Reducing Climate Change Could Be More Difficult in the Future

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A recent study has declared that limiting climate change in the future could be more difficult due to shifting conditions in the Amazon forest. The planet’s oceans and forests have long held climate change in check because they act as massive carbon sinks, soaking up excess carbon dioxide in the atmosphere that would otherwise contribute to global warming. About half of the carbon pollution from the result of human activities is absorbed by these so-called carbon sinks.

Scientists are now concerned, however, that their ability to do this is in jeopardy. A study done by researchers at the University of Leeds in Britain found that the capacity of the Amazon forest to absorb carbon has been weakening over time. This could ultimately make efforts to limit climate change that much more difficult. Even though the oceans and forest have kept up with the rising amount of emissions, this carbon sink might not last forever.

The study lasted 30 years and encompassed over 189,000 trees spread across 321 plots of land in the Amazon basin. Researchers found that the absorption of carbon in that particular location peaked in the 1990s at 2 billion tons a year. Since then, though, that amount has fallen by about half. While the forest responded well at first to rising carbon dioxide levels, it has since been tapering off.

Map showing locations of plots included in this study. Map: Brienen et al, 2015.
Map showing locations of plots included in this study. Map: Brienen et al, 2015.

There are various theories why this is occurring. Drought and other stressors could be a factor, and climate change seems to increase the incidence of harmful events like fires and beetle attacks. The main reason for this weakening, however, is held within the Amazon itself. Rising carbon levels lead to an increase in plant growth and this plant growth speeds up the metabolism of the trees. Over time, trees live faster but die younger.

More research is needed, of course, but scientists are being cautious. They are reminding us that assuming a robust carbon sink will always be there to protect us against climate change could be dangerous. The good news is that other studies suggest that the forests are still absorbing far more carbon than they release into the atmosphere. The forces of growth in the forests are outracing the rising forces of death for now.

Still, this new study reminds us that the forests are doing us a huge favor in keeping carbon pollution in check. It might be in our favor to make sure that they survive in order to protect future generations. There is the possibility that stricter regulation of carbon emissions will be needed because humans will not be able to rely as much on the forests to soak up carbon pollution.

To stabilize our climate and keep climate change under control, then, we might eventually have to make deeper cuts in emissions. What this will look like in the future remains to seen but tighter regulations could mean profound effects on the global economy.

Reference:

Brienen, R. J. W., et al. “Long-term decline of the Amazon carbon sink.” Nature 519.7543 (2015): 344-348. http://www.nature.com/nature/journal/v519/n7543/abs/nature14283.html

“Amazon Forest Becoming Less of a Climate Change Safety Net.” http://www.nytimes.com/2015/03/24/science/earth/amazon-forest-becoming-less-of-a-climate-change-safety-net.html?ref=science&_r=2

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