There are now just five months to go before world leaders gather in Glasgow for the big climate change conference. Meanwhile, the scientific evidence about our changing climate accumulates.

The 2015 Paris climate agreement committed countries to keep the global temperature increase to just 1.5C above late 19th century levels so as to prevent the worst effects of global warming. But the latest report from the World Meteorological Organisation says that there is a 40% chance that global temperatures will reach this 1.5C limit in the next five years.

This increase may not seem a lot, but its effects will be significant. Climate change is already affecting the UK with rising sea levels, higher average temperatures and more frequent very wet days. And globally, we are seeing heat waves, drought, more cyclones in the Atlantic, extreme rainfall and coastal flooding.

The cause is rising carbon dioxide (CO2) emissions and the solution is to get these down to zero. And that means we have to get on with changing the way in which we produce things, travel and heat our homes all of which are currently heavily dependent on fossil fuels – ie oil and natural gas.

Let’s take our homes as an example. Many households in South Leeds depend on gas central heating, but that’s going to have to change because eventually we won’t be able to use natural gas anymore.

This won’t be the first time in our history that we’ve made a significant change to how we heat our homes; the era where heating depended entirely on coal is almost completely gone.

So, the question now is what’s going to replace those gas boilers? There are two basic choices; one is electric heating – eg heat pumps – and the other is replacing gas with hydrogen.

The advantage of heat pumps – which work by extracting heat from the air outside our homes – is that for every unit of electricity used, a heat pump can produce three or four units of heat which makes it much more efficient than direct electric heating. And provided the electricity for the pump comes from renewable sources no CO2 is produced.

The same is true of hydrogen when it burns but it has to be made by electrolysis using water and renewable electricity (known as green hydrogen). There are other ways of producing hydrogen using natural gas but the issue is whether all the CO2 emissions can be captured in the process.

Heat pumps have a unit outside of the home but they don’t generally produce as much heat as current gas central heating, so we would probably need larger radiators and better internal insulation.

In the case of hydrogen, all that’s needed is to replace the boiler and everything else could remain the same. There are, however, practical issues to do with the safety and operation of hydrogen which are currently being worked on, and it will only succeed as a long-term replacement for natural gas if we can produce enough green hydrogen quickly enough. And that, in turn, will require a huge increase in renewable electricity.

How much will all this cost? What will the price be of a heat pump as opposed to a hydrogen-ready boiler and what will the respective running costs be? All this remains to be seen, but in the last couple of decades the cost of renewable electricity, which was originally very high, has come down significantly.

Should government decide which of these technologies to use or should it just set the standard – namely that by a certain date all homes must have zero emission heating – and then leave consumers to make the choice between the different technologies? What is certainly the case is that those making heat pumps and those working on hydrogen are busy producing and testing products because they can see what’s coming.

The final question is how will we pay for this change? This is really important because we cannot have a transition to a zero carbon future in which some people end up facing costs that they simply cannot afford. Tackling climate change has to be done in a way that is fair for our homes, our jobs and the way in which we live our lives.

So, the message from Glasgow will be that change is coming, and we need to be ready for it.

First published in the June 2021 edition of South Leeds Life, available online here https://southleedslife.com/newspaper/recent-issues-of-our-newspaper/