Sunday, 22 September 2019

Climate Change - Greenland

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

The Saga of the Greenlanders 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:

He called the land which he had found Greenland, because, quoth he, "people will be attracted thither, if the land has a good name." 

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




Greenland is losing ice, and the mass of ice lost is measured by satellites called GRACE.

Embedded image permalink

A survey of Greenland's glaciers has shown they are speeding up.

The speed has increased by about 30% in 10 years.

A paper published in June 2019 predicts that Greenland will very likely become ice free within a millennium without substantial reductions in greenhouse gas emissions.

A new NASA project called Oceans Melting Greenland (OMG) will observe changing water temperatures on the continental shelf surrounding Greenland, and how marine glaciers react to the presence of warm, salty Atlantic water.

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

Saturday, 21 September 2019

Climate Change - The End-Permian Mass Extinction

Five major mass extinction events are recorded in the rock record of the last 600 million years.
The biggest extinction was at the end of the Permian, around 252 million years ago.

It is called the End-Permian mass extinction.


Only about 8% of species survived to live on in the Triassic Period.



The event played out over 60,000 years.
Acidification of the oceans lasted for about 10,000 years.
Two separate pulses of CO2 into the atmosphere - a "one-two punch" - may have been involved in the die-off, according to new research.
CO2 was released by massive volcanism from the Siberian Traps, now represented as a large region of volcanic rock. 

A large amount of coal had been burned over a period of tens of thousands of years.
The coal was burned by the Siberian Traps volcanic activity.
The burning actually happened underground, with the carbon dioxide and ash mixing with magma.

This produced vast amounts of CO2 which warmed the Earth and changed the chemistry of the oceans.
The research team, led by Dr Matthew Clarkson from the University of Edinburgh, examined rocks in the United Arab Emirates. 
Siberian Traps
The rocks, which were on the ocean floor at the time, preserve a detailed record of changing oceanic conditions. 

The carbon was released at a similar rate to modern emissions. 
Dr Clarkson says "Scientists have long suspected that an ocean acidification event occurred during the greatest mass extinction of all time, but direct evidence has been lacking until now.
"This is a worrying finding, considering that we can already see an increase in ocean acidity today that is the result of human carbon emissions."

Friday, 20 September 2019

Climate Change - El Nino

El Niño is an oscillation of the ocean-atmosphere system in the tropical Pacific, and has important consequences for weather around the world.

El Niño happens every three to seven years.

“El Niño” is Spanish for “The Little Boy”.

Peruvian fishermen named the event many years ago.

They noticed that every few years around Christmas, virtually no fish could be found in the unusually warm waters. 
El Niño is marked by unusually warm ocean temperatures in the Equatorial Pacific.

The opposite conditions are called La Nina (The Little Girl), characterized by unusually cold ocean temperatures in the Equatorial Pacific. 

El Nino clearly affects global temperatures.

One piece of evidence that world temperatures are rising is that every La Nina ‘year’ since 1998 was warmer than every El Nino ‘year’ before 1995:  

As the Earth warms, each El Nino 'rides' on a higher base-line global temperature:

The record-breaking temperatures of 2015 were partly boosted by an El Nino event ... but 2015 would have been the warmest year in the modern record even if there had been no El Nino.

Information about El Nino is provided in bulletins produced by the US National Weather Service and the Australian Bureau of Meteorology.

Thursday, 19 September 2019

Planet Earth - Doggerland

For many years, fishermen in the North Sea, between Britain and Denmark, have found fossil bones in their nets.



This fossil catch has yielded over 200 tons of fossil bones, and over 15,000 mammoth teeth.   

The bones include remains of mammoths, three different species of woolly rhinos, hippos, lionsbears, wild horsesbison, elk, reindeer, hyenas, wolves, and Sabre tooth cats of at least two species.   

They tell us about a whole community of animals.

Beneath the North Sea lies a lost landscape.

This land was as big as modern Britain - hills and valleys, rivers and forests, marsh and moor. 

Sometimes warm and marshy, and at other times a frozen tundra.

This has been named "Doggerland".



"Doggerland" is a name given to a vast lowland plain, with the northern coastline stretching from Shetland to Jutland. 

The Thames flowed into the Rhine, which turned south, and made the English Channel its estuary. 

The highest point was a hilly region where the Dogger sand-banks are today.

It was finally flooded by rising sea levels around 6,500 BC.

Wednesday, 18 September 2019

Climate Change - The Experts

What do scientists who research climate change say?

Professor Tim Palmer FRS, Royal Society Research Professor in Climate Physics, University of Oxford:



“The threat of dangerous man-made changes to global climate is quite unequivocal. 
It follows that if we want to reduce this threat, we must cut our emissions of greenhouse gases."

Professor John Shepherd FRS, Ocean & Earth Science, University of Southampton:


“The evidence is very clear that the world is warming, and that human activities are the main cause. 
Natural changes and fluctuations do occur but they are relatively small."

