2. The science of global warming
Why does Carbon Dioxide (CO2) warm the planet?
The Earth cools naturally by emitting infrared radiation (IR). As the IR from the earth collides with molecules in the atmosphere like CO2 it causes vibration of the molecule which in turn results in secondary IR emission some of which heads back to Earth.
How long does most Carbon Dioxide stay in the atmosphere?
Between 65% and 80% of CO2 released into the air dissolves into the ocean over a period of 20–200 years. The rest is removed by slower processes that take up to several hundreds of thousands of years, including chemical weathering and rock formation
How much has the atmospheric CO2 concentration increased since pre industrial times?
Around 47%. At the pre industrial time the concentration was 280 parts per million. Currently the concentration is 412 ppm and is increasing by 3ppm annually. Carbon dioxide levels today are higher than at any point in at least the past 800,000 years. The annual rate of increase in atmospheric carbon dioxide over the past 60 years is about 100 times faster than previous natural increases, such as those that occurred at the end of the last ice age 11,000-17,000 years ago. The ocean has absorbed enough extra carbon dioxide to lower its pH by 0.1 units, a 30% increase in acidity (pH 8.2=6.3098 nmol/l H+, pH 8.055=8.88106nmol/l H+)
What is considered the safe concentration (parts per million) of carbon dioxide in the atmosphere?
350 parts per million.
What temperature rise (global warming) is the world currently on course for by 2100?
At least 3°C.
How many grams of carbon dioxide are typically emitted per kilo Watt hour (KWh) of energy use in the UK?
The CO2 produced by electricity generation in the UK usually varies from 200-300 g CO2 per kWh. Burning natural gas to produce a kWh energy of releases 185g CO2.
You buy and pay for your energy per kWh (kilo Watt hour) which is the amount of energy used if a 1000 Watt electrical device (a heater) was operating for 1 hour. It is the same as 3,600,000 Joules. One joule is equal to the energy transferred to a body with a mass of 1kg using 1 newton of force applied over the distance of 1 meter
Home Smart meters display the KWh energy consumption as well as CO2 emissions, and cost.
What are the main sources of global greenhouse gas emissions?
Fossil fuels, land use and agriculture. The green house gas emissions from these are currently going up, not down and the world remains on course for at least 3°C of global warming by 2100 (Haines and Ebie 2019).
What are the main gases in global greenhouse gas emissions?
Aside from water vapour, the four principal green house gases are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and the halocarbons or CFCs (the F-gases containing fluorine, chlorine and bromine). Although water vapour is a green house gas it does not stay in the atmosphere very long. The others gases can remain in the atmosphere for different and longer amounts of time, from months to millennia, and affect the climate on very different timescales.
How much have the different greenhouse gases increased since the year 1750?
Carbon dioxide rose by 50%; Methane by 29%; Nitrous oxide by 5% and others (including carbon monoxide, black carbon & halocarbons) by 16%.
What are Halocarbon F-gases used for?
In medicine, F-gases are used as propellants in metered dose asthma inhalers (MDI), for general anaesthetic gases and small quantities in ophthalmic surgery. At home they are used in refrigerants within refrigerator cooling systems.
What is CO2e?
CO2e, or carbon dioxide equivalent, is a standard unit for measuring carbon footprints. The idea is to express the impact of each different greenhouse gas in terms of the amount of CO2 that would create the same amount of warming.
Carbon dioxide equivalent (CO2e) is a measure of how much a gas contributes to global warming, relative to carbon dioxide. You calculate the carbon dioxide equivalent of a quantity the gas by multiplying the mass of the gas (in tonnes), by the gas’ global warming potential (GWP).
If we are to avoid dangerous global warming there is no ‘safe’ level of carbon emissions, and we must work together across the health sector, the UK and the world to achieve carbon neutrality as soon as possible.
With so many different Green House gases, how does one compare one with another?
GHGs differ in their capacity to absorb Infra Red (IR) and are compared with their individual Global Warming Potential (GWP). The GWP for CO2 is by definition 1. Nitrous oxide has a GWP of 295. This means that 1 tonne of nitrous oxide has the same warming effect as 295 tonnes of CO2.
What is the volume of a metric tonne (1000kg) of CO2?
At sea level and 20°C, 1000kg of CO2 would occupy 636 cubic metres of CO2 – the equivalent of just over 5.5 double-decker buses.
How far would you need to travel in a car to produce that volume?
A year’s worth of commuting the average distance (8.5 miles) in an average car (emitting 160g/km) generates 1 tonne CO2.
Using gas central heating in an average home, how many metric tonnes of CO2 are produced each year?
Almost three. Energy Catapult Analysis shows that in 2017, the average household generated 2745 kg of CO2 emissions from heating.
How do the emissions of different modes of transport compare?
When was the earth’s atmosphere discovered to act like the glass in a greenhouse, trapping the sun’s heat and stopping it from leaking back into space?
When were world temperature records begun?
World temperature records started in 1880. Proxy records of earlier surface temperature come from tree rings, pollen counts and ice cores.
When was a change in atmosphere carbon dioxide predicted to alter surface temperature?
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