Global Warming: CO2 Emission Trends



ACADEMIC PAPERS
OTHER
WHY IPCC EMISSION FORECASTS ARE LIKELY TOO HIGH

Joel Wood and wrote a paper on per capita CO2 emission patterns around the world: 
In it we test an idea that emerged from my paper with Mark Strazicich and Junsoo Lee, in which growth of emissions in one country or region appears to induce offsetting reductions elsewhere, leading to a constrained overall level of emissions per capita globally. Joel's and my conjecture is that the emergence of increasingly-integrated global energy markets worldwide increased the transmission of price signals across countries, so that growing fuel consumption in one region forces up prices in other regions and induces offsetting emission reductions elsewhere. This leads to the co-fluctuation patterns referred to in the title. We tested this by using PC analysis to construct an index of the linkages of emission fluctuations across countries and we showed evidence that they have become more linked over time and across wider geographic regions. We also found evidence that price signals are likely the coordinating forces. This means that emissions scenarios (like the ones the IPCC uses) that allow emissions to grow rapidly in one region without inducing offsetting reductions elsewhere are missing a key mechanism that applies in the real world, which would constrain the growth of overall emissions. The IPCC uses emission scenarios that are reasonable through this decade, but which accelerate starting around 2020, with the top end going to between 30 and 40 Gigatonnes of emissions globally. Since world population is expected to peak at around 10 billion people, this requires emissions per capita to reach between 3 and 4 tonnes, more than double current levels, a target that appears economically impossible. Instead, emissions per capita will likely remain in the neighbourhood of 1.3 tonnes per person (give or take a few tenths), implying peak global emissions of around 15 to 20 Gigatonnes, half the IPCC peak range. So we deem the lower half of the forecast range more likely than the upper half. 

Early in the preparation of my 2012 paper with Mark Strazicich and Junsoo Lee I wrote some non-technical papers drawing attention to the implausibility of the high IPCC emission forecasts. 
STATISTICAL EVALUATION OF IPCC EMISSION FORECASTS:  I have a paper in the Journal of Forecasting, coauthored with Mark Strazicich and Junsoo Lee, which looks at the probabilities of different IPCC emission forecasts. We examined the SRES forecasts which were used for the 3rd and 4th Assessment Reports. The IPCC has traditionally referred to these scenarios as mere "projections" and treated each as equally probable. We looked at them probabilistically and found the top half of the distribution less likely than the bottom half, and in particular the top quarter are very difficult to justify. Our paper is here. 
  
Mark Strazicich and I had an exchange with Bjart Holtsmark about our work in 2006 in Environment and Energy, at which time we did not know how delayed eventual publication of our scenarios paper would be. Since we did not want to break the embargo on our paper by presenting the contents in E&E, we only published a brief reply inviting readers to contact us for the more detailed version. Here is the updated version: