The one major climate anomaly that needs explanation is the Bronze Age warm period and its aftermath which we are living in today. During the Bronze Age, the climate appeared to be, at least on the basis of the science to date, a couple of degrees warmer than the present temperature regime. It ended with a bang as Hekla blew up, but why was recovery never full? We have had near attempts to restore that climatic regime, such as the medieval warm period, but all have ended badly. We are now clearly living through another such warm spell.
The chart shows a two thousand year warm spell that was untouchable. I have to accept that the data proxies are also fairly consistent for that era. The question remains, what mechanism lowered the global heat content?
For that we have the stripping of the Sahara by misplaced human agricultural practice. Today, solar energy is not absorbed or stored there at all. It is mostly reflected back into space. If that energy were been collected by vegetation, it would represent a huge addition to the earth’s heat content. The loss of that heat surely was responsible for post Bronze Age coolness.
We now have increasing evidence that the surplus CO2 in the atmosphere has now encouraged an increase in plant life throughout the globe. This should increase direct solar energy absorption and has likely contributed to the slightly warmer global conditions. Note the attached report.
With this excess of CO2 in the atmosphere, there is ample reason to restore the Sahara as growing environment. We have already addressed some of the needed methodology. I am not sure that I have added more since my earliest postings.
The first question is what really can be done using native dry land vegetation and is there any obvious engineering solutions. Solar driven atmospheric water extraction is a long way from been actually a feasible option although clunky demos have been built.
Before we start, it must be understood that reforesting the Sahara will lead to a far warmer Northern Hemisphere and that this is actually a good thing, It is also reasonable to anticipate the regreening of the entire Middle East. This will generate a warmer but moderated northern Hemisphere. This is one of the greatest single Terraforming tasks left to us to accomplish.
As I have posted earlier, the first step is the building of fenced range lands along the edge of the true desert. That controls the cropping behavior and allows a resurgence of vegetation promoting the retention of moisture. This perimeter culture will migrate backward into the more arable lands and also enhance their productivity. This should tend to encourage an increase in available moisture into the nearby desert lands.
Most critically, it has been shown that the establishment of acacia trees provides shade and a reduction in general temperature increasing the probability of night showers. It has also been shown that such an environment is conducive to the raising of indigenous cattle that are able to graze the developing grasses and possible under story. One would expect that the best strategy would also include other native ruminants that browse more difficult fodder. No goats should be permitted as they will attack and destroy the whole plant.
The idea is to advance this culture into the desert one fence row at a time as the following advance of available moisture accommodates. Without use of artificial means this does promise to take many years. Yet it will still be hugely advanced. The necessary population exists along the entirety of the southern edge of the Sahara with the necessary skills. In most cases it will be a problem of establishing title and supplying barb wire. It will be a lot like the spread of farming on the Great Plains.
We actually know that this was all likely viable grazing land in the beginning that was destroyed over a thousand years. Restoring it this way would likely take another thousand years.
To speed the process up, it should be possible to first design some large water diversion schemes that transfer water into suitable desert regions. It will never be enough but is will expand the watered regions and increase the atmospheric moisture content in those regions, once again allowing a gradual dry land expansion.
The principal prospect for this is the diversion of most of the water in the Upper Congo Basin over to the Chad Basin, perhaps not creating a lake so much as a fully watered basin with a sustainable lake that hopefully is large enough to drain. The possibility would also exist for additional diversion into the north. Work done seventy years ago suggested that this might be feasible.
It is also possible to create a biannual diversion of the Nile west of its current route but this may be of doubtful value until we are in the very late stages.
That then opens the remaining question of whether there is any method to divert some water north from the Niger Valley. At first blush, this appears very unlikely except the rainy season produces a huge amount of water that naturally is lost to the sea. It may be possible to divert sections of that river system to the north into valleys running into the Sahara. There should still be ample water for down river applications.
The truth is that that these engineering options help, but actually for a small fraction of the Sahara. The place is several millions of square miles and it would be a miracle to provide direct irrigation for even a quarter million square miles.
