Claims that global warming has stopped

I get so angry at all the ignoramuses in the blogosphere who claim that global warming has stopped since 1998. I see this claim repeated constantly in the comments section of articles about climate change. I have wasted hours of my life, posting comments to point out the fallacy of these claims. I see this claim posted so often in the comments, that it wouldn’t surprise me if some of the posters were being paid by climate change denial groups. Some of the $125 million which has been spent in climate change denial in the US over the last 3 years probably was spent to clutter the comments section with misinformation of new articles on climate change. It is estimated that half of the dark money which is given to right-wing groups goes to climate denial.

Claiming that global warming has stopped is currently the climate change deniers favorite argument, but anyone who takes 5 minutes to read the articles on can easily debunk it. For example, this article explains why the warming hasn’t stopped. If you read climate science news sites regularly as I do, the claim that global warming has stopped appears absolutely ridiculous. First of all, the deniers are taking 1998 as their starting year which was the warmest year in the 20th Century. It is easy to prove that warming has stopped when you are using an outlier as your comparison point.

I actually downloaded the global average surface temperature data from the Hadley Center, NASA GISS and NOAA NCAR to check these claims. Using a 60 month running average, I found that global average surface temperatures were still rising in the early 2000s. Nonetheless, global average surface temperatures did stop rising after 2003, so there is some validity to these claims.

The problem is that the deniers are ignoring all the evidence which doesn’t fit their claim. First of all, the Argo float studies have determined that 93% of excess heat gets absorbed by the ocean and only 2% of excess heat is trapped by the atmosphere, so global average surface temperature is a very poor way to determine if global warming is occurring since the deniers are only looking at 2% of the excess heat. Measures of ocean temperatures and ice melting show that global warming has not stopped, but rather it is actually increasing.

The second thing to keep in mind is that the Hadley Center’s HadCRUT data underestimates warming because it excludes much of the polar regions  where it doesn’t have many weather stations, but the polar regions are where the fastest warming is occurring. The best estimate of global average surface temperatures comes from NASA GISS, because it interpolates data in regions like the poles where there are fewer weather stations. Several recent scientific papers have reexamined surface temperatures with better data interpolation techniques for regions without weather stations and determined that average surface temperatures are actually rising.

Another thing to keep in mind is that there are a number of new low-level volcanoes which have appeared since 2000 and constantly spew SO2 which reflects sunlight and dampen the warming effect.

The biggest factor dampening surface temperatures however has been the dramatic increase in coal burning from China and India since 2000, which spews so much extra SO2 and other aerosols that James Hansen estimates that the world would experience 0.5ºC of warming if we suddenly stopped burning fossil fuels. The extra aerosols we are spewing also diffuse the sunlight, which stimulates plant growth and causes more CO2 to be absorbed by plants. Nonetheless, there is no guarantee that the carbon absorbed by plants won’t be emitted to the atmosphere when those plants die. It is widely predicted that climate change will cause most of the tropical forests to die off and places like the US Southwest, Northern Africa and Northern China will dry up, killing the vegetation in the future, so much of the carbon being absorbed today will be emitted to the atmosphere in the future.

The problem is that we are basically storing up warming which we will experience later. The excess heat currently being trapped by the ocean will eventually radiate out into the atmosphere and when we do stop burning coal, we will get all that excess warming which is currently being masked by aerosols. James Hansen calls this a Faustian bargain because we are spewing extra CO2 which will cause warming for thousands of years into the future, but we aren’t feeling the warming now because the SO2 from coal is blocking it in the short term.


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