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The Carbon Cycle - the earth's thermostat
The Carbon Cycle - the earth's thermostat
Carbon is the backbone of life on Earth. We are made of carbon, we eat carbon, and our civilisations—our economies, our homes, our means of transport—are built on carbon. We need carbon, but that need is also entwined with one of the most serious problems facing us today: global climate change.
Carbon flows between each reservoir in an exchange called the carbon cycle, which has slow and fast components.
The Fast Carbon Cycle takes place over a timespan measured in 10s of years, and is largely the movement of carbon through life forms on Earth, or the biosphere
By comparison, the Slow Carbon Cycle operates through a series of chemical reactions and tectonic activity. Carbon takes between 100-200 million years to move between rocks, soil, ocean, and atmosphere.
Any change in the cycle that shifts carbon out of one reservoir puts more carbon in the other reservoirs. Changes that put carbon gases into the atmosphere result in warmer temperatures on Earth
Over the long term, the carbon cycle seems to maintain a balance that prevents all of Earth’s carbon from entering the atmosphere (as is the case on Venus) or from being stored entirely in rocks. This balance helps keep Earth’s temperature relatively stable, like a thermostat.
Schematic of the Fast Carbon Cycle taken from The Carbon Cycle - NASA Earth Observatory 2011
This schematic show the fast carbon cycle with movement of carbon between the lan, atmosphere and the ocean. Yellow numbers are natural fluxes, and red number are human contributions in gigatons of carbon* per year. White numbers correspond to stored carbon.
*Note one ton of carbon equals 44/12 = 11/3 = 3.67 tons of carbon dioxide
*Note one ton of carbon equals 44/12 = 11/3 = 3.67 tons of carbon dioxide
The Carbon Cycle.pdfA full description of the Carbon Cycle may be found by clicking on the thumbnail link opposite which is a PDF version of the NASA Earth Observatory text.
Climate Change Science
Climate Change Science
Whilst the increase in atmospheric carbon dioxide and other greenhouse gases since the industrial revolution has upset the fine balance controlling the earth's temperature, the impact on on the climate and the underlying science are complex. It is an interactive system consisting of the atmosphere, land surface, snow and ice, oceans and other bodies of water, and living things. The atmospheric component of the climate system most obviously characterises climate; climate is often defined as ‘average weather’.
In the IPCC Fourth Assessment report in 2007, Chapter 1 provides an Historical Overview of Climate Change Science. An awareness and a partial understanding of most of the interactive processes in the Earth system that govern climate and climate change predate the IPCC, often by many decades. The chapter describes how research has led to a deeper understanding of those processes, and in particular, the progress in climate science since the IPCC First Assessment Report in 1990. Clicking on the thumbnail link opposite will open the chapter in PDF format in a new tab.
Climate science.pdfEl Niño and La Niña
El Niño and La Niña
El Niño and La Niña are terms which describe the biggest fluctuation in the Earth's climate system and can have consequences across the globe.
What is El Niño? The name 'El Niño' is widely used to describe the warming of sea surface temperature that occurs every few years, typically concentrated in the central-east equatorial Pacific. An El Niño is declared when sea temperatures in the tropical eastern Pacific rise 0.5 °C above the long-term average. El Niño is felt strongly in the tropical eastern Pacific with warmer than average weather.
The effects of El Niño often peak during December; it's name "the boy" is thought to have originated as "El Niño de Navidad" centuries ago when Peruvian fishermen named the weather phenomenon after the newborn Christ.
What is La Niña? 'La Niña' or "the girl" is the term adopted for the opposite side of the fluctuation, which sees episodes of cooler than average sea surface temperature in the equatorial Pacific. The conditions for declaring 'La Niña' differ between different agencies, but during an event sea temperatures can often fall 3-5 °C below average. Cooler, drier than average weather is experienced in the tropical eastern Pacific. There are also neutral phases of the cycle when conditions are closer to the long-term average (within +/- 0.5 °C). These may be within a period of warming or cooling in the cycle. Approximately half of all years are described as neutral.
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