Climate change

Faux Pause 2: Warmest November On Record, Reports NASA, As New Studies Confirm Warming Trend

Joe Romm

Climate Progress,

15 December, 2013

Last month saw the hottest global November surface temperature on record, according to the latest data from NASA.

Earth’s surface temperature in °C for each November since 1880 (compared to base period, 1951-1980). Red line is smoothing with a 15-year filter.

Of course, the global surface temperature is only one of many indicators the planet just keeps warming, as I wrote in my September post, “Faux Pause: Ocean Warming, Sea Level Rise And Polar Ice Melt Speed Up, Surface Warming To Follow.”

Now two new studies demolish the myth that warming — including surface warming — has not continued apace. Stefan Rahmstorf, Co-Chair of Earth System Analysis at the Potsdam Institute for Climate Impact Research, discusses the first paper at RealClimate:

A new study by British and Canadian researchers shows that the global temperature rise of the past 15 years has been greatly underestimated. The reason is the data gaps in the weather station network, especially in the Arctic. If you fill these data gaps using satellite measurements, the warming trend is more than doubled in the widely used HadCRUT4 data, and the much-discussed “warming pause” has virtually disappeared.

“There are no permanent weather stations in the Arctic Ocean, the place on Earth that has been warming fastest,” as New Scientist explained five years ago. “The UK’s Hadley Centre record simply excludes this area, whereas the NASA version assumes its surface temperature is the same as that of the nearest land-based stations.”

As I’ve discussed many times, that’s why we know with high certainty that the planet has actually warmed up more in the past decade than reported by the global temperature records, especially the Hadley Center’s.

The corrected data (bold lines) are shown compared to the uncorrected ones (thin lines). Via RealClimate.

Rahmstorf explains that two scientists, Kevin Cowtan and Robert Way have devised a new method that uses satellite data to fill in the data gaps:

Cowtan and Way apply their method to the HadCRUT4 data, which are state-of-the-art except for their treatment of data gaps. For 1997-2012 these data show a relatively small warming trend of only 0.05 °C per decade – which has often been misleadingly called a “warming pause”….

But after filling the data gaps this trend is 0.12 °C per decade and thus exactly equal to the long-term trend mentioned by the IPCC.

And so the pause is faux. The second study also reveals “Global warming is unpaused and stuck on fast forward,” as environmental scientist Dana Nuccitelli explains at Skeptical Science:

New research by Kevin Trenberth and John Fasullo of the National Center for Atmospheric Research investigates how the warming of the Earth’s climate has behaved over the past 15 years compared with the previous few decades. They conclude that while the rate of increase of average global surface temperatures has slowed since 1998, melting of Arctic ice, rising sea levels, and warming oceans have continued apace.

The widespread mainstream media focus on the slowed global surface warming has led some climate scientists like Trenberth and Fasullo to investigate its causes and how much various factors have contributed to the so-called ‘pause’ or ‘hiatus.’ However, the authors note that while the increase in global temperatures has slowed, the oceans have taken up heat at a faster rate since the turn of the century. Over 90 percent of the overall extra heat goes into the oceans, with only about 2 percent heating the Earth’s atmosphere. The myth of the ‘pause’ is based on ignoring 98 percent of global warming and focusing exclusively on the one bit that’s slowed.

Here’s a graphic illustration of that:

A visual depiction of how much global warming heat is going into the various components of the climate system for the period 1993 to 2003, calculated from IPCC AR4 5.2.2.3

As Nuccitelli explains, this study “also casts doubt on the conclusions of a few recent studies that estimated the Earth’s climate is less sensitive to the increased greenhouse effect than previously thought”:

Trenberth and Fasullo note that using their ocean heating estimate by itself would increase the equilibrium climate sensitivity estimate in the paper referenced by Ridley from 2°C to 2.5°C average global surface warming in response to a doubling of atmospheric carbon dioxide, and using other more widespread accepted values would bring the estimate in line with the standard value of 3°C.

… the main point of the paper is that global warming is stuck on fast forward. Ice continues to melt, sea levels continue to rise, and the oceans continue to warm rapidly.

In fact, “Greenland Ice Melt Up Nearly Five-Fold Since Mid-1990s,” as we reported in November 2012. Another study that month found “sea level rising 60% faster than projected.”

No wonder Politifact Texas rates the claim, “The Earth is not warming,” as “PANTS ON FIRE – The statement is not accurate and makes a ridiculous claim.”