SCIENCE IN UNEP

About Science-based Climate Policy Reports

Since 2010, the UNEP Office of the Chief Scientist has convened the scientific community to produce a series of science-based “synthesis” reports for policymakers that address critical issues on the international climate change agenda. These reports have been coordinated by the Office of the Chief Scientist in cooperation with UNEP divisions, including DTIE, DEWA and DELC and various governments and other institutions.

The reports include:


About the UNEP Nitrous Oxide Report
Drawing down N2O to protect climate and the ozone layer

This report addresses the benefits of drawing down nitrous oxide (N2O) emissions. N2O is now the most significant ozone-depleting substance emission and the third most important greenhouse gas released into the atmosphere. But there are indications that not enough attention has been given to reducing these emissions. With this in mind, UNEP has worked with the scientific community to produce a report which informs policymakers and stakeholders about the impacts of nitrous oxide emissions and options for their abatement.

Part 1 of the report points out that under business-as-usual conditions emissions of N2O will almost double between 2005 and 2050. The continued build-up of N2O in the atmosphere will make it more difficult to achieve climate targets and will to a certain extent undermine the achievements of the Montreal Protocol in restoring the ozone layer.

Part 2 explains that two-thirds of current anthropogenic N2O emissions originate from agriculture and that these emissions can be reduced by boosting nitrogen use efficiency, especially by making the use of fertilizer, manure, and feed more efficient. Improving nitrogen use efficiency can be accomplished through a wide variety of feasible options. This would bring added benefits of higher agricultural productivity, lower required agricultural inputs, as well as reduced air and water pollution due to nitrogen losses to the environment.

Drawing down N2O was compiled by more than 45 scientists and experts from over 35 organizations under the coordination of the UNEP’s Office of the Chief Scientist working with UNEP’s Division of Early Warning and Assessment (DEWA).


About the Emissions gap report 2013

Two of the most critical questions in the climate negotiations are:

  • Will climate targets be met if countries implement their pledges to reduce emissions by 2020 or will there be an “emissions gap”?
  • If there is a gap, how can it be closed?

Since 2010, UNEP has been convening scientists and experts to address these questions through the annual “emissions gap” report. Four reports have been produced, and have become a reference point for climate negotiators about the level of ambition needed for emission reduction targets.

The 2013 report gives an updated estimate of the 2020 emissions gap. Current global emissions are around 50 gigatonnes per year of equivalent CO2 which is substantially higher than the emissions level in 2020 consistent with a likely pathway of staying within the two degrees climate target. For the first time the report articulates in detail the consequences of not closing the gap in 2020 including the higher risks and higher costs. On the other hand, it points out that the 8-12 gigatonne gap can be closed by a combination of actions within the Convention and by stronger national and international measures. National and local measures such as promoting sustainable agriculture practices, building bus rapid transit systems, and legislating appliance standards, can be scaled up and help close the gap. At the same time they further national and local development goals such as reducing rural poverty, or lowering air pollution, or saving on household energy costs. On the international scale, the report points out that the number of “International Cooperative Initiatives” is multiplying and that they have a great potential in fostering emission reductions and closing the gap.

The Office of the Chief Scientist, working closely with UNEP’s Division of Early Warning and Assessment (DEWA), the UNEP Riso Centre in Denmark and the European Climate Foundation convened scientists from 44 different scientific groups in 17 countries to compile the report.  


About the Emissions gap report 2012

Two of the most critical questions in the climate negotiations are:

Will climate targets be met if countries implement their pledges to reduce emissions by 2020 or will there be an “emissions gap”?

If there is a gap, how can it be closed?

