It’s a concerning moment as the Carbon dioxide levels in the Earth’s atmosphere are rising day by day, scientists have announced. Soon they will reach threatening proportions and we will be unable to protect the environment, as the emissions have crossed the boundary of 400 parts-per-million (ppm) for the first time in the history. This fact has been measured at the top of the Mauna Loa Observatory on top of a volcano in Hawaii and has been reported by mirror.co.uk.

That means for every million molecules in the atmosphere, 400 of them are carbon dioxide. It might not sound like a lot but this can be very worrisome in the future, say experts. Crossing the 400 ppm boundary was predicted but it serves as a reminder of the growing threat from climate change. Scientists are skeptical that these levels will not decrease back to safer levels in the future.

The UN’s Intergovernmental Panel on Climate Change (IPCC) has predicted that once we go over the 450 ppm threshold, the results could be catastrophic. It would contribute to warming the planet by two degrees and cause unpredicted shifts in weather patterns on Earth. It is imperative to cut down the carbon emissions by about 40-70% or else in the next 20 years, we will cross the 450 ppm mark.

One of the main reasons for CO2 levels crossing the 400 ppm boundary this year is due to the gigantic El Nino that shook the Pacific Ocean during 2015. It caused high air pressure around the tropics that limited the ability of forests to draw in CO2 from the atmosphere. Another contributing factor to the increase in atmospheric CO2 is the constant burning of fossil fuels by humans.

“It’s important to note that this year’s rise in CO2is bigger than the last El Nino, in 1997/8, because human emissions have gone up by 25 percent since,” said professor Richard Betts at the Met office. “We could be passing above 450 ppm in roughly 20 years. If we start to reduce our global emissions now, we could delay that moment but it is still looking like a challenge to stay below it,” he added.

If the levels of carbon dioxide cross 450 ppm then it can be devastating for humans and the Earth. The planet may get warmed by another two degrees and the existing weather patterns may show an unpredictable shift says the Intergovernmental Panel on Climate Change (IPCC) of United Nations.