Global warming has been on a hiatus since the start of the 21st century and continues to be, a new paper claims.
Numerous experts do not believe that global warming has slowed down since the early-2000s. They said studies suggesting hiatus due to decreased global surface warming are exaggerated, lacks scientific foundation or are not backed up by adequate observations.
Now, a group of climate experts are determined to refute these claims.
The New Paper
"There is this mismatch between what the climate models are producing and what the observations are showing," says lead author and climate modeler John Fyfe from Canadian Centre for Climate Modelling and Analysis. "We can't ignore it."
In the observations made by Fyfe and colleagues, they used a measure that includes events that have affected temperature trends over the past decades.
For example, they discovered that previous climate models undervalued the cooling impacts of volcanic eruption and amplified the heat produced by solar radiation at the onset of the 21st century.
Some scientists are also said to investigate into the irregularities in the Pacific Ocean, including Pacific Decadal Oscillation, which examines sea surface temperatures.
All these investigations can affect the climate and hide the trends of warming in the long term.
This paper was published in the journal Nature Climate Change on Wednesday, Feb. 24.
The Previous Study
The recent discussions about global warming centers on the numbers of temperature trends.
The previous study, which doubted the global warming slowdown cleared up biases in surface temperature records set by the U.S. National Oceanic and Atmospheric Administration (NOAA).
The researchers' work resulted in a significant increase in warming values and included 2014 records, which was when a new record for the average high temperature was set.
The study, led by Thomas Karl from NOAA's National Centers for Environmental Information, looked into global warming rates from 1950 to 1999. They recorded a rate of 0.113 degrees Celsius during this period.
The authors also looked into the rates for the period of 2000-2014, which yielded a rate of 0.116 degrees Celsius. Such finding proves that the global warming slowdown claimed by the the famed Intergovernmental Panel on Climate Change in 2013 was no longer true.
Karl's study was issued, June 26, 2015 in the journal Science.
Fyfe's Rebuttal
Fyfe and colleagues beg to disagree to Karl's study by performing their own investigations. They said that Karl's approach was biased by a time of flat temperatures that occurred from the 1950s to the 1970s.
The group argues that greenhouse gas emissions back then were lower and that industrial emissions such as sulphate aerosols were decreasing the Earth's temperature by reflecting sunlight back to space.
Ultimately, they presented their own calculations to support their claims. In contrast to Karl's study, the team of Fyfe says that the global warming rate from 1972-2001 was 0.170 degrees Celsius per decade. Such number is higher than the rates he calculated for the 2000-2014, which is 0.113 degrees Celsius.
Which Is Which?
By the looks of the ongoing debates, nothing is certain. Even NASA's Gavin Schmidt has grown tired of the discussions. He said the talks boil down to definition and academic arguments. He adds that there will always be reasons for deviation in climate trends and why models are not able to capture it.
