Last week we discussed some new research connecting “excess” warming in Europe, excess being a word here meaning CO2-driven climate models can’t explain it so it must be something else, with reductions in sulphur dioxide emissions. This week we look at an alternative explanation, although they are not mutually exclusive: more sunlight hitting the surface. Before we get to those numbers, please note these ones. First, the IPCC figures that all the CO2 that’s ever been emitted since 1750 has added about 2 Watts per square meter of heat energy at the Earth’s surface. Second, it figures that methane and other greenhouse gases have added about 3 Watts per square meter more. Third, therefore, the total increase due to CO2 and other greenhouse gases is about 5 watts per square meter. Fourth, they say there’s been a cooling effect due to aerosol pollution of about 2 W/m2, which leaves a net gain of about 3 of those cumbersome units. And fifth, necessarily, because that is the total gain measured empirically, the IPCC therefore says the sun has done precisely nothing. But wait. The other important number here is that people have been measuring the amount of solar energy hitting the Earth’s surface for some time using satellites in combination with ground stations. A new study looking at the record just for Germany found that since 1995, the year all the satellite systems came online together, more solar radiation has been hitting the surface. So much more that the trend since 1995 is about +4 watts per square meter per decade, hence a 25-year total increase of around 10, double the effect of all the greenhouse gases ever emitted. With all that extra heat energy from the sun there’s nothing for CO2 to explain. Indeed, less than nothing, because we have to get down from that 10 to just 3. Something doesn’t add up.

The study was conducted by four scientists at Deutscher Wetterdienst, the German government meteorological service. Their results are as follows:

As noted, the graph shows Surface Solar Radiation (SSR) in watts per square meter relative to the 1995 to 2020 average. The trend is +4 watts per square meter per decade. Over the sample interval that adds up to a lot of radiative forcing. Moreover, many of the same authors were involved in a 2024 study that used one of the satellite products (SARAH-3) and estimated trends over the whole of Europe from 1991 to 2020 and the result, while more variable over a wider area, is the same in the big picture:

The vertical colour code shows that the upward trend in SSR ranges from about 2 to about 5 watts per square meter per decade depending on location. Again, far more than attributed to all the GHG emissions ever recorded.

Also, again, a puzzle in that we’re actually getting more of an increase in SSR from this one potent source so instead of there being even a residue to attribute to CO2, methane and other human greenhouse sins, we must identify a mystery actor decreasing the net total. What can it be?

Actually, first things first. What’s the cause of this increase in SSR? And the authors of these papers don’t actually offer an explanation but others have explored possibilities. For instance, as we reported this spring the DOE Red Team report last year reported that the Earth’s global albedo, its reflectivity, has been declining which means less incoming solar radiation gets reflected away and is instead absorbed at the Earth’s surface.

So the effect isn’t just confined to Europe, although it seems especially strong there. And there is almost certainly a connection to cloud cover which dropped globally after 1995, for reasons that appear to be connected to cyclical changes in the Pacific ocean not, again, CO2.

Alas, climate science isn’t like the other kind. So the skies are less cloudy, more sunlight gets in, and in Europe the effect over the past 25 years has been at least twice as strong as all the greenhouse gases emitted since 1750. But the IPCC assumes the sun doesn’t contribute to global warming.

This topic needs a lot more sunlight on it.