As World leaders meet for COP26 in Glasgow, the Earth has already reached 1.2 °C warming above pre-1880s industrial levels.

Making pledges to stem climate change is easy.  But without urgent mitigating intervention, humanity’s future on this planet is seriously compromised.  Solving this global issue has become an emergency.  And time is running out.

35 billion tonnes of CO₂ are emitted every year.

 

By now, the science is clear.

Long term, climate change is an even greater problem than a global pandemic.  It is more complex too with a broad range of effects that include:

• affecting lives and livelihoods
• displacing populations
• exposing and re-enforcing worldwide social inequalities.

Net zero is the internationally agreed upon goal for mitigating global warming in the second half of the century, and the IPCC concluded the need for net zero CO₂ by 2050 to remain consistent with 1.5 °C.

Canada’s Hot Spot

On 29 June 2021, as the temperature reached an all-time high of 49.6 °C, tragedy struck in Lytton, British Colombia, Canada.  Wildfires engulfed the small town, destroying 90% of it and killing two.

Since record-keeping began, Canada had never been this hot.  We are talking “Death Valley” hot!

This was the result of a heatwave in western North America that followed a pattern well-known to weather scientists – a Rossby wave.

As it broke down, the wave dumped all its energy leaving an area of high pressure over western United States and Canada.

As the air sunk through the atmosphere, it got squeezed and further heated.

An international research team concluded that the daily maximum temperatures in the heatwave region were so extreme that they would normally occur only once every 1,000 years.

Without human-induced climate change, that kind of heat would be 150 times rarer.

 

Extreme heat has real implications for human life, especially in conjunction with high levels of humidity.

Areas of the globe have already experienced conditions at or near the edge of humans’ survivability.

Study results indicate that limiting global warming to 1.5 °C would prevent most of the Tropics from reaching the wet-bulb temperature of the human physiological limit of 35 °C.

If the body cannot cool down, it is at risk of neurological failure, organ failure and death, particularly in the very young and the elderly.

It is therefore important to identify where dangerous heat and vulnerable population coincide.

The Heat Island Effect

City dwellers face a particular danger because of what is called the Urban Heat Island effect.

 

Heat is reflected and absorbed by buildings, roads and other urban structures, creating zones within cities that can be several degrees warmer than the surrounding countryside.

The phenomenon affects disadvantaged communities disproportionally.

Carbon Footprint of Cement and Steel

Architects are listening to environmental concerns.

Sustainability is now a key theme in building design.   Unfortunately, pledges are doomed to fail if they are not backed up with regulation.

If politicians cannot agree on a global carbon price, and make big business corporations pay for or trade carbon emissions, there will be little incentive for the construction sector to account for their actions.

The Devil is in the details.  Using 3D-mapping drones and smart sensors should provide a more accurate picture of carbon embedded within urban infrastructures.

Concrete is a great building material because it is cheap and tough.  It resists fire, rust and biological pests.  However, its main constituent is cement made by converting limestone (calcium carbonate CaCO₃) into lime (calcium oxide CaO).

A process that spews out roughly a tonne of carbon dioxide CO₂ for each tonne of cement produced.

Annual global cement production has been 4 x 10⁹ tonnes for the last decade.

Cement production accounts for 3% of global carbon emissions.

Concrete is usually reinforced  with steel.

This compounds the problem, as the manufacture of steel also releases CO₂.

Steel making accounts for 7-9% of all greenhouse gas emissions.

Devising cleaner ways of producing cement and steel, as well as developing alternative building materials, will be vital to achieving a net zero future.

Cloud Control

As vexing as they are mesmerizing, clouds play an important role in Earth’s planetary greenhouse.

Clouds are complex and ever changing.  Even a seemingly featureless low altitude stratus is a dynamic system with a dizzying array of temperatures, air pressures, humidity factors, wind directions and wind speeds.

Clouds have a dual nature in terms of climate science.

Not only do they reflect the Sun’s radiation and provide a cooling effect, clouds also trap infrared radiation emitted by the planet’s surface, which in turn has a warming effect.

Stratospheric clouds warm us, whereas low-lying clouds tend to cool us because their greenhouse effect is smaller.  Overall, clouds have a net cooling effect on the atmosphere.

For how long, is unclear.

As the average global temperature increases, the greenhouse effect from clouds will increasingly outweigh their reflective powers.

By how much, is unknown.

However, numerical simulations of cloud formation can be used to test assumptions built into climate models.

Modelling the Climate

Climate models must be tested against real-world data.

Satellites constellations have been tracking clouds for the past four decades.  For 20 years, LiDAR has captured high resolution 3D measurements about cloud dimensions and water content.

The CLOUD project has been using cloud chambers to analyse the role of cosmic rays in creating atmospheric aerosols.

Climate models predict that warming will be more pronounced at higher latitudes, though not by as much as in past climates.  With a rise of 2 °C over pre-industrial levels, countries at high latitudes are expected to get cloudier, wetter, and they are likely to suffer more extreme weather events and devastating floods, like in Europe or the U.S.

At the other extreme, most subtropical regions will become drier, with an increasing risk of drought and wildfires in the Mediterranean, Middle East and Australia.

As for the Tropics, the exact consequences of global warming are as yet uncertain.

Carbon Capture and Storage (CCS)

Capturing CO₂ from the air is difficult, because its concentration is so low, which is why many efforts focus on extracting it directly from exhaust gases at power plants.

Usually, the gas is compressed into a supercritical fluid state, then pumped into porous rocks covered with impermeable caprocks that form a natural seal.

CCS is an energy intensive process, that uses chemical solvents and heat, separating the CO₂ from flue gases, and uses energy to liquefy it, transport it and pump it into rocks.

Again, it is a process that must become more energy efficient if it is to become widespread and economically viable.

The Acorn project  will be the first commercial CCS facility in the United Kingdom when it opens mid 2020s.  It will be based at St Fergus gas terminal, near Peterhead, in Scotland.

The CO₂ will be pumped into a layer of sandstone, lying underneath shale.

Supporters of CCS insist there are fewer risks of leaking happening over time.  CO₂ gradually dissolves, sinks and gets trapped into rock pores, before precipitating as carbonate minerals.

More than 95% of injected CO₂ mineralized within two years.

When researchers modelled leakage rates under different scenarios, they concluded that well-regulated storage should keep any potential leakage below 0.0008% per year.

Over 98% of injected CO₂ could be stored for over 10,000 years.

In Iceland, a novel approach by Reykjavik Energy involves injecting CO₂ into basalt rocks.  These rocks can transform the gas into stone much faster than sedimentary rocks can manage it.  Although the process uses a lot of water, basalt can be found at the bottom of the World’s oceans.

The company has plans to apply the technology to cement, iron and steel production.

Today, climate change is no longer a slogan; it is an emergency.