Carbon Emissions

Carbon Emissions Photo credit: Clipart.com

Carbon emission rates may be higher than scientists thought.


A grim carbon emissions forecast. I'm Bob Hirshon and this is Science Update.

Carbon gases are prime culprits in global warming. Now, a new study suggests we're making even more of them than we thought. Co-author Chris Field is director of the Carnegie Institution's Department of Global Ecology.

He says that in the early 2000s, worldwide carbon emissions grew at triple the rate of the 1990s, and total emissions matched or exceeded the worst scientific predictions. A major factor is the spread of coal-powered, carbon-intensive power plants in developing countries like China and India.


Rapidly growing economies are associated with rapid increases in carbon emissions. What we need to figure out in the long run is some way to separate those two things.

Field says it may take innovation and investment from wealthier countries to make low-emissions power plants affordable worldwide. I'm Bob Hirshon, for AAAS, the science society.

Making Sense of the Research

Over the past two decades, the public has become much more aware of global warming: partly because the scientific evidence has gotten stronger and stronger, and partly because we're seeing more of its early effects. According to NASA's Goddard Institute for Space Studies, the top five hottest years, since records began being kept in 1890, have all happened since 1998. Four of them are 2002, 2003, 2004, and 2006.

Some efforts have been taken to reduce carbon gas emissions, a leading cause of global warming. But clearly, more needs to be done. As this study discovered, carbon emissions are not only still growing, they're growing faster than ever, and the outcome is even worse than scientists expected.

That's mainly because the scientific models underestimated the amount of carbon gas the world would be producing by now. Field's team looked at several different climate models, which were created at least several years ago. These models generally provided a range of predictions for global warming, based on a range of possible carbon emissions levels. It turns out that what we're really cranking out is equal to or even greater than the top of those estimates.

So why did the scientists guess wrong? Well, for one thing, Field says that for the past several decades, the world had slowly been improving its "carbon efficiency." In other words, every year, the world's nations were producing a little less carbon from factories, cars, and other sources to make the same amount of economic product (or, "stuff"). But in recent years, that improvement in efficiency has either slowed, stalled, or even reversed, depending on what part of the world you're in.

Why? Field says that if you look at the new power plants that have been built worldwide in recent years, most of them aren't state-of-the-art, low-emissions "green" power plants. They're coal-burning plants, which are inexpensive to build but produce lots of carbon. And most of them are being built in rapidly developing nations like China and India, which have weaker environmental regulations than most Western countries.

But before you blame China and India for cutting corners, ask yourself: Why are China and India's economies growing so quickly? In large part, it's because wealthier Americans and Europeans have come to depend on them for cheap products and cheap labor, whether it's a $5 shirt you buy at Wal-Mart or an entire telephone support staff for a software company. One of many ways these developing countries do things more cheaply is by using cheap energy. And in this case, cheap energy means more carbon.

So in many ways, the responsibility for reducing carbon emissions comes back to us. America alone still produces about 25 percent of the world's carbon emissions, even though we make up only 5 percent of the world's population. As Field points out, we're better able to afford newer, cleaner technologies, and to provide leadership in introducing those technologies abroad. And sooner or later, we're going to have to decide whether we're willing to pay a little more for sneakers in order to keep global climate change in check.

Now try and answer these questions:

  1. How do actual carbon emissions differ from predictions?
  2. Why were global carbon emissions underestimated in most scientific models?
  3. Based on this report, what are some economic and political challenges that you can see in reducing global carbon emissions?
  4. Do you think responsibility for controlling carbon emissions should mostly fall to the government (by enacting tough environmental laws), to consumers (by changing their buying habits), or to individuals and companies (by changing their energy usage)? Give reasons for your answer.

You may want to check out the June 22, 2007, Science Update Podcast to hear further information about this Science Update and the other programs for that week. This podcast's topics include: making sounds morph, a lost herd of elephants, twins' secret languages, runaway carbon emissions, and the marriage-obesity connection.

For Educators

In the NY Times Learning Network lesson plan, Adding Fuel to the Fire, students consider global warming and the greenhouse effect, and then explore how these issues are affecting countries with both growing and high energy usage.

In the National Geographic Xpeditions lesson, Climate and CO2, students speculate on various scenarios of future world climates if the greenhouse effect increases.

Related Resources

Vibrating Insoles
6-12 | Audio
Marine Reserves
6-12 | Audio
Art Algorithms
6-12 | Audio

Did you find this resource helpful?

Science Update Details

Grades Themes Project 2061 Benchmarks