Thursday, 30 April 2015

The Changing Earth - Farming, food & possible mass migrations

Farmers can put up with some bad weather, but climate change will make unusual events more likely.


20-30% of plant and animal species will be more likely to become extinct if the temperature rises by more than 1.5-2.5C.

There will be big effects on farming from droughts and floods.



The biggest effects will be seen first near the Equator.

Just being near the Equator makes it more difficult for countries to make economic progress.

Hotter conditions affect how crops grow.

Our agriculture is heavily reliant on grasses from the temperate regions.
Corn, wheat, and rice are all types of grass.

The Tropics is a hard place to grow an industrial society.



People will try to leave places where they cannot produce enough food.

Countries where food prices rise rapidly tend to become unstable, making conflicts more likely.



Providing food for everyone in the world involves farming, fertilizer manufacture, food storage, packaging, transport and many other activities.


Those activities are responsible for up to one-third of all human-caused greenhouse-gas emissions.

Global warming affects wheat production.

The Changing Earth - Climate Refugees? The Sundarbans & Oceania

Climate change will affect people in many ways.

Sea levels are rising more than twice as fast as the global average in the Sunderbans.
The Sundarbans are a low-lying delta region made up of 200 small islands in the Bay of Bengal.
Around 13 million impoverished Indians and Bangladeshis live in the Sundarbans.  
Scientists predict much of the region could be underwater in 15 to 25 years, forcing the largest ever human migration in history.
A 2013 study by the Zoological Society of London found the Sundarbans coastline retreating at about 200 metres a year.

Oceania is a region made up of thousands of islands throughout the Central and South Pacific Ocean. It includes Australia, the smallest continent in terms of total land area.

Many of the nations in Oceania are Small Island Developing States (SIDS).



Many scientists say that Oceania is more vulnerable than most parts of the Earth to climate change, because of its climate and geography. 

The heavily coastal populations of the continent’s small islands are vulnerable to flooding and erosion because of sea level rise. 

Fiji’s shoreline has been receding about 15 centimetres per year over the last 90 years.

Samoa has lost about half a metre per year during that same time span. 

Wednesday, 29 April 2015

The Changing Earth - Water supply in Australia & the Great Plains of the USA

In 40 years, the distribution of rainfall in Australia has changed.



Changes like this affect water supply to cities and to agriculture.

Many parts of the world will see problems with water supply as climate change continues.



Since the 1940s, farming on the southern Great Plains of the USA—Colorado, Kansas, Oklahoma and Texas—has relied on irrigation. 

On the high plains of Texas, tens of thousands of wells pumping from the 10-million-year-old Ogallala Aquifer have reduced the water content by 50 percent. 

Most of the remaining underground water source will probably be useless within about 30 years.



Katharine Hayhoe, professor and director of the Climate Science Center at Texas Tech University in Lubbock, says big changes are on the way for agriculture on the Great Plains.



"We're seeing major shifts in places and times we can plant, the types of crops we can grow and the pests and diseases we're dealing with.

"There's no question we can adapt to some of the change, but whether we can adapt to all of it is a very open question."

The Changing Earth - Who changed 'Global Warming' to 'Climate Change'? - No one, it's an urban myth

Some people claim that someone decided that 'global warming' should now be called 'climate change'. 

It never happened.

For example, Gilbert Plass published research in 1956 - 'The Carbon Dioxide Theory of Climatic Change'.

The two terms mean different things, and both have been used for decades.


The words climate change and global warming are often used interchangeably. 
However, they do have slightly different meanings:
Global Warming has a very clear meaning.


Global warming refers to increases in the Earth’s average temperature, because of greenhouse gases building up in the atmosphere. 

Global warming is a cause of climate change.
Climate Change is a broader term.


Climate change refers to changes (increases or decreases) to long-term weather patterns, such as temperature, rainfall or snowfall.
A warmer Earth, from global warming, will lead to changes including -

Rainfall patterns

Rise in sea level

and 

A wide range of impacts on plants, wildlife, and humans.

Tuesday, 28 April 2015

The Changing Earth - "The climate has always changed .......what is all the fuss about?"

The climate has changed before.


When people say "It's changed before without people, so people can't be involved this time" ....think of forest fires.



Fires happened throughout time, does that mean people can't start fires?

Ice ages, warm times ... the geological record in the rocks shows many events.

Even so, the current changes are very unusual.



The recent rise in temperature is very fast.

What other kinds of changes are happening?


Geologists have compared the past with the present.


This report -
Climate Change Evidence: The Geological Society of London


explains what they have discovered.

This is based on part of that report:

"Before the current warming trend began, temperatures were declining.

This cooling took Earth’s climate into the ‘Little Ice Age’ (1450 – 1850). 

Calculations indicate that this period of cool conditions should continue for about another 1,000 years. 

Nevertheless, after 1900 the overall decline in temperature sharply reversed." 

