Saturday, 28 February 2015

Corals and Coral Bleaching

Healthy coral can be very colourful.


Some coral reefs recently have started to look rather different.


This is called 'coral bleaching'.

To understand this, we need to start by looking at corals.

Corals are animals that make a framework around them that looks like rock.

Coral animals (polyps) have tiny plants - algae - living in their tissues.

The algae provide food to the corals, which they produce by photosynthesis.

Corals only live in a limited temperature range.

Like porridge, they should be 'not too hot and not too cold'.

Coral reefs are concentrated in a band around the equator, between 30°N and 30°S latitude.

Algae in corals need light

Corals grow in warm shallow waters that receive plenty of light

Most corals grow in the warmest water they can stand (about 85° F or 29° C). 

This means that slight increases in ocean temperature can harm corals.

High sea temperature is the main reason for coral bleaching.

The Rock Cycle

The materials of the Earth are constantly cycling through processes that change one sort of rock into another.

Rocks form in three main ways.

Igneous rocks form when molten magma cools and crystallises.

The most common igneous rocks are basalt and granite.

Basalt has small crystals because the magma has cooled quickly as a lava flow on the Earth's surface.

Granite has bigger crystals because it has cooled slowly underground.

But there are also chemical differences between types of igneous rocks.

Sedimentary rocks are made of material that has been broken up on the surface of the Earth, then gets deposited in layers.   

Fossils of ancient animals and plants are often found in sedimentary rocks.

Some examples of sedimentary rocks are sandstone, shale and limestone.

All three can be seen in the Grand Canyon.

Metamorphic rocks are made when other rocks are heated, pressed or both.

Examples are slate, schist, phyllite and gneiss.

So the Rock Cycle connects all these processes.

Try this animated version of the Rock Cycle.

Friday, 27 February 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 some cases.

Some recent events, however, are so extraordinary.... 

In 2015, Boston’s month of snow was a 1-in-26,315 year occurrence.

Yet the amount of wintertime cold air circulating around the Northern Hemisphere is shrinking to record low levels.

Some researchers are finding that there is probably a link to climate change in some cases of extreme weather.

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 fast, 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 PakistanGovernment 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.

Global Warming - How unusual is the rise in Earth's temperature?

The last major glacial stage of the "Ice Age" ended thousands of years ago.

Since the ice retreated, the temperature has not been totally fixed, but the recent rise is very different.
The graph shows that after the ice melted, temperatures continued to rise for a few thousand years.
Around 8,000 years ago the global temperature steadied (with some 'wiggles') until about 4,000 years ago.
Then the Earth began to cool slowly, and that continued until modern times, with some variations.

Hot Scottish rocks

There is a famous rock face just below Salisbury Crags in Holyrood Park, Edinburgh.

The rock face tells us about the hot volcanic past in Scotland.

It's called "Hutton's Section" after James Hutton who first noticed it.

The pale layered rock is broken and tilted by the reddish-brown massive rock.

Hutton realised the reddish-brown rock must have been molten magma, pushing with force into the older sedimentary rocks.

Edinburgh sits on an ancient volcanic centre.   

The volcanic activity happened in the Carboniferous Period.

In this view, Salisbury Crags palisade stands over the city - it is a sill.

On the right is Arthur's Seat, made of four eroded central volcanic vents.

This diagram explains how some volcanic landforms are made.

Thursday, 26 February 2015

Direct Observation of Carbon Dioxide’s Increasing Greenhouse Effect

Scientists have observed an increase in carbon dioxide’s greenhouse effect at the Earth’s surface for the first time. 

These graphs show carbon dioxide’s increasing greenhouse effect at two locations on the Earth’s surface. 

The first graph shows COradiative forcing measurements obtained at a research facility in Oklahoma. 

The second graph shows similar upward trends at a research facility on the North Slope of Alaska. (Credit: Berkeley Lab)
They link this upward trend to rising CO2 levels from fossil fuel emissions.

Radiative forcing is a measure of how much the planet’s energy balance is altered by atmospheric changes. 

Positive radiative forcing occurs when the Earth absorbs more energy from solar radiation than it emits as heat radiation back to space.

“We see, for the first time in the field, the amplification of the greenhouse effect because there’s more COin the atmosphere to absorb what the Earth emits in response to incoming solar radiation,” says Daniel Feldman.

