Category Archives: Tectonics

Climate Change: How do we know?

This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Credit: Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.)

What is Climate Change?

Climate change is the term used to describe changes in average weather over time periods ranging from decades to millions of years. These changes may be driven by external forces (i.e. predictable orbital variations or solar variation), result from processes internal to the Earth (i.e. plate tectonics or volcanic activity) or be caused by human activities (anthropogenic) such as global warming.

A volcano erupts in Iceland, spewing Greenhouse Gases into the atmosphere.

The current warming trend is of particular significance because most of it is very likely human-induced and proceeding at a rate that is unprecedented in the past 1,300 years.

To see how much the global temperature has risen since 1880, read here:

An increase in greenhouse gas levels (global warming) is one of the major impacts that humans have on climate.  These include carbon dioxide, water vapour, nitrous oxide, methane, ozone and halocarbons. There is no question that increased levels of greenhouse gases must cause the Earth to warm in response.

Ice core samples drawn from Greenland, Antarctica, and tropical mountain glaciers show that the Earth’s climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks. This ancient evidence reveals that current warming is occurring roughly ten times faster than the average rate of ice-age-recovery warming.

Every year trees grow a new layer of bark. When you cut through a tree you can see these different layers as rings. The thicker the ring the better the growing conditions were that year. That allows scientists to work out what the temperature, precipitation and carbon dioxide levels are likely to have been for each year.

To understand the greenhouse effect better, go here:

The evidence for rapid climate change is compelling

The Republic of Maldives: Vulnerable to sea level rise
Sea level rise
  • Global sea level rose about 17 centimetres (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century.

Texas State Park police officer Thomas Bigham walks across the cracked lake bed of O.C. Fisher Lake Wednesday, Aug. 3, 2011, in San Angelo, Texas. A bacteria called Chromatiaceae has turned the 1-to-2 acres of lake water remaining the colour red. A combination of the long periods of 100 plus degree days and the lack of rain in the drought -stricken region has dried up the lake that once spanned over 5400 acres. (AP Photo/Tony Gutierrez)
Global temperature rise
  •  All studies show that Earth has warmed since 1880. Most of the warming occurred in the past 35 years, with 15 of the 16 warmest years on record occurring since 2001. The year 2015 was the first time the global average temperatures were 1 degree Celsius or more above the 1880-1899 average. Even though the 2000s witnessed a solar output decline, surface temperatures continue to increase.

Globally Warming Oceans Are Killing Coral Reefs, like here in Samoa.

Warming oceans
  •  The oceans have absorbed much of this increased heat, with the top 700 meters (about 2,300 feet) of ocean showing warming of 0.302 degrees celsius since 1969.

This July 4, 2012, file photo provided by Ian Joughin shows surface melt water rushing along the surface of the Greenland Ice Sheet through a supra-glacial stream channel, south-west of Ilulissat, Greenland. Polar ice sheets are now melting three times faster than in the 1990s and the acceleration of the melting, especially in Greenland, has ice scientists worried. Michel Jarraud, secretary-general for the World Meteorological Organization, says the most troubling climate development in 2012 was the melting at the top of the world. (AP Photo/Ian Joughin)
Shrinking ice sheets
  • The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA  shows Greenland lost 150 to 250 cubic kilometres of ice per year between 2002 and 2006, while Antarctica lost about 152 cubic kilometres of ice between 2002 and 2005.


Warm temperatures and winds drove record declines in sea ice at both polar regions
Declining Arctic sea ice
  • Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades.

Carroll Glacier, Alaska. August 1906 and June 21, 2004
Glacial retreat
  • Glaciers are retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska and Africa.

Global warming is linked to extreme weather events.
Extreme events
  •  The number of record high-temperature events in the United States has been increasing, while the number of record low-temperature events has been decreasing, since 1950. The U.S. has also witnessed increasing numbers of intense rainfall events.

Coral reefs are a major concern in a world of increasing ocean acidification and nutrients.
Ocean acidification
  • Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30 percent. This increase is the result of humans emitting more carbon dioxide into the atmosphere and hence more being absorbed into the oceans. The amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by about 2 billion tonnes per year.

These two natural-color satellite images of the reduction of snow cover in the Sierra Nevada
Decreased snow cover
  • Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and that the snow is melting earlier.

Did you know?

Understanding global warming and climate change begins young:

How do volcanic eruptions affect the climate? Understand global dimming here:

What do volcanic eruptions mean for the climate?

Calbuco volcano eruption. Credit: Philip Oyarzo Calisto
See how Sunspots and Solar Cycles affect the climate:

Leave a reply!

1. Describe and explain two natural causes of climate change.
2. How has the earth’s climate changed since 1880 and why?
3. Describe how three of the pieces of evidence of climate change will affect you personally.

Panic in Sicily as Mount Etna blows in huge eruption on Italy holiday isle

Mount Etna has erupted sparking fear across Sicily as Europe’s biggest and most powerful volcano sends an ash cloud across the holiday isle in Italy.

