IPCC WGIII Fifth Assessment Report: Investments and Cross Cutting Issues

The Fifth Assessment Report of the IPCC was approved on Sunday April 13th.

The Summary for Policy Makers is available here.

Not major findings in my opinion. Maybe, the most important part is on the 2°C temperature limit.

In a nutshell: we can keep global mean temperature below 2°C if 1) ALL countries start 2) NOW using 3) ALL technologies available (including CCS and nuclear) and accept to loose 1.7% (1.0% – 3.7%) of consumption in 2030, 3.4% (2.1% – 6.2%) nel 2050 and 4.8% (2.9% – 11.4%) in 2100. If we start late, costs increase quickly and many models show that the 2°C is not feasible. If we do not use CCS, costs increase by 138%. Not really new findings, but good to see the IPCC endorsing results in the serious literature.

In practice (this is my opinion, not the IPCC opinion), the 2°C is not attainable with present technologies, if we do not (quickly) collectively embrace the life of Saint Francis of Assisi. A few years ago Carlo Carraro and I wrote a column for Vox-EU titled "The improbable 2°C target" on why we should prepare for 2.5 or 3°C.

The Chapter for which I was Lead Author is on Investments and Cross Cutting Issues (Ch 16). For the first time the report provides estimates of investments in key mitigation technologies (See the Figure below for change of investments in 2010-2029).

There are not many studies in the literature with investment estimates. Carlo Carraro, Alice Favero and I co-authored one of the few studies in the literature that estimates investments in mitigation technologies. You find a copy here. Hopefully the authors of the next report will have more observations to build more robust estimates.

Technical Innovation, Economic Development and Implications for Energy Use and Emissions

The UNESCO Energy Bulletin has published a longer and more articulated version of the World Bank Development Outreach article on emissions and economic development

Carlo Carraro and Emanuele Massetti. 2011. "Technical Innovation, Economic Development and Implications for Energy Use and Emissions." UNESCO Energy Bulletin, 2(11).

"In order to achieve the target of a 50% reduction of GHGs emissions by 2050 set forth during the G8 Summit in L’Aquila, Italy, in 2009, CO2 emissions per capita need to be lower than 1.14 tons in 2050, using 1990 as the benchmark year and assuming that an equivalent effort is undertaken to reduce emissions of all other GHGs. If we consider that in 2005 CO2 emissions per capita were about 4.5 tons and we expect a median future level in 2050 equal to 6 tons of CO2 per capita, we can easily conclude that we are definitely off-track. The historic pattern that links emissions to economic development needs to be reversed."


"Some solutions are already available and a well-crafted climate policy can stimulate their adoption. However, there are limited options available today to invert drastically the relationship between economic growth and emissions."

Contribution to the Special Report on Climate Change by the EBRD

 The European Bank for Reconstruction and Development has released the  'The low carbon transition' - a special report on climate change mitigation in the countries from central Europe to central Asia. The report looks back at the determinants of emission reductions in the region over the past 20 years and analyses the policies and institutions necessary to make the transition to a low carbon future.

Chapter 2: The economic impacts of climate change mitigation policy (1MB - PDF) uses scenarios that I generated with Massimo Tavoni using the WITCH model.

Chart 2.5 from the Report presents our major finding synthetically.