Voyager: Are there any benefits of increased levels of CO2?

As we currently understand the effects of rising CO₂ levels, the answer is probably “yes,” but the negative effects of increased levels of carbon dioxide in the atmosphere overwhelm the benefits.

Plants generally grow a little faster with increased carbon dioxide. Increased levels of the gas will also reduce drought stress in some plants since readily available CO₂ makes it easier for plant tissue to retain water.

Also, if you like it warm at high latitudes, such as in northern Canada and Europe, there are regions that will be more habitable as the earth heats up, although it will still be dark all winter.

In addition, melting sea ice from warmer temperatures will soon open up the Northwest Passage, a sea route typically blocked by ice in the Arctic Ocean, which connects the Atlantic and Pacific oceans. Soon vessels will be able to sail right through, making it attractive as a major shipping route.

The answer to your question is a mixed bag, but the overall outlook is overwhelmingly negative. That’s because the disruption of climate would be costly in many ways. Increased levels of carbon dioxide could disrupt the function of ecosystems and make the oceans more acidic. There is already evidence that warming associated with increases in carbon dioxide is jeopardizing the drinking water supply of millions of people. Other potential adverse changes such as rising sea level could threaten the many people who live near coastlines.

-- Ralph Keeling, geochemist, Geosciences Research Division