Most of these are model based studies but one thing is for sure that climate change is going to raise temperature at certain points while lowering of the same at other places.Same is case for rainfall but it will be diffrentailly affecting C4 or C3 plants.

Climate change issue is a reality. The world is now experiencing the increase of temperature and reduce of rainfall. However, the erotic or uneven nature of rainfall and temperature is the main concern for agriculture.

Both of these parameters shall be affected in climate change occurence.

Due to climate change, frequency of extreme weather and climate events like heat waves, droughts, floods & heavy precipitation, cyclones and wildfires etc, has increased.

Frequency of heat waves has increased in large parts of Europe, Asia and Australia due to which number of death tolls have risen in recent years in these regions.

Number of cold days and nights has decreased & the number of warm days and nights has increased on the global scale.

2018 report of Food and Agriculture Organization (FAO) of the United Nations (UN) says that, most of tropical regions are likely to experience production losses due to rising temperatures,

& production in temperate regions is expected to benefit from warmer climate as longer growing seasons & higher temperatures in higher latitude regions will increase their harvest.

& A 2016 report of Food and Agriculture Organization (FAO) of the United Nations (UN) said that, annual occurrence of climate-related disasters have increased from 149 in 1980-1990 to 332 in 2004 – 2014.

and the annual economic damage of climate-related disasters has increased from 14 billion USD in 1980-1990 to 100 billion USD in 2004 – 2014.

So there is a dire need to bring resiliency in agriculture in this changing climate.

http://www.fao.org/3/a-i6486e.pdf

https://www.cnbc.com/2018/09/17/un-report-shows-climate-change-effect-on-farming.html

Temperatures will increase, rainfall will decrease and crops will suffer. But not in all areas of the world. At other times it is possible to increase rainfall, for example, in dry places in South America (this is an example not based on science). You need a model of climatologists.

Dear Teodora Hristova , not only increasing but

Temperature is showing negative extremes on the other end as well.

Chicago touched -45 degree Celsius and turned as cold as the North Pole whereas New York’s touched -23 degree Celsius in the 1st week of February, 2019 this year, which is quiet below than the climatic normal of those areas.

https://timesofindia.indiatimes.com/travel/destinations/new-york-hits-23-chicago-turns-as-cold-as-the-north-pole/as67806026.cms

https://www.indiatoday.in/trending-news/story/chicago-polar-vortex-2019-boiling-water-freezes-viral-video-1443291-2019-01-31

& the general trend of rainfall in the changing climate is that

Its intensity is increasing (Amount of Rainfall per unit time),

No of rainy days are decreasing.

& Due to this uneven distribution and erratic pattern of rainfall, the agricultural farm management activities and final yields are significantly affected.

Dear Abhilash Singh Chauhan,

At these latitudes with enough snow cover, the crops should survive. Last year, temperatures in our country fell -20 degrees Celsius for 10 days, and in other parts to -30. There are some of the most fertile parts of my country.

From the summary of the question it is understood that you are asking about raising temperatures. Apparently I did not understand correctly.

While computing the agro-meteorological indices (Growing Degree Days, Helio thermal units etc) for the field Crops grown during winter season (Wheat, Barley, Mustard etc),

the base temperature is generally taken as +5 Degree Celsius i.e. this is the temperature below which all the metabolic activities of plants practically ceases,

although lower temperature is required by wheat crop for better tillering

and some of the horticultural crops may require the significant amount of Chilling hours ( temperature between 0 to 7o Celcius) for proper fruit set in Apple Trees

as if it doesn’t get enough chill hours,

the flower buds may not open at all

or they may open late in the spring,

Leaf production may also be delayed.

Blossoms may also bloom at irregular etc

Some of the crop may be hardy and tolerant to lower temperatures, But still, below freeing temperature will hamper the growth of economical Crops.

And i was generalizing that, climate change affects the weather/climatic normals/parameters/elements in both the extremes.

Like cold days are getting colder

& Warm days are getting Hotter.

Hope you understand Teodora Hristova

Kulvir Singh Thanks for the answer

Teodora Hristova tnx for the answer. I agree with your opinion

Abhilash Singh Chauhan With these comments in mind, I will consider the temperature factor.

Dear @ Abhilash Singh Chauhan

In the past, there have also been low temperatures, and more often than at present. They affected the farmers. Look for the 1200-1500 years in Europe. Here is a small sample of recent years. Absolute temperatures are not mentioned, but in the winter of 2012 temperatures are below -20 degrees.

It should not be forgotten that in different parts of the world the temperature changes have different amplitudes, and that the natural flora and fauna is adapted to them.

