Together, China and the US emit about 35% of today’s greenhouse gas emissions. Current global climate change action is insufficient to limit warming below 2°C. By improving action of China and the US to global best practice, these two largest emitters could decrease domestic emissions to a level compatible with 2°C and together close 23% of the 2020 emissions gap. For 2030, this would mean a decrease in emissions below current global policy projections by 10%.Comparing activity levels and greenhouse gas emissions per unit of output and respective policies of China and the US we find:
The average US citizen currently consumes four times more electricity than an average Chinese citizen. Both countries achieved significant reduction in emissions per kWh for produced electricity; both reduced the use of coal, but China started from a higher intensity level. Future policy will continue that trend in China but not in the US. Holding warming below 2°C means rapidly decarbonising the electricity production. Both countries are expected to deploy more coal capacity in the future than is compatible with the 2°C objective. According to the IEA (2013), 80% decarbonisation is needed in the US by 2030, and 60-70% decarbonisation in China.
In a 2°C world, total primary energy coal use/CO2 emissions from coal need to drop rapidly, reaching mid-1990 levels by 2030. Present policies in the US and China, where the US is reducing coal by around 20%, and where China is stabilising coal use by the 2030s, are far from the deep reductions indicated for both countries in coal use by that time.
Industrial activity is still growing significantly in China, while it is stagnating or declining in the US. China has more efficient cement plants, while the US is leading in efficiency of iron & steel plants. China has a generally more rigid policy framework, but is still growing absolute emissions due to expansion.
Floor space per inhabitant is roughly twice in the USA compared to China. Energy use per square metre of floor area in the residential sector is three times higher in the US than in China. The difference is decreasing as floor space and specific energy consumption is significantly increasing in China. Both employ building codes and appliance standards.
Car ownership is ten times higher in the USA compared to China, but the difference is declining. In addition, China has still lower emissions per car. Both countries implement vehicle emissions standards; those of China are slightly stronger.
In each category, if China and the US were to move to the more ambitious policy area of the two, they could achieve additional reductions below current policy projections of 170/3200Mt in China and 220/1100Mt in the USA in 2020/2030. In relative terms these are reductions of 1.2% in 2020 and 20% in 2030 below current policy projections for China and 3.2% and 16% for the US.If China and the USA were to both apply the most ambitious policy level found anywhere in the world (global best practice) in each area, they would both overachieve their 2020 pledges and be on a pathway compatible with the agreed 2°C warming limit. Our explorative scenarios show that under global best practice:
- Emissions in the US would be in the order of 18% below 2005 in 2020 and 32% in 2030 (excl. LULUCF).
- Emissions in China could peak below 12 GtCO2e/a in the early 2020s and then drop.
- Together the countries would reduce emissions in 2020 by 2.8 GtCO2e/a below current policy projections and thus close 23% of the emissions gap. In 2030, the reductions would be of 6.7 GtCO2e/a, or 10% below the Climate Action Tracker global current policy projections.