The Kyoto Protocol, which created the first binding targets to limit greenhouse gas emissions, went into effect in February 2005. Some experts say it was a "game changer," but others question its long-term effectiveness.
"It was tingling all the way to the end," said climate scientist and lawyer Hermann Ott, describing the marathon negotiations that stretched into the early hours of the morning and charted the course for humanity's fight against climate change. "Up to the last moment we were trembling about whether it would fail in the last few meters."
The result of the talks, which came into force eight years later, was the Kyoto Protocol: the first binding treaty under international law to reduce greenhouse gas emissions and a milestone in international climate policy. It set the tone for everything that followed, said Saleemul Huq, director of the International Center for Climate Change and Development.
First conceived in 1992 at the United Nations Framework Convention on Climate Change in Rio de Janeiro — which underlined the historical responsibility of rich countries for emitting greenhouse gases — the Kyoto Protocol made concrete how big emitters should take the lead in slowing climate change. One hundred and forty-one countries had ratified it by 2005.
The treaty committed 38 industrialized nations to reducing emissions of climate-damaging gases by an average of 5.2% by 2012 below 1990 levels. The signatories included the US and EU, known at the time as the European Community. "That's the first time we had anything in international law that was so binding," said Huq, who was involved in the negotiations for developing countries. "That was a breakthrough."
Huge success and yet too little
When the US — responsible for a large part of historic CO2 emissions — withdrew from the agreement in 201, and Canada in 2011, many observers thought the Kyoto Protocol had failed. But by 2012, the emissions of the industrialized countries had dropped 20% from 1990 levels — five times the Kyoto targets of the remaining nations. The EU cut emissions by 19%, and Germany by 23%. Over the same period, however, global emissions rose by around 38%.
The agreement is not enough to limit the rise in global warming in the long term, said Andrew Light, a senior fellow at the World Resources Institute, because it only applied to countries responsible for a quarter of global emissions. "That's just not enough to deal with the problem. You have to get an agreement with greater participation."
More than just cutting emissions, the agreement introduced the Clean Development Mechanism to trade carbon. This meant countries that did not meet reduction targets could "buy" the right to extra emissions from the budgets of less-polluting countries. They could also offset them through climate protection measures in developing countries.
One percent of the revenue from emissions trading has gone into a fund for adapting to climate change, which is spent on measures such as reforesting mangroves, building dams and limiting erosion in mountainous regions in developing countries. About $10 billion (€9.2 billion) has flown into projects via the fund and emissions trading, according to the World Bank.
Global trade in emissions proved less successful than negotiators had hoped for but, said Huq, CO2 had been given a price for the first time. Governments around the world are now thinking about implementing taxes on CO2, and several already have. Sweden charges the highest price for fossil fuel emissions, at €114 a ton.
For renewable energy, the treaty was a "game changer," said Karsten Neuhoff, head of climate policy at the German Institute for Economic Research. "In 2007, everyone was still saying that generating 20% of energy in Europe from renewables in 2020 would be utopian. Today it is reality."
"Kyoto is not solely responsible for investments in the energy transition, but it was an important stimulus," said Neuhoff.
Kyoto's weaknesses and the road to the Paris climate agreement
Experts say the major weakness of the Kyoto Protocol was that developing countries did not commit themselves to climate targets. The economies of countries such as China, India and Indonesia grew rapidly in the following years — and so did their greenhouse gas emissions.
Today, more than half of the world's emissions come from developing and emerging economies. "We don't do enough to tackle the problem at the global level," said Huq. "And so we all have to collectively do more."
A steep fall in solar and wind energy prices has made the switch to renewable energy in middle-income countries easier
In principle, industrialized countries still have obligations under the Kyoto Protocol, but a later treaty, the Paris Climate Agreement of 2015, has now superseded it. Under the Paris Agreement, all countries of the world agreed to reduce global warming to well below 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels. The signatories committed themselves to national climate and CO2 reduction targets that they themselves came up with.
But so far, hardly any country has met its targets.
Global greenhouse gas emissions have risen by 41% since 1990 and continue to rise. If CO2 emissions continue at current levels, the earth will warm up by about 3 degrees Celsius by the end of the century.
"The consensus principle has failed," said Ott. "Fossil fuel states such as Saudi Arabia, the US, Russia and Australia are blocking any real action. Therefore a new treaty is needed — a fast lane for those states that really have an interest in climate protection."