Monday, 31 October 2016

Climate Change - The Atmosphere



Space is not very far away.

Aircraft on long-haul flights travel at a height of about 10 km.

The lowest layer of the atmosphere, the Troposphere, ends at about 15 km.

The air in the layers above the troposphere is very thin indeed.

Think of a place around 15 km (9 miles) from where you are.

That's pretty much how near you are to space.

All the waste gases people dump into the air are trapped in the thin layer of air around the Earth.


Molecules in the air include nitrogen and oxygen as well as water, carbon dioxide, ozone, and many other compounds in trace amounts, some created naturally, others the result of human activity.

In addition to gases, the atmosphere contains extras such as smoke, dust, acid droplets, and pollen.


Atmospheric concentrations of some greenhouse gases over the last 2,000 years. 

Increases since about 1750 are due to human activities in the industrial era. 

Concentration units are parts per million (ppm) or parts per billion (ppb), indicating the number of molecules of the greenhouse gas per million or billion air molecules in an atmospheric sample.

Sunday, 30 October 2016

Climate Change - Can climate change increase earthquakes and volcanic eruptions?

Between about 20,000 and 5,000 years ago, Earth slowly changed from the frigid conditions of an Ice Age, to the world on which our civilization has developed.

As the ice sheets melted, colossal volumes of water flowed back into the oceans.



The pressures acting on the Earth's crust changed as a result. 

The weight of ice on the continents was reduced, and the rising seas put extra water pressure on the seafloors.

In response, the crust moved up and bent, creating extra volcanic activity, increased seismic shocks and giant landslides.



So if we continue to allow greenhouse gas emissions to rise unchecked, causing serious warming, will our planet's crust react once again?

In Alaska, climate change has pushed temperatures up by more than 3 degrees Celsius in the last half century, and glaciers are melting at a staggering rate, some losing up to 1 kilometre in thickness in the last 100 years. 


The reduced weight on the crust beneath is allowing faults to slide more easily, promoting increased earthquake activity in recent decades. 

The crust beneath the Greenland ice sheet is already rebounding in response to rapid melting, providing the potential for future earthquakes, as faults beneath the ice are relieved of their confining load. 



The possibility exists that these could trigger submarine landslides, making tsunamis capable of threatening North Atlantic coastlines. 

Eastern Iceland is bouncing back as its Vatnaj√∂kull ice cap melts. Research predicts a response from the volcanoes beneath. 

A rise in landslide activity will happen in the Andes, Himalayas, European Alps, and elsewhere, as the ice and permafrost that covers many mountain slopes melts away. 

As sea levels rise, the bending of the crust around the margins of the oceans might unlock coastal faults such as California's San Andreas, allowing them to move more easily.

At the same time, the extra weight of seawater could act to squeeze magma out of undersea volcanoes.



This post is based on the work of Bill McGuire, professor of geophysical and climate hazards at University College London.

Saturday, 29 October 2016

Climate Change - Tropical storms

Hurricanes, cyclones, and typhoons are all the same weather phenomenon.

We use those different names for these tropical storms in different places. 

In the Atlantic and North-East Pacific, the term “hurricane” is used.

So far, Hurricane Patricia is the strongest hurricane recorded at landfall. 

Embedded image permalink
Image of Hurricane Patricia tweeted by astronaut Scott Kelly.

In the North-West Pacific a tropical storm is called a “typhoon”, and “cyclones” occur in the South Pacific and Indian Ocean.

Three strong tropical storms (KiloIgnacio, and Jimena), formed in the Pacific in 2015. 

On Sunday 30th August, all of them were a category 4. This was the first time the north-eastern Pacific had seen three category 4 hurricanes at the same time.

Picture hurricanes in Pacific Ocean



Tropical storms can’t form outside the tropics - water temperatures are too cold.

Sea surface temperature must be at least 27°C, and this temperature is actually required to a depth of at least 50 m

The warm tropical atmosphere heats up the water at the ocean surface and begins to evaporate it. 

The trapped water vapour in the air rises up through the atmosphere. 



When the rising air cools, and the water vapour condenses into liquid water, the heat is released back into the atmosphere.

The warm air rushes upward, because it has a lower density than its surroundings. 

This then draws air up from below, and speeds up the rising air near the surface. 

Surface air around the growing disturbance rushes in to replace it. 


A satellite image from the National Oceanographic and Atmospheric Administration shows Hurricane Katrina bearing down on the Gulf Coast on Aug. 28, 2005.

As this cycle continues, more warm, moist air is drawn into the developing storm, and more heat is transferred from the surface of the ocean to the atmosphere. 

This continuing heat exchange creates a wind pattern that spirals around a relatively calm centre, or eye, like water swirling down a drain.

