Soil erosion and degradation: a global problem – Effects (Part 2)

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The consequences of soil erosion are primarily centered on reduced agricultural productivity, as well as soil quality. But also, water ways may be blocked, and it may affect water quality. This means, most of the environmental problems the world face today, arises from soil erosion.

Particularly, the effects of soil erosion go beyond the loss of fertile land. In other words, it has led to increased pollution and sedimentation in streams and rivers, clogging these waterways and causing declines in fish and other species. And degraded lands are also often less able to hold onto water, which can worsen flooding.

So, the effects of soil degradation include:

  1. Loss of arable land: Lands used for crop production have been substantially affected by soil erosion. Soil erosion eats away the top soil which is the fertile layer of the land and also the component that supports the soil’s essential microorganisms and organic matter. In this view, soil erosion has severely threatened the productivity of fertile cropping areas as they are continually degraded. Because of soil erosion, most of the soil characteristics that support agriculture have been lost, causing ecological collapse and mass starvation.
  1. Water Pollution and Clogging of Waterways: Soils eroded from agricultural lands, carry pesticides, heavy metals, and fertilizers which are washed into streams and major water ways. This leads to water pollution and damage to marine and freshwater habitats. Accumulated sediments can also cause clogging of water ways and raises the water level leading to flooding.
  1. Increased flooding: Land is commonly altered from its natural landscape when it rids its physical composition from soil degradation. In other words, soil degradation takes away the soil’s natural capability of holding water thus contributing to more and more cases of flooding.
  1. Drought and Aridity: Drought and aridity are problems highly influenced and amplified by soil degradation. As much as it’s a concern associated with natural environments in arid and semi-arid areas, the UN recognizes the fact that drought and aridity are anthropogenic induced factors especially as an outcome of soil degradation. Hence, the contributing factors to soil quality decline such as overgrazing, poor tillage methods, and deforestation are also the leading causes of desertification characterized by droughts and arid conditions.
  1. Destruction of Infrastructure: Soil erosion can affect infrastructural projects such as dams, drainages, and embankments, reducing their operational lifetime and efficiency. Also, the silt up can support plant life that can, in turn, cause cracks and weaken the structures. Soil erosion from surface water runoff often causes serious damage to roads and tracks, especially if stabilizing techniques are not used.
  1. Desertification: Soil erosion is also responsible for desertification. It gradually transforms a habitable land into deserts. The transformations are worsened by the destructive use of the land and deforestation that leaves the soil naked and open to erosion. This usually leads to loss of biodiversity, alteration of ecosystems, land degradation, and huge economic losses.

Finally, we all understand that the erosion of the soil is a very serious issue, especially in our days. That is why we need to take action and prevent the unpleasant effects.

Dipla Aikaterini (Arid Zone Afforestation)

Sources:

 

 

Soil erosion and degradation: a global problem – Causes (Part 1)

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Soil degradation, defined as lowering and losing of soil functions, is becoming more and more serious worldwide in recent decades, and poses a threat to agricultural production and terrestrial ecosystem.

Particularly, soil degradation simply means the decline in soil quality, which comes about due to aspects such as improper land use, agriculture and pasture, urban or industrial purposes. It involves the decline of the soil’s physical, biological and chemical state. In other words, it is a process that leads to decline in the fertility or future productive capacity of soil, as a result of human activity.

It is well known that all soils undergo soil erosion, but some are more vulnerable than others, due to human activities and other natural causal factors. The severity of soil erosion is also dependent on the soil type and the presence of vegetation cover.

Here are few of the major causes of soil degradation:

