Carbon dioxide (CO2) is airborne plant food.
CO2 is not a pollutant.
The term "carbon pollution" is a meaningless term used by people ignorant of science, or smarmy people using it as propaganda.
All plants benefit from higher levels of CO2 in the air.
The current level of CO2 in the air is near the lowest ever on our planet.
Plants, and the animals and people who eat them, would all benefit from deliberately adding more CO2 to the air.
Greenhouse owners have been using CO2 enrichment to enhance crop production for decades.
There is no evidence in 4.5 billion years of climate history that CO2 has ever been a 'temperature controller' -- anyone claiming that is making it up out of thin air.
The ONLY effect of CO2 discovered in climate history proxy studies, such as ice cores, is that natural global warming of the oceans, causes unknown, releases some of the CO2 dissolved in the oceans, with a 500 to 1,000 year-lag
Based on extrapolations from laboratory experiments, most scientists believe adding CO2 to the air will cause mild global warming.
A small group of "scientists" who do computer modeling predict triple the CO2 warming suggested by those CO2 laboratory experiments, and their beliefs resulted in three decades of grossly inaccurate computer model average temperature predictions.
I disagree with the assumption that more CO2 in the air MUST cause warming because there are so many decades when CO2 increased, but the average temperature remained flat, or went down, such as from 1940 to 1975 (downtrend), and from 1998 to 2015 (flat trend).
Pointing out that CO2 levels and average temperatures both rose from 1975 to 1998, while ignoring other decades, is good propaganda, but bad science.
Fortunately, greenhouse gas warming would be mainly at night ... a time of day when most people are sleeping.
The C3 and C4 photosynthetic pathways are most important, because the other pathway (CAM) is only used by cacti and similar plants that are not part of the human diet.
The C3 process evolved over 400 million years ago when CO2 levels were many times current levels, and is used by about 85% of current plant species.
The predecessors to evergreens evolved about 360 million years ago when CO2 levels were about 4,000 ppm (vs. 400 ppm today).
C3 plants include beans, rice, wheat, barley, rye, oats, soybeans, peanuts, cotton, sugar beets, spinach, potatoes, all woody trees. and most lawn
grasses.
Flowering and deciduous trees evolved about 160 million years when CO2 levels were about 2,000 ppm (vs. 400 ppm today).
The C4 process evolved about 30 to 40 million years ago, when CO2 levels had dropped to levels higher than todays, but much lower than when C3 plants evolved.
C4 plants include corn, sugarcane, sorghum, millet, Bermuda grass and poa.
Most C3 plants lose about 90% of biomass production at about 150 ppm CO2.
So it was very good news that CO2 levels did not decline below about 175 ppm during the peak glaciation about 20,000 year ago, when the colder oceans held more CO2 than today (just like cold soda pop holds more dissolved CO2 than a warm soda pop does).
C3 plants show a larger response to more CO2 in the air, but C4 plants also benefit.
As CO2 levels increase, up to certain limits, plants also use water more efficiently.
The stomata, or pores, on the leaves of plants must remain open longer at low CO2 concentrations to allow sufficient CO2 to enter the plant.
While stomata are open, water vapor escapes from the plant as transpiration.
The longer the stomata remain open to allow sufficient CO2 to enter the leaf for photosynthesis to occur, the more water escapes.
That means plants are more drought resistant when there are higher levels of CO2 in the air.
At the CO2 levels during the last peak of glaciation 20,000 years ago, C3 plants were under stress from CO2 levels of about 175 ppm.
Rising CO2 levels accelerate the growth rates of most plant species existing today.
Does you favorite media source ever mention that fact?
The benefit from burning fossil fuels, of greening the planet, should be considered in addition to the costs of burning fossil fuels (toxic substances added to the air, such as soot, nitric oxides, sulfur dioxides, and trace amounts of radioactive material).
Global vegetation appears to be responding to more CO2 in the air.
There are three long-term satellite leaf area index (LAI) records since the 1980s.
There has been a widespread increase of growing season integrated LAI (greening) over 25% to 50% of the global vegetated area.
Less than 4% of the globe shows decreasing LAI (browning).
CO2 fertilization effects explain most of the observed greening trend, especially the greening trends in the tropics.
During the 400 million years that plants have existed on Earth, the average CO2 level has been about 1,000 ppm -- and 1,000 ppm would be a good target for future CO2 levels.
If you ignore the false CO2 scaremongering, there is an obvious answer to the question of what level of CO2 is optimal -- our plants want MORE CO2 in the air -- double or triple today's level of 400 ppm. would be a logical goal.
Ask any greenhouse owner!