Reuters reports: China and the United States agreed on Wednesday to new limits on carbon emissions starting in 2025, but the pledge by the world’s two biggest polluters appears to be more politically significant than substantive.

As China’s President Xi Jinping agreed to a date for peak CO2 emissions for the first time and also promised to raise the share of zero-carbon energy to 20 percent of the country’s total, President Barack Obama said the United States would cut its own emissions by more than a quarter by 2025.

At its best, the announcement threw the political weight of the world’s two biggest economies behind a new global climate pact to be negotiated in Paris next year.

But the United States has already pledged to cut its carbon emissions by 17 percent by 2020 and it’s not clear if the new proposals will pass a Republican-dominated Congress. [Continue reading…]