The Intergovernmental Panel on Climate Change has produced Part 3 of a report, and with only about 2900 pages, that has one stark message: we need aggressive action to curb greenhouse gas emission AND we need aggressive action to absorb CO2 from the atmosphere, and the action must start now, not some indefinite time in the future. As I recall, this problem was highlighted thirty years ago, and in that thirty years, emissions have increased. There was not even a hint of a reduction. To give some idea of how seriously some take this matter, Germany closed down its nuclear power plants, and now it threatens not to use Russian gas, but instead burn lignite. We cannot do much worse than that can we?
Maybe we can, and maybe we are. According to an article by Lawrence et al. (Front. For. Glob. Change https://doi.org/10.3389/ffgc.2022.756115 (2022) tropical rain forests not only secrete carbon and take it out of circulation, saving around 0.5 of a degree C, but they also physically cool the planet by a further 0.5 degrees C. What the trees do is to emit much humidity from their leaves, with the result that they cool themselves (similar to sweating) and this humidity creates clouds, which reflect sunlight back to space. This is the sort of a geo-engineering proposal often made, but the trees do it for free. So, what are we doing? Why, cutting down the rain forests. Apparently a third has been removed, and another third has been heavily logged so it is not as functional as it should be. We are supposed to be trying to hold the temperatures to an increase of no more than 1.5 degrees C, we are nearly there already, so do we really need another degree of heating added in for no good reason?
According to the IPCC, carbon emissions will have to decline rapidly after 2025, halve by 2030, and hit “net zero” by the early 2050s. Given current efforts, a warming of 3 degrees is forecast. Emissions from existing and planned projects already exceed the allowable carbon budget. But even going to zero emissions will not suffice in the short term. Nations also need to extract carbon dioxide from the atmosphere.
So, what can we do? First, consider the problem. For our electricity, which has a little under 750 GW global capacity, wind power provides a little over 6%; solar provides a little over 2%, hydropower about 16%, nuclear about 10%. For fuels, earth consumes about 3.8 trillion cubic meters of natural gas, 35.4 billion barrels of oil, and 8.5 billion t of coal a year. Why we have a problem should be clear. Currently, about 2/3 of our electricity comes from burning fossil fuel. Worse, you don’t build a coal-fired power station today and turn it off tomorrow. Wind turbines need solid support. Making a tonne of cement produces roughly 800 kg of CO2, making a tonne of steel releases 1.85 t of CO2; combined they sum to about 16% of the world’s CO2 production. Wind power might be “green” but look at the CO2 emitted making and installing the equipment. Solar is free, but the demand for electricity is when solar is weak or non-existent, so massive storage is required, and that gets expensive, both in terms of money and in CO2 emissions for making the batteries. The point is, all new infrastructure is going to involve a lot of CO2 emissions before any energy is generated.
Transport is a particularly difficult problem. I think it is a common problem, but where I live the cities expanded significantly after WW 2, and they expanded with the automobile in mind. The net result is it is most people get around by car. Most people have access to a car, and that is petrol driven. The electric vehicle that might replace the petrol-driven car costs (here, at least) over twice that of the petrol driven car and you cannot really convert them. The reason is the electric vehicle needs a huge mass of batteries to have a useful driving range. Further, as I pointed out in a previous post, we cannot have everyone driving electric cars because we do not have the cobalt to make the batteries, and we still need ships and aircraft, which use a rather small fraction of the oil cut. We have to do something with the rest of the fuel cut. You may have noticed that large electricity production above and how so much comes from fossil fuels. Transport uses about 25% of the total energy production. That means to convert transport to electricity, we need to expand electricity generation by about another 250 GW. That is easy to write down, but just think of all the CO2 emitted by making the concrete and steel to build the power stations. Our current wind power would have to expand by a factor of 5.5 and we have to hope there are no still days. Of course, you may legitimately argue that if we charged batteries at night that would even the base load and you do not need all the additional installation. That is true, except green electricity generation usually is not optimal for base loads.
My view is it cannot be done the way the enthusiasts want it done. We shall never get everybody to cooperate sufficiently to achieve the necessary reductions because society simply cannot afford it. We need a different approach, and in some later posts, I shall try to offer some suggestions.