Concrete is tipping us into a climate catastrophe

HS2: the new high-speed rail line in the UK to connect London to Birmingham and ultimately Scotland

From The Guardian:

Tucked away in volume three of the technical data for Britain’s £53bn high speed rail project is a table that shows 20m tonnes of concrete will have to be poured to build the requisite 105 miles of track, culverts, bridges and tunnels. It is enough, it has been calculated, to pave over the entire city of Manchester.

A more modest 3 million tonnes of concrete will be needed to construct the Hinckley B nuclear power station in Somerset, and the proposed new runway at Heathrow will require one million tonnes.

Cement, the key component of concrete and one of the most widely used manmade materials, is now the cornerstone of global construction. It has shaped the modern environment, but its production has a massive footprint that neither the industry nor governments have been willing to address.

Because of the heat needed to decompose rock and the natural chemical processes involved in making cement, every tonne made releases one tonne of C02, the main greenhouse warming gas.

Including the new Crossrail line through London, the building of Britain’s four largest current construction projects will, if completed, together emit more than 10m tonnes of CO2 – roughly the same amount as a city the size of Birmingham, or what 19 million Malawians emit in a year.

Nearly 6% of all UK greenhouse gas emissions, and up to 8% of the world’s, are now sourced from cement production. If it were a country, the cement industry would be the third largest in the world, its emissions behind only China and the US.

So great is its carbon footprint that unless it is transformed and made to adopt cleaner practices, the industry could, on its own, jeopardise the whole 2015 Paris agreement which aims to hold worldwide temperatures to a 2C increase. To bring it into line, the UN says its annual emissions need to fall about 16% in the next 10 years, and by far more in the future.

While some of the biggest cement companies have reduced the carbon intensity of their products by investing in more fuel-efficient kilns, most improvements gained have been overshadowed by the massive increase in global cement and concrete production. Population increases, the urban explosion in Asia and Africa, the need to build dams, roads and houses, as well as increases in personal wealth have stoked demand.

Annual cement production has quadrupled from nearly one billion to over 4 billion tonnes a year in 30 years. In the next decade it is expected to increase a further 500m tonnes a year. Unless there is a dramatic change, cement emissions are expected to continue to rise beyond 2050.

Industry leaders are now embarrassed, aware that they are in danger of being financially penalised and tarred as climate laggards who refuse to change in the face of the climate emergency. They well know that not only is it quite possible to build most structures safely without cement, but their own research has shown that green, cement-like products using recycled byproducts which are just as strong can be made from other industries, such as steel slag, fly ash from coal-fired facilities or some types of clay. Instead they trust that nascent technologies like carbon capture and storage which could allow emissions to be buried will come on stream, and that more efficient plant will reduce cement emissions by as much as 20-25%.

This is wishful-thinking. The great bulk of the industry is inherently conservative, ignorant of the alternatives to cement and reluctant to adopt change. Conventional, or Portland, cement is trusted to be safe and strong and developers continue to specify it because it is cheap and the alternatives are not well-known. Without major demonstration projects showing what is possible, and the education of architects and planners, progress will be incremental and possibly too late.

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More and more, I'm coming round to thinking that we have to have a carbon tax.  To reduce political opposition, it will need to be repaid to residents of a country as a "carbon dividend", perhaps by way of a monthly cheque or bank credit.  To reduce economic impact, it would have to start out low, but rise each year.  As a possibility, an initial level of $20/tonne, rising  by $5/tonne every year after that.  And it would have to be levied on imports from countries which do not have a similar carbon tax, to encourage them to also levy a tax, and to stop emissions from being "outsourced".  A carbon tax would also accelerate the transition to green electricity in the grid and to replacing ICEVs with EVs.