China is reportedly set to impose a modest carbon tax, as well as effectively increase taxes on its coal industry. As the world's largest emitter of greenhouse gases continues to take steps to curb climate change, the oft-repeated conservative argument that the U.S. can't act until China does becomes increasingly tenuous.

In 2011, the International Energy Agency warned that unless dramatic action is taken by 2017, it will be effectively impossible to meet the international commitment to limit warming to 2 degrees Celsius (3.6°F) -- a goal that many nations said still would not be enough to guarantee their survival. Experts say that the longer we delay, the more it will cost to reach the target. In light of this, arguing that we can't work to reduce the greenhouse gas emissions until other nations agree to do the same could be seen as immoral.

But in recent years, it's also become nearly counterfactual: China has been taking steps, including investing more in clean energy than the U.S. and creating a long-term, comprehensive plan for expanding its renewable energy industries. Now this developing nation is set to put a price on carbon -- a move that most economists from across the ideological spectrum agree is one of the best ways to reduce carbon dioxide emissions (along with cap-and-trade). Yet the U.S. -- a much wealthier nation -- is no closer to making such a move.

It is true that China will play a critical role in whether we are able to limit catastrophic climate change. In 2007, China overtook the U.S. as the largest contributor to global carbon emissions (although the U.S. still emits far more per person), and its emissions are expected to grow until at least 2030. If China goes through with plans to expand coal production, it will emit more carbon than any other planned energy project in the world. However, China has recently signaled that it will take steps to limit its coal consumption.

And with good reason -- a recent scientific report found that global warming would increase the cost of growing food in China and lead to flooding along the coast. And China's coal use isn't merely a hindrance for future economic growth, it has already had adverse effects on the health of its citizens, and in turn the health of its present-day economy.

It's important to note that China's carbon tax will reportedly be modest -- one past proposal set the price at about the equivalent of $8 per ton of carbon emitted by 2020. A recent MIT study found that if all regions imposed a tax of $10 per ton of carbon starting in 2020 that would rise 5 percent each year, the global rise in temperatures would likely be limited to 3.5°Celsius (6.3°F) by 2100 relative to 2000 -- or approximately 7.7°F relative to pre-industrial levels. A World Bank report found that a similar increase (a 7.2°F rise compared to pre-industrial levels) would still lead to “unprecedented heat waves, severe drought, [m]ajor floods in many regions” and “life-threatening sea level rise.” However, if implemented properly, China's carbon tax would still be a step in the right direction -- and a clarion call to the U.S.

Max Greenberg contributed research to this report.