being while providing habitat and resources for other species in the urban area.”

Tree city.

They also supply a lot of ‘pretty’.
Image credits Timofey Iasinskii.

To reach the figures reported on in this study, the team estimated existing and potential tree cover in each city and compared that to the ecosystem services the plants provide. Their analysis spanned 10 megacity metropolitan areas across different biomes over five continents. The cities used in the study were Beijing, Buenos Aires, Cairo, Istanbul, London, Los Angeles, Mexico City, Moscow, Mumbai, and Tokyo. As far as ecosystem services are concerned, the team estimated the benefits trees bring to the table in reducing air and water pollution, their effect in mitigating runoff from precipitation, absorption of carbon emissions, and finally building heating and cooling energy savings associated with the plants — both indirect, such as shade, and indirect such as transpiration which helps take the edge off during heatwaves.

“Placing these results on the larger scale of socio-economic systems makes evident to what extent nature supports our individual and community well-being by providing ecosystem services for free,” said Professor Sergio Ulgiati of University Parthenope of Naples, co-author of the paper.

“A deeper awareness of the economic value of free services provided by nature may increase our willingness to invest efforts and resources into natural capital conservation and correct exploitation, so that societal wealth, economic stability and well-being would also increase.

While the sum smaller settlements save on trees is likely smaller, they also house fewer people, meaning that the per capita figures reported by the team probably aren’t that different for smaller towns or cities. And, given the looming threat of climate change and deadly heat waves in both Europe and the United States, trees might be the last line of defense in keeping our cities — if not pleasant — at least habitable.

Practical reasoning notwithstanding, I think we can all agree that cities simply feel better when they’re full of greenery. Plus, we can turn their hand (branches? roots?) and erect some strikingly awesome elf-like architecture — or chic residences. Ample reasons to plant them as often as we can.

The paper “Implementing and managing urban forests: A much needed conservation strategy to increase ecosystem services and urban wellbeing” has been published in the journal Ecological Modelling.

These are the world’s fastest growing cities. They’re all in Africa

Worldwide, more and more people are starting to move from rural areas to urban areas. But nowhere is this as prevalent as in Africa.

Image via WE Forum.

Village –> City

According to UN data, more people live in urban areas than in rural areas, with 54 per cent of the world’s population residing in cities in 2014. The figure is continuing to increase, and although the overall population of the planet continues to rise, rural population is nearing its peak or has already peaked. That means that almost all of the world’s extra population will live in cities. Overall, just three countries (India, China, and Nigeria) are expected to account for 37 per cent of the projected growth of the world’s urban population by 2050’. — and that will mostly be in cities. India is expected to add 404 million urban dwellers by then, China 292 million and  Nigeria 212 million. But if you take India and China out of the picture, it’s all Africa. In fact, the fastest growing cities are all African.

Some of these cities are relatively small, with the fastest growing one (Zinder, in Nigeria) hosting just over 200,000 residents. But some are already sprawling urban centers. Take Dar es Salaam for instance. It’s the largest city in eastern Africa, the capital of Tanzania, home to over 4.4 million people. In less than ten years, it will add over 2 million more. When you consider that in the 1970s, Dar es Salaam hosted under 400,000 residents, the rate of growth becomes evident. It’s grown ten times in four decades, and the growth is accelerating — and this is not a singular case. Bamako, the capital of Mali (whose name means “crocodile tail”), has experienced a staggering population growth. In 1884, it had only 2500 inhabitants, 8000 in 1908, 37,000 in 1945, and 100,000 in 1960. Today, the population is at least 18 times what it was in 1960, with over 1,800,000 recorded at the 2009 census. When you consider that these are just the official figures, with many other squatters and illegal residents in the city, the rate of growth is even more impressive. More and more people desperately move from poorer rural areas to cities. But is that a good thing?

