Your kettle and the milk you put in your hot drink are actually both powerful weapons with which to slash greenhouse gas emissions, research has underlined this week. For example, the energy the kettle uses could produce up to 60% more greenhouse gas emissions than governments have been assuming, claims Imperial College’s Adam Hawkes. “This means any reduction we make in our electricity use could have a bigger impact on the amount of carbon dioxide emitted by power stations than previously thought,” Hawkes explained. “However, this also acts in reverse: a small increase in the amount of electricity we use could mean a larger increase in emissions than we previously thought, so we need to make sure we do everything we can to reduce our electricity use.”
Hawkes studied emissions in the UK from 2002 to 2009, where the government estimates that CO2 emissions are 0.43 kilograms per kilowatt hour. That figure comes from averaging the amount of emissions produced by each different type of power source, a method commonly adopted across the world. However this ignores the fact that in the UK sudden changes in electricity demand are mainly met by coal-fired power stations, which produce lots of CO2. “A change in demand does not act upon all elements of the electricity system proportionally,” Hawkes wrote in a paper published in the journal Energy Policy last Tuesday.
When power consumption does change, Hawkes therefore calculates that CO2 emissions reach 0.69 kilograms of carbon dioxide per kilowatt hour, and as a result the overall average is 0.51 kilograms per kilowatt hour. All these averages are set to fall as lower-emission power generation technology comes online in the future. Consequently, Hawke recommends that governments now forecast how these figures will change “to help inform policy development”.
Your milk consumption also has an impact on your greenhouse gas emissions, researchers at the Potsdam Institute for Climate Change have been emphasising this week. In the August issue of Global Environmental Change Alexander Popp and colleagues point out that agriculture accounts for 15% of humanity’s greenhouse gas emissions. Most of this is methane and nitrous oxide, also known as laughing gas, mainly released directly from the soil and from animal waste. “Meat and milk really matter,” Popp says. “Reduced consumption could decrease the future emissions of nitrous oxide and methane from agriculture to levels below those of 1995.”
Popp’s team has created a computer model that looks at how land is used across the whole planet, targeted at understanding agricultural emissions. That model folds in information ranging from population, income and food demand to crop yields and production costs. In 2005, agricultural nitrous oxide and methane emissions were equivalent to 5-6 billion tonnes of CO2. “In our baseline scenario, where food energy consumption and dietary preferences remain constant at the level of 1995, total non-CO2 greenhouse gas emissions climb up to the equivalent of 8.69 billion tonnes of CO2 in 2055,” the scientists write. This increase would only be due to the anticipated increase in world population, from around 6.5 billion today to 9 billion by 2055.
However the mix of food consumed will also vary over this time. Popp’s team notes that if dietary preferences shift towards higher value foods associated with higher incomes, like meat and milk, emissions will rise even more. In contrast reducing the demand for livestock products by 25 percent each decade from 2015 to 2055 would lead to lower non-CO2 emissions than in 1995. Popp underlines that food choices aren’t the only way to tackle these agricultural emissions – scientific solutions will also play a role. “Besides the conscious choice of food on the consumers’ side there are technical mitigation options on the producers’ side to reduce emissions significantly,” he says.