Earlier estimates of climate sensitivity offered hope that the global carbon emissions may not heat up the planet to dangerous levels, but findings of a new study suggest that Earth may experience far worse temperature rises in the future than previously estimated.
Slow Mode And Fast Mode Of Warming
How the temperatures increase for a particular level of carbon emission is known as climate sensitivity. It is considered as an important measure of climate change.
Computer models have long suggested of high levels of sensitivity of up to 4.5 degrees Celsius when the atmospheric level of carbon dioxide doubles, but researchers in recent years made estimates of climate sensitivity that relied on historical temperature data that were recorded over the past century.
"The historical pattern of warming is that most of the warming has occurred over land, in particular over the northern hemisphere," Cristian Proistosescu, of Harvard University's Department of Earth and Planetary Sciences explained.
"This pattern of warming is known as the fast mode — you put CO2 in the atmosphere and very quickly after that, the land in the northern hemisphere is going to warm."
Estimates based on historical pattern of warming suggested that the temperature may not increase to more than 3 degrees Celsius, which means that the warming of the planet may be kept at safe levels with lower cuts in carbon emissions.
The findings of a new study by Proistosescu and colleagues, which was published in the journal Science Advances, however, dampened hope that countries need not drastically reduce their carbon emission levels, which is difficult and costly to achieve.
Researchers of the new study found that the low range of temperature rise based on historical observations did not take into account long-term warming patterns.
The researchers used mathematical model that parsed the fast mode and the slow mode of warming, which can take centuries to realize, within different climate models.
The findings show that estimates based on historical temperature data do not take into account the slow heating of the world's oceans that occurs over long period spanning decades and even centuries after carbon dioxide has been added to the atmosphere.
Temperature May Rise Up To 6 Degrees
The researchers found evidence suggesting of temperature increases that may even possibly reach 6 degrees, which could mean worse consequences. Global warming at its current level has already been attributed to the spread of diseases, wars, and unwanted ecological changes.
"Some have suggested that we might be lucky and avoid dangerous climate change without taking determined action if the climate is not very sensitive to CO2 emissions. This work provides new evidence that that chance is remote," said Bill Collins, of the University of Reading, in the UK.