The US National Hurricane Center gives regular information about hurricanes.

Friday, 28 October 2016

Climate Change - Oceans Are Losing Oxygen



Marlin can hunt in water a half mile down, and sailfish often dive deep too.

In more and more places around the world, ocean predators are sticking near the surface.

Why?

Warming temperatures are sucking oxygen out of waters even far out at sea, making enormous stretches of deep ocean hostile to marine life.



Vast stretches of the ocean interior suddenly lost oxygen during the transition out of the last glacial stage, between 17,000 and 10,000 years ago. 

This event was the most recent example of large-scale global warming.

Thursday, 27 October 2016

Climate Change - The Last Interglacial

This graph shows how carbon dioxide has increased and decreased over hundreds of thousands of years.


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

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

The peaks in the graph show times when carbon dioxide was high, matching times called 'interglacial stages'.

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

The last interglacial period occurred before it, from around 130,000 to 115,000 years ago.

It's official international name is the Eemian, but it has other names in specific places.
Climate information from that time is particularly useful.
During that time, temperatures on earth were higher at the poles than they are now. 
The sea level was between five and nine metres higher than current levels, because of the melting of ice in Greenland and Antarctica.
In the UK, this last interglacial period is called the 'Ipswichian'.
Pleistocene, Ipswichian raised beach deposits at Hope's Nose, Torquay, Devon, seen from the sea, 6th January 2012, photograph by Nikolett Csorvasi
Above, an interglacial 'raised beach' deposit at 9 metres above sea-level
This pebble, shell and sand accumulation is "Ipswichian" in age.
The warming during the last interglacial period was due to natural causes.

These were basically changes in solar radiation hitting the earth, due to the tilt of the earth on its axis. 
This earlier warm period is useful to estimate what the future has in store.
We can use past climates as a natural experiment on the Earth’s systems, to consider the way it reacts to warming. 

The Eemian began when the previous glacial stage ended.

New research has helped to explain that event.

Wednesday, 26 October 2016

Climate Change - 1816: The "Year Without a Summer" - Volcanic Cooling

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.

A new study has found that 15 of the 16 coldest summers recorded between 500 B.C. and A.D. 1,000 followed large volcanic eruptions.

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

Tuesday, 25 October 2016

Climate Change - Oil Geology

Oil is a fossil fuel.

It was formed from chemicals from ancient living things.

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

The oil (and gas) will only stay in the reservoir if there are suitable structures in the rocks:



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.

Diagram of how oil is made
Source: Library and Archives Canada
© Library and Archives Canada

Monday, 24 October 2016

Climate Change - Hyperthermal Events

What is the worst-case scenario for climate change?

The geological record shows that when the atmosphere suddenly changes, there are big effects on living things.


Every time in the geological past that gigatonnes of CO2 entered the atmosphere, the changes were very significant.
The geological record contains examples of major temperature changes, associated with changes in atmospheric CO2.
Events in which the temperature rose by several degrees in a geologically short time are called hyperthermals.
Matthew Huber at Purdue University calculated that warming slightly in excess of 10 degrees C—like that of the PETM and of pessimistic scenarios for future fossil-fuel burning—could render large portions of the planet uninhabitable for many creatures. He has said:
"There used to be subtropical forests near the poles 50 million years ago, and that doesn’t sound so bad.
"But the fossil record closer to the equator is really poor, and that may be an indication that life was extremely stressed during these warm periods.
"If over half the surface area of the planet becomes inhospitable, it will not render Earth uninhabitable, but it will be unrecognizable and existentially challenging for the majority of the people, species and communities on Earth."
Some researchers suggest the Palaeocene-Eocene Thermal Maximum, might be partly connected to an impact event that ignited forests.

During the PETM, a massive influx of carbon flooded the atmosphere and Earth warmed by 5 - 8 C degrees.

There hasn't been a hyperthermal event for tens of millions of years.
Some of them are linked to fossil fuel deposits being ignited by volcanic action.
However, in those natural events, the process usually took tens of thousands of years, and only affected a limited amount of fossil fuel.
Human activity is replicating that process on a much bigger scale, and in only a few hundred years.
This time, human activity is producing something potentially very extreme.

Currently CO2 is rising at 20 ppm per decade.

Nothing like this has happened in the time of Homo sapiens.

Uncontrolled addition of CO2 to the atmosphere is dangerous and will have serious consequences.
This is an accidental experiment on Earth's systems, which will change the planet beyond imagination.
A recent research paper contains this quote:
"Given currently available records, we demonstrate that the present anthropogenic carbon release rate is unprecedented throughout the Cenozoic (past 66 million years)."
This graph compares the current situation with the PETM event around 56 million years ago:
We are doing something very extraordinary......