  1. Physical factors: There are several physical factors contributing to soil degradation, distinguished by the manners in which they change the natural composition and structure of the soil.  Rainfall, surface runoff, floods, wind erosion, tillage, and mass movements result in the loss of fertile top spoil thereby declining soil quality. All these physical factors produces different types of soil erosion (mainly water and wind erosion) and soil detachment actions, and their resultant physical forces eventually changes the composition and structure of the soil by wearing away the soil’s top layer as well as organic matter.
  1. Chemical factors: The reduction of soil nutrients because of alkalinity or acidity or water logging, are all categorized under the chemical components of soil degradation. In the broadest sense, it comprises alterations in the soil’s chemical property that determine nutrient availability.
  1. Biological factors: Biological factors refer to the human and plant activities that tend to reduce the quality of soil.  Some bacteria and fungi overgrowth in an area can highly impact the microbial activity of the soil through bio-chemical reactions, which reduces crop yield and the suitability of soil productivity capacity. Also, human activities such as poor farming practices may also deplete soil nutrients thus diminishing soil fertility.
  1. Deforestation: Deforestation causes soil degradation on the account of exposing soil minerals by removing trees and crop cover, which support the availability of humus and litter layers on the surface of the soil. When trees are removed by logging, infiltration rates become elevated and the soil remains bare and exposed to erosion and the buildup of toxicities.
  1. Improper cultivation practices: There are certain agricultural practices that are environmentally unsustainable and at the same time, they are the single biggest contributor to the worldwide increase in soil quality decline. For example, due to shortage of land, increase of population and economic pressure, the farmers have adopted intensive cropping patterns of commercial crops in place of more balanced cereal-legume rotations.
  1. Misuse and Extensive cultivation: The excessive use and the misuse of pesticides and chemical fertilizers kill organisms that assist in binding the soil together. In other words, it increases the rate of soil degradation by destroying the soil’s biological activity and builds up of toxicities through incorrect fertilizer use. We all know that due to tremendous population increase, the use of land is increasing day by day.
  1. Overgrazing: The rates of soil erosion and the loss of soil nutrients as well as the top soil, are highly contributed by overgrazing. Overgrazing destroys surface crop cover and breaks down soil particles, increasing the rates of soil erosion. As a result, soil quality and agricultural productivity is greatly affected.
  1. Industrial and Mining activities: Soil is chiefly polluted by industrial and mining activities. For example, mining destroys crop cover and releases a myriad of toxic chemicals such as mercury into the soil thereby poisoning it and rendering it unproductive for any other purpose. Industrial activities, on the other hand, release toxic effluents and material wastes into the atmosphere, land, rivers, and ground water that eventually pollute the soil and as such, it impacts on soil quality. Altogether, industrial and mining activities degrade the soil’s physical, chemical and biological properties.
  1. Roads and Urbanization: Urbanization severely affects the erosion process. Land denudation by removing vegetation cover, changing drainage patterns, soil compaction during construction and then covering the land by impermeable layers of concrete or asphalt, all of them contribute to increased surface runoff and increased wind speeds.

Finally, taking into consideration all the above, we understand that soil erosion is a continuous process and may occur either at a relatively unnoticed rate or an alarming rate contributing to copious loss of the topsoil. So, we have to be careful and avoid all the above problems.

Dipla Aikaterini (Arid Zone Afforestation)

Sources:

 

 

 

Greenland: how rapid climate change on world’s largest island will affect us all

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The largest wildfire ever recorded in Greenland was recently spotted close to the west coast town of Sisimiut, not far from Disko Island.  The fire has captured public and scientific interest not just because its size and location came as a surprise, but also because it is yet another signpost of deep environmental change in the Arctic.

Greenland is an important cog in the global climate system. The ice sheet which covers 80% of the island reflects so much of the sun’s energy back into space that it moderates temperatures through what is known as the “albedo effect”. And since it occupies a strategic position in the North Atlantic, its meltwater tempers ocean circulation patterns.

But Greenland is especially vulnerable to climate change, as Arctic air temperatures are currently rising at twice the global average rate. Environmental conditions are frequently setting new records: “the warmest”, “the wettest”, “the driest”.

The ice sheet is melting

Between 2002 and 2016 the ice sheet lost mass at a rate of around 269 gigatonnes per year. During the same period, the ice sheet also showed some unusual short-term behaviour.

The 2012 melt season was especially intense – 97% of the ice sheet experienced surface melt at some point during the year. Snow even melted at its summit, the highest point in the centre of the island where the ice is piled up more than 3km above sea level. 

In April 2016 Greenland saw abnormally high temperatures and its earliest ever “melt event” (a day in which more than 10% of the ice sheet has at least 1mm of surface melt). Early melting doesn’t usher in a period of complete and catastrophic change – the ice won’t vanish overnight. But it does illustrate how profoundly and rapidly the ice sheet can respond to rising temperatures.

Despite its icy image, the margins of Greenland are actually quite boggy, complete with swarms of mosquitoes. This is the “active layer”, made up of peaty soil and sediment up to two metres thick, which temporarily thaws during the summer. The underlying permafrost, which can reach depths of 100m, remains permanently frozen.

If thawing continues, it’s estimated that by 2100 permafrost will emit 850-1,400 billion tonnes of CO₂ equivalent (for comparison: total global emissions in 2012 was 54 billion tonnes of CO₂ equivalent). All that extra methane and carbon of course has the potential to enhance global warming even further.

