Research Feature

Most developed countries struggle to meet their 2009 Copenhagen climate mitigation targets

Nineteen out of 34 developed countries surveyed failed to fully meet their 2020 climate commitments set 15 years ago in Copenhagen, according to a new study by Prof. Dabo Guan’s research group from the Department of Earth System Science, Tsinghua University.

The study, published in Nature Climate Change, compared the actual net carbon emissions of more than 30 nations to their 2009 pledged emission reduction targets set during the Copenhagen Climate Summit.

The research, jointly led by researchers at Tsinghua University and University College London, is the first effort to comprehensively gauge how well countries were able to meet their Nationally Determined Contribution reduction pledges from COP15.

Of the 34 developed countries analysed in the study, 15 successfully met their goals while 12 failed outright. The remaining seven countries fell into a category the study authors termed the “halfway group”: nations that reduced the carbon emissions within their own borders but did so in part by using trade to shift emissions they would have made to other countries. Known as “carbon leakage” or “carbon transfer”, this outsourcing of carbon emissions is a growing concern amongst environmental policy makers as countries seek to meet newer net-zero targets.

CO2 emission trends and emissions-mitigation target range of COP15

To track this carbon leakage the researchers used a “consumption-based” emissions tracking method which provides a more comprehensive scheme to calculate a country’s total carbon emissions. It not only accounts for the emissions originating from economic activities within the nation’s territorial borders, but the carbon footprint of imported goods manufactured abroad.

The first author Shuping Li said: “It is vital to differentiate between actual territorial emission reductions and potential outsourcing activities by accounting for consumption-based emissions. We hope this study can highlight the importance of the need of timely tracking of countries’ progress in meeting emission reduction targets across phases and gives crucial insights for future emission reduction strategies.”

These emissions goals were set in 2009 at the COP15 international climate summit in Copenhagen. There, despite being unable to reach a comprehensive global agreement, individual countries around the world established their own individual emissions reductions targets. This meant that established goals varied widely, from Croatia’s modest but successful pledge to reduce carbon emissions by 5%, to Switzerland’s relatively ambitious but unsuccessful effort to reduce its carbon emissions by 20-30% by 2020, relative to 1990 levels.

The research also highlights the disparities between the countries’ different starting points. Though four eastern European nations – Estonia, Lithuania, Latvia and Romania – were successfully able to achieve their goals, the researchers point out that this was largely because much of the region’s industry involved many outdated and highly inefficient technologies left over from the early 1990s that they’ve more recently transitioned away from using.

In addition, the research cautions that the countries that struggled the most to meet their COP15 goals are likely to encounter even bigger challenges in the future as they face even greater demand for energy as their economies further expand and develop.

Professor Guan notes that reducing emissions is critical to combat the ongoing climate crisis. To do this, it’s imperative we have an accurate and reliable account of emissions, and this research shows some of the challenges countries face to reduce emissions while maintaining their economic growth. Developed countries have a dual role – rapidly reducing their own emissions, and providing financial aid and capacity building to developing countries, which most of them deliver insufficiently.

The main ways that countries were able to meet their emissions targets were by increasing the amount of clean energy they produced, especially transitioning away from coal power, and making more efficient use of the energy produced. Countries unable to meet their targets were largely unable to do so because increased consumption associated with rising GDP per capita and population grown outpaced their efforts to increase efficiency, even though many of the countries were able to increase their efficiency somewhat.


Li, S., Meng, J., Hubacek, K. et al. Revisiting Copenhagen climate mitigation targets. Nature Climate Change. (2024).

Editor: Guo Lili 

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