Tuesday, 19 September 2017

Climate Change - The Carbon Cycle

Carbon dioxide is always in the atmosphere as part of the Earth's carbon cycle.

The global carbon cycle transfers carbon through the Earth’s different parts - the atmosphere, oceans, soil, plants, and animals. 

So carbon moves around — it flows — from place to place.



Carbon dioxide (CO2) is the main greenhouse gas emitted through human activities. 

Human activities are changing the carbon cycle.

First, by adding more CO2 to the atmosphere, mainly by burning fossil fuels.

Also by changing the ability of natural sinks, like forests, to remove CO2 from the atmosphere. 

Human-related emissions are responsible for the increase that has occurred in the atmosphere since the industrial revolution. 




The carbon sinks, on land and in the oceans, have responded by increasing the amount of carbon they absorb each year.

Carbon sinks cope with about half of human greenhouse gas emissions. 

The other half has accumulated in the atmosphere.

Monday, 18 September 2017

Climate Change - Iceland

Iceland lies on the Mid-Atlantic Ridge, which is why it has volcanic activity.





Iceland also has ice caps and glaciers.

Iceland is one of the fastest-warming places on the planet – as much as four times the Northern Hemisphere average. 
The glaciers that cover more than 10 percent of the island are losing an average of 11 billion tons of ice a year. 
              Iceland glacial meltwater - photo Tom Harding
The water melting from Iceland's glaciers would fill 50 of the world's largest trucks every minute.
Parts of Iceland are rising as the ice caps melt, reducing the weight on the Earth's crust.

The thinning of the ice caps reduces the pressure on the rocks.
Geologists know lower pressure from above makes volcanoes erupt more easily.
Lower pressure allows volcanic gases to expand, and mantle rocks melt more easily at lower pressure as well.


So more magma can rise into the volcanic systems.
As that happens, Iceland's volcanoes may get more active.

Sunday, 17 September 2017

Climate Change - 2016 - Warmest year in modern record

2016 was the warmest year in NOAA's 137-year series. 

This is the third consecutive year a new global annual temperature record has been set. 


All 16 years of the 21st century are included in the seventeen warmest years in the modern record (1998 is currently the eighth warmest.) 

The five warmest years have all occurred since 2010.

It is increasingly likely the Earth is now warmer than at any time since the Eemian Interglacial, over 115,000 years ago.

The Eemian was warmer than the Holocene because of higher insolation.

Insolation refers to the amount of solar energy received per unit time at any one location, and it was higher due to astronomical cycles.

Saturday, 16 September 2017

Climate Change - The Pliocene Rebooted?

Atmospheric carbon dioxide concentration is now around 400 parts per million (ppm).

It last reached similar levels during the Pliocene, 5.3-2.6 million years ago.


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.

Of course, there were no modern humans at that time.



Hominids of the Pliocene

Nor was there a global system of food supply relying on stable climates for agriculture.

Friday, 15 September 2017

Climate Change - Permafrost and greenhouse gases

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

“The release of greenhouse gases resulting from thawing Arctic permafrost could have catastrophic global consequences,” said Dr. Max Holmes, a Senior Scientist at the Woods Hole Research Center (WHRC).


Greenhouse gases and permafrost.  

Thawing permafrost releases greenhouse gases (carbon dioxide and methane) into the atmosphere, which accelerate climate change, which in turn cause more thawing of the permafrost. 

This may be a fairly slow process, and there is a lot more research to be done in this area.

Thursday, 14 September 2017

Climate Change - Oceania

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. 


An international team of researchers has produced this graph of ocean levels, for a period of time going back to around 500 BC. 

Five of the Solomon Islands have been swallowed whole by rising sea levels between 1947 and 2014. 
"It’s a perfect storm,” says Simon Albert of the University of Queensland. “There’s the background level of global sea-level rise, and then the added pressure of a natural trade wind cycle that has been physically pushing water into the Western Pacific."
Albert and his colleagues analysed aerial and satellite images from 1947 to 2014 to study the effects of creeping sea levels on the coastlines of 33 reef islands in the Solomons.

Five islands present in 1947, ranging in size from 1 to 5 hectares, had completely disappeared by 2014.
Another six islands had shrunk by 20 to 62 per cent in the same period, confirming anecdotal reports of people living in the area.
Homes in Solomon Islands close to edge of sea
The most populated of these, Nuatambu Island, is home to 25 families, who have witnessed 11 houses wash into the sea since 2011.
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. 

The global sea level graph is from this paper: 
"Temperature-driven global sea-level variability"

Wednesday, 13 September 2017

Climate Change - Why isn't every year a record year?

Heat can affect things without causing a temperature rise.

Extra heat can be used in ‘changing state’ instead of raising temperature.
A change of state could be … a solid melting to a liquid
Or a liquid evaporating to a gas.

So heat is needed to change ice at zero degrees C to water at zero degrees C.
And to change water into water vapour….. without raising the temperature.
Scientists call the heat used to change state latent heat.
Also, there are natural variations in the global climate, El Nino events being the ones that affect world temperature the most.
The opposite to 'El Nino' is 'La Nina', a cooling effect.
If global temperatures are plotted on a graph in a way that shows these variations, it makes the overall warming trend very obvious.
Bar chart of temperature anomalies 1880-2015 indicating El NiƱe phase
Every La Nina year since 1998 has been warmer than every El Nino year before 1995.

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