Answer:
No it does not. The effects of global warming have taken drastic effects on Earth and the carbon dioxide is not good whatsoever in the Earth's atmosphere. It may play a role but having a larger quantity is not good.
Step-by-step explanation:
Most plants have a sweet spot for photosynthesis between 85 and 95 F. Below this, and chemical reactions are slower, above this, and the plant starts shutting down because it's losing water too rapidly. (Plants in very humid climates can do better this way). So plants in areas that have cool summers will generally do better -- as long as it isn't *so* much warmer that they are no longer adapted. Plants that are in warmer areas will do worse -- they spend more time, on average at temps too high to photosynthesize.
But WAIT, there's MORE.
With more CO2 plants grow faster. This is used in greenhouses, and they will run the CO2 up to a thousand parts per million.
There are two classes of photosynthesis referred in the literature as C3 and C4. Turns out that C3 plants don't benefit much from increased CO2, but C4 plants do. A lot of our food crops are C3. Most of our weed crops are C4. So increased CO2 overall helps the weeds at the expense of the crops.
THAT's not ALL
If you don't act now, we will include at NO EXTRA CHARGE, Shifting Rainfall Patterns. Your farm can have a different amount of rain than everyone is used to.
Even in places that get the same average rainfall each year, the variance may be different. E.g. June rain records for 10 years:
3, 3.5, 3, 4, 3.5, 4, 5, 2.5, 3, 2.5 = average 3.4
2, 5, 2,3, 3, 2, 6, 2.5, 5, 1.5 = average 3.4
(if I've not screwed up my arithmetic) But look at how much more variation there is in the second one. The century from 1880 to 1980 was one of the most stable ones in history. This means more crop failures. More heat waves AND more cold snaps -- but with the heatwaves over balancing the cold snaps overall. More droughts and more floods. Take a look where you live. If you live on a flood plain, think about moving. If your street has ever had a rain that was more than the storm drains could cope with; if you are on a coast that has *ever* been hit with a hurricane, or paralyzing winter storm that brought the city to a halt and created wide spread property damage; if you live in a region subject to evacuations for forest fire then give some thought to how you are going to cope with the next natural disaster.
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Now to the main center: Does a higher concentration of CO2 in the atmosphere enhance photosynthesis?
It can. It’s not the only factor, but everything else being equal, an increase in CO2 from the pre industrial level of 280 PPM up to current 420 PPM does help plants grow faster.
Everything else isn’t always equal though, so the entire Earth isn’t getting greener, contrary to what some people claim. Parts of the Earth are less green as a result of the increase in CO2. Some parts are flooded by salt water and the soil is harmed. Some parts are drier and prone to increased drought or wild fires, or prone to larger temperature shifts, so it’s not all good news. Not even close. In fact, climate change brings significantly more harm than benefit.
But to the specific question, higher CO2 can increase the rate of photosynthesis and the rate of plant growth, which can also lead to less nutrition in those plants if they are being grown for food.