Sorry, in the last 3 years this number has been all over the map.
I did a rambling explanation of this but it/s fairly straightforward. There are basically TWO sets of numbers for the RoW variable right now. NASA/GISS and Hansen.
According to GISS Global Warming has been.
1850-1980 = +0.08C/decade
1980-2010 = +0.18C/decade
2010-2020 = +0.25C/decade
2020-2023 = +0.39C/decade
This is the "low" number for the current rate of warming. It is the OFFICIAL number or the LCD (lowest common denominator) number that the Moderates accept.
I use it for the same reason Hansen uses it in his papers. Even when you know it/s 'too low" you lose credibility if you insist on using your own "personal" estimates.
In LiBT-022 I stated that using Goode's number for the Albedo dimming was 'conservative', that the CERES data indicated REALITY was worse that than the +0.36C/decade that I was going to use for the new RoW in my articles.
Remember, GISS was refusing to even admit warming was accelerating at that point in time. They were holding onto a RoW of no more than +0.25C.
Since then.
GISS has bumped the RoW to +0.39C/decade. Which in normal times should be fucking headline news.
The MOST CONSERVATIVE estimate possible possible for the Rate if Warming is now +0.39C/decade.
Hansen thinks it's closer to +0.49C/decade. I agree.
Way back in LiBT-05 (Nov. 2020) I did a long analysis of the warming between 2010 and 2020 and concluded it had been around +0.25C.
I broke it down like this.
1850–1980 — The first phase of warming
1850 — the baseline “preindustrial” global temperature year
0.07C — the amount of warming per decade from 1850 to 1980
0.91C — the total amount of warming from 1850–1980, almost a full degree
We tend to discount this degree of warming because it came after the planet had been in the 500-year cooling phase termed the “Little Ice Age”. This warming made the 20th a lot more pleasant than any period since the 13th, when the “Medieval Warm Period” aka “the Long Summer” ended and the Little Ice Age started.
However, another way to see this, is to consider that roughly 6,500 years of gradual cooling was erased in a single century.
We flipped the climate from the natural cooling phase it had been in for 6,500 years into a rapid warming phase. This degree of global warming in only a century was about 10X the normal rate of temperature increase during a regular interglacial warming period.
This was the period when we “primed the pump” for the next phase of warming.
1980–2010 — The second pulse of warming
1980 — the “modern” global temperature baseline.
When climate studies talk about 1C or 2C of warming this is the year they are often measuring against.
They use this year because the global temperature was roughly equal to what it had been during the Holocene Optimum. The period of warm temperatures that stabilized after the phase of rapid global warming that ended the last Ice Age.
So, in 1980 the global temperature was as high as it has been since the beginning of the Agricultural Revolution roughly 11,000 years ago.
0.18C — the amount of warming per decade between 1980–2010
Notice how much the rate of warming jumps around 1980.
From 1850–1980 the rate of warming was about 0.07C per decade. Then around 1980 there is a huge jump of over a tenth of a degree of warming per decade. The rate of warming more than doubled during this period.
Why?
***Now, this next bit I got wrong.***
It’s not hard to figure out. Around 1950 there was a huge postwar global economic boom. The increase in the yearly amounts of CO2 dumped into the atmosphere was explosive.
What is really important though, is the lag-time between the increase in CO2 emissions and the subsequent increase in the rate of global warming.
30 years — the amount of time it takes for rate of global temperature increase to climb in response to an increase in the global CO2 level.
0.54C — the total amount of warming between 1980–2010, just over half a degree from the modern global temperature baseline at a rate of roughly 20X faster than normal interglacial period warming.
The 30 year Climate System "response lag" was a theory that I had believed in for about 25 years. When it became clear in the 90's HOW MUCH warming had accelerated around 1980, it seemed like a reasonable theory.
It has since been disproved.
However, my calculation of +0.25C for 2010 to 2020 was 'spot on'.
Over the course of 2021, as new data came in they refined the number for the amount of warming for the 2010 to 2020 decade. As they did, it leapt out at me that there was 'too much" ENERGY in the system.
Which is what I concluded in my State of the Climate Report 2022 if you recall.
The RoW had already jumped to around +0.25C per decade BEFORE the change in albedo caused the EEI to DOUBLE starting around 2015. The change caused the RoW to jump to around +0.49C/decade according to Hansen in his Dec 14th paper.
I agree, that number makes more sense to me than the +0.39C that GISS likes.
