A Position Statement on Climate Change from the Agriculture Sector

AgMRC Renewable Energy & Climate Change Newsletter
August 2011

Don HofstrandDon Hofstrand
Agricultural Economist


Three agricultural societies recently published a position statement on climate change.  The American Society of Agronomy (1), the Crop Science Society of America (2) and the Soil Science Society of America (3) released a statement in May of 2011.  The information below is taken from the statement which can be found in its entirety this link.

The position statement begins, “A comprehensive body of scientific evidence indicates beyond reasonable doubt that global climate change is now occurring and that its manifestations threaten the stability of societies as well as natural and managed ecosystems.  Increases in ambient temperatures and changes in related processes are directly linked to rising anthropogenic (4) greenhouse gas (GHG) concentrations in the atmosphere.” 

It goes on to state that “The potential related impacts of climate change on the ability of agricultural systems, which include soil and water resources, to provide food, feed,fiber, and fuel, and maintenance of ecosystem services … as well as the integrity of the environment, are major concerns.”

Moreover,the report states that crop production will face increasing challenges linked to climate change.  Even though long-term projections suggest that temperatures will increase gradually, potential increases in variations of temperature and rainfall can produce profound impacts on food and energy security.  In near-term decades, higher CO2 may provide some benefits to plant growth and water use, but these are likely to be offset by negative effects of rising temperatures and altered rainfall,especially in subsequent decades.  Understanding the impact of climate change variables and their progressive interactions is critical to developing agricultural systems that will enhance productivity even in a changing climate.

Global temperatures rose 1.25 degrees Fahrenheit (0.75 degrees Centigrade) in the 20th century, and are projected to increase 3.22 to 7.20 degrees Fahrenheit (1.8 to 4.0degrees Centigrade) by the end of the 21st century.  Changes in temperature have already begun to affect crops, water availability, and pests in some areas.  Such changes have advanced the spring green-up of perennial crops in the Northern Hemisphere and contributed to an increase in forest fires and pests in North America.

Climate Effects on Crops

The report outlines four major ways in which climate changes impact crops.

  1. Higher temperatures and heatwaves affect the growth and development of crops, influencing potential yields.  An example is the number of days a crop is exposed to temperatures exceeding specific thresholds during critical growth stages such as flowering, pollination and grain filling.
  2. Changes in the patterns of precipitation alters water supply for crops.  Climate change is expected to destabilize pre-existing rainfall regimes in many regions, resulting in changes in duration and intensity of flooding episodes and period of drought. 
  3. Increased atmospheric carbon dioxide (CO2)concentrations may have positive effects on some crops, the effects being species-dependent.  The photosynthesis, growth, and yield of C3plants such as wheat and rice tend to benefit more from high CO2 than doC4 plants such as corn.  Higher CO2 in the air also increases the efficiency of water use by crops.
  4. Changes in temperature, precipitation and CO2 will interact with other environmental stresses such as ozone, which tend to reduce crop productivity.

Mitigation and Adaptation

The report stresses two approaches to combat the impact of climate change. The first focuses on mitigation or slowing the speed of warming by reducing greenhouse gas emissions and removing existing atmosphericCO2.  Many opportunities exist to mitigate emissions and to sequester carbon. 

The other is adaptation which refers to the process of system adjustments to changes in environmental conditions.  It includes actions taken in response to actual climate changes and actions that prepare for future climate changes. 

A combination of both mitigation and adaptation actions are critical for successfully dealing with this problem. 

Stages of Adaptation

As climate changes proceed in agricultural regions, the report outlines three stages of adaptation related to the level of effort required.

Stage 1: When climate changes are relatively small, many current techniques are available to help farmers adapt.  These early-stage adaptations include varying sowing dates and cultivar, fertilization, and irrigation scheduling; as well as changing to better-adapted alternative crops.

Stage 2: As climate change proceeds, more extensive changes may be needed including the genetic improvement of crops to create greater tolerance to elevated temperatures and drought and improve responsiveness to rising CO2 and the development of new technologies.

Stage 3: In later decades, severe climate changes in agricultural regions may necessitate transformative shifts to entirely different agricultural systems, such as from temperate-zone to subtropical or semiarid-zone forms of agriculture.

Climate change has the potential to increase weather variability as well as gradually increase global temperatures.  Both of these impacts have the potential to negatively impact the adaptability and resilience of the world’s food production capacity; current research indicates climate change is already reducing the productivity of vulnerable cropping systems. 

There is a pressing need to improve agricultural productivity for food security while simultaneously protecting the environment as climate is changing. The goal is to:

  • produce higher yields with reduced greenhouse gas emissions per unit of production,
  • conserve and enrich the organic content of soils,
  • promote efficient water use, and
  • promote ecosystem integrity. 

Other Position Statements on Climate Change (5)

A large number of other scientific organizations have issued position statements on climate change. The listing may not be inclusive of all scientific organization position statements.

Statements by concurring organizations

  • Academies of Science -- joint statement by 32 national science academies
  • InterAcademy Council
  • European Academy of Sciences and Arts
  • International Council of Academies of Engineering and Technological Sciences
  • Network of African Science Academies
  • Royal Society of New Zealand
  • Royal Society of the United Kingdom
  • Polish Academy of Sciences
  • National Research Council (US)
  • American Association for the Advancement of Science
  • American Chemical Society
  • American Institute of Physics
  • American Physical Society
  • Australian Institute of Physics
  • European Physical Society
  • European Science Foundation
  • Federation of Australian Scientific and Technological Societies
  • American Geophysical Union
  • European Federation of Geologists
  • European Geosciences Union
  • Geological Society of America
  • Geological Society of Australia
  • Geological Society of London
  • International Union of Geodesy and Geophysics
  • National Association of Geoscience Teachers
  • American Meteorological Society
  • Australian Meteorological and Oceanographic Society
  • Canadian Foundation for Climate and Atmospheric Sciences
  • Canadian Meteorological and Oceanographic Society
  • Royal Meteorological Society (UK)
  • World Meteorological Organization
  • American Quaternary Association
  • International Union for Quaternary Research
  • American Association of Wildlife Veterinarians
  • American Institute of Biological Sciences
  • American Society for Microbiology
  • Australian Coral Reef Society
  • Institute of Biology (UK)
  • Society of American Foresters
  • The Wildlife Society (international)
  • American Academy of Pediatrics
  • American College of Preventive Medicine
  • American Medical Association
  • American Public Health Association
  • Australian Medical Association
  • World Federation of Public Health Associations
  • World Health Organization
  • American Astronomical Society
  • American Statistical Association
  • Engineers Australia (The Institution of Engineers Australia)
  • International Association for Great Lakes Research
  • Institute of Professional Engineers New Zealand

Non-committal statements

  • American Association of Petroleum Geologists
  • American Association of State Climatologists
  • American Geological Institute
  • American Institute of Professional Geologists
  • Canadian Federation of Earth Sciences

Statements by dissenting organizations

No dissenting statements on climate change by scientific organizations were listed.  However, a number of individual scientists are on record as dissenters.  Regardless, a number of surveys have revealed that a substantial majority of scientists believe that global warming is occurring and that human factors are a major contributor.


1  The American Society of Agronomy is an international scientific society with 8,000+ members. 

2  The Crop Science Society of America is an international scientific society with 6,000+ members. 

3  The Soil Science Society of America is a progressive, international scientific society with 6,000+ members. 

4  Anthropogenic greenhouse gas emissions are emissions caused by human activity.