The consensus arrived at the 2015 United Nations Climate Summit in Paris, that was, to limit warming up to 1.5-degree Celsius may not be helpful unless the CO2 concentrations are not limited. A recent study done by the researchers from the Oxford University and Bristol University have been published in the journal Nature Climate Change. The study demonstrates that higher atmospheric Carbon Di Oxide (CO2) concentrations directly increase temperature and rainfall extremes which means there can be dangerous changes in these extremes even if the global mean temperature rise remains within 1.5-degree Celsius.
“Future work is needed to confirm exactly why we see this direct CO2 effect, but current research points to a combination of circulation and cloud cover changes, and an increase in the amount of direct radiation on the Earth’s surface due to simply having more CO2 in the atmosphere,” said Hugh Baker, a DPhil student at Oxford University.
The atmospheric CO2 concentrations required to limit warming to 1.5 degree Celsius depend on the climate response. Some models have been devised by the researchers which show that CO2 levels at the higher end of this range directly increases Northern Hemisphere Summer temperature, heat stress, and tropical precipitation extremes.
The researchers said that even if a low-temperature response helped us to meet the temperature target, there might still be ‘dangerous’ changes in extremes-in other words, severe weather impacted beyond those currently expected at 1.5 degrees Celsius. The research highlights to implement immediate explicit CO2 concentration goals to limit the adverse effects of high-impact weather extremes. It considered the current geoengineering solutions which give emphasis only on reducing global warming impacts without reducing CO2 concentrations as ineffective. Dann Mitchell from the University of Bristol said that geoengineering techniques had been fixed as a way to achieve Paris Goals because it decreased the surface temperature.
“However, our results show that for an extreme climate such as heatwaves, changing the global mean temperature is not enough, you need to reduce CO2 concentrations themselves”, said Mitchell.