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'Sooty Birds' Reveal Hidden US Air Pollution (bbc.com)
Soot trapped in the feathers of songbirds over the past 100 years is causing scientists to revise their records of air pollution. From a report: US researchers measured the black carbon found on 1,300 larks, woodpeckers and sparrows over the past century. They've produced the most complete picture to date of historic air quality over industrial parts of the US. The study also boosts our understanding of historic climate change. [...] This new study takes an unusual approach to working out the scale of soot coming from this part of the US over the last 100 years. The scientists trawled through natural history collections in museums in the region and measured evidence of black carbon, trapped in the feathers and wings of songbirds as they flew through the smoky air. The researchers were able to accurately estimate the amount of soot on each bird by photographing them and measuring the amount of light reflected off them. "We went into natural history collections and saw that birds from 100 years ago that were soiled, they were covered in soot," co-author Shane DuBay, from the Field Museum and the University of Chicago, told BBC News. "We saw that birds from the present were cleaner and we knew that at some point through time the birds cleaned up -- when we did our first pass of analysis using reflectance we were like wow, we have some incredible precision." Their analysis of over 1,000 birds shows that black carbon levels peaked in the first decade of the 1900s and that the air at the turn of the century was worse than previously thought.
It really isn't that extraordinary of a claim.
We know the properties of Carbon Dioxide from reproducible lab experiments, in particular its interaction with infrared light, and at the concentrations found in the atmosphere.
We know with reasonable precision the concentrations of CO2 in the atmosphere for the past few thousand years, and that it has gone up dramatically in the past few hundred years.
We have pretty good temperature measurements since the dawn of the industrial age, and good proxies that go back much further.
We know, with reasonable precision, how much carbon dioxide we as humans emit into the atmosphere on an annual basis, based on analysis of fossil fuel consumption, industrial growth, and so forth.
All of these numbers jive, and point to us as the root cause.
The only extraordinary claim is that we as humans are not responsible, and that our very obvious release of CO2 has not caused the warming we have seen. Claiming that means either denying the rise in temperature, the known physical effects of CO2, or denying the known concentrations of CO2. That requires extraordinary evidence.
...si hoc legere nimium eruditionis habes...
So you're saying it's just coincidence that 100 years after we started pumping billions of tons of pollutants into the atmosphere every year we start seeing meteoric rises in global temperatures, the kind which match exactly the predictive models that simulate 100 years of pumping billions of tons of pollutants into the atmosphere... and that every single climatologist on the planet, the kind who are smart and went to college and know what they're talking about, are all wrong and you're right because, well, how could you possibly be wrong about anything?
You're absolutely correct to say that correlation does not imply a causality. However, in this case, we do know the causal mechanism.
CO2 (and similar gasses) absorb infrared radiation at various wavelengths, and that absorbed energy translates into increased molecular motion, aka heat. This is a property that can be demonstrated experimentally in the lab, with completely reproducible results.
Those ice cores you dismiss? They're excellent time capsules of atmospheric gas composition. As the snow falls, and the cores build up, it traps small amounts of atmospheric gasses in the ice. You extract these tiny bits of gas, run them through a GCMS, and measure the concentrations of the various components. Typically these ice cores come from places that aren't subject to significant local human population (Antarctica, Greenland). They're also stratified, just like tree rings, so the date of the gas samples can be determined with a high degree of confidence.
These two things are undeniable facts. They are reproducible, and traceable.
So the real question is, if you're going to claim what you do, how has the increase in CO2 not caused an increase in temperature? What mechanism would prevent that?
...si hoc legere nimium eruditionis habes...