An unusually warm year or two cannot be blamed on climate change – what does Watts think about this?

From Dr. Roy Spencer's Global Warming Blog

Author: Dr. Roy W. Spencer

As of July 17, 2024, NOAA Climate Data Assimilation System (CDAS) July 2024 surface air temperatures deviated from the 30-year normal (chart provided by Weatherbell.com).

This title might raise some eyebrows, so let me explain. Yes, in a world that warms due to rising carbon dioxide emissions, the statistics of “unusually warm” years will increase. But assuming that the warming is entirely due to a slight energy imbalance in the climate system (currently about 1%) caused by a steady increase in carbon dioxide, the resulting warming would be about 0.02 degrees. C every year.

What a difference from that small 0.02 degrees. C is getting warmer every year due to natural climate changes.

This can be easily proven using a simple one-dimensional energy balance model. Any differences are due to natural weather and climate changes.

If we take the UAH global lower tropospheric temperature product as an example, the temperature in 2023 will rise by 0.51 degrees. C is above the 1991-2020 average. Use our +0.14 degree trend. C per decade is used as the baseline for the warming rate, then it should be +0.25 degrees Celsius in 2023. C is higher than the baseline, but the temperature is twice as high. So about half of the warming is natural (again…assuming the background warming trend is 100% human-caused).

So when we get a very warm year, like 2023 and possibly 2024, something other than carbon dioxide is to blame. All the media and environmentalist hype is just noise. Really warm years will be offset by cooler years (which no one reports because it's not newsworthy), so the long-term temperature trend remains about 0.02 degrees Celsius warming per year (+0.014 degrees Celsius per year in our satellite data).

Again, this assumes that the long-term warming trend is 100% attributable to carbon dioxide, and the 0.02 value assumes that climate sensitivity is at the low end of IPCC projections, which is consistent with observation-based climate sensitivity diagnostics; you can change this to 0.03 if you wish. My point still stands.

It's really that simple.

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