With this in mind, it is clear to see why the recent wildfire, which was burning in dried-out peat in the active layer, was especially interesting to researchers. If Greenland’s permafrost becomes increasingly degraded and dry, there is the potential for even bigger wildfires which would release vast stores of greenhouse gases into the atmosphere.

Learn more here: https://theconversation.com/greenland-how-rapid-climate-change-on-worlds-largest-island-will-affect-us-all-82675

The US cities at risk of flooding – and how they deal with it

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Tropical storm Harvey may have bared its teeth at Houston, but other cities in the US have felt the pangs of nervousness. Several cities are vulnerable to the fiercer storms and sea level rise that are being fueled by climate change.

Cities, by their very nature, struggle during flood situations. Water that would have been soaked up by grass and other vegetation washes off the concrete and asphalt of urban areas and, if not properly diverted away, can inundate homes.

Add in, as in Houston’s case, lax rules around property zoning and a federal flood insurance system that repeatedly pays out for damage to poorly situated houses, and it’s clear cities have much work to do to cope with the changes upon them.

Harvey brought a huge amount of rainfall, but cities now face flooding threats even without a major storm. “Rare events are going to become more common in the future strictly due to sea level rise,” said William Sweet, an oceanographer at the National Oceanic and Atmospheric Administration (Noaa).

“We are already seeing flooding in property and the streets in Charleston, Norfolk and Miami on sunny days, driven by the tides. That is a looming crisis that is only going to grow more severe over time.”

The nightmare of a Harvey (or Katrina or Sandy) has led to many cities opt for huge sea walls and other expensive engineering fixes. But there is no easy solution – a sea wall simply pushes the water elsewhere, perhaps on to a neighbor’s head. The water has to go somewhere and decades of development on flood-prone land has left little space to maneuver for some municipalities.

“There are coastal cities at risk from an extreme event and they have giant sea walls or houses on stilts,” said Sweet. “But then there are communities that don’t face a big hurricane threat but water is bubbling up from underneath them. They can’t defend against this sort of flooding. You can’t build a wall everywhere.”

Some progressive cities have started to look at alternative approaches, most notably from the Netherlands, where communities “live” with the water, allowing certain areas to flood while aggressively defending critical infrastructure. Natural sponges such as parklands, wetlands and dunes are now also in vogue with city planners.

But as attitudes to flooding slowly shift, the problem is escalating. Scientists are now confident that hurricanes will become more powerful, fed by a warming, moisture-laden atmosphere, while more common “nuisance” flooding will become so frequent along parts of the US east coast that they will occur once every three days by 2045. By around this time, a majority of US coastal areas are likely to be threatened by 30 or more days of flooding each year.

So which cities are at risk and what are they doing about the threat?

Follow the link to learn more about that serious problem, and how climate change is responsible for this situation: https://www.theguardian.com/environment/2017/aug/31/us-risk-flooding-harvey-boston-new-york-miami-beach

World has missed chance to avoid dangerous global warming – unless we start geo-engineering the planet

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The world has missed the chance to avoid dangerous global warming – unless we start geo-engineering the atmosphere by removing greenhouse gases, according to new research.

Scientists used computer models to assess what needs to be done to restrict global warming to between 1.5 and 2 degrees Celsius, the limits adopted by the Paris Agreement on climate change. They found that the world was likely to overshoot this temperature but could bring it back down to 1.2C by the end of this century by using techniques to remove carbon dioxide from the air.

Giant biological machines could be created to do this by growing vegetation which absorbs carbon, then burning the resulting biomass in power stations that capture the emissions.

The researchers also said other techniques to remove carbon from the atmosphere would need to be developed. Another team of researchers reached similar conclusions last month, finding that geo-engineering would be required to restrict warming to 1.5C but 2C could be achieved without it.

Scientists previously thought limiting global warming to 2C would avoid the most dangerous effects, but there is increasing evidence that allowing it to go much above 1.5C could lock in considerable sea level rise for the next few centuries. So far the world has warmed by just under 1C in little over a century.

The world would have to bring about a “complete shift” to an energy system based on renewables, nuclear, hydrogen, and bio-energy with carbon capture and storage.

Follow the link to learn more about the research: http://www.independent.co.uk/environment/world-global-warming-avoid-geo-engineering-planet-climate-change-man-made-a7904966.html

Global warming doubles growth rates of Antarctic seabed’s marine fauna – study

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Marine life on the Antarctic seabed is likely to be far more affected by global warming than previously thought, say scientists who have conducted the most sophisticated study to date of heating impacts in the species-rich environment.

