The European Union and China recommitted Friday to the 2015 Paris climate deal, one day after the United States announced it would withdraw from it.
In a joint statement, the EU and China said climate change and clean energy "will become a main pillar" of their bilateral partnership.
European Council President Donald Tusk said the fight against climate change would continue, with or without the United States:
"Today, China and Europe have demonstrated solidarity with future generations and responsibilities for the whole planet," he said. "We are convinced that yesterday's decision is a big mistake."
Chinese Premier Li Keqiang, in Brussels for an EU-China business summit, said it was important for China and EU relationships to become more stable.
"We believe that there have been changes in the international situation, and there will be rising uncertainty and destabilizing factors," he said. "This requires our efforts to resolve existing issues."
Besides climate change, other issues discussed at the summit included trade, investment, the migration crisis, North Korea and the security partnership in Africa.
Li had expressed China's continued support for the global climate deal on Thursday during his meeting with German Chancellor Angela Merkel, saying, "China will stand by its responsibilities on climate change."
European Commission President Jean-Claude Juncker said China agreed with the EU on the "unhappiness" about America's unilateral decision to abandon the climate agreement.
The 2015 agreement, signed by 195 countries, calls for reducing the impact of climate change by keeping the global temperature rise this century well below 2 degrees Celsius above pre-industrial levels.
The EU and China committed to actions related to climate change, such as developing ways to change into zero-emissions economies, promoting zero-carbon transitions in developing countries and developing long-term decarbonization plans.
Wendel Trio, director of the Climate Action Network Europe, called the EU-China statement a milestone in the history of global climate diplomacy.
"This historic partnership to push forward with the Paris Agreement is a significant advance in the fight against climate change. Through deeper cooperation on climate action, the EU and China can propel the global clean energy transition," Trio said.
China and the EU are two of the three biggest economies in the world with a large carbon footprint. If one of them were to follow the U.S. withdrawal, it's unlikely that the Paris accord would lead to large-scale reduction of emissions.
Push from Greenpeace
Ansgar Kiene of the environmental activist group Greenpeace said it was clear from the global response to the American decision that leaders around the world were united in the fight against climate change. But Kiene urged leaders to translate their words into actions.
"The EU and China are switching to clean energy production too slowly to keep global temperature rises below levels that will cause catastrophic changes in our climate," Kiene said. "The EU's investment in renewable energy, once the highest in the world, has dropped off in recent years as its targets for renewables were too low compared to the real rate of growth."
China still produces 62 percent of its energy with coal, according to Greenpeace. But despite its bad record in the past, China's investments in recent years in solar and wind energy have been much larger than those of any other country. Investments in renewable energy in Europe, though, have dropped by half in the past six years.
In withdrawing the United States from the climate accord, which was signed by his predecessor, Barack Obama, U.S. President Donald Trump cited the predicted economic burden and job losses associated with complying with the accord as some of his reasons.
"The Paris climate accord is simply the latest example of Washington entering into an agreement that disadvantages the United States to the exclusive benefit of other countries," Trump said.
Trump said the U.S. could re-enter negotiations on the climate pact, but that idea was dismissed by the EU Commissioner for Climate Action Miguel Arias Cañete, who said Friday that "the 29 articles of the Paris Agreement are not to be renegotiated, they are to be implemented."
China and the European Union wrote in their joint statement that they thought investing in tackling climate change would actually contribute to job creation, investment opportunities and economic growth.
Many world leaders have condemned the U.S. withdrawal. French President Emmanuel Macron even invited scientists to relocate to France, saying in a speech televised in English, "Make our planet great again."
The United States joined Nicaragua and Syria as the only countries in the world that are not part of the Paris Agreement.