So the Earth should be cooling.

There's lots of evidence for human involvement in these changes.  
Atmospheric CO2 is now around 400 parts per million (ppm).
It last reached similar levels during the Pliocene, 5.3-2.6 million years ago.
Outcrop view

In the middle Pliocene, the concentration of carbon dioxide in the air ranged from about 380 to 450 parts per million. 

During this period, the area around the North Pole was much warmer and wetter than it is now.

Summer temperatures in the Arctic were around 15 degrees C, which is about 8 degrees C warmer than they are now.
Global average temperatures were 2-3°C warmer than today.

Sea level rose by up to 20 metres in places.

What are the risks?
This source gives examples relating mainly to the USA ..........

but applicable more widely too.

For more interesting information, see -

Fact Sheets produced by 

The Changing Earth - The Medieval Warm Period and The Little Ice Age

Why can’t recent climate change just be an effect of 'natural causes'?

There have been climate changes in the past 2000 years.

People talk about times called the Medieval Warm Period and the Little Ice Age.

Careful research has shown that the current temperature rise is much bigger than the Medieval Warm Period. 


Climate scientists have discovered that the Medieval Warm Period had a number of causes.

The Sun was more active, and volcanic activity was low, which both increase warming. 

Other evidence suggests ocean currents changed, bringing warmer seawater into the North Atlantic.

When these factors changed, the Earth resumed cooling, creating the Little Ice Age.

The Industrial Revolution, when coal burning began on a large scale, started the recent rise in temperatures, reversing the cooling trend.

Monday, 27 April 2015

The Changing Earth - Early steps in Climate Change science


1800-1870 

Level of carbon dioxide gas (CO2) in the atmosphere, as later measured in ancient ice, was about 290 ppm (parts per million).



Global temperature for 1850-1870 was about 13.6°C.

1824
Jean-Baptiste Joseph Fourier calculated that the Earth would be far colder if it lacked an atmosphere. 



1859
John Tyndall discovered that some gases block infrared radiation. 



He suggested that changes in the concentration of the gases could bring climate change.





1930s 
Milutin Milankovitch proposed orbital changes as the cause of ice ages. 

1938 
Guy Callendar showed that global warming was underway, reviving interest in the question. 


1950s 
By accident, Russell Coope discovered that some past climate change events happened in just a few decades.


This came from his research into beetle fossils in 'Ice Age' layers.

1958 
Telescope studies showed a greenhouse effect raises temperature of the atmosphere of Venus far above the boiling point of water. 



1960 

Charles David Keeling accurately measured CO2 in the Earth's atmosphere.

He was not expecting to detect an annual rise.

The CO2 level was 315 parts per million (ppm)and global temperature (five-year average) was 13.9°C.

Keeling's measurements have been continued.

Current chart and data for atmospheric CO2

At the end of 2014 the level was around 400 ppm.

Global temperature in 2014 was 14.57°C.

The Changing Earth - The Experts

"Reaching the 400 ppm mark should be a reminder for us that carbon dioxide levels have been shooting up at an alarming rate in the recent past due to human activity. 
"Levels that high have only been reached during the Pliocene era, when temperatures and sea level were higher. 
"However, Earth's climate had never had to deal with such a drastic change as the current increase, which is, therefore, likely to have unexpected implications for our environment."
– Dr. Carmen Boening



Scientists know that recent climate change is caused by human activities.
 

The speed of the current climate change is faster than most past warming events, making it more difficult for human societies and the natural world to adapt. 

The key ideas are explained in a publication called -

Climate Change: Evidence and Causes

It was put together by the Royal Society and the National Academy of Sciences, their equivalent in the USA.
The Royal Society is a self-governing Fellowship of many of the world’s most distinguished scientists. 

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" 

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.....

Climate Change: Evidence from the Geological Record

Another expert who is good at explaining climate change is 



Dr Marshall Shepherd.

Sunday, 26 April 2015

The Changing Earth - Weather on Steroids

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

It might be hard to prove in many cases.

Some recent events, however, are extraordinary.

The phrase 'weather on steroids' has been used to describe these events.


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.

Researchers are looking at possible links to climate change in some cases of extreme weather.

One scientist investigating this problem is Professor Jennifer Francis.




Prof Francis is interested in how the odd behaviour of the jet streams may link to the warming of the polar areas.

For example, in 2010 ......



























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

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

It might be hard to prove in many cases.

Some recent events, however, are extraordinary.

The phrase 'weather on steroids' has been used to describe these events.


In 2010, 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 (3.6 metres) of rainfall in one week

The province normally averages slightly above 3 feet (around 1 metre) 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.



Thanks to the Russian drought of 2010, global food prices in early 2011 were the highest since the food crisis of 1972 - 1974. 

This event has been linked to the "Arab Spring" of 2011.

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

The Changing Earth - 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.