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New UNEP report says bridging emissions gap to meet 2-degree target doable, outlines pathways to 2020

The emissions gap. Click to enlarge.

Cutting emissions by 2020 to a level that could keep a global 21st century temperature rise below 2 °C is technologically and economically feasible, according to a new study released by the UN Environment Programme (UNEP). The Bridging the Emissions Gap report, the second of three being released by UNEP prior to the upcoming Durban meetings (earlier post), suggets that accelerated uptake of renewable energy, fuel switching and energy efficiency improvements can deliver a large slice of the necessary cuts.

Other measures include sectoral improvements ranging from increased penetration of public transport and more fuel efficient vehicles to ones in areas such as, agriculture and waste management.

Bridging the gap. Click to enlarge.

The report cites aviation and shipping as a special but important case, as currently these international emissions fall outside the Kyoto Protocol. Together they account for around 5% of CO2 emissions and could account for up to 2.5 Gigatonnes (Gt) of carbon dioxide equivalent (GtCO2e) annually, by 2020.

Options for reducing emissions from both sectors include improving fuel efficiency and using low-carbon fuels. For the shipping sector, another promising and simple option is to reduce ship speeds, according to the report.

Specifically, the study reviewed 13 scenarios from nine different scientific groups. The scenarios were all able to reduce greenhouse gas emissions to meet the 2-degree target by 2020 by using a combination of the following:

  • Improving energy efficiency: primary energy production would need to drop up to 11% from business-as-usual models in 2020, and the amount of energy used per unit of GDP would need to fall 1.1-2.3% each year from 2005 to 2020.

  • Up to 28% of total primary energy would need to come from non-fossil sources in 2020 (up from 18.5% in 2005).

  • Up to 17% of total primary energy in 2020 would come from biomass (up from about 10.5% in 2005).

  • Up to 9% of total primary energy in 2020 would come from non-biomass renewable energy (solar, wind, hydroelectricity and the like).

  • Non-CO2 emissions would fall by up to 19% relative to business as usual by 2020.

The report’s authors note that all the scenarios examined had different mixes of these options, indicating that there are many different pathways to bridging the gap. The report also looks at what these options would cost. Globally, the average marginal costs range from $US25-$US54 per tonne of equivalent carbon dioxide removed, with a median value of $US34 per tonne.

The study also examined research on various economic sectors to consider technical potential for emissions reductions by 2020. It found the following potential:

  • Electricity production: 2.2 to 3.9 GtCO2e per year through more efficient power plants, and by introducing renewable energy sources, carbon capture and storage and fuel shifting.

  • Industry: 1.5 to 4.6 GtCO2e per year through improved energy efficiency, fuel switching, power recovery, materials efficiency and other measures.

  • Transport (excluding aviation and shipping sectors): 1.4 to 2.0 GtCO2e per year through improved fuel efficiency, adoption of electric drive vehicles, shifting to public transit and use of low-carbon fuels.

  • Aviation and shipping: 0.3-0.5 GtCO2e per year through improved fuel efficiency and low-carbon fuels, and other measures.

  • Buildings: 1.4 to 2.9 GtCO2e per year by improving the efficiency of heating, cooling, lighting and appliances, and other measures.

  • Forestry: 1.3 to 4.2 GtCO2e per year by reducing deforestation and making changes in forest management that increases above and below ground carbon stocks.

  • Agriculture: 1.1 to 4.3 GtCO2e per year through changes in cropland and livestock management practices that reduce non-CO2 emissions and enhance soil carbon.

  • Waste: about 0.8 GtCO2e per year by improving wastewater treatment, waste gas recovery from landfills, and other measures.

The total emission reduction potential adds up to about 17 GtCO2e, plus/minus 3 GtCO2e, with marginal costs of up to $US50-100 per tonne of GtCO2e. This is consistent with the cost estimates from the scenarios mentioned above.

As a result of improved modeling from last year’s assessment, the emissions gap is now estimated, under the most optimistic scenarios, to be 6 GtCO2e rather than 5 Gt of GtCO2e. The report also outlines far more pessimistic scenarios. If the commitments and pledges of developed countries, including levels of financing amounting to $100 billion a year by 2020, and the intentions of developing ones are not fully realized, the gap by 2020, could be 11 GtCO2e. Under business-as-usual conditions, it could even be 12 GtCO2e.

The calculated emissions reduction potential is larger than the estimated emissions gap of 12 GtCO2e under business-as-usual conditions, and as such provides policymakers with clear insights into options for the way forward to stay below the 2 °C target, the report said.

The report concludes that policymakers could narrow or close the emissions gap in 2020 by:

  • Agreeing to implement their more ambitious emissions reduction pledges with stricter rules for complying with these pledges;

  • Deciding to target their energy systems, using more non-fossil fuel and renewable energy sources, and making significant improvements in energy efficiency;

  • Putting in place strong, long-term, sector-specific polices to achieve the full emissions potential of the different economic sectors.

The study brought together 55 scientists and experts from 28 scientific groups across 15 countries to examine the newest scientific research on the gap between the pledges that countries have made to cut their greenhouse gas emissions and what will be needed to be on track to reach the 2 degree target by 2020.

Bridging the Emissions Gap is the second in UNEP’s series of reports on the topic. UNEP released the first—the Emissions Gap Report—at last year’s international climate negotiations in Cancun, Mexico.

There, policymakers asked UNEP to prepare a follow-up report that, not only updated emissions gap estimates, but which also provided ideas on how to bridge the gap. That follow-up is the new report, Bridging the Emissions Gap.




When you see that you have to rely on scenarios that have zero chance to happen to stay below 2C warming you realize that we are in really big trouble...


A dedicated national program to research affordable and safe nuclear energy in Molten Salt Reactors could make a key difference.

The existing Light Water Reactor nuclear infrastructure has proven to have reached its limit in deployment.

If we do this right, we could deploy carbon free nuclear plants at costs lower than coal.

Nick Lyons

What TexasDesrt said.

Under business-as-usual, our existing PWR reactor fleet will age out faster than replacements can be built. Time for an Apollo-type program to develop inherently safe, cheap and plentiful nuclear power, and that means thorium and MSRs.

The good news is that China is going ahead full steam on such a program, so maybe the competition will wake us up.


hmm molten salt reactor look good on the paper, but the problem is that it is an entirely new type of reactor and it will probably take 20 years to develop and another 20 years to scale. My understanding is that there is serious corrosion issue with these type of reactor that need to be addressed. Personally I don't believe in a single solution to solve such a vast problem. On the short term gain in efficiency are the way to go, but you need to tax fossil fuel to stimulate them, and people are too stupid to understand that. In light of the last number who say that CO2 emission are accelerating I have little reason to be optimistic. But let see...

Bob Wallace

Nuclear. Too expensive. Too slow.

Wind is already cheap. Wind farms are commonly built in under two years, sometimes one.

Solar has reached grid parity in some places and the price will continue to fall. Large solar arrays are installed in only weeks.

After the normal 20 year payoff for a wind farm or solar array the price of electricity drops to super cheap for a few more decades. Paid off solar produces electricity at about $0.01/kWh. Wind only slightly higher.

We're seeing very promising new battery technology which promises to give us the storage we need to make renewables 100% of our power supply.

China has been continually cranking up their wind and solar targets. China seems to be putting more effort into renewables than into their nuclear program. It's a country run by engineers. They know how to do math.

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