In a speech Tuesday at the United Nations, President Barack Obama trumpeted America's response to climate change, saying that over the past eight years the country has "reduced our total carbon pollution by more than any other nation on Earth." That may be true, but the statement isn't as significant as it might seem. During that time span, the U.S. was the world's second-most prolific polluter. Even modest changes to policy and practices were likely to reduce emissions by large volumes. 

But Obama had to make a big deal about what the U.S. has done already because he couldn't make such a big deal about what the U.S. will do in the future.

His administration is now putting in place major new regulations on power plants—a critical move that will make a significant reduction in U.S. emissions and allow it to hit targets that Obama set years ago, during negotiations in Copenhagen. But simply hitting those targets isn't enough. To avoid the most catastrophic scenarios of climate change, the nations of the world must do more to reduce emissions that continue to rise every year. The heavy lifting will have to come from places like China and India, and even less developed nations. The U.S. has a critical role to play in this process, but it will require steps Obama couldn't promise on Tuesday—perhaps because, though he would happily support them, his political opposition would not.

Consider what the President did announce—an executive order directing federal agencies to plan for climate change impacts in all of their investments and decisions on international development. The idea is to help make sure these investments are durable and effective in a world where it's becoming impossible to consider funding parts of the world without considering impacts like extreme weather.

The executive order is less about the climate negotiations process than a broader signal to the world that the U.S. takes climate change seriously (even if congressional Republicans don't). “The president is setting the right course with his executive order," World Resources Institute's Climate and Energy Director Jennifer Morgan said in a statement. "We can't pursue development around the world without recognizing the risks that climate change poses every day. Making sure climate resilience is built into all of our development planning is essential to combating poverty in the 21st century.”

Still, Obama gave no specific commitment to the Green Climate Fund—a fund to help poor countries adapt to climate change—and that's seen as key vehicle to facilitate climate negotiations in the next 15 months leading up to a potential binding global treaty on emissions in Paris. The fund arose from the Copenhagen Accord in 2009 with the goal of channelling $100 billion annually to poor countries by 2020. So far, at about $3 billion, it is nowhere near that target.

France announced it would pledge $1 billion today to the Green Climate Fund, in addition to $1 billion from Germany and $100 million from South Korea. These commitments are "extremely important and bear more directly on the internal climate negotiations than any of these other climate announcements" this week, says Center for American Progress international energy and climate expert Peter Ogden. By contrast, Ogden, a former White House climate policy aide, says Obama's announcements "aren't as uniquely tailored to the climate negotiation process." Instead they show the world that the U.S. has sought public-private partnerships and stakeholders so it can "make the direct climate change negotiation announcements at the right time." The administration announced one of those public-private partnerships last week, in which companies will work with regulators to phase out a greenhouse gas—hydrofluorocarbons—found in air conditioners and refrigerators.

Obama had to consider several audiences with his speech. One is the domestic political crowd. That certainly includes environmentalists, but Republicans and other interest groups will be on the attack too, and are looking to use this against Democrats on the campaign trail. Americans for Prosperity did just that before Obama gave his speech, with President Tim Phillips saying in an email that Obama's "radical" energy agenda "will severely damage the US economy" and "America's poorest and most vulnerable will end up paying the price." Then there is the international audience, and Obama wants to send a strong message to leaders of big polluters like China, India, and Europe that the U.S. isn't backing away from a commitment to act. 

This tension is the reason why Obama might not want to make too big a splash today. Obama would only say that by next March, "we will put forward our next emission target, reflecting our confidence in the ability of our technological entrepreneurs and scientific innovators to lead the way." Until then, we just have Obama's word to go on that it'll be what the world needs.

This article has been updated.