re: #435 Salamantis

But whether or not human emissions contributes a significant percentage to global warming, or whether the lion’s share of global warming is due to solar cycle or terrestrial orbit permutations beyond human control, is the question that has NEVER been empirically answered, and always seems to be avoided.

As far as solar goes:

Total Solar Irradiance (TSI): Also known as total incoming solar radiation (insolation). The amount of solar radiation reaching the Earth can change as solar activity changes. This is a known factor influencing global temperatures and thus climate. Sometimes people will reference sunspots, which correlate fairly well with TSI (more sunspots generally means more incoming solar radiation), but solar irradiance is the specific factor impacting the Earth’s climate.

Since 1978 we’ve had satellites measuring TSI directly, and prior to that scientists use “proxies”. A proxy variable is something that is probably not in itself of any great interest, but from which a variable of interest can be obtained. For example, climate scientists use tree rings and ice core layers as proxies to determine past global temperatures. In the case of TSI, one such proxy is beryllium-10 concentrations.

So the question again arises - could changes in TSI be responsible for the recent global warming? Since we’ve had satellites measuring TSI directly since 1978, and this is the period of the greatest warming in recent history (0.5 degrees Celsius over the past 30 years), all we have to do is look at the satellite data to determine if solar irradiance has similarly increased over that period.

Again, the answer is no. On average, TSI has remained essentially unchanged since 1978. According to the Max Planck Institute for Solar System Research, it hasn’t increased (on average) in about 70 years.

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