Saturday, 31 January 2015

Is it true when people say temperatures havn’t risen for ??? years? No, that's an Urban Myth

Claiming "global temperatures have not risen" is a popular quote.

But actually the temperature has risen.
This chart shows the annual average global temperatures……from NASA's Goddard Institute for Space Studies (GISS)


One thing to note ….. every La Nina ‘year’ since 1998 was warmer than every El Nino ‘year’ before 1995.  

It's useful to look at average global temperatures by comparing decades.
This chart comes from the World Meteorological Organisation

The high figures in the 1930s and 1940s were produced because there were strong El Ninos over a period from about 1939 to 1942.

Since the mid 20th century global temperatures have risen, decade by decade.

Volcanic hazards

Volcanoes can cause great damage and loss of life.

One famous example is the eruption of Vesuvius in 79 AD, which buried the Roman towns of Pompeii and Herculaneum.



Many of the people killed in that eruption were killed by pyroclastic flows, which are hot clouds of gas full of tiny particles of volcanic rocks.

These clouds rush down at high speed.

The towns were buried in volcanic ash, and excavation has revealed buildings and streets.

The 79 AD eruption of Vesuvius, and the buried towns, are famous in the history of geology and in archaeology.

This diagram gives examples of some types of volcanic activity.

Friday, 30 January 2015

Iceland, its volcanoes and ice caps

Iceland lies on the Mid-Atlantic Ridge, which is why it has volcanic activity.



Iceland also has ice caps and glaciers.

Iceland is one of the fastest-warming places on the planet – as much a four times the Northern Hemisphere average. 
The glaciers that cover more than 10 percent of the island are losing an average of 11 billion tons of ice a year. 
              Iceland glacial meltwater - photo Tom Harding
The water melting from Iceland's glaciers would fill 50 of the world's largest trucks every minute for the entire year.

Parts of Iceland are rising as the ice caps melt, reducing the weight on the Earth's crust.

The thinning of the ice caps reduces the pressure on the rocks.
Geologists know that lower pressure from above makes volcanoes erupt more easily.

Lower pressure allows volcanic gases to expand, and mantle rocks melt more easily at lower pressure as well.



So more magma can rise into the volcanic systems.

Iceland's volcanoes may get more active.

The Pole Star and the Two Bears

In the Northern Hemisphere some of the stars of Ursa Major are easy to see on clear nights.

They make a pattern sometimes called the Big Dipper or the Plough.

Ursa Major and Ursa Minor are the 'Great Bear' and the 'Little Bear'.



The two brightest stars of Ursa Major are known as the Pointers, because they point at the brightest star of Ursa Minor, Polaris, the Pole Star.

The Pole Star, or North Star, has always been used for navigation.



Photographs show that as the Earth turns, Polaris is almost fixed in the centre of the turning star pattern.



Like many stars, the stars of the Plough have Arabic names.

One star, Mizar, is actually a double star.

Alcor probably orbits Mizar, taking around 750,000 years to complete one orbit.

Some people with good eyesight can see Alcor and Mizar as two stars on a clear night.

They can certainly be seen very easily with binoculars.

Thursday, 29 January 2015

Do volcanoes make more CO2 than human activities? No - that's an urban myth

Some people think volcanoes produce more carbon dioxide than humans.

Not the case.




Geologists have checked this problem very carefully.

This chart compares the yearly production of carbon dioxide by human activities and volcanoes......

This information comes from the United States Geological Survey.

Saturn's rings

Saturn's rings are made of chunks of ice, orbiting around the planet.

The gaps are made by the gravity of Saturn's moons pulling on the ring fragments.



To see how thin the rings really are, this picture of Saturn shows the rings edge-on, with Saturn's biggest moon Titan.



Many pictures of Saturn and its moons have been sent back to Earth by the Cassini probe.





Wednesday, 28 January 2015

Carbon dioxide and the ice age - not the same as the current climate change

Some people think that because the climate has changed before, the current changes must be natural as well.

They also say that CO2 does not change the climate because in the past CO2 has only risen AFTER temperatures rise.

Things are not that simple.

CO2 levels only follow temperatures when glacial stages end.

The 'Ice Age' is actually a long set of colder (glacial) stages and warmer (interglacial) stages.


When the Earth comes out of a glacial stage...

The warming is started by changes in the Earth's orbit. 



The warming causes the oceans to release CO2

The CO2 boosts the warming.