Therefore without actual atmospheric moisture recovery, we are looking at relying on natural recovery aided at least by our direct land management efforts. This might be at the rate of a mile per year, so that you are always followed closely by emergent tree cover. It will require two thousand years at this rate to do the Sahara, and assuming a simultaneous effort in the Middle East, much the same time.
The process may go faster if appropriate grasses can be used.
The chart shows a two thousand year warm spell that was untouchable. I have to accept that the data proxies are also fairly consistent for that era. The question remains, what mechanism lowered the global heat content?
For that we have the stripping of the Sahara by misplaced human agricultural practice. Today, solar energy is not absorbed or stored there at all. It is mostly reflected back into space. If that energy were been collected by vegetation, it would represent a huge addition to the earth’s heat content. The loss of that heat surely was responsible for post Bronze Age coolness.
We now have increasing evidence that the surplus CO2 in the atmosphere has now encouraged an increase in plant life throughout the globe. This should increase direct solar energy absorption and has likely contributed to the slightly warmer global conditions. Note the attached report.
With this excess of CO2 in the atmosphere, there is ample reason to restore the Sahara as growing environment. We have already addressed some of the needed methodology. I am not sure that I have added more since my earliest postings.
The first question is what really can be done using native dry land vegetation and is there any obvious engineering solutions. Solar driven atmospheric water extraction is a long way from been actually a feasible option although clunky demos have been built.
Before we start, it must be understood that reforesting the Sahara will lead to a far warmer Northern Hemisphere and that this is actually a good thing, It is also reasonable to anticipate the regreening of the entire Middle East. This will generate a warmer but moderated northern Hemisphere. This is one of the greatest single Terraforming tasks left to us to accomplish.
As I have posted earlier, the first step is the building of fenced range lands along the edge of the true desert. That controls the cropping behavior and allows a resurgence of vegetation promoting the retention of moisture. This perimeter culture will migrate backward into the more arable lands and also enhance their productivity. This should tend to encourage an increase in available moisture into the nearby desert lands.
Most critically, it has been shown that the establishment of acacia trees provides shade and a reduction in general temperature increasing the probability of night showers. It has also been shown that such an environment is conducive to the raising of indigenous cattle that are able to graze the developing grasses and possible under story. One would expect that the best strategy would also include other native ruminants that browse more difficult fodder. No goats should be permitted as they will attack and destroy the whole plant.
The idea is to advance this culture into the desert one fence row at a time as the following advance of available moisture accommodates. Without use of artificial means this does promise to take many years. Yet it will still be hugely advanced. The necessary population exists along the entirety of the southern edge of the Sahara with the necessary skills. In most cases it will be a problem of establishing title and supplying barb wire. It will be a lot like the spread of farming on the Great Plains.
We actually know that this was all likely viable grazing land in the beginning that was destroyed over a thousand years. Restoring it this way would likely take another thousand years.
To speed the process up, it should be possible to first design some large water diversion schemes that transfer water into suitable desert regions. It will never be enough but is will expand the watered regions and increase the atmospheric moisture content in those regions, once again allowing a gradual dry land expansion.
The principal prospect for this is the diversion of most of the water in the Upper Congo Basin over to the Chad Basin, perhaps not creating a lake so much as a fully watered basin with a sustainable lake that hopefully is large enough to drain. The possibility would also exist for additional diversion into the north. Work done seventy years ago suggested that this might be feasible.
It is also possible to create a biannual diversion of the Nile west of its current route but this may be of doubtful value until we are in the very late stages.
That then opens the remaining question of whether there is any method to divert some water north from the Niger Valley. At first blush, this appears very unlikely except the rainy season produces a huge amount of water that naturally is lost to the sea. It may be possible to divert sections of that river system to the north into valleys running into the Sahara. There should still be ample water for down river applications.
The truth is that that these engineering options help, but actually for a small fraction of the Sahara. The place is several millions of square miles and it would be a miracle to provide direct irrigation for even a quarter million square miles.
Therefore without actual atmospheric moisture recovery, we are looking at relying on natural recovery aided at least by our direct land management efforts. This might be at the rate of a mile per year, so that you are always followed closely by emergent tree cover. It will require two thousand years at this rate to do the Sahara, and assuming a simultaneous effort in the Middle East, much the same time.
The process may go faster if appropriate grasses can be used.
