This from Roy W. Spencer's excellent blog:

Why Blaming Recent Warming on Humans is Largely a Matter of Faith

As I continue to see all of the crazy proclamations of how human-caused climate change is disrupting lives around the world (e.g., the Feb. 28 release of the IPCC report from Working Group 2, [Pielke Jr. analysis here]), I can’t help but return to the main reason why human causation for recent warming has not been convincingly established. I have discussed this before, but it is worth repeating.

As a preface, I will admit, given the lack of evidence to the contrary, I still provisionally side with the view that warming has been mostly human-caused (and this says nothing about whether the level of human-caused warming is in any way alarming).

But here’s why human causation is mostly a statement of faith…

ALL temperature change in any system is due to an imbalance between the rates of energy gain and energy lost. In the case of the climate system, it is believed the Earth each year absorbs a global average of about 240 Watts per sq. meter of solar energy, and emits about the same amount of infrared energy back to outer space.

If we are to believe the last ~15 years of Argo float measurements of the ocean (to 2000 m depth), there has been a slight warming equivalent to an imbalance of 1 Watt per sq. meter, suggesting a very slight imbalance in those energy flows.

One watt per sq. meter.

That tiny imbalance can be compared to the 5 to 10 Watt per sq. meter uncertaintyin the ~240 Watt per sq. meter average flows in and out of the climate system. We do not know those flows that accurately. Our satellite measurement systems do not have that level of absolute accuracy.

Global energy balance diagrams you have seen have the numbers massaged based upon the assumption all of the imbalance is due to humans.

I repeat: NONE of the natural, global-average energy flows in the climate system are known to better than about 5-10 Watts per sq. meter…compared to the ocean warming-based imbalance of 1 Watt per sq. meter.

What this means is that recent warming could be mostly natural…and we would never know it.

But, climate scientists simply assume that the climate system has been in perfect, long-term harmonious balance, if not for humans. This is a pervasive, quasi-religious assumption of the Earth science community for as long as I can remember.

But this position is largely an anthropocentric statement of faith.

That doesn’t make it wrong. It’s just…uncertain.

Posted by: Timothy Birdnow at 11:42 AM | Comments (5) | Add Comment
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