2050: What the experts are saying about population growth, and some implications.

Note: This was also posted on my new Substack page (click here). Please bookmark that page as I may eventually stop posting here. 

My last post outlined climate change mitigation technologies that arguably aren’t ready today, and which may not be ready in time to make a difference – 25 years is not a long time in the annals of new technology development and deployment. And some of these remediation approaches are energy hogs when we should be looking at increased energy efficiency. Here are some other ideas, based on increased energy efficiency.

Over the period 2020 to 2050, the IEA predicts total energy supply per capita declines from 76 gigajoules per year (GJ/y) to 56 GJ/y, a decline of 26%; but in spite of population growth, total global energy use actually decreases by 7.5% from 587 exajoules (EJ) to 543 EJ. This is an excellent result if it could be achieved, as it represents a serious decoupling of economic growth (up by almost 150%) and population growth (up 25%) from resource extraction and use.

This brings us to population growth, the other major driver I identified in my first post in this series. 

The United Nations predicts an increase in world population from 7.8 billion to 9.7 billion by 2050, an increase of 25%. Furthermore, the percentage of the population living in cities will increase from 50% to 70%. The global urban population will thus increase from 3.9 billion to 6.8 billion, an increase of 75%. Most of this is likely to take place in the developing world; Africa alone will see a population increase of 1.1 billion, from 1.340 to 2.489 billion; if the 70% worldwide urban average holds across the continent, this implies urban Africa’s population will increase from 938 million to 1.742 billion in 2050. These people will need housing and transportation options.

The IEA has energy consumption in transport declining from 102 EJ/y to 80 EJ/y by 2050, a welcome 22% reduction. But passenger car travel increases from 14,260 billion person-kilometers (bpk) to 24,520 bpk. Distance travelled per capita thus increases from 1840 km/y to 2523 km/y. Total number of personal vehicles is predicted to increase from 1.2 billion (one car per 6.4 people) to just under 2 billion (one car per 4.8 people). This is consistent with the decline in transportation energy use, as the fleet will be largely electric with the attendant efficiencies compared to internal combustion engines.

But gridlock will arise regardless of energy source. Congestion charges, carbon and fuel taxes (which do not work on electric vehicles) and distance-based insurance and registration fees (the sticks) are among the policy levers for reducing gridlock, along with improvements in public transit (the carrot). Examples are congestion charges in London and New York; in Tokyo one must prove one has a parking spot as a prerequisite to licensing a vehicle. As the average personal vehicle is parked well over 90% of the time, the amount of space required for all these automobiles concentrated in cities is huge.

Note that carbon savings from ridesharing, cycling and walking are relatively small, and disappear once the competing options are all electric, but that gridlock remains a function of number of automobiles regardless of propulsion system.

So: more cars, driven longer distances. But this is inconsistent with gridlock.

Moving on to residential floor space, the IEA estimates that worldwide average residential floor space per capita will increase from 25 m² in 2020 to 35.6 m² by 2050. Given the predicted increase in urban population, total urban residential floor space is expected to increase from 102 to 242 billion m², an increase of 137%. In Africa, assuming the floor space figures apply equally here, the increase is from 23 to 62 billion m², an increase of 170%.

Population growth will be concentrated in developing and emerging nations, where increased floor space per capita will rise with economic growth; nonetheless it is reasonable to wonder where all this extra floor space is going to come from in urban settings. As urban sprawl is not compatible with public transit or land use change imperatives, perhaps societal changes could reduce the energy demand for both residential space and personal transportation in a synergistic fashion. This would be best accomplished through multistory residential complexes clustered around light rail or other rapid transit hubs, where space for parking is likely to be at a premium, if it is available at all. Other options for transport include systems where automobiles are used more intensively than in private ownership. This could include car sharing schemes, Uber or similar services, taxis, rental cars or other similar systems.

The result, hopefully, would be a reversal of the trend to more automobiles driven more kilometres, with the attendant savings in gridlock, energy use and land use change due to suburbanisation. 

These new homes, furthermore, need to be built with the latest in passive heating and cooling systems, local or distributed energy systems such as roof-mounted solar panels and battery storage, heat pumps, electric cooking, state of the art building envelope systems for insulation, etc.

The author’s residence, small for North America, closely matches the world average floor space per household today; but as the author’s household is made up of only one person, its space per capita is just over four times the world average. (The author consumed a comfortable 0.518 GJ/m² in 2020. Embarrassingly, this is 10% higher than today’s world average.)

The role of urban planning and permitting, which would play a role in moderating the growth of so-called McMansions in suburban or rural belts around Western cities, does not explicitly appear in the Roadmap.

So the IEA has proposed a range of technologies, such as carbon capture and a shift to electric vehicles, which tend to focus on supporting a business-as-usual lifestyle for citizens of OECD member countries. They also provide a lifeline for industries whose products are perhaps not essential if we can provide the necessary energy-related services – reasonable amounts of well-heated or cooled residential spaces, serviced by reasonable transportation options – in other ways.

Overall, the IEA report is a well researched document providing a reasonable roadmap to net zero by 2050. But it is not surprising that the IEA, as an arm of the OECD, has not put a lot of stock in societal changes that might prove a difficult political sell. This is critical: as the best vaccine is the one in your arm, the best climate change policy is the one that gets implemented, even if it is not technically the best or fastest one, because it is better than no policy. A recent publication (Mark Jaccard, The Citizen’s Guide to Climate Success: Overcoming myths that hinder progress. Cambridge University press, 2020, digital version available free by clicking here) describes this well, and is very highly recommended, whether the reader tackles the full IEA Roadmap or not.

Reference: International Energy Agency (2021), Net Zero by 2050, IEA, Paris: Net Zero by 2050 Scenario - Data product - IEA. License: Creative Commons Attribution CC BY-NC-SA 3.0 IGO.