Climate Change in Agriculture

Agriculture is strongly influenced by weather and climate and in turn influences climate through greenhouse emissions and land clearance. Farmers are generally adept at managing inter-annual variability in weather conditions. However, changes to average long-term variables such as temperature, rainfall and climate extremes pose real challenges to food production. Climate change will not only directly change crop yield and livestock production but also impact agriculture indirectly through local changes in the distribution and prevalence of weeds, pests, and diseases, and access to water, as well as potentially changing global markets. These changes will be variable across the Wheatbelt (Avon) NRM region, providing both challenges and opportunities for the farming community.

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Climate Change and frost

Frost generally occurs in early spring when skies are clear and air temperatures drop below 2oC. It can have serious consequences for agriculture in the Wheatbelt NRM region by causing damage to cereal crops, especially during the crucial stage of flower development resulting in reduced yield and poor grain quality. Several factors can influence the occurrence and severity of frost including soil type, local topography and physical barriers such as trees. There has been an increase in frost risk over the last 30 years in the Wheatbelt NRM region; however this trend may reverse under future climate scenarios. Predictions for how frost occurrence will change into the future can be roughly based on projected temperature changes using the minimum temperature threshold of 2oC to map areas where frost may occur.

Climate Change and Frost

The layers presented in the map are derived from two main sources, the CSIRO Climate Change in Australia Threshold Calculator and the Bureau of Meteorology potential frost days dataset. The values represent the number of days per season with the potential to develop frost based on a minimum temperature threshold of 2oC. Projected frost data are based on two climate change scenarios (RCP 4.5 = moderate emission, RCP 8.5 = high emission) and timeframes (2030 and 2070), while the historical data are based on actual temperature data collected throughout the region from 1976-2005. Further explanation of the models used and scenario development can be found here:

Climate Projections: Model Choices for this Portal

Climate Change and heat stress

Projected increases in temperature in the Wheatbelt NRM region may have drastic consequences for the productivity of cereal crops and the growth performance of livestock into the future. Productivity is generally reduced following episodes of high temperatures during the reproductive period and intensifies with the duration of the hot spell. Temperatures above ~32-35oC can result in significant yield loss depending on the type of crop and the stage of development (as well as other external factors such as soil moisture and wind). Heat stress is a challenge that will have increased influence in the future of agriculture.

Maps and tables: Heat stress

false Climate Change: Heat Stress

false Climate Change and heat stress on Sandalwood host richness

false Regional analysis of heat stress

false Sub-regional analysis of heat stress

 

 
 
 
 
 
 
 
 

Climate Change: Heat Stress

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Climate Change and heat stress on Sandalwood host richness

The layers presented in the map are derived from the CSIRO Climate Change in Australia Threshold Calculator. Projected heat stress data are based on the number of days above the threshold of 35°C however; it is acknowledged that yield losses can occur at lower 

The maps show areas of the Avon River Basin where the projected climate may be suitable for species that host the hemiparasite sandalwood tree (Santalum spicatum). In the short-term, potential habitat for sandalwood host species may expand with increased CO2; however in the long term, suitable habitat may contract significantly.

Regional analysis of heat stress

  • Annual heat stress is projected to increase by up to 35% to 2070.
  • Spring heat stress is projected to increase up to 10-fold to 2070.

Table 1. The mean number of days > 35°C. Projected data for the whole region and historical data from Merredin BoM weather station (010092).

Period

Annual average

Spring maximum

Timeframe

Historical

2030

2070

Historical

2030

2070

RCP

N/A

4.5

8.5

4.5

8.5

N/A

4.5

8.5

4.5

8.5

Number of days above 35°C

43

52

67

52

61

1

9

9

7

10

Sub-regional analysis of heat stress

  • The Great Western Woodlands have the highest historical average annual number of days exceeding 35oC however, this region has the smallest increase in the face of projected climate change of ~10-30%; compared to the Central sub-region which is projected to increase by more than ~30-40% into the future.
  • For the most part, the number of days exceeding 35oC during spring will more than double into the future for all sub-regions except the Great Western Woodlands. The Central sub-region will potentially have the greatest increase in heat stress days for the region.

 

Table 2. The mean number of days > 35°C by sub-region. Projected data for the whole region and historical data from Merredin BoM weather station (010092).