Aerial view of Dar es Salaam. Image credits: BBM Explorer

Aerial view of Dar es Salaam. Image credits: BBM Explorer

Bigger cities, bigger opportunities, bigger challenges

In 1990, there were only ten so-called ‘megacities’ in the world (cities with over 10 million inhabitants). Soon, we’ll have 28 megacities, accounting for 12% of total urban population. We have more and bigger cities in virtually all parts of the world. This is generally regarded as a good trend because living in urban areas is associated with improvements in health, education, and overall standard of life.

People in cities are generally more educated and healthier than those in rural areas. They tend to live longer, but interestingly, they tend to have fewer kids. In fact, it may very well be that growing urban populations do a lot to limit overall population growth — as more people (especially more women) move to cities, they will be more educated and have fewer children, a correlation that has long been established. This could go a long way to limiting our planet’s population, growth, which is unsustainable as it is.

‘Urban living is often associated with higher levels of literacy and education, better health, greater access to social services, and enhanced opportunities for cultural and political participation’ explains the report.

But it’s not like moving to cities will make everything magically better. Growing urban areas come with a great deal of challenges as authorities in the developing world will certainly struggle to provide sufficient transport, sanitation, education, health care, housing and utilities. According to the WHO, urban population growth, in absolute numbers, is concentrated in the less developed regions of the world. It is estimated that by 2017, even in less developed countries, a majority of people will be living in urban areas, and that makes those challenges even more tough to beat. In fact, as the UN themselves highlight, cities often harbor great inequality, which threatens to get even wider in the following decades.

“Nevertheless, rapid and unplanned urban growth threatens sustainable development when the necessary infrastructure is not developed or when policies are not implemented to ensure that the benefits of city life are equitably shared. Today, despite the comparative advantage of cities, urban areas are more unequal than rural areas and hundreds of millions of the world’s urban poor live in sub-standard conditions. In some cities, unplanned or inadequately managed urban expansion leads to rapid sprawl, pollution, and environmental degradation, together with unsustainable production and consumption patterns.”

All in all, the world’s population is changing, and it’s changing most in Asia, South America, and Africa. Don’t ignore it just because it’s not in front of your eyes.

Commuters, traffic, and offices make cities hotter during the week

Humans have a much more direct impact on weather than you’d think. The huge number of commuters pouring into cities during the week actually makes them warmer and shifts local wind, rain, and cloud patters, a new study found.

Image credits Pat McKane / Pixabay.

During the week, all the people, cars, and operating buildings in cities pour out a lot of heat into the environment. Recently, Nick Earl at the University of Melbourne, Australia found that you can actually tell if it’s a workday or the weekend by the average temperature. Based on more than 50 years’ worth of recordings from Australia’s Bureau of Meteorology, Earl and his team showed that morning temperatures in Melbourne are typically 0.3 degrees C hotter on Thursday or Friday than on a Sunday.

“That’s just the average,” he says. “Some days will heat up more, if for example there isn’t much wind.”

It’s not surprising, given that the city sees some 250,000 extra people and heavy traffic every weekday compared to the weekends. All the air conditioning in office buildings also plays a part. This weekly cycle caught Earl’s eye in the first place.

“Nothing in nature occurs on a weekly cycle, so it must be due to human activity.”

Earl and his team have shown that Sydney, Brisbane, and Adelaide have similar weekly temperature cycles. Tokyo or Moscow also show the same cyclicity. Other weather phenomena, such as wind speeds, precipitation, and cloud cover also tend to be greater in urban centers during the week. These are effects of higher heat and pollution levels, Earl says.

“For example, warmer temperatures in the city create convection, which can suck in more air from outside, affecting wind speeds and direction,” he added.

Knowing how human activity impacts weather and average temperatures can help adapt to freak weather patterns and save lives. This can become especially useful in hot areas or countries, such as Australia, where heatwaves can claim the lives of a lot of people.

“For example, during heatwaves, you could ban cars from the city so that it doesn’t warm up as much.”

It could also help urban planners counteract the effect, for example by requiring roofing to be made of deflecting material which can cool down cities.

