I completely agree. Just the amount of precipitation and temperature have a large impact on productivity. Start adding other variables such as CO2 concentration and it makes for even more changes. Some good, some bad.

Climate change have some possitive effective on farm productions that results will be published soon.

very good comments

I don't see how climate change greatly increases risk in farming. Natural variation in weather is the biggest contributor to risk of failed crops. Global warming in general will increase the number of growing degree days, which may alter which crops are grown in specific regions. Increases in temperature will also increase evapotranspiration, which means water use will increase. Alternatively as CO2 levels rise, plants do not need to open their stomata as much, thus reducing transpiration (the question is if this will offset the increase in evaporation due to temperature). Precipitation patterns are the hardest to predict because there will be variation in regional areas. This is the only aspect that I see contributing greatly to increased risk of crop failures (via drought and flooding). Unfortunately our limited data for global weather patterns makes it difficult to separate natural variation in precipitation from climate change imposed changes in precipitation. I believe that climate change will cause farmers to change their practices, but I don't believe that it is entirely doom and gloom where climate change will cause massive crop failures on a global scale aside from what humans have already experienced in regional crop failures (e.g. Irish potato famine, etc).

I agreed your state but the farmer has started adaptive resilience corp patterns which already practiced our ancient. In my suggestions also, the short term crop cultivation season may be varied but in the out come of net production will be increased in future.

Sidney, I know that 2010 is recorded as setting a heat record in the modern era. Please explain to me how this increases risk of crop failure unless there is an issue with precipitation/water for irrigation. Increased temps will increase evapotranspiration, but not necessarily spell doom for farmers unless there isn't enough water in the form of irrigation or rainfall to make up for this increase in water loss. Here in the mid-west of the USA we are currently experiencing the opposite effect of flooding which has already caused crop loss in much of the fertile areas near the major rivers.

An increase in growing degree days (as caused by increased temperatures) could allow farmers to produce multiple harvests and provide more time for planting between first/last frost. I believe these are the reasons Raja supports increased yield over time. However, the biggest component that is not as well modeled is precipitation. My guess will be that some areas will benefit while others will be hurt by regional changes caused by global climate change. Figuring this all out is the multi-billion dollar question.

There is a danger in jumping to conclusions that more extreme weather is directly related to climate change rather than natural variation in the weather patterns. To do so without a strong understanding will invariably work against scientists creating distrust by the general public. While I believe something needs to be done to help minimize the impact of global climate change, I caution jumping to conclusions about regional weather events and saying they are definitely caused by global climate change.

Sidney, another point. I have a strong case against climate change as the rationale behind the tornadoes this spring. It is known that El Nino years that tornado increase in frequency.

http://www.spc.noaa.gov/publications/schaefer/el_nino.htm

In fact, it was predicted that this year would be especially bad with tornadoes.

http://www.usatoday.com/weather/storms/tornadoes/2010-03-09-tornado_N.htm

Aside from the meteorological reasons, there are those of human demographics. This year seems especially bad due to the destruction in heavily populated areas (Joplin, MO) and in areas where people live in very unsafe housing (e.g. trailer homes). Due to increases in population and urban sprawl and the lack of meaningful wage increases, we will continue to see the number of horrific stories of people devastated by natural events. More people increases the risk of someone being affected. Secondly, low wage earners are more likely to live in sub-adequate housing, which will increase the number of fatalities and seriously injured as they have no safe place to take shelter.

Anthony i agree with what you say but a natural change in Climate is aggravated by human activities.This is all as a result of increase carbon dioxide in the atmosphere.I think what we should be looking at is what contributions do we have to reduce the incidence of climate change.to me reforestation and agroforestry is an option,What do you think.

Keghah, I agree that an increase in CO2 is a factor, there are many other greenhouse gasses to consider. Reforestation and agroforestry is a wonderful option, but shouldn't be the only options. There are other benefits to reforestation besides sequestration of CO2 (biodiversity is one of many). A move to a more sustainable use of natural resources should be the goal of all governments. Proper forestry practices would use selective logging. Unfortunately these strategies are less likely to be adopted since they cost more to implement.

