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