The last graph shows an increase in the amount of carbon dioxide that leads to warming. It is a problem that in previous cycles of concentration increase there was another kind of plant. This is now expected to negatively affect crops and humans.

https://www.google.com/search?q=%D0%B3%D1%80%D0%B0%D1%84%D0%B8%D0%BA%D0%B0+%D0%BD%D0%B0+%D0%BD%D0%B8%D1%81%D0%BA%D0%B8%D1%82%D0%B5+%D1%82%D0%B5%D0%BC%D0%BF%D0%B5%D1%80%D0%B0%D1%82%D1%83%D1%80%D0%B8+%D0%B7%D0%B0+%D0%BF%D0%BE%D1%81%D0%BB%D0%B5%D0%B4%D0%BD%D0%B8%D1%82%D0%B5+20+%D0%B3%D0%BE%D0%B4%D0%B8%D0%BD%D0%B8&tbm=isch&source=univ&sa=X&ved=2ahUKEwjd162CtbbgAhVTUhUIHbFbBOwQsAR6BAgFEAE&biw=1350&bih=640#imgrc=FmoaoQywniqfUM:

Climate changes represent a global problem for current status, but about the far future the natural selection will be active to resume the balance in the bio-ecosystem, hence the unsuitable genotypes ( may be species) will leave the life and extinct and new species will appear in the live, which have genotypes suitable for the new environments

Well, I agree with your point Teodora Hristova that

Carbon dioxide being a primary greenhouse gas is one of the major driver of climate change which is leading to global warming.

and this alarming rate of increase of of Greenhouse gases is now expected to negatively affect crops and humans, particularly in tropical areas, because the carbon fertilization effect (rate of photosynthesis in plants that results from increased levels of carbon dioxide in the atmosphere) is nullified by higher prevailing temperatures , resulting in the loss of accumulated photosynthates due to respiration.

Temperate regions are at least risk in context to agricultural productivity, due to rising temperature and CO2 levels, because these lands will experience more ambient temperatures that will suitable for more number of Crop species.

And, Since 1950's Post industrialization, the CO2 has increased significantly in the atmosphere, which has reached about 410 ppm, last month. So we have to cut off these emissions to combat the climate change.

https://www.esrl.noaa.gov/gmd/ccgg/trends/

Climate change leads to extreme weather conditions like severe droughts, floods, hurricanes, cyclones and change in monsoon pattern which will significantly affect the productivity of agricultural products.

Respected @Khalid Hassan Sir

This theory of "Survival of the fittest" of yours as proposed and inspired by Darwin, describing the mechanism of natural selection is partly apposite, but there are thousands of Critically Endangered and Vulnerable species as mentioned in the Red list of International Union for Conservation of Nature (IUCN), which meets the criteria of unsuitable genotypes/species as mentioned by you, & if not taken care of, will surely extinct in near future.

So we, being human should just not be concerned about seeking ways of our survival only,

but also of other flora and fauna, as they (more or less) also contribute to maintain the ecological balance of this planet.

Dear Abhilash Singh Chauhan

I agree with your comment, It is important issue to stop the irresponsible fast changes in the global environment which result by human activities.

Climate change may affect fitness traits of populations leading to population decline and further extinction much faster than evolution of new varieties/ species with adaptive traits. Thus, preventing loss of biodiversity of both flora and fauna becomes key factor.

It’s not due depends on whi kind of plants and tree some of themes like that some not

One of the dramatic consequence of climatic changes is the increase of drought in certain regions of the world. For this reason many scientists are working hard on the breeding and engineering of new drought resistant plants.

In addition, spells of dry periods i.e their spam and magnitude is increasing in most of arid zone.

These recurrent drought spells cause wide spread problems of resource degradation (like higher evaporation losses in arid regions, leaves salts on the surface of soil, rendering them barren for agricultural purpose) and consequently, limiting the profitability of farmers living in these areas, which ultimately leads to continued low level of overall socio-economic development.

Impact of Climate Change on Agriculture is manifested in both the ways.

1. Increase or Decrease in Temperature

2. Increase or Decrease in Rainfall

Both Increase in Temperature & Decrease in Temperature have significant effects on agriculture production. Crops are sensitive to both High and Low temperatures and require an Optimum Temperature.

In case of Rainfall, the entire Agriculture is dependent on Monsoon in one way or the other. Therefore any reduction of rainfall may cause different types of droughts which are

1. Meteorological Drought

2. Agriculture Drought

3. Physiological Drought.

These droughts are having a significant effect on the agriculture.

Jean-Pierre Jost Veeresh S Wali Abhilash Singh Chauhan Kulvir Singh Ihab Alfadhel Thanks for the answer

Dear Ashkan, I hope you are well. To answer this question, is not simple. But the most simpliest way is that climate change will exarcerbates the negative effects that limitates production and/or access to food, in every part of the world. In my best knowledge, one reason because the the human activities now exceeds the human safe operating space boudaries as instance, the biogeochemical cycles of Carbon, Nitrogen and Phosphorus. (Eessential elements for energy transfer, accumulation an dissipation for every kinf of life activities at landscape level). Best wishes!

The rise in temperature leads to an increase in the amount of water loss through Evaporation and transpiration. Therefore, greater quantities of water are needed for agricultural production, and higher temperatures lead to an increase in fungal and viral diseases and insect infestation.

I think that high temperatures are more dangerous than a reduced rainfall