The paper will be presented at the annual conference of the Australian Meteorological and Oceanographic Society in Canberra next month.


Cosmic dust identified on cities’ rooftops for the first time in history

Space dust is all around us — if you happen to be in Paris, Oslo, or Berlin, at least. New research has identified such tiny particles for the first time in urban environments.


Image credits Unsplash / Pexels.

Space has the unusual property of being void and full of stuff at the same time. Part of that stuff — including some that’s left over from the formation of the Solar System 4,6 billion years ago — coalesces in tiny bits of matter known as cosmic dust. A new study now proved that this dust is still falling on Earth today, and has isolated them from urban samples for the first time ever.

“We’ve known since the 1940s that cosmic dust falls continuously through our atmosphere,” says planetary scientist Matthew Genge from Imperial College London in the UK. “[But] until now we’ve thought that it could not be detected among the millions of terrestrial dust particles, except in the most dust-free environments such as the Antarctic or deep oceans.”

Previous attempts to find cosmic dust in cities have proven unsuccessful because of the sheer quantity of dust, grime, and industrial pollution we have in our cities. But Dr Matt Genge from Imperial College London’s Department of Earth Science and Engineering working together with Jon Larsen, a science buff who runs micrometeorite site Project Stardust, found some 500 cosmic dust particles after sifting through more than 300 kilograms of gutter-sediment from three European cities: Paris, Oslo, and Berlin.

The duo knew they were looking for a needle (only smaller, cause it’s a speck of dust) in a huge haystack (which was also made of dust.) So they turned to the oldest trick in the book: magnets. Cosmic dust particles contain magnetic minerals, so the two separated magnetic particles from the rest of the sediment then identified cosmic dust by composition.

Fastest moving dust on Earth

They found S type (silicate-dominated) cosmic spherules which were melted into disk and other non-spherical shapes — an effect of the extreme temperatures they experienced during atmospheric entry. Cosmic dust specks are usually incredibly tiny, measuring around 0.01 millimeters (0.003 inches) in size, but the ones the team found were larger, measuring about 0.03 millimeters. Based on the shape and size, Genge believes they fell to Earth with speeds around 12 km/s (7.5 miles/s), which would make them the fastest-ever dust particles on Earth.

While they’re the fastest, they’re probably not the oldest dust specks we’ve seen. The crystal structures found in these samples resemble those of particles dating from medieval times — by contrast, older samples that date back millions of years which were found in Antarctica show a different crystal make-up. Exactly why these differences arose is still unknown, but the team speculates it’s the effect of planetary orbit changes in the Solar System. Over millions of years, gravitational fluctuations cause planets to shift their orbits around the sun slightly, which in turn affects their gravitational effect on the matter around them.

They could in fact be the most recently-crashed bits of cosmic dust on Earth. Since the rooftops of commercial buildings are cleaned regularly and there was little rusting of the dust’s metallic content (which only started after they got to Earth,) the team estimates that they fell down sometime within the past six years.

The team points out that while they found these particles only in cities, they could be found anywhere on the planet. And the more of it we can collect and analyze, the more we’ll understand about how the Solar System and Earth evolved from birth all the way up to today.

“This find is important because if we are to look at fossil cosmic dust collected from ancient rocks to reconstruct a geological history of our Solar System, then we need to understand how this dust is changed by the continuous pull of the planets,” says Genge.

“The obvious advantage to this new approach is that it is much easier to source cosmic dust particles if they are in our backyards.”

The full paper “An urban collection of modern-day large micrometeorites: Evidence for variations in the extraterrestrial dust flux through the Quaternary” has been published in the journal Geology.


That ATM keyboard you’ve touched earlier is covered in germs from all over town

ATMs may be excellent city-wide DNA repositories, a new New York University study concludes. Their keypads are a melting pot for bugs from human skin, household surfaces, even traces of food.


Image credits Emma Blowers / Pixabay.

