Besides calculating global warming by correlating it to the carbon dioxide concentration in the atmosphere—which, incidentally has now risen from 280 ppm to nearly 430 ppm—another method is to measure the direct heating of Earth’s surface that comes from sunshine. This is done by measuring the energy that strikes the surface of our planet as watts per square metre. This energy is then reflected from Earth’s surface as radiant heat, blocked from escaping back into space primarily by the carbon dioxide in the atmosphere.

Without the warming effect of any greenhouse atmospheric gases, the energy we get directly from the sun would only heat Earth to -18°C. In other words, the unique gaseous composition of the atmosphere enveloping our planet warms it to the so-called “Goldilocks Zone”—not too hot and not too cold for sustaining life as we understand it.

Unfortunately, writes Madeleine Cuff in New Scientist (“Earth Warms as Heat Trapping Doubles”, June 15, 2024). “Earth’s atmosphere is trapping more than twice as much excess heat as it did in 1993.” The surplus heat “in the climate system… is the difference between how much energy enters Earth’s atmosphere from the sun, and how much is radiated back into space.”