Italy’s Mount Etna has started spewing lava in what is its second eruption of the year.
Giant fountains of lava could be seen sprouting from the volcano, located on the isle of Sicily, as far away as Catania, around 30 kilometres away, and the resort town of Taormina.

An orange air alert has been issued, meaning that airspace will remain open but authorities will continue to monitor the situation.



Mount Etna is located in Sicily

While civil protection authorities has declared a yellow alert level and, as prescribed by the municipal emergency plan, an ordinance was issued to restrict access to the summit of Etna.

Authorities added that there have been no reports of injuries or fatalities, and expect it to remain that way with the eruption posing little threat to nearby settlements.

At 3,329 metres tall, Mount Etna is the largest active volcano in Europe.


Mount Etna has begun erupting


The eruption could be seen as far away as Catania.

The large volcano began erupting on February 27, and the eruptions are expected to continue for several days.

Strombolian activity at the new south-east crater has gradually intensified, creating a lava flow that quickly reached the base of the mountain.

While in the villages of Zafferana and Linguaglossa, citizens reported seeing clouds of dust fall from the sky after ash caught in an easterly wind.

As the upper-level winds grab the ash from the eruption, they will steer it away from Mount Etna, affecting the weather elsewhere.

AccuWeather Meteorologist Tyler Roys said: ”Over the next several days, the ash will be swept northeastward across far southwestern Italy, which will see the worst effects.


accuweather ash clouds from Etna

“Depending on how long the eruption lasts, the haze could be around for several days.”

From the early hours of this morning, the average amplitude of volcanic tremor – although remaining at high levels – has shown small fluctuations.

But experts say they have not found any significant changes associated with the intensification of the eruptive activity.


Mount etna erupting

The eruption comes a month after Etna first burst this year

This latest eruption is the second this year, and comes just a month after Mount Etna experienced a flurry of activity in late January, which brought 8 months of inactivity to an end.

Schools in nearby towns were evacuated, but only a very small eruption occurred.

Read the original article here:

Leave a reply!

  1. Based on your observations of the volcanic eruption, what kind of volcano is Mt Etna?
  2. What are some of the negative impacts of this eruption on the people in the surrounding region?
  3. What were some of the measure taken by the local officials to mitigate the effects of this eruption?

Did you know?

Mt Etna has a very long history of eruptions, with the first record of eruption as early as 396BC!

Watch the live stream here:

Or an older video here:

Plate Boundaries: an introduction

Based on the work of Society geophysicists Bruce Heezen and Marie Tharp, this 1968 map of the ocean floor helped bring the concept of plate tectonics to a wide audience.


There are a few handfuls of major plates and dozens of smaller, or minor, plates. Six of the majors are named for the continents embedded within them, such as the North American, African, and Antarctic plates. Though smaller in size, the minors are no less important when it comes to shaping the Earth. The tiny Juan de Fuca plate is largely responsible for the volcanoes that dot the Pacific Northwest of the United States.

The plates make up Earth’s outer shell, called the lithosphere. (This includes the crust and uppermost part of the mantle.) Churning currents in the molten rocks below propel them along like a jumble of conveyor belts in disrepair. Most geologic activity stems from the interplay where the plates meet or divide.

The movement of the plates creates three types of tectonic boundaries: convergent, where plates move into one another; divergent, where plates move apart; and transform, where plates move sideways in relation to each other.

They move at a rate of one to two inches (three to five centimeters) per year.


The Himalayas from above.


Where plates serving landmasses collide, the crust crumples and buckles into mountain ranges. India and Asia crashed about 55 million years ago, slowly giving rise to the Himalaya, the highest mountain system on Earth. As the mash-up continues, the mountains get higher. Mount Everest, the highest point on Earth, may be a tiny bit taller tomorrow than it is today.

These convergent boundaries also occur where a plate of ocean dives, in a process called subduction, under a landmass. As the overlying plate lifts up, it also forms mountain ranges. In addition, the diving plate melts and is often spewed out in volcanic eruptions such as those that formed some of the mountains in the Andes of South America.

At ocean-ocean convergences, one plate usually dives beneath the other, forming deep trenches like the Mariana Trench in the North Pacific Ocean, the deepest point on Earth. These types of collisions can also lead to underwater volcanoes that eventually build up into island arcs like Japan.



The Great African Rift Valley.


At divergent boundaries in the oceans, magma from deep in the Earth’s mantle rises toward the surface and pushes apart two or more plates. Mountains and volcanoes rise along the seam. The process renews the ocean floor and widens the giant basins. A single mid-ocean ridge system connects the world’s oceans, making the ridge the longest mountain range in the world.

On land, giant troughs such as the Great Rift Valley in Africa form where plates are tugged apart. If the plates there continue to diverge, millions of years from now eastern Africa will split from the continent to form a new landmass. A mid-ocean ridge would then mark the boundary between the plates.

Mountains and a rift can be seen along the San Andreas Fault.



The San Andreas Fault in California is an example of a transform boundary, where two plates grind past each other along what are called strike-slip faults. These boundaries don’t produce spectacular features like mountains or oceans, but the halting motion often triggers large earthquakes, such as the 1906 one that devastated San Francisco.