News just in: ATM keyboards are just littered with germs, bits of people, and all sorts of DNA. With how much use these things see, it’s hardly surprising; but the range of what you can find here is. NYU scientists went around Manhattan, Queens, and Brooklyn, swabbing off of ATMs in eight neighborhoods. That netted them a total of 66 samples which they then compared with known microbial markers.

Just like the germs on our smartphones’ screens can tell a lot about our individual lifestyle, the germs on the ATM tell the story of a city. The team found a wide range of human skin microbes, most of which can be traced back to household surfaces such as TVs, restroom and kitchen surfaces, as well as pillows. Microbes associated with bony fish, mollusks, and chicken were also found in different neighborhoods, suggesting that residues from meals can find their way to the keypads upon use.

The team also points out that the data suggests a geographic zoning, but only for certain types of microbes.

“The sampling strategy was designed to target geographic areas with distinct ethnic and population demographics, known as neighborhood tabulation areas,” the paper reads.

Store- and laundromat-based ATM keypads showed the highest number of biomarkers, with Lactobacillales (lactic acid bacteria) being the most prominent. This kind of bacteria is usually found in spoiled or rotting milk products and plants — it’s what makes milk go sour and pickles become pickled. Samples taken in Manhattan tested positive for the biomarker Xeromyces bisporus, a mold that grows on spoiled backed goods. There was no significant difference in the biomarkers of indoor or outdoor ATMs.

“Our results suggest that ATM keypads integrate microbes from different sources, including the human microbiome, foods, and potentially novel environmental organisms adapted to air or surfaces,” explains senior author Jane Carlton, director of the Center for Genomics and Systems Biology and professor of biology at NYU.

“DNA obtained from ATM keypads may therefore provide a record of both human behavior and environmental sources of microbes.”

While most of you are probably going through an ew-fueled bristling right now, from a microbiologist’s point of view the findings are actually quite exciting. Because each machine sees probably hundreds of uses each day and come in direct contact with air, water, and microbes adapted to live on different types of urban surfaces, the communities sampled here represent an “average” — a snapshot of each city‘s own microbial footprint. Each ATM effectively pools strains from a lot of different sources together.

Still, the machine samples showed low diversity and apart from the few bugs I’ve mentioned earlier, there was no obvious geographic clustering. The team believes this low diversity comes down to periodic cleaning of the ATMs — which would wipe out some of the bugs. Tourists and commuters also have a hand to play in mixing the communities throughout town, the team said.

Such mixing is probably limited to an in-city range, so in the end, each city might actually be unique — they may each have their own DNA.

The full paper “Microbial Community Patterns Associated with Automated Teller Machine Keypads in New York City” has been published in the journal mSphere.

European Space Agency releases map of continent’s urban footprint

Just a few days ago, the European Space Agency revealed this enthralling map which highlights Europe’s urban agglomerations. They didn’t offer too many details about it, just offering some technical specs:

“The urban footprint extracted from the Global Urban Footprint Europe. GUF-2012 is derived from (commercial) 3 m-resolution TerraSAR-X/TanDEM-X SAR data and is available in 12 m resolution for any scientific use and in 84 m for any non-profit use. Commercial applications have to check with Airbus for the licensing.”

Currently, over 50% of the world’s populations lives in cities, and the figure is rapidly increasing as urban areas continue to draw more and more individuals. The Global Urban Footprint, which the ESA references, aims to deliver the worldwide mapping of settlements with an unprecedented spatial resolution of ~12 m. What you’re basically seeing in black are settled areas.

“The resulting map shows the Earth in three colors only: black for “urban areas”, white for “land surface” and grey for “water”. This reduction emphasizes the settlement patterns and allows for the analysis of urban structures, and hence the proportion of settled areas, the regional population distribution and the arrangement of rural and urban areas,” the project’s website reads.

This is yet another indicator of what an impact mankind is having on the planet, but these maps can be even more valuable, in offering the potential to  enhance climate modeling, risk analyses in earthquake or tsunami regions and the monitoring of human impact on ecosystems. It can also serve as a basis to study urban growth.

