Global Warming Science -


CO2 Increases Agricultural Productivity


[last update: 2010/10/31]



Warmer, wetter climate helping U.S. farmers grow more crops



Warmer and wetter weather in large swaths of the country have helped farmers grow corn, soybeans and other crops in some regions that only a few decades ago were too dry or cold, experts who are studying the change said.


Bruce Babcock, an Iowa State University agriculture economist, said soybean production is expanding north and the cornbelt is expanding north and west because of earlier planting dates and later freezes in the fall. "The Dakotas are pretty big corn producers now and soybeans have dramatically increased in North and South Dakota," Babcock said


Brad Rippey, a U.S. Department of Agriculture meteorologist, said warming temperatures have made a big difference for crops such as corn and soybeans."It bends the boundaries of where crops can be planted," Rippey said. "I think we'll continue to see some shifting in crop patterns." For example, data from the National Agricultural Statistics Service show that in 1980, about 210,000 soybean acres were planted in North Dakota. That has gradually increased to more than 3 million acres in recent years.


The following section examines the climate data using NOAA National Climatic Data Center (NCDC) data plotted at




North Dakota: Soybean production has increased tremendously since 1980


Are the claims reported above substantiated by the climate data? The following graphs are North Dakota data.


More rain? The data show no statistically significant trend in spring or summer rainfall – the critical times for crops.




Earlier planting dates? But spring temperatures have been declining in recent decades.




Later freezes in the fall? But there is no statistically significant change in fall temperatures.




The most likely scenario? More soybean acreage is being planted.




Warmer Weather or Increased CO2?


The USDA provides agricultural productivity data [] listing state-by-state yearly data. The data has been graphed by David Archibald [] and is shown below for 1960 to 2005 for several states. I have added the thick red line showing atmospheric CO2 at Mauna Loa over the same time period (CO2 graph from


Agricultural Productivity for Six States, Plus Atmospheric CO2 (Red – Scale at right)



One of the states with the highest increase in agricultural productivity is Minnesota. While fall temperatures have increased, neither spring nor summer have. The following graphs are from the NCDC data.

[] (According to the IPCC the CO2-based warming only shows up in the record since the mid-1970s – see



See also:




CO2 Increases Crop Production


Studies of crop growth rates under various concentrations of CO2 also show a positive effect of the current increase in atmospheric CO2. The following figures show an example. []





A study of tree growth in Maryland indicates that “forests in the Eastern United States are growing faster than they have in the past 225 years” and is attributed to increased CO2 []


Studies of peanut growth in the United States have found increased crops with elevated CO2. For example a study of the effects of increase O3 (ozone) and CO2 [] found: “adverse effects of tropospheric O3 on C3 crop plants are ameliorated by elevated concentrations of atmospheric CO2


Another 2009 study [] states: “Growth at elevated [CO2] stimulates photosynthesis and increases carbon (C) supply in all C3 species.”




CO2 Is Increasing Vegetation Worldwide


The following figure is from the United Nations UNEP [] showing a substantial increase in global productivity from 1981 – 2003 (the UNEP’s figure caption was “losses in land productivity due to land degradation” – typical of the UN’s cup-half-empty viewpoint).




The following figure is from a study “Long Term Monitoring of Vegetation Greenness from Satellites”





The following figures show crop production in China and India for 1968-2009 (“Crop production index shows agricultural production for each year relative to the base period 1999-2001. It includes all crops except fodder crops.” [])





Why is central Africa having a decrease in NPP instead of increase?

(From figure shown previously)

 Because Africa is burning with human-caused deforestation.



These African countries are the ones said to be most vulnerable to global warming (see: What they are most vulnerable to is overpopulation.


Agricultural productivity has been increasing in most of Africa. Africa’s problems are not due to US CO2 emissions causing “climate change”. According to a UN report: “Africa has 733 million hectares of arable land (27.4 per cent of world total) compared with 570 million hectares for Latin America and 628 million hectares for Asia. Only 3.8 per cent of Africa’s surface and groundwater is harnessed, while irrigation covers only 7 per cent of cropland (3.6 per cent in SSA). Clearly, there is considerable scope for both horizontal and vertical expansion in African agriculture. … Insecurity in land ownership has been blamed for accelerated land degradation and lack of long-term investments in sustainable land management and stewardship of natural resources.” Like most studies of Africa agricultural problems, the UN report recommends “Increase fertilizer use from the low levels of 125 gm/ha to at least 500 gm/ha, which is about half of the world average, and increasingly aim to reach the world average. …Strategies for transforming African agriculture have to address such challenges as low investment and productivity, poor infrastructure, lack of funding for agricultural research, inadequate use of yield-enhancing technologies” []


 See: IPCC Misleads on African Agriculture:




See also:


Increasing Arctic Plant Biomass: