However, the lower economic growth decreasing the demand for energy after the global financial crisis of 2008–2009 partly explained the reduction in energy use.
Notably, the countries where CO2 emissions dropped the most were those with the greatest number of energy and climate policies established.
The scientists compared countries where emissions decreased with countries where emissions increased. They discovered that policies supporting energy efficiency were associated with declines in emissions across all countries.
Moreover, they found that policies that supported renewable energy were also associated with reductions in emissions, but mostly in developed economies with declining emissions alone, and not in any other economies.
The data imply that efforts to decrease emissions are ongoing in several countries, but these efforts have to be expanded and improved to reduce climate change to well below 2 °C of warming, in accordance with the Paris Agreement.
The authors argue that “untangling” the reasons behind recent changes in emissions is important to direct efforts to deal with climate change.
Our findings suggest that policies to tackle climate change are helping to decrease emissions in many countries. This is good news, but this is just the start. There is a long way to go to cut global emissions down to near zero, which is what is needed to stop climate change. Deploying renewable energy worldwide is a good step but by itself, it is not enough, fossil fuels also have to be phased out.
Prof Corinne Le Quéré, Lead Researcher, Tyndall Centre for Climate Change Research, UEA
New scientific research on climate change tends to ring the alarm bells ever more loudly. Our findings add a thin sliver of hope. It is possible for countries to peak and then decline their emissions year in year out. Eighteen countries so far have shown us how concerted policy ambition and action on energy efficiency, renewables, and climate targets can work. Now we must make sure these early precedents become the rule not the exception. This is a huge global challenge.
Dr Charlie Wilson, UEA
Global CO2 emissions should decrease by almost a quarter by 2030 to reduce climate change well below 2 °C, and to decrease by half to maintain below 1.5 °C. On average, global CO2 emissions increased by 2.2% every year from 2005 to 2015.
Global carbon dioxide emissions rose in 2017 and 2018, suggesting that the rapid rollout of renewable energy has so far not been sufficient to arrest the growth in fossil fuel use. Energy and climate policy has been successful at supporting renewables and energy efficiency, but to realize meaningful emission reductions supporting policies are needed to penalize the emission of carbon dioxide.
Dr Glen Peters, Study Co-Author, CICERO Center for International Climate Research, Oslo