In terms of molecules and radiation, would someone explain the Greenhouse Effect for me?

Bob Hamilton, Engineer

Richardson Texas USA

Bob, The answer to your question has been answered to you directly in previous post. Please do not continue to ask the same questions over and over again. You will continue to get the same answers over and over.

The only description I have ever seen is the one in 'National Geographic Magazine' in December, 2009. If you know of another please post a URL or other reference.

Thanks for your time and Enjoy the Day

Robert L Hamilton, Engineer

Bob,

I did give you a Peer-reviewed source on April 24th.

"What I described is exactly what the greenhouse effect is in very simple terms. Please see the peer-reviewed 1989 paper by John F. Mitchell titled "The "Greenhouse" Effect and Climate Change" in Reviews of Geophysics, 27(1)."

See my post in the thread:

http://www.researchgate.net/group/Climate_Change/board/thread/26842_Climate_change_and_landfills

Here is a link to the paper so you can read it:

http://www.webpages.uidaho.edu/envs501/downloads/Mitchell%201989.pdf

If you have only read the description in National Geographic than you have clearly not examined any peer-reviewed sources. A google scholar search "Greenhouse Effect and Climate Change" yields plenty of peer-reviewed sources.

http://scholar.google.com/scholar?hl=en&q=Greenhouse+Effect+and+Climate+Change&btnG=Search&as_sdt=0%2C28&as_ylo=&as_vis=0

Even Wikipedia has a description of greenhouse gases with links to 33 references. (Although I admit I hate using Wikipedia as a 'source')

http://en.wikipedia.org/wiki/Greenhouse_effect

So I am not sure how you can be limited to reading only 1 article and have such a negative view on the science because you clearly have not read enough about the science of greenhouse gases.

The article has the exact same misconception. It shows radiation being absorb near the earth's surface then 'bouncing' up to another molecule. What you cannot understand is that the molecule near the earth's surface has to cool when it radiates energy upward. There is no net increase in energy; if there was such the atmosphere would be thousands of degrees. What you et al. espouse is a violation of the most basic Law of Physics and Thermodynamics.

Robert L Hamilton

Richardson Texas USA

No water on the moon, either.

Robert L Hamilton, Engineer

Richardson Texas USA

Sorry for my late comments. I am out of the country now and I can't post a detailed responses due to poor internet access where I am, but I will try to make a simple response now.

Sidney, while I agree that CO2 can increase the temperature due to absorption of heat in the IR, I disagree that global warming is causing these droughts. They are cyclical in nature. See the rainfall patterns for the past 60+ years in Texas here:

http://doublehelixranch.com/FlyGapRainTrends.html

Rather than claim that global warming is causing droughts, I can see that global warming can increase the severity of the drought (using processes you described). In fact this process can bring more moisture to regions (due to higher water capacity) and cause more severe flooding. Ultimately these occurrences are cyclical and (mostly) independent of global warming. Huge changes in global temperature can effect weather pattern (e.g. massive melting of glacial water can reduce sea water circulation, which can severely affect global weather). Global warming will increase the risk that these events are more severe.

Bob, there is no violation of the laws of thermodynamics. The process of global warming is not heating the atmosphere with new energy but retaining heat in the atmosphere longer.

Why call it 'global warming'?

Bob Hamilton

Richardson Texas USA

It is called global warming because as heat is not released into space, the surface of the earth increases in temperature. So to us on the surface of this planet, the entire globe is warming, hence global warming.

heat wave and cold wave also affect the crops and productivity

http://www.lse.ac.uk/GranthamInstitute/wp-content/uploads/2016/07/Working-Paper-248-Costa-et-al.pdf

Article Implications of climate change for agricultural productivity...

http://www.worldbank.org/content/dam/Worldbank/document/Climate/Climate%20and%20Poverty%20Conference/D2S3_Park_Labor%20Productivity%20Impacts%20from%20Climate%20Change%20-%20Feb%2010%202015%20v13short.pdf