Make a list, in your mind, of all the things that contribute to global warming. Go ahead and take your time. If you’re like most people, that list probably looks something like: burning fossil fuels, deforestation, emissions from cars and other transportation, livestock, and chemicals used in agriculture. That’s a pretty good roundup of the leading causes – at least, so far. Scientists have just penned a study that points to a contributing factor that has evaded detection, until now. When it comes to our planet’s ability to ‘trap’ carbon and prevent it from further harming the atmosphere, the biggest problem is likely to be the rapid rate of increase of nighttime temperatures in tropical climes.

climate change, global warming, greenhouse gas emissions, carbon emissions, carbon sink, carbon release, tropical nighttime temperatures, rising global temperatures, William Anderegg, university of utah, princeton university

Carbon emissions have soared dramatically since the beginning of the industrial age, and for a time, plants and other features on Earth managed to trap a percentage of the carbon dioxide that humans created, offsetting the environmental destruction by a fraction. However, rising global temperatures – particularly the tropical nighttime temps – are making it more difficult for plants to do that dirty work and, at some point, forests around the globe will not only be unable to absorb carbon, but they may actually reach a saturation point and begin emitting it, thus worsening the effects of global warming.

Related: All major forest biomes on Earth are dying, and fast

The amount of carbon consumed by the world’s forests isn’t fixed. Capacity for carbon storage fluctuates annually due to changing environmental factors, including temperature and precipitation, which make plants and even the Earth’s soil itself take up more or less carbon, depending on the state of things. With global temperatures on the rise and precipitation patterns becoming ever more erratic, it’s easy to see how this could create a lot of problems. Whether we realize it or not, we’ve relied on the forests to keep our greenhouse gas emissions in check, at least to a small degree, and that could come back to haunt us in a very literal sense if those forests begin leaking carbon into the air.

The paper’s lead author is William Anderegg, an assistant professor of biology at the University of Utah and an assistant research scholar at Princeton University. Anderegg and his colleagues tested four hypotheses to determine what had the biggest influence on carbon absorption versus carbon release in land systems like forests. The first three – tropical mean temperature, tropical precipitation, and both temperature and precipitation in semi-arid regions – had all been previously examined in the scientific community and are generally accepted as being important. Anderegg’s fourth theory – related to tropical nighttime temperatures specifically – hasn’t been studied much. Based on the findings in this paper, that is likely to change as we seek to understand more about the impact of carbon emissions on the delicate ecosystems of our dear planet.

Via Washington Post

Images via Shutterstock (1, 2)