A United Nations Environment Programme (UNEP) report last month calculated that the existing pledges would result in emissions of 50-55 billion tonnes in 2020, compared with a level of 44 billion tonnes needed to meet the 2 degrees Celsius target.
The emissions gap by 2020 which, as a result of improved modeling from last year’s assessment, 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 then, by 2020, could be 11 GtCO2e. Under business-as-usual conditions, it could even be 12 GtCO2e.
The report cites aviation and shipping as a special but important case, as currently these ‘international emissions’ fall outside the Kyoto Protocol-the emission reduction treaty.
Together they account for around five per cent of C02 emissions and could account for up to 2.5 Gigatonnes (Gt) of carbon dioxide equivalent (GtCO2e) annually, by 2020.
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 per cent 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 per cent each year from 2005 to 2020.
Up to 28 per cent of total primary energy would need to come from non-fossil sources in 2020 (up from 18.5 per cent in 2005).
Up to 17 per cent of total primary energy in 2020 would come from biomass (up from about 10.5 per cent in 2005).
Up to 9 per cent 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 per cent 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.
Importantly for policymakers, 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.
Sector by sector
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.
This 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 promising options for the way forward to stay below the 2-degree C target.
Actions on Short Term Climate
A package of 16 measures could, if fully implemented across the globe, save close to 2.5 million lives a year; avoid crop losses amounting to 32 million tonnes annually and deliver near-term climate protection of about half a degree C by 2040.
The report estimates that implementing these measures would help keep a global temperature rise below the 2 degrees C target, at least until mid-century.
The measures, outlined in a new report compiled by the UN Environment Programme (UNEP) with an international team of experts, target short-lived climate forcers (SLCFs)—black carbon which is a major component of soot, methane and tropospheric ozone.