Why have global temperatures remained constant since 1998?
The claim of climate change stopping since 98 is a myth. Statisticians and other scientists have debunked this claim over and over again. It is true that the heating up has slowed since this time, but it still shows a positive increase in the global temperatures. No accredited or peer reviewed science organization can back the claim that global temperatures have stopped increasing or that temperatures have cooled. Published peer-reviewed scientific research from the likes of NOAA, NASA are just a few of the organizations that find the claim of no heating or cooling dubious at best. In fact National Oceanic and Atmospheric Administration and NASA show 2005 has topped 1998.
To make such a claim of no global temperature rise one has to cherry pick dates and take a small set rather than look at trends before and after the dates they choose to back such a claim, in other words not a statically sound nor a scientifically sound claim. Of the 10 hottest years recorded by NOAA, eight have occurred since 2000. What's more, globally, the hottest 12-month period ever recorded was from June 2009 to May 2010.
Here is what statisticians say about these claims of no heating or that there was cooling.
"If you look at the data and sort of cherry-pick a micro-trend within a bigger trend, that technique is particularly suspect," said John Grego, a professor of statistics at the University of South Carolina.
"Saying there's a downward trend since 1998 is not scientifically legitimate", said David Peterson, a retired Duke University statistics professor.
Identifying a downward trend is a case of "people coming at the data with preconceived notions," said Peterson, author of the book "Why Did They Do That? An Introduction to Forensic Decision Analysis."
All of this talk did make NOAA take a second look at their numbers though, finding temperatures have actually increased.
"The last 10 years are the warmest 10-year period of the modern record," said NOAA climate monitoring chief Deke Arndt. "Even if you analyze the trend during that 10 years, the trend is actually positive, which means warming."
There is a 'climate scientist' who publishes his own work without peer review who claims there was no warming, he also claims that 10 year sections are more important than overall trends. Here is a NASA write up on the subject. They show how cherry picking a subset of numbers is not scientifically valid as you can make the claim for anything when your data is not in context.
Here is a NASA link that shows the top 5 hottest years since 1890.
Here is a chart that shows the temperatures in context, it should be evident why cherry picking 98 is not statistically sound.
I didn't look at the data, I got it from an interview with Professor Judith Curry of the Georgia Institute of Technology. She never said there was cooling, and she agreed that it was the warmest decade on record, but she said that the upward trend had leveled off.
Her explanation for this was that climate change is a more nuanced and complex than what is presented. Climate models do a poor job of accounting for oceanic fluctuations which may account for the leveling off.
The point was that, when presented with indications such as this people seem too eager to discount it rather than account for and understand it within their models. She also noted that people are quick to get angry about this topic. I didn't read a science journal, but this interview with a Stanford Economist and a Georgia Tech Climatologist is hardly the opinion page.
'Remaining constant' as the original debate was worded is not a correct framing of what actually is happening. The warming has slowed down, but that isn't what the debates claim started nor the sources claim of 'leveled off'. 'Leveled off' implies flat which the links I provided shows the temperatures still have increased. If you have a link it would help to see her exact wording.
As written, it is easy for people to be "eager to discount" as it is inaccurate.