Dr Feldman is a scientist in Berkeley Lab’s Earth Sciences Division and is lead author of the paper.

Jupiter and the Galilean Moons

The planet Jupiter has been known ever since anyone looked at the sky.

It is a bright object which moves slowly across the starry background, taking about 12 years to track all the way around.

Through a telescope it looks spectacular, and even better in pictures taken by space probes.

In this picture, the coloured belts of clouds are clear, with a black shadow of one of Jupiter's moons.

Small telescopes show four moons, but there are also lots of smaller moons orbiting Jupiter.

The four larger moons were first seen by Galileo when he first used a newly-invented telescope in 1610, so they are called the Galilean moons.

The four Galilean moons were just small fuzzy objects until space probes visited Jupiter and showed that they are all different.

 Io has active volcanoes, Europa has an icy crust which may cover an ocean, Ganymede and Callisto are made of rock and ice, but Callisto has far more craters.   

Wednesday, 25 February 2015

Russell Coope - the man who counted beetles, and discovered abrupt climate change.

Many people think climate change always happens slowly, but that is not the case......rather than hundreds, or thousands, of years, sometimes it can happen in decades.

"Abrupt climate change" was discovered by accident by Russell Coope (1930-2011), over 50 years ago.

More recently he said:

"We are messing with the trigger that causes climate change....the outcome is likely to be ferocious."

In the 1950s, Russell Coope was a young geologist.

He was studying layers of sediment formed during the "Ice Ages", a time geologists call the Quaternary.

He spotted something unusual in a quarry in the English Midlands.  

This is his own description of what he found ...

"I happened, entirely by accident, to visit a Quaternary gravel pit in which were exposed the spectacular bones of mammoth, woolly rhinoceros and bison. 

Looking at their sediment matrix I was amazed to find enormous numbers of equally spectacular, if somewhat smaller, insect remains. 

I was hooked instantly! 

Particularly exciting to me was the fact that these insect fossils showed that Quaternary climates had changed abruptly. 

Thus, at times, fully glacial climates gave place to temperate interglacial conditions within the span of one human lifetime."

A well-developed sequence of ice age deposits at Bridgwalton Quarry near Bridgnorth, Shropshire. (Photo: Dave Evans).

This was the first discovery of evidence that the climate can change really quickly.

His discovery was later confirmed by evidence from ice cores from the Greenland ice sheet.

So how does Russell Coope's method work?

Different beetles prefer different temperatures.

By identifying the beetles in layers of sand or gravel, Coope could tell what climate existed in that place, and how it changed.

Experts still use Russell Coope's method.

This fossilised beetle is well preserved.

Scientists often identify the fossil beetles from fragments.

This particular fossil is of a diving beetle found in the La Brea Tar Pits in California.

There are about 380,000 known species of beetles.

Inside the Earth

We can't drill right down to the centre of the Earth to see what it is made of.

The waves from earthquakes are the key to mapping the inside of the Earth.

Seismic waves are bent (refracted) or reflected when they hit layers of different types.

Studying this information shows that there are several layers.

The core has an inner core of solid iron, an outer core of liquid iron.

The mantle is made of solid heavy rocks.

The thin outer layer, the crust, is the outline of the circle.

The crust does not sit on a 'molten sea'.

which is part of the upper mantle.

The rocks are kept nearly solid by the pressure of the rocks above.

They only melt if the pressure drops slightly.

The crust can move up and down slowly if the load on top changes.

Parts are still rising due to the melting of ice sheets over 10,000 years ago

Tuesday, 24 February 2015

Unburnable fossil fuels

Burning fossil fuels produces carbon dioxide.

Carbon dioxide emissions need to be limited. 

However, the potential carbon dioxide emissions contained in fossil fuel reserves are vast.

So it's not possible for all current fossil fuel reserves to be used, if the Earth's warming is to be kept below 2 °C.

The chart below is from The Guardian (7 Jan 2015) 

The Moon and its rocks

The Moon is near enough to see well with binoculars.

Its main features stand out clearly.

The same side of the Moon faces Earth all the time.

Most maps of the Moon use Latin names for the features, but it is interesting to see the names in English.