Growth rates of some fauna doubled – including colonising moss animals and undersea worms – following a 1C increase in temperature, making them more dominant, pushing out other species and reducing overall levels of biodiversity, according to the study published  in Current Biology.

The researchers who conducted the nine-month experiment in the Bellingshuan Sea say this could have alarming implications for marine life across the globe as temperatures rise over the coming decades as a result of manmade greenhouse gases in the atmosphere.

Gail Ashton of the British Antarctic Survey and Smithsonian Environmental Research Center said she was not expecting such a significant difference. “The loss of biodiversity is very concerning. This is an indication of what may happen elsewhere with greater warning.”

Sub-zero conditions near the south pole mean there are comparatively few species on the usually frozen land, but below the ice, the relative lack of pollution, traffic and fishing has left an abundance of marine life that divers and biologists compare to coral reefs.

Previous studies of warming impacts have focused on single species, but the latest research examines an assemblage of creatures. Twelve identical 15cm sq heat plates were set in concrete on the seabed. Four were warmed by 1C, four by 2C and four left at ambient temperature as a control.

Until recently, most of the coverage of temperature rises has focused on the north pole, where the shrinking of arctic ice has been most visibly dramatic. But concerns are growing about the impact of global warming on the far bigger southern ice cap.

Follow for more information: https://www.theguardian.com/environment/2017/aug/31/global-warming-doubles-growth-rates-of-antarctic-seabeds-marine-fauna-study

Wildfires across southern Europe amid scorching heatwave – in pictures

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Extreme weather across southern Europe has spawned and fanned numerous wildfires, including at the beach resort of Kalamos near Athens and in central Portugal.

Generally, there is a very well documented scientific evidence that climate change has been increasing the length of the fire season, the size of the area burned each year and the number of wildfires. Wildfires are typically either started accidentally by humans – such as a burning cigarette carelessly tossed out of a window – or by natural causes like lightning.

Flames and smoke plumes ascend from Kalamos, seen from the island of Evia, opposite

Especially, here in Greece, the situation is very serious.  The fire started in Kalamos, a coastal holiday spot some 45 km (30 miles) northeast of the Athens, and has spread to three more towns, damaging dozens of homes and burning thousands of hectares of pine forest. A state of emergency has been declared in the area.

Also, across Greece, firefighters were battling more than 55 forest fires, an outbreak fed by dry winds and hot weather that fanned blazes in the Peloponnese and on the Ionian islands of Zakynthos and Kefalonia.

Here, there are some pictures of the fires in Greece, but also in Portugal: https://www.theguardian.com/world/gallery/2017/aug/15/wildfires-across-southern-european-amid-scorching-heatwave-in-pictures

 

 

 

Climate change to cause humid heatwaves that will kill even healthy people

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Extreme heatwaves that kill even healthy people within hours will strike parts of the Indian subcontinent unless global carbon emissions are cut sharply and soon, according to new research.

Even outside of these hotspots, three-quarters of the 1.7bn population – particularly those farming in the Ganges and Indus valleys – will be exposed to a level of humid heat classed as posing “extreme danger” towards the end of the century.

The new analysis assesses the impact of climate change on the deadly combination of heat and humidity, measured as the “wet bulb” temperature (WBT). Once this reaches 35C, the human body cannot cool itself by sweating and even fit people sitting in the shade will die within six hours.

The revelations show the most severe impacts of global warming may strike those nations, such as India, whose carbon emissions are still rising as they lift millions of people out of poverty.

“It presents a dilemma for India between the need to grow economically at a fast pace, consuming fossil fuels, and the need to avoid such potentially lethal impacts,” said Prof Elfatih Eltahir, at Massachusetts Institute of Technology in the US who led the new study. “To India, global climate change is no longer abstract – it is about how to save potentially vulnerable populations.”

Heatwaves are already a major risk in South Asia, with a severe episode in 2015 leading to 3,500 deaths, and India recorded its hottest ever day in 2016 when the temperature in the city of Phalodi, Rajasthan, hit 51C. Another new study this week linked the impact of climate change to the suicides of nearly 60,000 Indian farmers.

Read here more information: https://www.theguardian.com/environment/2017/aug/02/climate-change-to-cause-humid-heatwaves-that-will-kill-even-healthy-people

A third of the world now faces deadly heatwaves as result of climate change

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Nearly a third of the world’s population is now exposed to climatic conditions that produce deadly heatwaves, as the accumulation of greenhouse gases in the atmosphere makes it “almost inevitable” that vast areas of the planet will face rising fatalities from high temperatures, new research has found.

