原帖由 jasonpoon 於 2017-4-29 07:03 發表
this is worth more thinking... if rapid "global cooling" could happen in such a case by the (rapid) re-growth of tropical forest the size of, say, half or one-third of the amazon, then co ...
The carbon dioxide concentration decrease that likely contributed to the Little Ice Age is in the magnitude of 5-10ppm. The carbon dioxide increases after the industrial revolution is in the magnitude of 100-120ppm. Reforestation programmes are helpful, but I'm afraid they are insufficient to even maintain the carbon dioxide concentration at current levels (400ppm) given the high rates of carbon dioxide emissions. Not to mention that once forests are cut down and converted into human settlements/farmland or even cities, it is simply politically impossible to force people to abandon their land in a large scale.
Regarding the debate about whether the the oceans or the forest is more important in sequestering carbon dioxide. Yes, oceans are storing enormous amounts of carbon dioxide in dissolved solution form, much more than what the forests or terrestrial biomes are storing. However, I think it is meaningless to compare the absolute amount of carbon stored. Instead, we should focus on whether these systems have the potential to pull down what is in the atmosphere, i.e. net carbon sequestration. Regarding the flow of carbon between the atmosphere and forests/oceans, the numbers are as following:
: 120Gt of carbon pulled down by photosynthesis, but net photosynthesis (subtracting respiration) is around 62.5Gt. Decomposition in forests account for another 60Gt release in carbon dioxide. Hence the net carbon sequestration is about 2.5Gt.
: Amount of carbon that enters the oceans is around 92.5Gt, but around 90Gt comes back out. The net 2.5Gt carbon sequestration is attributed to marine organisms, especially algae. Algae received much attention in recent years because it pulls down less carbon dioxide than forests (only around 50Gt) but achieved similar net sequestration as forests, likely due to its extremely high turnover rate.
I would say that forests and oceans sequester similar amounts of carbon if left undisturbed, both systems together contribute to a net carbon sequestration of 5Gt a year. There are indeed programmes to try to increase the ocean net carbon sequestration by fertilizing the oceans with iron to promote algal growth or storing carbon into rocks, but many of these programmes are unrealistic (If you allow me, fertilizing the sea is just stupid) and I have reservations in whether these programmes could save us.
At the end of the day, cutting the 7Gt fossil fuel+deforestration/habitat conversion emissions is really the key, but sadly, as you've mentioned, we're definitely not doing enough.
the population dynamics of local wild boars should therefore be studied fast and detailed enough to allow more informed conservation decision. is local farming (in the traditional way) virtually non-existent now in hk? i do not know about the present views of farmers toward boar disturbances but they are of some concern for birds, insects and boars even the Red Muntjac back in the 80's. if and how are the few "organic" farms today bothered by those "pests" are not known to me.
I agree that the wild boar population dynamics should be studied. To convince people that wild boar going over it's carrying capacity is an issue to be dealt with, we need solid data, and educated guesses, like the ones I have stated in #24, are hardly enough to convince the authority to take action. The problem is, we simply don't know enough about the past. How effective are tigers/leopards in controlling the wild boar population? What is a 'health' population of wild boars? It is virtually impossible to obtain data from the past and make a case that the current situation is problematic..........