New York Galaxy

Cities grow and thrive much in the same way galaxies do in space

Human social behavior is strikingly governed by laws that describe how the masses congregate or interact one another. Yet, despite the empirical evidence, scientists know very little what stems these mass behaviors. An individual is highly unpredictable, but masses are not (in this respect, Isaac Asimov’s Foundation takes it to the extreme with his fictional psychohistory). Now, some of these laws that predict the probability that one person will befriend another or the size of the cities they live in have been explained by mathematicians at the Harvard-Smithsonian Centre for Astrophysics in Cambridge. According to the researchers, these so-called urban behavioral laws are mathematically equivalent to the way galaxies grow in space.

Cities and galaxies have much in common

New York Galaxy

Credit: HD Me

The spatial and density distribution of cities throughout the world is freakishly predicted by an empirical law called Zipf’s law. American linguist George Kingsley Zipf noticed that given some corpus of natural language utterances, the frequency of any word is inversely proportional to its rank in the frequency table. Thus the most frequent word will occur approximately twice as often as the second most frequent word, three times as often as the third most frequent word, etc. For example, in the Brown Corpus of American English text, the word “the” is the most frequently occurring word, and by itself accounts for nearly 7% of all word occurrences (69,971 out of slightly over 1 million). True to Zipf’s Law, the second-place word “of” accounts for slightly over 3.5% of words (36,411 occurrences), followed by “and” (28,852). Only 135 vocabulary items are needed to account for half the Brown Corpus. The same law applies to cities: If cities are listed according to size, then the rank of a city is inversely proportional to the number of people who live in it.  Say the biggest city in a country is 8 million people large, then the second biggest will house 8 million divided by two, the third biggest 8 million divided by four and so on.

This relationship is known as the scaling law, exemplified by another urban case: the probability that one person will be friends with another turns out to be inversely proportional to the number of people who live closer to the first person than the second.

Henry Lin and Abraham Loeb at the Harvard-Smithsonian Centre for Astrophysics in Cambridge made a mathematical model  of the way human population density varies across a flat Euclidean plane, thus ignoring the curvature of the Earth. Their approach was very similar to how cosmologists consider the evolution of galaxies: first they consider the matter density in the early Universe; then follows the mathematical structure of any variation in density; finally, they explain how this density can change over time as more matter is added or taken away from specific regions.

Lin and Loeb tested the model against publicly available data, and found “the results are in good agreement with the theoretical prediction across a broad range of spatial scales, from a few km to ∼ 10^3 km.” Using the model, the researchers calculated the number of cities past a certain population threshold and found their quantity has a logarithmic slope equal to -1. “This statement is equivalent to Zipf’s law: the rank of a city is inversely proportional to its size,” point out Lin and Loeb. They also computed the average number of friends a person might have within a given region. And once again their model comes up with the inverse-rank friendship law that urban sociologists are already familiar with.

Moreover, initial conditions seems to matter very little as the model always comes up with the same rules. It’s easy to think this is just some mathematical show and tell, but the findings are quite important since the same model could be used to follow other factors that are related to population density, such as the spread of disease.

“Just as the development of models for non-linear structure formation in the universe led to a wealth of theoretical and observational work in cosmology, future work here could include the calculation of new observables such as the bias factor for the spread of epidemics,” they conclude.

Via Technological Review


Trees can capture 50% of particulate pollution cities

Trees planted along a city street could screen residents from sun and noise – but more importantly, they can also protect them from the polluted air. A new study has shown that tree leaves can capture more than 50% of the polluting particulate matter – the main source of urban pollution and a trigger for disease.

The trees and birches used in the study. Credit: Environ. Sci. Technol.

The trees and birches used in the study. Credit: Environ. Sci. Technol.

