In a report entitled Carbon Dioxide: The Good News, Dr Goklany says that carbon dioxide (CO2), the principal man-made greenhouse gas, has many benefits for the natural world and for humankind. The scholar and author, who is a member of the Global Warming Policy Foundation, a think-tank which aims to "put balance back into the climate change debate", says that CO2 “fertilises plants, and emissions from fossil fuels have already had a hugely beneficial effect on crops, increasing yields by at least 9%-11%”.
The policy analyst, who holds a PhD in electrical engineering, says this has “not only been good for humankind but for the natural world too, because an acre of land that is not used for crops is an acre of land that is left for nature”.
Goklany says thousands of experiments since the 1800s have shown that the majority of plants grow faster and larger, both above and below ground, if they are exposed to higher CO2 concentrations. He says the optimum level for this growth is twice the level of today’s ambient concentration of 400 parts per million (ppm), and adds that some plants may continue to respond positively at even higher CO2 levels.
The report refers to a database of peer-reviewed papers assembled from studies of the effect of CO2 on plant growth by the Centre for the Study of Carbon Dioxide and Global Change. These studies show that for the 45 crops that account for 95% of global crop production, an increase of 300ppm of carbon dioxide would increase yields by between 5% and 78%.
According to the report, CO2 has also been found to increase the efficiency with which plants consume water and, consequently, “under higher carbon dioxide conditions, less water is needed to increase a plant’s biomass by any given amount. In other words,” the author states, “higher carbon dioxide levels increase plants’ ability to adapt to water-limited (or drought) conditions, precisely the conditions that some environmentalists claim are already occurring.”
Lower variation in yields
Dr Goklany also refers to a study which found that higher CO2 levels are associated with lower variation in yields for each crop.
“This is consistent with the notion that increased CO2 levels reduce the sensitivity of yield to other factors (eg water shortages and air pollution). All else being equal, lower variation translates into a more stable supply of food, as well as more stable food prices, which benefits all consumers everywhere.”
Dr Goklany’s report flies in the face of other scientific views on the negative impact of CO2 emissions on food production reliability. For example, a 2010 study from researchers at the University of California, Davis, demonstrated the inhibition of wheat crops to convert nitrate into a protein, due to increased CO2 levels, which affects its nutritional value. Lead author of study and plant scientist Professor Arnold Bloom said “Food quality is declining under the rising levels of atmospheric carbon dioxide that we are experiencing.”
The study says that if carbon dioxide levels continue to rise and negatively effect plants and crops, the amount of food proteins in the whole world could drop as much as 3% in just a few decades. Referring to the initial increase in growth, as described by Oklany's report, Bloom says, "at first higher levels of CO2 reduces photorespiration, which boosts photosynthesis in plants. In time, however, the increase in the rate of photosynthesis tapers off as the plants adjust to increased atmospheric carbon dioxide, and plant growth slows."
Moreover, the US Environmental Protection Agency acknowledges that warmer temperatures can increase crop yields, but adds the caveat that more extreme temperatures, precipitation, and pest multiplication, also caused by CO2, can prevent crops from growing. Oklany's report dismisses the likelihood of these events, saying the "science is not settled" on these issues.
Ireland's environmental obligations
As for Ireland’s responsibilities on CO2, the European targets to which we are bound, in round figures, require EU-wide emissions reductions (relative to 1990 levels) of 20% by 2020, 40% by 2030 and an envisaged 80% to 95% by 2050. More than 30% of Ireland’s emissions come from agriculture and most of these are from dairy and beef production.
At world level, the UN is preparing for a major climate conference in Paris in December, aimed at reaching international agreement on a global reduction of greenhouse gas emissions.