After 4 years of intensive work, the fifth assessment report of climate change by the Intergovernmental Panel on Climate Change (IPCC) has finally been published. It says that it is urgent to begin reducing emissions, otherwise we will not be able to stay below the articulated limit of two degree temperature rise. Sure, but that was already the main message of the fourth asssessment report in 2007. Having contributed to this report as a lead author of the energy chapter, I have made my personal list of most important findings.

Key findings – IPCC WGIII AR5
1. The past decade has seen an unprecedented rate of increase in Greenhouse gas (GHG) concentrations in the atmosphere as a result of the global rise in emissions. The primary cause for the rise in emissions was the rapid coal-fueled industrialization and urbanization of emerging economies, combined with continued high emissions in industrialized countries. The carbon footprint of rich countries has kept rising, but mainly due to the increased import of emissions-intensive products from middle income countries (see figure; for country classification). The world is now on the upper end of the emissions scenarios considered in earlier IPCC assessments.

A "Glen Peters" chart showing the emissions embodied in trade and how carbon footprints (broken lines) have developed over time.

A “Glen Peters” chart showing the emissions embodied in trade and how carbon footprints (broken lines) have developed over time.

2. A strident development of low carbon technologies demonstrates now the viability of climate mitigation. Progress includes substantial reductions in cost and initial market penetrations of technologies such as wind power, solar heat and power, highly efficient building shells, and electric vehicles. These technologies present alternatives to established technologies based on fossil fuel combustion. Our capacity to build solar and wind power plants is now nearly large enough to achieve the share of renewables of mitigation scenarios.
3. A range of national, regional and local climate policies have been implemented. While these policies have been insufficient to halt the global rise in emissions, they provide important experiences with various policy approaches and instruments, such as emissions trading, carbon taxes, technology standards, and market penetration programs.  They also constitute an important reason for the technological progress achieved.
4. Limiting the global average temperature increase to the internationally agreed target of 2 degrees centigrade or even 3 degrees above the preindustrial levels requires the cessation of CO2 emissions from fossil fuel combustion and industrial processes already within this century. Considering the long investment horizons of infrastructure and industrial equipment, a continued increase of CO2 emissions for a decade or more will most likely results in an “overshoot” of both atmospheric concentrations and temperature above the 2 degree target. Reducing the global average temperature back to 2 degrees above preindustrial level would require a massive employment of so-called negative-emissions technologies, such as bioenergy with CO2 capture and storage or CO2 removal from the atmosphere, by 2070. These are unproven and expensive technologies, shouldering future generations with substantial costs.
5. Replacing fossil fuel utilization by energy efficiency and a range of renewable and nuclear energy technologies, if properly chosen, may lead to a substantial reduction of pollution and associated health and ecological impacts, as well as a reduction of fatalities related to severe accidents.  The extraction and utilization of fossil fuels, in particular of coal and unconventional oil, causes a range of serious environmental and occupational health and safety issues. Low-carbon energy technologies also cause such impacts, but rates of pollution and severe accidents are commonly lower. In addition, for many countries, reducing fossil fuel use will result in a reduced dependency on imported resources.  Climate mitigation may hence help societies to achieve other social objectives, such as clean air and autonomy.
6. The efficiency of industrial production processes and transportation technologies has increased in the past decades. Gains from a further improvement of individual technologies, while important, are by themselves not sufficient to deliver the necessary emissions reductions, and more systemic solutions need to be achieved, such as urban design approaches to limit emissions from transportation and construction, or longer lived products, urban mining, reuse and recycling approaches to reduce emissions from materials production. The field of Industrial Ecology has delivered significant insights into these more systemic approaches to climate mitigation.

Here is a video where I describe one issue I contributed to the report.

Here is my summary presentation of the report (in Norwegian).

Lyspunkter i klimapolitikken