1.5ºC that will change the world

GLOBAL temperatures could exceed 1.5ºC above their preindustrial levels within the next 15 years, according to a new scientific study, crossing the first threshold under the Paris climate agreement and placing the world at a potentially dangerous level of climate change.

The report comes as climate agreement participants are watching the US – where the Trump administration is debating whether to withdraw from the Paris accord – and as scientists with the Intergovernmental Panel on Climate Change (IPCC) are working on a special report about the 1.5ºC goal and the consequences of overshooting it.

That report and the increasing urgency about minimising global warming were one impetus for the study.

The study focuses on a natural planetary system known as the Interdecadal Pacific Oscillation, or IPO (it’s also sometimes referred to as the Pacific Decadal Oscillation). It’s an alternating pattern of ocean temperatures that shifts periodically between warm and cool phases, helping to drive temperature and weather patterns all over the world.

During cool, or “negative,” phases, tropical regions of the Pacific Ocean tend to be colder, and the global mean temperature is lower. The system is similar to the El Niño/La Niña cycle, the major difference being that phases of the IPO tend to last much longer – sometimes a decade or more.

For most of the 2000s, the IPO has been in a negative phase, and scientists think its cooling effect has helped to slightly offset the effect of climate change.

Many scientists believe the planet is now transitioning back into a positive, or warm, phase, which could amplify, rather than offset, human-caused climate warming.

This means we could reach milestone temperature thresholds faster.