Global Warming Scenarios

Global Warming Metrics

I wondered if it was possible to get a crude idea of the future and what is likely to happen based on a few scenarios, using only the climatic trends of the past and adding in the effect of renewable (or non CO2 emitting energy sources) and carbon capture on atmospheric CO2 concentrations. So I did a bit of maths and produced a few graphs, the output is very similar to other global warming projections, and the main take home message is we need to start capturing the CO2 that is already in the atmosphere to stand the slightest change of mitigating global warming. Personally I think our global "leaders" have let us down badly left it too late and we are destined to live in a very different paradigm.

The graphs and calculations were done in 2017 and we are still on track for the worst scenario "Very High Emissions" at the close of 2021 and I think with the current crop of intellectual inadequates at the helm of world governments this is unlikely to change.

The graphs may seem a little confusing but they are simple, here are the main points:-

  • The black line is effectively energy demand, where all the demand is supplied by the fuel mix of 2018 (mostly fossil, some nuclear fission etc).
  • The white area under black line represents new long term CO2 added to the atmosphere, the current trajectory adds 195,000,000,000 tonnes to the atmosphere which adds 25ppm to the concentration.
  • The Blue represents the CO2 removed by the planet naturally (estimated 18 Gt per annum), planetary saturation is not considered here, but Earth has its limits, evidenced by the acidification of the oceans.
  • The Lilac represent renewables and non CO2 emitting sources of energy, that substitute fossil fuel use. They must subsitute (not add), currently renewables seem to just add evidenced by the the fact that fossil fuel use continues to increase.
  • The Green represents theoretical use of carbon capture, to remove atmospheric CO2. Personally I can see no other way as things stand.
Scenario 1 - Very High Emissions - Just a few years ago this seemed like an unlikely Scenario, but it is the way things are headed. In this scenario, the world sits on its hand and does little more to prevent global warming. Very low renewables growth and little carbon capture.
20302040
CO2 added to the atmosphere  Gt ( ppm)  Gt ( ppm)
Projected total ppm CO2 in the atmosphere  ppm  ppm
Global warming added in the period oC oC
Projected total global warming  oC  oC
Scenario 2 - High Emissions - A likely Scenario, by 2040 20% of the worlds fossil consumption is substituted by renewables, another 20% uses carbon capture technology. In this scenario, the world moves slowly towards renewables and carbon capture more aggressively but it is still not enough; this includes, power generation, industry, homes and transport (by using more electric vehicles and a grid with more renewables in the mix).
20302040
CO2 added to the atmosphere  Gt ( ppm)  Gt ( ppm)
Projected total ppm CO2 in the atmosphere  ppm  ppm
Global warming added in the period oC oC
Projected total global warming  oC  oC
Scenario 3 - Medium Emissions - It would be nice to be a least heading here but we are not. In this scenario, the world moves towards renewables and carbon capture twice as fast as scenario 2, but is still not enough. In this scenario more electric transport substitutes direct combustion in engines so more power generation is required.
20302040
CO2 added to the atmosphere  Gt ( ppm)  Gt ( ppm)
Projected total ppm CO2 in the atmosphere  ppm  ppm
Global warming added in the period oC oC
Projected total global warming  oC  oC
Scenario 4 - Low Emissions - Another Unlikely scenario, it is an extension of scenario 3, with an yet more aggressive approach to cut carbon emissions, with the current political will in the world it as likely as me winning the Tour de France. To achieve this direct removal of the carbon from the atmosphere is require by some means, as fossil fuels will still be burned where they cannot be easily replaced, for example aviation.
20302040
CO2 added to the atmosphere  Gt ( ppm)  Gt ( ppm)
Projected total ppm CO2 in the atmosphere  ppm  ppm
Global warming added in the period oC oC
Projected total global warming  oC  oC
Scenario 5 -Negative Emissions - In this very unlikely scenario the world really takes the situation seriously, the move to renewables is enormous and carbon capture solutions again target carbon removal direct from the atmosphere again allowing some fossil fuel use where there are no alternatives. I will bet my pension we will not get to this point by 2040.
20302040
CO2 added to the atmosphere  Gt ( ppm)  Gt ( ppm)
Projected total ppm CO2 in the atmosphere  ppm  ppm
Global warming added in the period oC oC
Projected total global warming  oC  oC