Plants and trees absorb up to 29 per cent of the world's carbon emissions, but scientists think they are reaching their threshold. Image Credit: Unsplash/David Vig

For decades, we’ve been counting on plants and trees to absorb carbon out of the atmosphere, and help mitigate climate change. But what if, one day, they stop?

Click start to play today’s Crossword and answer a few botanical clues.

Ever since the Industrial Revolution, which started in the West in the early 20th century, human activity has been responsible for the rise of carbon in the atmosphere. In fact, according to The Keeling Curve, which is maintained by US-based Scripps Institution of Oceanography and University of California San Diego, and provides a daily record of global atmospheric carbon dioxide concentration, the latest reading stands at 419.67ppm – one of the highest levels ever recorded.

These greenhouse gases absorb solar energy and keep heat close to the Earth’s surface, rather than letting it release into space – the heat trap, or greenhouse effect, is why our planet grows warmer with each passing year.

But Mother Nature has been working harder than ever before to maintain the peace. According to a May 2019 study published in the journal Trends in Plant Science, ecophysiologists used computer models to find that photosynthesis has increased by 30 per cent. And plants are systematically removing about 29 per cent of emissions that would have otherwise contributed to the carbon dioxide concentration in the atmosphere.

The process is benefiting plants to some extent. According to a May 2019 report in the National Geographic, the excess carbon acts like a fertiliser, making trees leafier, and creating more wood. But the make-up of certain plants is changing. Scientists at US-based Oak Ridge National Laboratory found that plants that are exposed to greater levels of carbon dioxide have larger sized pores on their leaves. When the plant’s tissue composition changes, it makes it harder for herbivores to chew on the leaves, and more difficult for larvae to grow on them.

Eventually, scientists think plants won’t be able to keep up with the rising levels of atmospheric carbon dioxide. Once they stop, climate change is bound to occur even faster, unless we scale back two of the biggest influences on the carbon cycle – clearing land for agriculture, and fossil fuel emissions.

Do you think the world is ready for this inevitability? Play today’s Crossword and tell us at