Climate Change and Food Security
Global Warming and Agriculture: Impact Estimates by Country, W. Cline 2007
The 2007 Cline food security assessment was based on a global temperature increase of 3.3ºC. We are currently on track for a 3C rise by 2050. We are looking at the world that today's children will see.
The climate models used in Cline's study predicted that under the IPCC's scenario A2 scenario (a high scenario as the world is on), that global mean temperature would rise by 3.3ºC, so these results are a for a global temperature of 3.3C. This is the increase that we are committed to by today's policy being the result if all national proposals were carried out (Climate Tracker).
Because of the uncertainty of the potential carbon fertilization benefits to some crops in some regions Cline gave results for crop yield changes with and without fertilization benefits.
Risk management demands that changes without fertilization would be the basis of food security security assessment, but instead the IPCC assesses based on the assumption of large CO2 fertilization benefits based on crop experiments of doubtful validity in the real world.
Land areas would warm more than oceans, with the average surface temperature increasing by 5.0ºC weighting by land area and 4.4ºC weighting by farming area. By the 2080s, global agricultural productivity would decline by about 3% with carbon fertilization effect and by about 16% if the carbon fertilization effect did not materialize.
These losses would be disproportionately concentrated in developing countries, which would suffer losses of 9% with carbon fertilization effect and 21% without carbon fertilization effect, in contrast to an 8% gain (with carbon fertilization effect) and 6% loss (without carbon fertilization effect) in industrial countries. The detailed estimates by country and region reported in Table 2 indicate that South Asia and Africa would be the two regions most harmed by climate change. In Southeast Asia, the damages of climate change to agriculture would also be severe, ranking from 15.1% for Viet Nam to 26.2% for Thailand if carbon fertilization effect did not materialize..
Numerical table of results
Click for presentation
William Cline is an agricultural economist. His report separates out the potential CO2 fertilization effect.
However the report is on a global temperature increase of 3.3C and the IPCC says the CO2 fertilization effect no longer increases crop growth at 1.5-2.0C, therefore the Cline with CO2 fertilization does not apply.
Today global emissions are tracking this worst case IPCC scenario.
1. USDA report 2013
2. William Cline 2007
3. Food & Forestry for a Warming Planet PNAS 2007
Report: Climate change could devastate agriculture - US
February 5, 2013
A comprehensive USDA study concludes rising temperatures could cost farmers millions as they battle new pests, faster weed growth and get smaller yields as climate change continues.
• Climate change could cost farmers millions, study finds
• Warmer temperatures will make fighting pests, weeds more difficult
• Heat could make productivity of crops and livestock unpredictable (they will decline)
WASHINGTON — Climate change could have a drastic and harmful effect on U.S. agriculture, forcing farmers and ranchers to alter where they grow crops and costing them millions of dollars in additional costs to tackle weeds, pests and diseases that threaten their operations, a sweeping government report said Tuesday.
An analysis released by the Agriculture Department said that although U.S. crops and livestock have been able to adapt to changes in their surroundings for close to 150 years, the accelerating pace and intensity of global warming during the next few decades may soon be too much for the once-resilient sector to overcome.
"We're going to end up in a situation where we have a multitude of things happening that are going to negatively impact crop production," said Jerry Hatfield, a laboratory director and plant physiologist with USDA's Agricultural Research Service and lead author of the study. "In fact, we saw this in 2012 with the drought."