Read the full article here:

Leave a reply!

  1. What are some of the features formed by the movement of tectonic plates?
  2. Can you name one country that has been formed almost entirely by volcanoes?
  3. Millions of years from now, do you think the African continent will split in two and why?

Did you know?

The Mariana Trench is so deep, it’s frightening! Yet exploration continues despite the dangers lurking beneath the surface.


Some videos about plate movements:

Iceland: The country that tourism has taken by surprise

Read the full article here:

What happens to an economy when a country has a sudden and unexpected influx of tourists? Iceland offers intriguing lessons about the impact on cities, the environment and even food supply.

A girl scoops up a huge dollop of sticky white mud and ladles it into the hands of her friend, who smiles and gasps as it spills back into the water. Dozens of people are here, neck deep in a heated pool of soothing seawater. The late November air temperature is around 0 degrees celcius but the lagoon is like a hot bath. An electronic display at the exit to the changing rooms reads 38 degrees celcius. People apply mud masks and video themselves on smartphones encased in little plastic pouches.


Tourist numbers are increasing

Over the last 20 years, the number of international tourists has risen steadily. In 1995, around 500 million people travelled abroad – last year, around 1.2 billion people did. It is also an increasingly lucrative industry. In 2015, global revenue from tourism was $1.26 trillion – double what it was in 2005. It contributes more than $7 trillion to the global economy and supports one in 11 jobs around the world.


The Blue Lagoon is well known to Iceland’s visitors. The artificial pool, warmed by a nearby geothermal power plant, is particularly arresting at night. Huge clouds of steam billow into the starry black sky above the crowds of British, French, American, Russian and Chinese holidaymakers who have all come here to soak.

(Credit: Getty Images)

The Blue Lagoon has long been one if Iceland’s most popular attractions. The artificial pool is warmed by a nearby geothermal power plant (Credit: Getty Images)

Iceland’s hot pools have long been popular. But the number of people visiting the country has increased dramatically in the last few years. Iceland has a population of just over 330,000. Last year, around 1.7 million tourists came to visit. And the numbers are expected to continue rising. Iceland is experiencing a tourism boom that has taken it by surprise – and the influx is changing the once isolated country in interesting ways.

After the 2008 financial crisis, the value of the Icelandic krona fell heavily. As part of its economic recovery, Iceland made deliberate efforts to attract foreign visitors. But even those responsible for marketing Iceland abroad have been struck by the numbers. “I don’t think anyone could have expected this,” says Inga Hlin Palsdottir at Promote Iceland, a PR organisation for the country.

Iceland is experiencing a tourism boom that has taken it by surprise

What’s going on? In many ways, Iceland provides a snapshot of several shifts going on in the world: a move everywhere towards service industries like tourism, which now supports one in 11 jobs on the planet; fluctuations in national economies that have knock-on effects at home and abroad; and the impact of cheaper and more available air travel.

The uptick in visitors may also partly be down to people’s growing awareness of the country. Iceland has been in the news quite frequently in recent years. There was the financial crisis that broke its banks and sent the country into political turmoil. There were the eruptions of its Eyjafjallajökull volcano in 2010, which grounded flights across Europe. And last year Iceland’s football team won fans around the world when it reached the quarter-finals in its first ever appearance at the European Championships.

(Credit: Chris Baraniuk)

Iceland has a population of just over 330,000 – last year, around 1.7 million people came to visit (Credit: Chris Baraniuk)

But one of the biggest factors has surely been the growing availability of low cost airline tickets from Europe and the United States. Passenger numbers at Keflavik International airport have grown steadily over the last 10 years. In 2016 alone the number of people passing through the airport leapt by 40%, from nearly five million to nearly seven million.

In 2016 the number of people passing through Keflavik airport jumped by 40%

In particular, Icelandair’s offer of a free stop-off in the country for passengers travelling across the Atlantic has had a big effect, says David Goodger at analysts Oxford Economics. “People are breaking their trip to spend a few nights in Iceland itself,” he says. “They’ve done a very good job at selling into that market.” Other stop-off destinations for flights between Europe and the Far East have pulled the same trick. “It’s what the likes of Dubai and Singapore did very successfully a few years ago.”

The effect of tourist spending is clear, especially in Reykjavik. “Look at this area here,” says Palsdottir, gesturing out of the window of a trendy hotel in Reykjavik’s marina. “During the financial crisis, this was a dead area.”

(Credit: Chris Baraniuk)

Minke whale meat is popular with some tourists – but tourism is not a driving factor in Iceland’s whale-hunting quota, as this sign suggests (Credit: Chris Baraniuk)

(Read the full article here:

Leave a reply!

  1. What are the current tourism trend around the world at the time of this article?
  2. What are some reasons for the rapid growth of tourism in Iceland?
  3. What are some of the possible impacts of this dramatic rise in tourism on Icelanders?(Hint: Read the full article to find out!)

Did you know?


Want to find out more about the volcanic eruption that drew so much attention to Iceland?ökull