Missing from many discussions on climate change is an exploration of what average temperature we would ideally like the climate to have. On the low side snowball earth is clearly bad, and raising the temperature to the point of cooking everyone would be very unfortunate. Somewhere in the middle is the ideal temperature - what temperature is that?
There seems to be an implicit assumption by many environmental advocates that any rise in temperature is detrimental. There are several possible justifications for this:
1. We are already at the ideal temperature, any change up or down will make things worse.
2. We are already above the ideal temperature, and we should be trying to cool the planet.
3. We are not at the ideal temperature, but the consequences of changing the status quo have negative effects in the short term, with the positive benefits only being realized in the long-term.
Of course we can ask the question - what is meant by ideal temperature - ideal for who? For the sake of argument let's say the ideal temperature is one that maximizes biological productivity on the planet.
Option 1 then seems pretty unlikely - anyone advocating that the long term ideal temperature just happens to be the one we have now is in need of strong proof to show they are not the subject of status quo bias.
Option 2 is also almost certainly wrong - paleological records indicate that planetary bioproductivity was higher in the past during times of warmer climate, and the overall long-term trend in the last several hundred million years has been to a colder, less productive environment.
This leaves option 3 - it is possible that the environment is "balanced" around the current temperature, and that warming the planet even though of benefit in the long term (say 1 million years from now) would have negative effects in the short term. But how likely is this really? Plants and animals already adapt to day/night and seasonal temperature changes. Even though climate effects may be unevenly applied the changes we are talking about are still small compared to seasonal variation in both degree and time scale. There may be negative consequences for humans, but we can adapt and move around pretty easily too.
There is another position:
4. We don't know enough to know what the ideal temperature is, and so we should avoid making drastic potentially irreversible changes until we know better.
I am sympathetic to this position, but there are consequences to no-change just as there are to change.
Taking a position on a divisive topic such as climate change can put the advocate into a 'tug-of-war' scenario with their opponents. There is an unwillingness to give up any ground whatsoever, for fear that every inch conceded is a gain for the opposition. This can lead to arguing weak positions, and in the case of climate change a reluctance to ask "what _is_ the best temperature that we should be aiming for?"
There's a fifth position too, or maybe a variation on the fourth, which is that there's a potentially big difference between being dragged along unintentionally in the direction of something good and making an informed choice to carefully walk in that direction. Even if we were to say that the ideal temperature for earth is a degree or two warmer than now (you forgot to provide a reference for that biomass point btw), moving in that direction via uncontrolled, rapid, indirect changes to the atmosphere seems like it would have a high probability of overshooting by quite a large margin. Given that global warming happens by emitting CO2 and that CO2 hangs around in the atmosphere for a long time, it would be very difficult, after the temperature has risen to an ideal 3 degrees more than today, to say "ok, that's good, stop rising now."
ReplyDeleteWe may be at or past the point where the amount of CO2 already released will give us a nice cozy 3 degree increase 50 years from now, so stopping any further emmissions would make sense even though we are not yet at our ideal temperature.
You also seem more sanguine about the potential disruption to human life specifically than I would be. In other words, your option 3 could yield a 'short term' of >10,000 years during which the number of humans would be less than it would otherwise be and in the very short term, many lives could be lost and much technological progress too.
The questions "where we'd like to get to" and "how we're going to get there" are separable. You can advocate for restricting CO2 emissions while at the same time acknowledging that we are better off with a climate that is warmer than pre-human times. I would argue that once most accessible fossil fuels run out, we'll still want to maintain atmospheric carbon dioxide levels above pre-human concentrations (e.g. by deliberately expending energy to accelerate weathering of limestone)
DeleteAgreed that the questions of what the temperature should be and how to get there are different. The problem is that policy makers and pundits (particularly those whose job it is to misrepresent climate science) often fail to make that distinction. If we can agree that we should stop uncontrolled emissions of CO2 first and get the temperature stable and only then make a considered decision as to what the temperature should be, then I could consider your limestone weathering plan.
ReplyDeleteHowever, even then, sustainability will probably be important. If we consume a functionally static source of carbon to 'artificially' raise the temperature of the earth then we would need a plan for what to do when the limestone runs out.
That's a problem for the far future though. Step 1 is to get the current process under control so that the level of CO2 becomes a conscious decision.