Professor Joanna Haigh CBE FRS, Professor of Atmospheric Physics, Imperial College London:



The concentration of carbon dioxide in the Earth’s atmosphere now exceeds anything it has experienced in the past 3 million years and its continuing upward trend is almost certain to result in further global warming."

Professor Sir Brian Hoskins FRS, Director of the Grantham Institute for Climate Change at Imperial College London:




“The evidence of changes in many different aspects of the climate system, from the ice sheets to the deep ocean, shows that climate change is happening.   
To reduce the serious risks posed by increasing changes in the climate, we need to redouble our efforts globally to limit carbon dioxide and other greenhouse gas emissions.”

The Royal Society has also published a "Short Guide to Climate Change" 

In addition, the Royal Society has produced a 2017 update on recent research -

"What have we learnt since the IPCC 5th Assessment Report?"

Another organisation offering an important document is the Geological Society of London.

                                 
The Geological Society of London say -

This rate of increase of CO2 is unprecedented.....

even in comparison with the massive injection of carbon into the atmosphere 55 million years ago that led to the major PETM warming event....

and is likely to lead to a similar rise in both temperature and sea level. 

From.....

Tuesday, 17 September 2019

Climate Change - 1816 - The Year Without a Summer

The climate can react to sudden shocks.

The weather in 1816 was very strange. 

Spring arrived, but then everything seemed to turn backward, as cold temperatures returned. 

The sky seemed permanently overcast. 


The lack of sunlight became so severe that farmers lost their crops.

Food shortages were reported in Ireland, France, England, and the United States.

1816 became known as "The Year without a Summer" or "18-hundred-and-frozen-to-death".

It was over 100 years before anyone understood the reason for this weather disaster.

The eruption of an enormous volcano on a remote island in the Indian Ocean a year earlier had thrown enormous amounts of volcanic ash into the upper atmosphere.

The dust from Mount Tambora, which had erupted in early April 1815, had shrouded the globe. 

With sunlight blocked, 1816 did not have a normal summer.

In Switzerland, the dismal summer of 1816 led to the writing of a famous story. 

A group of writers, including Lord Byron, Percy Bysshe Shelley, and his future wife Mary, challenged each other to write dark tales, inspired by the gloomy and chilly weather.

During the miserable weather Mary Shelley wrote her classic novel Frankenstein.


This event was not unique.

Volcanic events can cool the Earth for a few years.

The large eruption of Mount Pinatubo caused a dip in global temperatures in the early 1990s:

Mount Pinatubo 1991

In 1258 there was a European famine across many countries, and this is now linked to a major eruption in 1257 on Lombok in Indonesia - it has a much bigger sulphate peak in the ice cores than Tambora, so it was a bigger eruption.

In 536 AD a mysterious fog plunged Europe, the Middle East, and parts of Asia into darkness, day and night—for 18 months.

An analysis of ice from a Swiss glacier by a team at the Climate Change Institute of The University of Maine (UM) in Orono has reported that a cataclysmic volcanic eruption in Iceland spewed ash across the Northern Hemisphere early in 536. 

Two other massive eruptions followed, in 540 and 547. The repeated blows, followed by plague, plunged Europe into economic stagnation that lasted until 640.

Temperatures in the summer of 536 fell 1.5°C to 2.5°C, initiating the coldest decade in the past 2300 years. Snow fell that summer in China; crops failed; people starved. The Irish chronicles record "a failure of bread from the years 536–539." 

Researchers have investigated how future volcanic eruptions might affect the current trend of global warming.

They produced this graph showing that even a period of very active vulcanism would not affect the long-term trend -

The red curve shows how the temperature evolves from year to year in a simulation without volcanic activity. The blue curve shows the result for the simulation of the study with largest volcanic activity.

This new research shows that strong volcanic eruptions would produce short periods of cooling. 

These would generally be followed by periods of accelerated warming, as the effects of the volcanic emissions subside, and the effects of CO2 emissions catch up. 

Monday, 16 September 2019

Climate Change - Glacial archaeology

Norway is dotted with small glaciers, and 'permanent' snow patches .

Around 7,000 years ago (5000 BC) the Earth was experiencing a warm climate:



Then it cooled, allowing those icy areas to form.



Now those glaciers and patches of perennial ice in the high mountains of Southern Norway have started to melt again, as the Earth is warming. 

They contain all sorts of archaeological treasures.

Anything from ancient shoes to 5000-year-old arrowheads. 

As a result a new kind of archaeology has begun - Glacial archaeology.

6_norways-oldest-shoe

In 2006, an amateur archaeologist came across an amazingly well-preserved ancient leather shoe in the Lendbreen ice patch in Norway. 

When the shoe was examined and tested, archaeologists discovered the shoe was over 3,000 years old, and dated from the Bronze Age.

"Actually we should be slowly approaching a new ice age. 
But in the past 20 years we have witnessed artefacts turning up in summer from increasingly deeper layers of the glaciers." says Lars Pilø.
Lars does fieldwork in glaciers and ice patches, finding things discarded or lost by people long ago.

Glacial archaeology is becoming a fascinating new field of research.