Yield is a key measurement for agricultural commodities. The effect of climate change on yield would mostly be related to drought severity and frequency. Regression modeling would be important in this regard. These issues would mostly be a function of the susceptibility of crop. For instance the use of soybean would be a potential indicator sensitive to water availability fluctuation in the farm fields. To get an influence from the climate issue optimized and deficit years can be compared statistically.

Dr. Hepperly is correct that final harvest able yield is the main variable of effects of climate change. I will suggest to include some physiological traits like photosynthesis rate, leaf are index and leaf surface area, temperature, CO2 conc along with other air variables(being indicators of climate change) and then to run multiple regression to estimate their inter-relationships and dependencies. 

Thank you Dr.s Hepperly and Ghafoor.

I had it in mind to focus on yield

sir!! biomass is an important aspect related to carbon. and the variables like atm. co2 and o2 can also be included

Air Humidity, may be an important factor

As a result of climate change towards its extremity, farmers in developing countries, which are the victims of that climate change initiated by industrialized nations, have to use more fertilizer, pesticides and herbicides for the shake of high yield. They have to face change in biodiversity. All these factors are variable  and shall be considered.

Dear Dr. Fernanda Figueroa the question is important, open and wide. So many parameters in addition we all have highlighted could be included.

 Various views have been indicated about the variables prone to climate change. No doubt, the crop yields are to be affected ultimately and all the factors contributing towards yield will be considered as variables. 

However, still there are other variables which will affect the agriculture of a country. These depend upon the outcomes of climate change that will be particular to a country depending upon its geographical location. Major ones are;

1. Consistent or partial drought, water shortage and change in hydrological cycles. It is expected that areas already facing water deficiencies will be prone to more severe situations. Resultant, there will be more utilization of saline groundwater and more salinization of lands that may change the whole agriculture evening the cropping patterns.

2. The expected high temperatures will cause more evaporation and transpiration increasing water requirement of plants.

3. Melting of ice and elevation of sea surface will cause more floods, thus not only disturbing agriculture but also causing a lot of soil erosion.

We can conclude that we should think and plan keeping all these effects in mind and fore see what will the shape and status of future agriculture when a part of climate change occurred which has already started.  

Dear Dr. Abdul Ghafoor. I do agree with you, and I think that different answers refer to the different questions posed by Dr. Ikehi. My response has to do with the first one, that was not answered completely by the former responses. Most suggestions are centered on the response of plants facing climate change. I am centering on the climate variables only.  I hope that this answer clarifies my intention. Greetings!

Most important climate variable is rainfall quantity and its distribution, which determines economic viability of any system. Recent years it has been observed that there may not be much change in quantity of rainfall but extream rainy events causing much havoc. Next variable is temperature. 

You ask about agriculture while I made some publications about carbon stock (from economic point of view) of forest: see the following link. If you are interested also to forest aspects I'll send you another publication.

http://www.sciencedirect.com/science/article/pii/S0013935115301225

The reduction in rainfall, increased extreme events, both temperatures and precipitation and increased frequency and intensity of droughts are expected effects of climate change on large agricultural areas of the planet, which will have significant economic defects.

What are climate change variables? Most common variables: temperature, humidity, wind and precipitation could be important variables to be considered in climate change studies.

What variables bear direct economic effect (whether positive or negative) to agriculture? Temperature, humidity, precipitation and wind can affect both positively (growing of new species of trees in a degraded land, e.g:  Jatropha Curcas, ) and negatively (dehydration of plants, slow growth, fruits productions…).

I really want to know if the effects of these variables have been measured or can be measured:

The effects could be measured, by statistical tools (cob douglas production function: linear or multi-factors…also estimating the yields of selected crops: e.g maize or other crops very sensitive to drought and increase in temperature…).

Please any help, file attachment or webpage redirection will be well appreciated:

http://ageconsearch.umn.edu/bitstream/31698/1/44040524.pdf

file:///C:/Users/Utilisateur/Downloads/ehsa-1-54.pdf

(interesting German projects working on the issues in West Africa) http://www.wascal.org/

Best wishes,

Abou

What are climate change variables? Most common variables: temperature, humidity, wind and precipitation could be important variables to be considered in climate change studies.

What variables bear direct economic effect (whether positive or negative) to agriculture? Temperature, humidity, precipitation and wind can affect both positively (growing of new species of trees in a degraded land, e.g:  Jatropha Curcas, ) and negatively (dehydration of plants, slow growth, fruits productions…).

I really want to know if the effects of these variables have been measured or can be measured:

The effects could be measured, by statistical tools (cob douglas production function: linear or multi-factors…also estimating the yields of selected crops: e.g maize or other crops very sensitive to drought and increase in temperature…).

Please any help, file attachment or webpage redirection will be well appreciated:

http://ageconsearch.umn.edu/bitstream/31698/1/44040524.pdf

file:///C:/Users/Utilisateur/Downloads/ehsa-1-54.pdf

(interesting German projects working on the issues in West Africa) http://www.wascal.org/

Best wishes,

Abou

What are climate change variables?

Basically they are variables or elements that partly or wholly describes  characteristics of the climate

What variables bear direct economic effect (whether positive or negative) to agriculture?

Temperature, rainfall, humidity, sunshine hours, solar radiations, water vapour etc

What staitical tool or regression model could be adopted?

The Ricardian based model

Thank you all for taking out time to response to this question. They were really helpful.

Fran