So CO2 causes warming AND those rising temperatures cause CO2 levels to rise.

About 90% of the global warming occurs after the CO2 increase.


In the graph below, the cores mentioned in the key are ice-cores drilled from the ice of Antarctica.

MLO refers to the Mauna Loa Observatory in Hawaii.

It is clear the current rise in the level of carbon dioxide is far bigger than 'natural' changes.

In the graph, the jagged peak around 115,000 to 140,000 years ago is the Eemian Interglacial, when carbon dioxide was fairly high.

Interglacials often have local names - in Britain the Eemian is known as the Ipswichian.

After that, CO2 levels dropped.

The Earth cooled into a long glacial stage, which ended around 12,000 years ago.  In the UK that stage is called the Devensian.




Carbon dioxide levels are now rising much faster than normal.



Of course carbon dioxide is only one factor involved in glacial-interglacial stages.

Henrietta Leavitt and the discovery of Cepheid Variable Stars.

Distances in space were largely a mystery at the start of the 20th century.

The distances of some stars had been measured using a method called 'parallax'.



Finding distances of objects far out in space needed a new discovery.



The person who made that discovery was Henrietta Leavitt.

She discovered that certain types of variable stars changed brightness in a regular way.



These pulsating stars are known as Cepheid variables, named after the star Delta Cephei. 

Henrietta Leavitt looked at large numbers of these stars in a feature called the Small Magellanic Cloud, and discovered that brighter Cepheids pulsed more slowly than dimmer ones.

Tuesday, 27 January 2015

Global Warming - where does the heat go?



As global warming continues, heat goes into all parts of the Earth's systems.

The Earth is gaining more heat than it loses, and most of that heat is going into the oceans.

More heat is going into the upper parts of the oceans.

The water in the oceans is expanding, which is one reason sea level is rising.



The deepest oceans are still cold.

Some of the heat is involved in melting ice, including Arctic sea ice.



The recent reduction in Arctic sea ice is very dramatic.

The ice covering the Antarctic continent is also melting.

Fingal's Cave

Fingal's Cave is on Staffa, an island near Scotland.

The island, like many of the Inner Hebrides, is made of volcanic rock.



The vertical lines seen in the photograph were formed when hot lava cooled.

The shrinking lava produced a columnar pattern.

These volcanic rocks date from around 50 to 60 million years ago.

At that time, the North Atlantic was starting to form, with Europe beginning to split from North America.

This diagram shows how volcanoes developed between Europe and North America 60 million years ago, as magma from deep in the Earth moved upwards and was erupted at the surface. Volcanism has continued ever since along a structure called the Mid-Atlantic Ridge, creating new ocean floor and pushing the continents steadily apart at a rate of a few millimetres a year. In Iceland, this steady volcanism has interacted with a hot mantle plume to create the volcanic island we see today. (Image: © Elizabeth Pickett

This diagram shows how volcanoes began to separate Europe and North America 60 million years ago.

Magma from deep in the Earth moved upwards and was erupted at the surface. 

Volcanism has continued ever since along a structure called the Mid-Atlantic Ridge.

It created the Atlantic ocean floor and is still pushing the continents steadily apart at a rate of around 2.5 centimetres a year. 

In Iceland, this steady volcanism has interacted with a hot mantle plume to create the volcanic island we see today. (Image: © Elizabeth Pickett)

Monday, 26 January 2015

Climate change and extreme weather

Each time there are extreme weather events, people debate "Is there a link to climate change?"

It might be hard to prove either way in many cases.

Some researchers are finding that there is probably a link in some cases.

One scientist investigating one area of this problem is Professor Jennifer Francis.




Prof Francis is particularly interested in how the odd behaviour of the jet streams is being linked to the way the polar areas are warming faster than other parts of the Earth.

For example, in 2010 ......




There were some very unusual weather events in 2010, which may be a warning of future effects of climate change.

China and Brazil had serious droughts, and in the first part of the year the Northern Hemisphere warmed quickly, melting the winter snow cover very quickly.



The picture shows the dried-up River Negro in Brazil, with a bridge in the distance.  

But the biggest events were the heatwave in Russia and the flooding in Pakistan.

In Pakistan, Government officials said that from July 28 to Aug. 3, parts of Khyber Pakhtunkhwa province recorded almost 12 feet of rainfall in one week. 

