Man made Global Warming is another matter: our impact, particularly the role of CO2, can be measured but there is NO verifiable proof that it has made much difference to Climate Change. All the so called evidence is circumstantial.
Empirical data from NASA and others not good enough for you then, Peter?
We know that human activity has massively increased the amount of CO2 in the atmosphere. There's no doubt about this, it has been confirmed by multiple empirical studies.
We know that Carbon Dioxide, along with Methane and Ozone, is the major contributor to warming through surface radiative forcing,as measured by Evans et al in 2006:
We can also empirically measure the amount of long wavelength radiation leaving the Earth, and this data clearly shows that the amount of heat being retained due to CO2 matches the decrease in radiation:
That's the data which proves the case in my view. We can measure the amount of heat retained by our increasing the levels of greenhouse gas in the atmosphere, and we can match that with the data that shows that it's affecting overall heat loss. Ergo, it's our CO2 emissions that are driving global warming.
So now we need to consider how much contribution this is making to overall climate change. We know that over geological time periods, the climate has changed back and forth, driven mostly by changes in atmospheric CO2, Methane, and Ozone, leading to episodes like the medieval warm period, periodic ice ages, and so on.
But we also know that these changes happened largely over extended time periods, meaning that species had time to adapt to and survive them. And we also know that when we had sudden dramatic changes in atmospheric CO2, like in the Permiam and Triassic periods, we had mass extinctions. Furthermore we know that humans are increasing CO2 levels in the atmosphere far faster than any of these natural processes ever managed. So our actions are precipitating a rapid change, at a similar scale to those which we know before have had catastrophic results.
It may well be that we've left it too late to be able to do anything about it, the current predictions are implying that we can expect to see Wet-bulb temperatures in excess of 35C within a couple of decades in places like India. At this temperature, there's no point even a healthy human sitting still in shade, they will be dead in 6 hours regardless.
If this is the case, the next mass extinction will be of humans. I haven't got any children or grandchildren, so I'm quite relieved I won't be confronted with them asking me "Why didn't you do something about it when you had the chance?"
