I have the great honor to be selected to serve on the IPCC as  lead author of the fifth assessment report. It has always been my desire  to contribute to addressing environmental problems. Climate Science is  fascinating – the ways scientists have found to tease out evidence about  past climate are amazing. It is scary to see how the various pieces of  the puzzle – not all of them yet found or correctly placed – provide an  increasingly complete and compelling picture that – in rich and  unforeseen detail –confirms the basic physics laid out by the Swedish  scientist Svante Arrhenius 110 years ago.

My task is to contribute to the volume on Climate Change Mitigation – how to reduce emissions of greenhouse gases as to limit climate change to a not-too-disruptive level (IPCC WG3).  Specifically, I am selected to serve as lead author to the chapter on  energy systems. The selection comes somewhat as I surprise – my group  has become a leader in another aspect, connecting the emissions of  greenhouse gases to the ultimate causes of their emissions – the goods  and services enjoyed by final consumers. This topic would have fit to  other chapters. My qualification for the chapter on energy systems comes  from work on the life-cycle assessment of various energy conversion  technologies, such asbioenergy, wind power and fossil fuels with CO2 capture and storage.  For the nomination, I suggested that life-cycle environmental impacts  need to be addressed for the full scale at which the technologies will  be implemented.  ‘Impacts’ should include resource requirements,  pollution, and a quantification of net-greenhouse gas benefits. I plan  to draw heavily on the expertise of my collaborators and my colleagues  at NTNU.

Without prejudging the outcome of our work, my impression is that  assessments so far have ignored some of the environmental costs of  climate-friendly technologies. They have thus been overly optimistic  regarding the prospects of technologies – the degree of mitigation that  can be offered and the associated costs. I am not yet satisfied about  the scientific information available on the environmental impacts and  resource requirements of those technologies compared to resource  availabilities. It is premature to judge the effect of these  limitations. This information is important because resource and  environmental factors must be considered in our decisions about what  energy technologies to develop and deploy.

Knowledge gaps regarding the constraints and costs of climate  mitigation technologies illustrate that details of climate mitigation  have not yet received the required level of attention, compared to the  science of the greenhouse effect or the economic assessment of whether  to mitigate or not. The research investment has been smaller, as it can  easily be seen from just the references in the three different volumes  of the IPCC’s 4th assessment report. Technology development is finally  receiving more focus, but is still not at an adequate level especially  when it comes to large-scale demonstration and deployment. Mitigation  science, however, is developing rapidly and I am optimistic about the  prospect of offering important, interesting insights to the world once  the 5th assessment report will be published in 2013.