In reality, high carbon levels are life-threatening to plants.
But if Santorum did sit down for a heart-to-heart with a plant or (more practically) the scientists who study them, they would tell him that carbon dioxide is not only dangerous to many plants, it’s life-threatening. Plants do need carbon dioxide to breathe, as Santorum implied, and increased concentrations can help them thrive—until the negative effects of climate change set in. Then they must deal with rising temperatures, thriving insects and fungi, and water shortages. For plants, these aren’t inconveniences, but hazards that could kill off huge swaths of the world's flora in a matter of years.
These scourges already are contributing to massive forest die-offs. In Alaska, almost 500,000 acres of yellow cedar trees—which generally live for more than 1,000 years—have died. In the western United States, so many huge swaths of aspens have shriveled up that scientists coined a name for the condition, Sudden Aspen Decline. (Yes, that’s SAD.) Researchers have predicted that up to 85 percent of the Amazon rainforest could disappear.
In the areas where yellow cedars live, for instance, the snow pack has been declining for years. Snow acts as an insulator for soil: Once it’s down on the ground, it traps heat underneath it, like a blanket spread over a bed. When snow melts, the ground can grow colder than it would otherwise, as it’s exposed for longer to lower winter temperatures. The roots of yellow cedars are sensitive to the cold, and without a blanket of snow to protect them, they freeze and die.
The aspens have succumbed to a plague of mountain pine beetles. The beetles have feasted on trees for decades, but their life span was short and the damage to the forest manageable. Warmer temperatures have extended their lifespans and made it possible for more than one generation of beetles to attack trees each year. Meanwhile, drought weakened the tree’s resilience.
A carbon-filled atmosphere will help insects like these multiply in numbers and destructiveness. One of the most chilling descriptions I’ve come across about what rising temperatures could mean is this passage from A Great Aridness, William deBuys’ book on climate change in the Southwest. Describing a bark beetle population taking over during a particularly warm year, deBuys writes, “You could walk among the piñons and hear a faint mechanical drone, as of a thousand tiny chisels rhythmically chipping away. It was hordes of beetles, tunneling and feeding.”
These are the dangers of carbon dioxide—for plants, and for the people who depend on them to survive. Forests provide timber. Plants provide food. Climate change will mean that the places we’ve come to depend on to grow corn, potatoes, and cassava won’t be able to support those crops anymore. The rainforest will melt into savannah. But try telling that to Rick Santorum—or Mitt Romney, or Newt Gingrich, or any politician who's downplayed climate change—how dangerous carbon dioxide can be.
Photo courtesy of the U.S. Forest Service
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