The flatter dark areas were called seas (maria) and oceans when nothing was really known, but they are actually large, mainly flat, areas of basalt lava.

  Notice the gas bubbles in the basalt lava

The highland areas are lighter in colour, and made of anorthosite rock.

The surface is covered by fine dust, mixed with rock fragments and glass beads.

This lunar 'soil' is usually referred to as regolith.

The tiny glass beads were formed when meteors hit the moon and caused rock so melt.

The molten material flew up and cooled quickly in the cold airless lunar environment to make drops of glass.

The far side of the Moon was unknown until space-probes photographed it in the late 1950s.

This picture was taken by a Chinese space probe in 2014.

It shows a large part of the far side of the Moon, as well as the Earth.

Monday, 23 February 2015

The Earth's icy poles - what's happening?

Icewater and water vapour - the three states of H2O....solid, liquid and gas.
The Earth has all three, which is unusual.

Planets are usually too hot or too cold to have them all.

Ice on Earth is melting.
The Arctic includes an ocean covered by sea ice.

Arctic sea ice melts in Summer and then refreezes in Winter.

The area of Arctic sea ice is largest in March each year, and at its lowest each September.
It is reducing over time - the graph comes from the US National Snow and Ice Data Center.

ice extent trend graph

The Antarctic is a continent covered by ice, unlike the ocean in the Arctic.

The sea ice surrounding Antarctica melts almost to the coast each summer.

The winter sea ice has increased by around 1 % over the last few decades.

This is due to complex processes.

It is linked to melting of the land ice on Antarctica…..

Here is an outline of what is happening in the seas around Antarctica.

Seawater does not freeze until around minus 2 degrees C because it is salty.

This effect of salt, of course, is used to help defrost roads.

The meltwater off Antarctica’s ice sheets is freshwater.

Freshwater has a low density, so it forms a layer on top of the sea.

Freshwater freezes (of course) at zero degrees C.

So the top layer freezes more easily.

Also windchill helps to freeze that top layer.

Here is a useful comparison of Antarctic and Arctic sea ice ……

The Earth's poles are warming faster than the rest of the planet.

One reason is that energy is carried to the poles by large weather systems.

The long-term decline in Arctic sea ice is illustrated in these two graphics.

The Great Orme Copper Mine

The Great Orme is a headland on the north coast of Wales.

When part of the summit area was being cleared for a country park in the 1980s, ancient mineshafts were found.

Excavations showed these were very old.

Tools made of deer antlers were found, which had been left by the miners.

Carbon dates showed the mines were operating from around 2000 BC to around 1000 BC, so they are Bronze Age mines.

What were they mining?

A copper ore called chalcopyrite.

It would have been smelted to extract copper.

Copper mixed with tin makes bronze.

Bronze axe heads were a big improvement on stone axes.

Sunday, 22 February 2015

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

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

It is often claimed that the Sun is causing global climate change.

One scientist who claimed that the Sun is responsible for the current climate change has been revealed to have been funded by the fossil fuel industry.

In the graph below, from the Stanford Solar Center, carbon dioxide data comes from the Law Dome ice core in Antarctica, and from the observatory on Mauna Loa in Hawaii.

Mary Anning finally gets her name on a species of Ichthyosaurus

A remarkable discovery in the fossil collection of the Doncaster Museum and Art Gallery has led to the naming of a new species.  

Ichthyosaurus anningae

A new species of Ichthyosaurus.

Picture Credit: Dean Lomax and Judy Massare

The name honours Dorset fossil collector Mary Anning.

It was Mary, along with her brother Joseph, who found the first Ichthyosaurus fossils to be scientifically studied in 1811.

Until now, no species of Ichthyosaurus has been given her name, so this is long overdue.

Dean Lomax, Honorary Scientist at The University of Manchester, examined the specimen in 2008.  

Working with Professor Judy Massare of Brockport College, New York, Dean spent over five years comparing the Doncaster Ichthyosaur with other museum specimens from around the world.

Saturday, 21 February 2015

It's a warm world these days.

The Earth is going through an extraordinary process.... the planet is warming, the ice is melting, and the climate is changing. 

This graph shows show world temperatures have changed over the last 100 years.

The red lines show the overall rising trend in temperatures, but there are short-term 'wiggles' as well - the most significant is a green wave pattern.