Alate_One
Well-known member
There are quite a few threads covering climate change on ToL and most of them are filled with all sorts of arguments, but one in particular concerning plants. Since I am actually a botanist by training I thought I'd break this one out to address in more detail.
For those interested in other climate myths and oversimplfications Skeptical Science is a great resource.
Here is a short video that covers some of the issues
One of the big issues not mentioned in the video is that not every plant actually benefits from increasing CO2 levels. This is because there is more than one type of photosynthesis found in plants.
Photosynthesis is the capturing of carbon dioxide in the air and the conversion of it into food molecules such as sugar. While all plants use the same basic pathway there are two major versions, C4 and C3 photosynthesis.
C3 plants take in Carbon dioxide from the air directly and can actually be hampered by high oxygen levels, because the enzyme that actually captures CO2 from the air can also capture oxygen.
C4 plants have developed a way around this problem by first concentrating CO2 in one cell type with a "co2 pump" so they can operate at relatively low CO2 levels.
This means that while C3 plants can readily take advantage of increased CO2 levels, C4 plants cannot do so very effectively. However, C4 plants can prosper under much drier conditions than C3 plants and one impact of climate change is thought to be increased droughts in many areas. This is especially important since major crops like Maize and Sugar Cane are C4 plants.
So the actual impacts of climate change are likely to be complex, but the net effects on agricultural production worldwide have not been shown to be positive.
Large increases in crop yield have not been borne out in open air CO2 enrichment experiments such as FACE.
Complicating matters more is the fact that plants, like animals must carry out respiration to make use of their stored carbohydrate. This releases CO2 into the atmosphere. Higher temperatures can increase respiration rates and if plants die from drought and burn in wildfires or decompose, they become sources of CO2 themselves.
Warming temperatures are certainly not uniformly good for plants. While some are adapted to very hot and dry conditions, others do not survive intense heat or if they survive, produce reduced yield.
Green beans (Phaseolus vulgaris), for example, will drop their flowers and not produce any beans if temperatures exceed 90 degrees Fahrenheit for very long.
Some plants also produce toxins in higher quantities under high CO2 levels and have altered nutrient profiles.
So simply saying CO2 is plant food and assuming all will be well is rather like the video, have everyone eat ice cream all the time!
For those interested in other climate myths and oversimplfications Skeptical Science is a great resource.
Here is a short video that covers some of the issues
| CO2 and plants | |
One of the big issues not mentioned in the video is that not every plant actually benefits from increasing CO2 levels. This is because there is more than one type of photosynthesis found in plants.
Photosynthesis is the capturing of carbon dioxide in the air and the conversion of it into food molecules such as sugar. While all plants use the same basic pathway there are two major versions, C4 and C3 photosynthesis.
C3 plants take in Carbon dioxide from the air directly and can actually be hampered by high oxygen levels, because the enzyme that actually captures CO2 from the air can also capture oxygen.
C4 plants have developed a way around this problem by first concentrating CO2 in one cell type with a "co2 pump" so they can operate at relatively low CO2 levels.
This means that while C3 plants can readily take advantage of increased CO2 levels, C4 plants cannot do so very effectively. However, C4 plants can prosper under much drier conditions than C3 plants and one impact of climate change is thought to be increased droughts in many areas. This is especially important since major crops like Maize and Sugar Cane are C4 plants.
So the actual impacts of climate change are likely to be complex, but the net effects on agricultural production worldwide have not been shown to be positive.
Large increases in crop yield have not been borne out in open air CO2 enrichment experiments such as FACE.
Complicating matters more is the fact that plants, like animals must carry out respiration to make use of their stored carbohydrate. This releases CO2 into the atmosphere. Higher temperatures can increase respiration rates and if plants die from drought and burn in wildfires or decompose, they become sources of CO2 themselves.
Warming temperatures are certainly not uniformly good for plants. While some are adapted to very hot and dry conditions, others do not survive intense heat or if they survive, produce reduced yield.
Green beans (Phaseolus vulgaris), for example, will drop their flowers and not produce any beans if temperatures exceed 90 degrees Fahrenheit for very long.
Some plants also produce toxins in higher quantities under high CO2 levels and have altered nutrient profiles.
So simply saying CO2 is plant food and assuming all will be well is rather like the video, have everyone eat ice cream all the time!