In cities, this type of pollution mostly comes from car exhaust, brake pad wear, and road dust, but it can contain dangerous substances, such as iron and lead. The Environmental Protection Agency classifies particulates depending on size, but virtually all particulates are small enough to be inhaled. Researchers wanted to understand exactly how trees capture this pollution and how they can use this mechanism to our advantage. However, modeling this process is extremely challenging because air flow and particle movement on a street follow complex fluid dynamics.

Barbara A. Maher and her colleagues at Lancaster University, in the U.K., wanted to get some numbers from a real-life situation, so they moved from the lab to the street – analyzing row of eight houses without any trees screening the air. They tracked the amount of dust and particulate matter entering two of the houses as controls and then also used dust monitoring devices to gather data for every 10 minutes for five days. They also used simple wet wipes to gather dust from LED or plasma television screens inside four houses and tested them for metal concentrations.

After they had their initial data, they planted a screen of 30 young silver birch trees in wooden planters in front of four of the houses, including one of the control houses, for 13 days and then gathered data using the exact same techniques. Their results showed 52 to 65% lower concentrations of metallic particles and an overall 50% decrease in the quantity of polluting particulates in the houses.

trees particulates 2

A scanning electron micrograph shows particulate matter captured on the surface of a silver birch leaf.
Credit: Environ. Sci. Technol.

Then, they analyzed the birch leaves with a scanning electron microscope and confirmed that the trees indeed captures the missing pollution. However, it’s still unclear what the trees actually do with it – it can be estimated that at one point or another it reaches the soil, and while that isn’t exactly good either, it’s pretty much the best thing you can do in terms of common urban pollution.

Interestingly enough, oysters do something similar in the marine environment – they’re filter feeders and get a lot of the sediment out of the water, leading to cleaner, clearer water. When the Europeans first came across the Atlantic the Chesapeake bay had so many oysters that the bay was described as crystal clear! As any local or visitor probably knows, that’s really not the case nowadays. Needless to say, just like with trees in most cities of the world, oyster populations are also dwindling – a worrying fact, considering the beneficial effects they have.

Journal Reference:

Barbara A. Maher *Imad A. M. Ahmed , Brian Davison , Vassil Karloukovski , and Robert Clarke – Impact of Roadside Tree Lines on Indoor Concentrations of Traffic-Derived Particulate Matter. Environ. Sci. Technol., Article ASAP. DOI: 10.1021/es404363m

Tianjin Eco City

China’s eco-city of the future hints towards its green turnaround

Tianjin Eco City

China is the most pollutant country in the world, and as it continues to develop industrially, one can only expect greenhouse gas emissions to grow as well. The country is taking steps towards its ecological rehabilitation, however. The first step was to acknowledge that it faces a dire problem, one whose consequences reverse on the entire world. One of the most interesting green projects China is currently involved in is centered around an experimental city, which incorporates smart and green technology extensively through out its whole infrastructure, but all applied with the characteristic Chinese sense of practicality.

China is home to some of the biggest and most modern cities in the world, however at the same time these massive urban centers area beacons of pollution – its streets filled with dust, its air filled with noxious fumes, smog so thick that sunlight can barely creep in. It’s very clear that China will become a wasteland in decades to come if something is not done about it. The Sino-Singapore Tianjin Eco City, the world’s largest projected eco-city, is the nation’s hope towards the future of its urban centers.

Tianjin Eco City

Just an hour away by train from Beijing, and  just 10 minutes away from the business parks at the Tianjin Economic-Development Area, Tianjin Eco City is expected to house 350,000 people when completed. The city’s designed infrastructure is set to target all of the current major hurdles Chinese urban life is facing at the moment – permanent gridlock, a lack of water and ruinous electricity bills.

One of the biggest problem green cities face at the moment, besides the huge development cost compared to the conventional alternative, is the prerequisite of having an involved populace. Tianjin, isn’t glamorous by any means, and at first glance it looks just as gray and desolate as any Chinese city, however under the hood things are a lot greener – this without any kind of effort needed from its inhabitants’ part.