Since 2010, UNEP has been convening scientists and experts to address these questions through the annual “emissions gap” report. The 2012 report gives an updated estimate of the 2020 emissions gap of 8 to 13 gigatonnes of equivalent CO2, larger than earlier estimates because of higher than expected economic growth. Current global emissions are around 50 gigatonnes per year of equivalent CO2 which is substantially higher than the emissions level in 2020 consistent with a likely pathway of staying within the two degrees climate target. The report also finds that policy actions such as building codes, appliance standards, and bus rapid transit systems are achieving substantial reductions in greenhouse gas emissions even though they are largely being implemented because of local and national priorities. If scaled up, these and other policies can make a major contribution to closing the emissions gap. 

To compile the report, the Office of the Chief Scientist convened scientists from 43 different scientific groups in 22 countries and worked closely with the European Climate Foundation and the UNEP Riso Centre. 


About the Bridging the emissions gap report (2011)

The Emissions gap report (2010) confirmed that there could be a large emissions gap in 2020 between temperature targets and emission reduction pledges. In the Bridging the Emissions Gap report, scientists provide the evidence that it is economically and technically feasible to close the 2020 gap by concerted actions on the international, national and sub-national level. Most of these actions have to do with reducing CO2 emissions by more rapidly implementing renewable energy and increasing energy efficiency. But sustainable management of agriculture, forestry and wastes also play an important role in bridging the emissions gap.

This report was coordinated by the Office of the Chief Scientist and Ecofys in cooperation with the European Climate Foundation, the Government of South Africa and UNEP’s Division of Early Warning and Assessment.


About the Emissions gap report (2010)

Since 2009 many countries have pledged to reduce their greenhouse gas emissions or constrain their growth up to 2020. The question remains, however, whether these pledges are sufficient to achieve the 2.0 degree and 1.5 degree temperature limits, or if there will be a gap between what is needed and what is expected as a result of the pledges. Many scientific groups have identified global emission pathways that are consistent with various temperature limits, while others have estimated global emissions in 2020 based on the Copenhagen Accord pledges. This report compiles and summarizes estimates from twenty-five research groups and concludes that it is likely that a large gap will occur between global emissions consistent with temperature targets and those expected based on country pledges. The size of the gap will depend on how the pledges are implemented. – It was found that 60% of the gap could be closed if pledges were strictly implemented.

To develop this report, the Office of the Chief Scientist convened more than 30 scientists/experts and worked closely with the European Climate Foundation and the National Institute of Ecology, Mexico.


About the report: Near-term climate protection and clean air benefits – Actions for reducing short-lived forcers (SLCFs) (2011)

Although it is necessary to reduce CO2 in order to close the emissions gap and protect climate over the long run, a complimentary strategy is gaining traction – namely, to reduce black carbon and methane over and above CO2 reductions. This report points out that reductions of black carbon and methane emissions will not replace needed reductions of CO2, but that they will help slow near-term global warming, lessen regional climate change, and reduce the risks caused by air pollution. Reducing the risks of air pollution to public health and crops is an especially important consideration since it shows that action on SLCFs would lower a major barrier to sustainable development. Science is now pointing the way to the most effective measures for reducing these substances at the national, regional and global scales. Among the most promising new ideas developed in this report is the prospect of achieving global climate goals through regional air pollution policies and agreements on all continents.

To prepare this report, the Office of the Chief Scientist convened more than 30 scientists/experts and cooperated closely with UNEP’s Division of Environmental Laws and Conventions and Stockholm Environment Institute.


About the report: HFCs: A critical link between protecting climate and the ozone layer(2011)

The message of this report is “Let’s not solve one problem (ozone depletion) and end up causing another (climate change)”. Hydrofluorocarbons (HFCs) are planned as substitutes for ozone-depleting hydrochlorofluorocarbons but themselves are potent greenhouse gases and will eventually make it more difficult to close the emission gap. In fact, projections for the next two decades show that HFCs have the potential to become one of the most important greenhouse gases. But this report also shows that it is possible to avoid this pathway, because substitutes for HFCs are available and feasible, and are actually being used in many parts of the economy.

To prepare the report, the Office of the Chief Scientist brought together top experts in HFC science and management and worked with UNEP’s Division of Technology, Industry, and Economics.