Thursday, 22 February 2018

Climate Change - Mammoths (and methane) from the permafrost

The permafrost of places like Siberia is not so permanently frozen any more.

As it slowly melts, wonderful things are emerging, some frozen for tens of thousands of years.

Baby mammoths are sometimes found in an extraordinary state of preservation.



"As the Earth warms, scientists worry that some of the carbon in permafrost could escape to the atmosphere as carbon dioxide or methane. 

Increasing the amount of these gases in the atmosphere could make Earth's climate warm up even more."

Arctic permafrost – ground that has been frozen for many thousands of years – is now thawing because of global climate change. 



There are many effects of global warming, including melting permafrost, discussed in this useful document: 



The results of melting permafrost could be disastrous and irreversible.

Wednesday, 21 February 2018

Climate Change - Measuring the Greenhouse Effect

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



The graphs show carbon dioxide’s increasing greenhouse effect at two locations. 

The first graph shows COradiative forcing measurements obtained in Oklahoma

The second graph shows similar upward trends in Alaska. (Credit: Berkeley Lab)
The researchers link this to rising CO2 levels from fossil fuel emissions.

Radiative forcing measures how 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.

Tuesday, 20 February 2018

Climate Change - The Carbon Bubble

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. 

This huge excess quantity of fossil fuel is sometimes called the 'Carbon Bubble'.

Many say the number is simply too high.

Archbishop Desmond Tutu has pointed out that a two-degree global average rise might result in Africa’s temperature rising as much as 3.5 degrees—a potentially disastrous change.

Various scientific research projects have looked at what would happen if all the fossil fuels were burned.

One project concluded:
The Antarctic Ice Sheet stores water equivalent to 58 metres in global sea-level rise.  
... burning the currently attainable fossil fuel resources is sufficient to eliminate the ice sheet. 
...........with an average contribution to sea-level rise exceeding 3 metres per century during the first millennium.
 

Monday, 19 February 2018

Climate Change - Climate prediction is not weather forecasting

The chaotic nature of weather makes it unpredictable beyond a few days. 
To predict the weather you need to know exactly what is happening in the atmosphere down to the smallest scale. 
Climate is the average weather pattern of a region over many years (usually a period of 30 years).

Weather forecasts depend on knowing exactly what is going on in the atmosphere, down to the smallest scales. 

Climate forecasts look for patterns over a longer time. 
Will it be generally wetter in winter? 
Will there be more heavy downpours?
A paper published in the journal Science in August 1981 made several projections regarding future climate change.

The projections were rather accurate — and their future is now our present.
"Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climate zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.”
Their predictions have turned out to be correct.

"Drought-prone regions" are receiving less rainfall.

The West Antarctic ice sheet is melting.

Some ships are using the Northwest Passage as a polar short-cut. 

Projecting changes in climate due to changes in atmospheric composition or other factors is easier than predicting the weather.


It is impossible to predict the age at which any particular man will die, but we can say with high confidence what the average age of death for men is.

Similarly, a climate prediction might say that average summer rainfall over London is predicted to be 50% less by the 2080s.

It will not predict that it will be raining in London on the morning of 23rd August 2089.

Another way to predict the outcomes of climate change is to examine the geological record of ancient events.

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.


Global average temperatures were 2-3°C warmer than today.


Sea level rose by up to 20 metres in places.

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.

Sunday, 18 February 2018

Climate Change - 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.



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.





People who are struggling to cope with their food supply will move to cities, or aim to move to other countries, where they may not be welcome.

Farming developed in the stable climate of the Holocene.

Humans were around from over 200,000 years ago, and it is likely reliable farming was not possible until the climate settled down, according to researchers:
"....the possibility of cultivation is not excluded for the late Pleistocene, however we argue that it did not become a reliable means of subsistence until the Holocene. 
 This period coincides with a decrease in the amplitude of climatic oscillations ........"

Saturday, 17 February 2018

Climate Change - Comparing the Polar Regions

Earth's polar regions are warming faster than the rest of the planet.

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


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.

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


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.



Ice shelves around Antarctica are also affected by global warming.

For a useful comparison of Antarctic and Arctic sea ice follow this link……

Arctic vs Antarctic




You can explore the Earth's melting ice using NASA's Global Ice Viewer.

Friday, 16 February 2018

Climate Change - "Weather on Steroids" 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.