Period

Timeframe

RCP

Avon Arc

Central

Eastern

Southern

Great Western Woodlands

Annual average

Historical

N/A

37

43

49

28

51

2030

4.5

46

59

62

34

57

2070

4.5

61

74

79

45

74

2030

8.5

47

59

62

34

57

2070

8.5

55

69

72

41

67

Spring maximum

Historical

N/A

3

4

6

3

7

2030

4.5

7

10

12

6

11

2070

4.5

7

10

12

6

11

2030

8.5

5

8

9

4

8

2070

8.5

6

11

12

8

13

Crop Yield Projections

The layers presented in the map are derived from the Western Australian Department of Food (DAFWA) Agricultural Crop Potential Yield projections for Barley, Canola, Lupins, Oats and Wheat crops in the Wheatbelt NRM region (Avon River Basin) of WA. The values represented are the projected percentage change from 2005 potential yields to the year 2050.

Climate change scenarios to 2050 used in the analysis were generated using OzClim. The temperature change scenario used was the SRES A2 CSIRO Mark II. For methodology and caveats refer to the report.

The distribution of crops is based on the DAFWA Land Capability Assessment which can be used to determine whether land is suitable for various agricultural land uses.  Note that the original data included drainage basins in the analysis. Wheatbelt NRM Inc. removed these features before calculating the regional statistics.

Crop Yield Projections

In theory, more carbon dioxide in the atmosphere should mean more vigorous plant growth (CO2 fertilisation); at least in the short-term. Therefore, on some levels, climate change may be good news for farmers. However, the positive benefits of CO2 fertilisation on growth rates (nitrogen and water-use efficiency) may be counter-balanced by decreases in plant nutritional value and increases in plant toxicity reducing the benefit to humans and livestock. Furthermore, the projected concurrent reductions in rainfall in our region may complicate the plant response. The actual consequences of CO2 fertilisation for agricultural production remain to be proven at a broad scale and will become evident over the next century. 

 

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Regional analysis

  • The total yield of all crops is predicted to decrease on average by ~9% across the region.
  • However, there are areas where all crops are predicted to show some moderate (2-9%) increases in yield.
  • Wheat yields are most likely to be adversely affected by climate change.
  • Canola and lupin yields are predicted to show the least change in the face of climate change.

 

Table 1. The regional percentage change in crop yield to 2050 due to climate change.

Crop

Average change

Max change

Min change

Range

Barley

-10

9

-14

23

Canola

-9

4

-12

16

Lupins

-6

2

-6

14

Oats

-10

8

-17

25

Wheat

-11

2

-18

20

Sub-regional analysis

  • The Avon Arc sub-region is predicted to have lowest decreases in yield for all crops while all other regions are roughly equally impacted.
  • Lupin yields are generally the least adversely affected by climate change in all sub-regions.
  • Wheat yields are the most adversely affected by climate change for all sub-regions except the Avon Arc.
  • There are areas in all sub-regions where crop yields are predicted to stay the same or show a low increase; these are roughly associated with 1. Currently high rainfall zones (Avon Arc) and; 2. The river channels where soils types and water availability have the potential to buffer crops from any potential changes in climate.

Table 1. The average percentage change in crop yield to 2050 due to climate change; by sub-region.

Crop

Avon Arc

Central

Eastern

Southern

Great Western Woodlands

Barley

-2

-11

-12

-11

N/A

Canola

-5

-10

-9

-9

N/A

Lupins

-4

-7

-5

-8

N/A

Oats

-6

-12

-11

-11

N/A

Wheat

-3

-13

-14

-13

N/A

Maps and tables: Perennial Productions Systems

Perennial Productions Systems

Perennial Productions Systems

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The carbon refugia and carbon richness maps show areas where future climate may be suitable for the success of species considered useful for carbon sequestration planting. In the short-term, the western tip of the Avon Arc, Eastern sub-region and northern half of the Great Western Woodlands may have the least suitable habitat for carbon plantings. The area of suitable habitat contracts to parts of the Avon Arc and southern third if the region in the long-term.

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Areas of suitable climate for species with potential as forage for livestock are represented in the forage refugia and forage richness maps. In the short-term, forage appears to benefit from CO2 fertilisation; however in the long term, suitable habitat for forage crops may contract significantly.

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The maps show areas of the Avon River Basin where the projected climate may be suitable for species that have a demonstrated tolerance to elevated salinity. In the short-term, potential habitat for salt tolerant species may expand with increased CO2; however in the long term, suitable habitat for salt tolerant species may contract significantly.

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