“Our eco-city is an experiment, but it is also practical,” said Wang Meng, the deputy director of construction. “There are over 100 eco-cities in the world now, and they are all different. If you look at the one in Abu Dhabi, they spent a huge amount of money and bought a lot of technology. It is very grand, but is it useful?”

Tianjin Eco City

Tianjin will be a huge urban experiment, probably the largest in the world. For instance, General Motors is using Tianjin to work out if electric driverless cars can function in a normal traffic system, and road-test the next generation of vehicles: small urban cars that drive themselves but are safe in an environment full of unpredictable drivers, pedestrians and cyclists. Other interesting green projects currently discussed and most likely to be implemented are low energy lighting systems from Philips or rubbish pins that automatically clean up themselves by sucking the trash though special ducts, developed by a Swedish company called Envac. Government-owned buildings will be powered by geothermal energy, have shutters that move with the light, in order to keep buildings cool, and heating systems that use solar energy.

The area on which Tianjin is currently being built is roughly half the size of Manhattan, but what’s interesting is that only three years ago it used to be huge desolate landscape, ruined by chemical pollution from the factories that border it. By using a special process, the Chinese authorities have managed to clean-up the site and hope to implement the same solution around other sites in the country – there are countless such sites through out China.

Tianjin Eco City

The city of Tianjin is projected to be completed by the end of the decade, after a projected investment of around 250 billion yuan (£25 billion), part of a joint financial and administrative collaboration between the Chinese and Singaporean governments. Currently, 60 families have already moved in. If successful, Tianjin might be the first of many green, yet cheap and practical, cities in China, quite possibly turning the country around ecologically.

via Telegraph

African cities and their ecological impact

No other continent in the world (that’s not counting Antarctica) is studied by less ecologists than Africa; that is actually paradoxal, because cities are growing here faster than any other continent on Earth. Just less than a century ago, 5% of people lived in urban areas, while now, almost 40% call a city their home.

This rapid growth is causing numerous problems that are (or at least, if I’m mistaking, seem) overlooked by almost everybody. Very few ecologists are actually studying the n environment and effect of cities on rural areas.

Despite the fact that the areas with many problems (such as hunger, virtually lack of hygiene, lack of water, diseases, areas controled by rebels, etc) haven’t improved almost at all (except for the first two perhaps), the other safer and wealthier parts of Africa have developed significantly, creating a gap between the two. The desire for charcoal, oil and wood are causing deforestation.

But perhaps, as Joy Clancy from the University of Twente claims, the biggest problem could be around the periurban areas, where huge portions of wood are being cut down to allow agriculture. Add this to an increased demand of water and the disposal of garbage in the water, and you get to a very siginificant damaging impact. So what could the solution be?? First of all, an improvement of the tools and techniques of agriculture could bring an increase of productivity so there would be no need for other areas. Still, people have the tendency of asking for more and more, and as long as the law isn’t applied more strictly there, the chances of accomplishing ecological progress are practically inexistant.

Cities as seen from space, at night


Recently, the NASA observatory published some great images of some cities. For a man looking at those cities at night, man’s work seems both impressive and insignificant. But the view would be fantastic: regular patterns of irrigated cropland, straight lines of roads and railways running across continents, reservoirs on river systems, and the cement rectangles of ports and seawalls along coastlines.But nothing would be as gorgeous as the cities. During the day, it’s not really spectacular: gray smudges is pretty much all you get. However at night… things change a bit. The lights pinpoint how humanity have changed the environment to make it adapt to his own needs.



If anything rocks about being an astronaut, it’s being able to see the earth at night: from 350-400 kilometers above the surface you get to see the magnificent display of lights and patterns.


But taking pictures in the dark is difficult at best, made even more difficult by the fact that the International Space Station moves more than 7 kilometers per second (15,659 miles per hour) relative to Earth’s surface. Still, hopefully you From a geographic perspective, cities at night tell different stories about a region. They took way more pictures than we’ve shown here. You can check them all out here.