The truth is that humans have been heavily affecting their environment since long before even what we today call “agriculture”. According to something I read just recently maybe the entire biome of the Amazon basin for example, is actually mostly the result of human “gardening” (i.e. pre-agricultural horticulture). And some of this interference has probably been reducing biodiversity for just as long… but until recently not terribly significantly.

Now we’re in an entirely different situation… today our interference is causing the 6th great extinction. We have to accept that by our very existence we dramatically alter our environment, more so than other species, and go ahead and start doing so willfully, keeping as our only overriding goal to preserve as much biodiversity as we can through the progression of this great extinction. In other words, to hell with caution, try everything that might preserve biodiversity even if some of those actions are sure to be giant disasters. Because giant disasters are guaranteed either way.

:j

According to orbital forcing theory, which matches the last few hundred thousand years quite well, the climate should be very slowly cooling and for the next 50,000 years. At that time, it might be cool enough to tip into another ice age.

Sunspot activity varies on an 11 year cycle and the variation in solar insolation is extremely small. This is a second or third order effect on climate. No other variations in solar isolation, over periods of centuries, appear to withstand careful scrutiny.

While each of these statements is true in its own right, the implied conclusion that decreasing the level of greenhouse gases will lead to a significant reduction of global warming is not supported by the evidence. One important question has been overlooked: What percentage of the global warming that we observe is due to an increase in greenhouse gases and what percentage is due to other factors, such as normal fluctuations in solar activity? All of it? Half of it? One percent of it?
If most of the global warming we are seeing is due to fluctuations in solar activity over which we have no control and if only a small percentage of the global warming is due to an increase in greenhouse gases, then efforts to reduce greenhouse gases will have little or no effect on the earth’s climate.
Historical data inform us that there have been fluctuations in earth’s climate repeatedly in past centuries from the medieval warm period spanning the 10th to the 14th century and the “little ice age” from the 16th to the 19th century. These fluctuations have been linked to sunspot activity and solar output and have nothing to do with greenhouse gases.
Absent better data, I’m inclined to the opinion that global warming is not related in a significant way to the emission of greenhouse gases and that these “the sky is falling!” scenarios are mostly political rather than scientific in nature.

I think we should try moving animals and plants. For one thing, it will show us just how difficult it will be to colonize other planets in the galaxy. Remember that Biosphere II failed.

That would be cats.

Except of course, the squirrels here. These are not native. Locally we need more squirrel-eaters, whatever those are.

PS How’s the book coming along? Is there a publication date yet? Just finished rereading PR… again. Lookin forward to the next one.