The province normally averages slightly above 3 feet for an entire year.

        
       Pakistan Floods                                  Russian forest fire

In Russia, the heatwave went on for weeks, causing forest fires and destroying crops.

The Russian harvest was reduced in 2010, so the government stopped exports of grains.

The link between the floods and the heatwave was a blocked jet stream

The Sun and Nuclear Fusion

The Sun is by far the biggest object in the Solar System.



In the picture, the planets at the right are shown to scale. The Earth is the first planet in the third row.

The Sun makes energy by a process called nuclear fusion.

Hydrogen atoms in the centre are under great pressure and temperature.

When they combine to make helium they release energy.

Sunday, 25 January 2015

Greenland - the melting ice giant

The invention of the name Greenland may mark the start of the advertising industry.

One story tells how Erik the Red, the Icelandic Viking who wanted to get people to join his planned settlement, called it Greenland because a pleasant name would attract more settlers.

The ice sheet on Greenland covers most of this huge island.



Each summer the ice surface melts in places, but the area where melt happens is increasing over time.



Greenland is losing ice

The mass of ice lost is measured by satellites called Grace.

 

Updates about Greenland's ice sheet are regularly posted by the National Snow and Ice Data Center.

2014 Warmest Year in Modern Record



The year 2014 ranks as Earth’s warmest since records began in 1880.


9 of the 10 warmest years in the instrumental record have now occurred since the year 2000.

The exception was 1998, which was affected by a very strong El Nino event.




That means nobody born since 1976 has experienced a colder-than-average year.

2014 was not even affected by an El Nino, which has been the case for previous record years.

Chart showing global mean temperature anomaly in comparison to the El Nino phase





Saturday, 24 January 2015

Is the Sun to blame for Global Warming? - No, that's a Climate Myth

The Sun is the source of the heat on the Earth, but it has not suddenly become more active recently.

In the graph below, older carbon dioxide data comes from the Law Dome ice core in Antarctica and the more recent data from the observatory on Mauna Loa in Hawaii.


Ammonites

Ammonites are an extinct group of sea creatures.

They are found as fossils, formed when the shells of the animals became buried in sediment which later solidified into rock.



The oldest ammonite fossils are found in Jurassic rocks, from around 200 million years ago. 

They became extinct at the end of the Cretaceous around 65 million years ago.




Ammonites had shells made of chambers. The air in the chambers helped them to swim.



There are hundreds of types of ammonites, with different shapes.

Here are just a few examples.




Friday, 23 January 2015

Climate change and atmospheric oxygen


Current climate change is slowly reducing the amount of oxygen in the air. 

Billions of tonnes of carbon have been released from fossil fuels - coal, oil, and gas.



The carbon joins up with atmospheric oxygen when it burns.



Each carbon atom joins with two oxygen atoms to make carbon dioxide. 


Several scientific organisations measure the gases in the air.

One major set of measurements are from a laboratory in Hawaii.

This is all extra evidence that extra carbon dioxide in the air comes from burning fossil fuels. 

How oil forms

Oil is a fossil fuel.

It was formed from chemicals that were produced from ancient living things.



To make the chemicals in oil, the temperatures and pressures needed to be just right.

The carbon compounds from the plants and animals have been trapped for hundreds of millions of years.

They have been burned to make carbon dioxide in a very short time.

The amount of carbon dioxide in the air has changed very quickly.

Thursday, 22 January 2015

How ice ages come and go.

Some people wonder if the current climate change has "natural causes".

They sometimes refer to the changes during the 'Ice Age' and think the current events must be natural as well.

Scientists say that is not the case.

The current situation is different.

The things that caused the changes in Ice Age are not exactly the same.

The graph shows that carbon dioxide in the air has increased and decreased over hundreds of  thousands of years.

The recent increase in carbon dioxide is much bigger and faster than the natural changes.



The low readings match with times called 'glacial stages'.

During glacial stages, ice covered large areas of the Earth.


The most recent glacial stage occurred between 115,000 and 11,500 years ago. 


The Earth's movements cause warming or cooling.

This changes the amount of carbon dioxide that can dissolve in the oceans.

As the Earth warms, more carbon dioxide leaves the oceans.

The extra gas in the air boosts the warming effect.

The Milankovitch Cycles now are tending to cool the Earth.

So the current warming is not part of natural processes.


Law Dome is a site in Antarctica where scientists have drilled into the ice.