Climate change has escalated the heatwave risk across the globe, the study states, with nearly half of the world’s population set to suffer periods of deadly heat by the end of the century even if greenhouse gases are radically cut.

“For heatwaves, our options are now between bad or terrible,” said Camilo Mora, an academic at the University of Hawaii and lead author of the study.

Mora’s research shows that the overall risk of heat-related illness or death has climbed steadily since 1980, with around 30% of the world’s population now living in climatic conditions that deliver deadly temperatures at least 20 days a year.

The proportion of people at risk worldwide will grow to 48% by 2100 even if emissions are drastically reduced, while around three-quarters of the global population will be under threat by then if greenhouse gases are not curbed at all.

“Finding so many cases of heat-related deaths was mind blowing, especially as they often don’t get much attention because they last for just a few days and then people moved on,” Mora said.

“Dying in a heatwave is like being slowly cooked, it’s pure torture. The young and elderly are at particular risk, but we found that this heat can kill soldiers, athletes, everyone.”

Follow the link to learn more: https://www.theguardian.com/environment/2017/jun/19/a-third-of-the-world-now-faces-deadly-heatwaves-as-result-of-climate-change

Invasive species

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Britannica identifies the invasive species as follows: “Invasive species, also called introduced species, alien species, or exotic species, any nonnative species that significantly modifies or disrupts the ecosystems it colonizes.” The way a species arrives in a new environment can be done in numerous ways; either by natural migration or by activities of other species. Humans do it directly through pet trade or global commerce or indirectly by unintentional “hitchhiking” invaders in ships, planes, trucks, shipping containers or packing materials. Another reason for such a phenomenon is that a species can no longer adapt to the environmental conditions of their habitat. Therefore the invasive species may have more opportunities in an alternative future climate than they have at present.
Recently in Greece there have been many headlines about a species that swarmed the Korinthian Gulf- the tropical scyphozoan Rhopilema nomadica, a kind of Jellyfish. This particular species is listed as one of the “100 worst invading species” in the Alien Invasive Species Inventories for Europe (DAISIE 2009).
There are several reasons that an invasive species can flourish. But before blaming it for destroying our weekend by the beach, let’s get to know it better. Rhopilema nomadica known in english as Nomad Jellyfish, is native in East Africa and Red Sea but its known introduced range is Egypt, Israel, Lebanon, Turkey and Greece. Its natural predators are fish, like tuna, mackerel and marine turtles; apparently,overfishing these natural predators helps the species in question thrive. Spawning occurs between June and August and the sexually reproducing swimming scyphomedusae appears when the water temperature exceeds 24º C. It entered the Mediterranean through the Suez Canal in the late 70s and it first appeared in Greece in Lakonikos Gulf in 2006 (Siokou-Frangou et al. 2006). Nonetheless, several other factors could help or hinder the rise of Nomad jellyfishes. Temperature is directly correlated with the population of this particular species and wind traffic at sea affects them. They are offshore and with the help of currents produced by the wind gather up at beaches.
Cost is another important factor that should be considered regarding alien species. When the costs have become apparent, they can be vast; one study in the United States in 2001 estimated that costs associated with alien species amount to some US$136 billion per year and Canada in 2004, estimated that a preliminary review of alien species pegged them conservatively at $13,3 millions to $34,5 millions, annually, for 16 invasive species alone (Joanne Laucious, 2017). These costs must usually be covered by someone other than those who sponsored or promoted the introduction of the species, usually the general public. Decision-makers need to invest more in assessing the potential impacts before allowing potential introductions as well as incorporate more biosecurity measures once the species has been introduced (Jeff McNeely, 2001).
Yet, the nomad jellyfish is a minor incidence of invasion. The most memorable examples of invasive species are the kudzu plant from Japan, the cane toad from America, the asian tiger mosquito, zebra mussels from southern Russia, rats etc. People have always been on the move, carrying other species with them. Australian aborigines brought in the dingo, Polynesians sailed with pigs, and the Asians who first peopled the Americas brought dogs with them (Jeff McNeely, 2001). In the very end,the worst invasive species known to human, is human.

Mara Vasileiou for Arid Zone Afforestation

Sources:
http://www.europe-aliens.org/pdf/Rhopilema_nomadica.pdf
http://jellyrisk.eu/media/cms_page_media/266/1.Daly-Yahia%20et%20al.%202013_1.pdf
http://ageconsearch.umn.edu/bitstream/47850/2/paper01-02.pdf