The Holocene, by chance, had a mostly stable climate.
That stability allowed agriculture to develop, which allowed human population to rise rapidly.
It's unlikely that agriculture was possible until then, which is why humans remained as hunter-gatherers for over 200,000 years.
n
That comfortable window of time is closing.
That's the weakest link in human society.
Climate change creates the dangers of an increasing number of 'failed states' taken over by warlords, potentially leading to a 'failed world'.

Sunday, 23 October 2016

Climate Change - The link with mass extinctions

What is the worst-case scenario for climate change?

The geological record shows that when the atmosphere suddenly changes, there are big effects on living things.

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 Permianaround 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.

This photo shows geologists investigating tilted sedimentary rocks at Shangsi in South China.

Triassic rocks (at the top right) lie over the older Permian rocks.

Researchers have found evidence of a compound called fly ash, one of the products of coal combustion, in rocks laid down just before this extinction event. 

A large amount of coal had been burned over a period of tens of thousands of years.



The coal was burned by volcanic eruptions that happened in Siberia, which produced a large area of volcanic rocks called the Siberian Traps.

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.

Saturday, 22 October 2016

Climate Change - What does 'climate' actually mean?

Lots of people discuss 'climate change'.

Some people confuse 'climate' with 'weather' - but if 'climate' and 'weather' are the same, why would there be two words?

Other people say "We call climate change 'winter' and 'summer'...."  

What does the word 'climate' mean?

It normally means the average of conditions over 30 years.


Climate normally means 'an average over 3 conventional decades'.

conventional decade is, for example, 2001-2010, or 1961-1970.

So ..... 3 full, conventional decades......such as 1981 to 2010.

For example .... rainfall in Ireland.


And another example - 'Average temperature 1951-1980'

The definition of 'climate' goes back at least 100 years.

So if we are discussing climate change, that is what 'climate' means.

But in recent times, there has been a lot of variation in global temperatures.

So it can be useful to look at single conventional decades.


Chart from the World Meteorological Organisation.

Friday, 21 October 2016

Climate Change - The Long-Term Effects

Animated gif showing maps of temperature patterns in 2015 overall and each month.

According to the Royal Society.......

If human emissions of CO2 stopped altogether...


.... it would take thousands of years for atmospheric CO2 to return to ‘pre-industrial’ levels.

"The climatic impacts of releasing fossil fuel CO2 to the atmosphere will last longer than Stonehenge," says University of Chicago oceanographer David Archer.

"Longer than time capsules, longer than nuclear waste, far longer than the age of human civilization so far."

Why is that?

It takes a long time for deep oceans to bury the carbon dioxide in ocean sediments. 


abyssal sea floor life

Lifee on the abyssal sea floor (depths ranging from 4000-6000 m) near the Hudson Canyon off the coast of New Jersey. Photo taken using the Deep Submersible Research Vessel (DSRV) Alvin'scamera system. Image courtesy of Deep East 2001, NOAA/OER.

Surface temperatures would stay high for at least a thousand years.


Humans would face a warmer planet due to past and current emissions.


Ice would still be melting from places like Antarctica and Greenland.



So sea level would continue to rise for many centuries, even after temperature stopped increasing.

new study published in Nature Climate Change looks at the next 10,000 years.
The researchers found that the catastrophic impact of another three centuries of carbon pollution will persist for thousands of years after the carbon dioxide releases cease.

The current warming of the Earth can't be reversed on a human timescale. 


But if fossil fuels are not phased out soon, the situation will be far worse.



Research that investigated what would happen if all the fossil fuels are burned has come to some worrying conclusions:
“Burning all fossil fuels” would warm land areas on average about 20°C (36°F) and warm the poles a stunning 30°C (54°F). 
This “would make most of the planet uninhabitable by humans, thus calling into question strategies that emphasize adaptation to climate change.” 
Calculated warming over land areas averages approximately 20°C. 
Such temperatures would eliminate grain production in almost all agricultural regions in the world.

Thursday, 20 October 2016

Wednesday, 19 October 2016

Climate Change - Arctic sea ice

The Arctic includes an ocean covered by sea ice.
The area of Arctic sea ice is largest in March each year, and at its lowest each September.



The NSIDC also publish this graph, which is normally updated every day.

More graphs and other data are also available from the Arctic Data Archive System, operated by the Japanese Arctic Environmental Observation Center.

The total volume of Arctic sea ice has declined dramatically over time.


New research shows the decline in Arctic sea ice area since 1850:

Research suggests the remarkable decline of  Arctic sea ice over the last century is far beyond anything seen for a long time.