only in the sense we can see other warm periods and look at the changes in the biome and where the temp went against C02 levels.
in particular the Siberian traps which represents another time when CO2 was a driver of climate change. That we are putting more in annually than occurred then is pretty scary as we know the outcome of that anomaly.
http://www.ibtimes.com/permian-mass...traps-may-have-triggered-really-rapid-wipeout
That said....it was over a much longer time. So yes paleoclimate has an informative role to play but should not be mixed with current and near term climate change issues.
This reflects more the position that I hold. I do not have a problem discussing any of the instances (periods) of globally warmer (or colder) climate temperatures. It isn't like climate science denies or ignores naturally driven climate shifts. In fact, it is essential to understand both the commonalities and differences between geologic (regional and planetary) climate change episodes and the modern climate change episode(s).* At least if we expect to be able to prepare and adapt to the inevitable, and hopefully, to minimize the potential of, modern climate changes.
That said, the immediate focus should be upon how different the modern climate is becoming from the climate within which our species (the last 3M to 300K years) and later our civilization (last 8000 years) and nation (last 2 centuries) have originated, grown and evolved. It is important to understand the conditions which we are already committed to moving toward at largely unprecedented rates.
For instance, it is important to understand that even if we could stop all human-sourced emissions tomorrow, the atmospheric changes are already set much higher than the system has equilibrated to as of yet. In other words, if we stopped tomorrow, temperatures and climate changes will continue to occur for several more centuries before all of the feed back systems have brought the climate response up to the forcing level of the GHGs in the atmosphere.
Some might ask, what does that mean? It means that we can look back at the living history book that is our planet's geologic record, find out what the planet was like (generally) the last time our planet was in an equilibrated climate at atmospheric CO2 ratios similar to what we have currently. The last time our planet had an equilibrated atmospheric composition of 400 parts per million carbon dioxide. Looking back in the geologic record, the last time the Earth's atmosphere contained 400ppm CO2 was a period of about a million and a half years between around 2 and 3.5 Million years ago (Mya). During this period of the late Pliocene/early Pleistocene:
The Arctic was ice-free (in general) about 8-10°C (14.4 - 18°F) warmer, on average, than it is now (global temperature averages were 3-4°C (5.4 to 7.2°F) warmer than today). On average, annual global rainfall was three times what it is today (indicative of a much more tempestuous weather pattern, at least in some regions of the globe). Sea levels were (on average) 22.5 meters higher than today (~72 feet!).
The unfortunate side of this information is that these are the results if we could stop all further human-sourced emissions from this point on, and the changes that would be realized if we could magically freeze things at today's atmospheric composition. At current levels of increase and even optimistic considerations of future mitigation measures,
we are looking at a tripling (at least) of pre-industrial CO2 ratios (~750-1000ppm), and conditions that have not been seen since mammals have been the dominant major forms of life on this planet.
The real problem isn't just the enormous added cost to virtually every aspect of modern society and commerce of the tripling of the CO2 component of our atmosphere by burning fossil fuels, it's what happens when we trigger massive natural carbon reservoirs to begin emitting their stores of carbon which would replace humanity as the main source of active carbon cycle carbon additions and leave us with no possibility to limit or restrict the greatly enhanced and further damages of a climate change process that we initiated through the lack of consideration of, and later refusal to accept, our responsibility for the consequences of our actions.
How many times do we need history to teach us this lesson?
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good to hear.