Chapter 1 describes the CropWatch Agroclimatic Indicators (CWAIs) rainfall (RAIN), temperature (TEMP), and radiation (RADPAR), along with the agronomic indicator for potential biomass (BIOMSS) in 105 global Monitoring and Reporting Units (MRU). RAIN, TEMP, RADPAR and BIOMSS are compared to their average value for the same period over the last fifteen years (called the “average”). Indicator values for all MRUs are included in Annex A table A.1. For more information about the MRUs and indicators, please see Annex B and online CropWatch resources at www.cropwatch.com.cn.  

1.1 Introduction to CropWatch agroclimatic indicators (CWAIs)

This bulletin describes environmental and crop growth conditions over the period from July to October 2024, JASO, referred to as "reporting period". CWAIs are averages of climatic variables over agricultural areas only inside each MRU and serve the purpose of identifying global climatic patterns. For instance, in the "Sahara to Afghan desert" MRU, only the Nile Valley and other cropped areas are considered. MRUs are listed in Annex B. Refer to Annex A for definitions and to table A.1 for AMJJ numeric values of CWAIs by MRU. Although they are expressed in the same units as the corresponding climatological variables, CWAIs are spatial averages limited to agricultural land and weighted by the agricultural production potential inside each area. 

We also stress that the reference period, referred to as "average" in this bulletin covers the 15-year period from 2009 to 2023. Although departures from the 2009-2023 are not anomalies (which, strictly, refer to a "normal period" of 30 years), we nevertheless use that terminology. The specific reason why CropWatch refers to the most recent 15 years is our focus on agriculture, as already mentioned in the previous paragraph. 15 years is deemed an acceptable compromise between climatological significance and agricultural significance: agriculture responds much faster to persistent climate variability than 30 years,which is a full generation. For "biological" (agronomic) indicators used in subsequent chapters we adopt an even shorter reference period of 5 years (i.e., 2019-2023). This makes provision for the fast response of markets to changes in supply. 

Correlations between variables (RAIN, TEMP, RADPAR and BIOMSS) at MRU scale derive directly from climatology. For instance, the positive correlation between rainfall and temperature results from high rainfall in equatorial, i.e., in warm areas. 

Considering the size of the areas covered in this section, even small departures may have dramatic effects on vegetation and agriculture due to the within-zone spatial variability of weather. It is important to note that we have adopted an improved calculation procedure of the biomass production potential in the bulletin based on previous evaluation.

1.2 Global overview

This report covers the hottest summer on record according to the Copernicus Climate Change Service. 2024 is on track to be the first year in which the critical threshold of 1.5ºC above pre-industrial levels is surpassed. Heat waves affected Japan throughout the summer. In some parts of China, heat waves occurred in August and record-setting high temperatures exceeding 40ºC were recorded in Australia during August as well. El Niño has ended, but some regions, such as in southern Africa and the Amazon basin, still suffered from its lingering effects, as the extreme droughts, exacerbated by global warming, continued. Rainfall may return to normal levels in the coming months, as the El Niño–Southern Oscillation (ENSO) is forecasted to stay in a neutral phase.

1.3 Rainfall

In South America, the patterns of rainfall departures from the 15YA were similar to those reported in the two previous bulletins: The most severe deficit  (<-30%) was recorded for the entire Amazon Basin, including the Cerrado and Mato Grosso, which are important producers of soybean and maize. The severe deficit also affected the Andes from Bolivia to Colombia. Southern Brazil and the Pampas in Argentina, which are important wheat producers, had a rainfall deficit in the range of -10 to -30%.  Central Chile had above average rainfall (>=30%). Central America, as well as the Caribbean coast of Mexico and the southern High Plains of the USA, had average rainfall. In the Southeast of the USA, it was above average (>=10 to <30%). All other crop production regions of North America had rainfall deficits that exceeded 10%. The most severe deficits were recorded for the northern High Plains as well as the Canadian Prairies, where the deficits exceeded 30%. Conditions in Western Europe were above average, while Central Europe had average rainfall. The Ukraine, as well as Russia west of the Ural had a rainfall deficit in the range of -10 to -30%. In Africa north of the equator, rainfall levels ranged from below average, predominantly in West Africa to normal and above average, such as in parts of Ethiopia and the Sudan. The drought conditions in southern Africa continued, with the exception of the Cape Mountains in South Africa, which had ample rainfall (>=30%). Rainfall was also above average in Central Asia, Kazakhstan, Pakistan, and northern China. The other crop production regions of China, as well as South and Southeast Asia, had average or even above average rainfall, such as southern India. The only exception was Myanmar and the Central Himalayas, which experienced below average rainfall. Western Australia had above average rainfall, while the deficit ranged from more than 30% in the Murray-Darling basin to 10 to 30% in eastern Australia.

Figure 1.1 Global map of rainfall anomaly (as indicated by the RAIN indicator) by CropWatch Mapping and Reporting Unit: Departure of July to October 2024 total from 2009-2023 average (15YA), in percent.

1.4 Temperatures

There was only one region for which the average temperatures were cooler by more than 0.5ºC: The west coast of Peru ,northern Chile and south end of Africa continent. All other regions experienced average temperatures and above. The strongest positive departures, with the surplus exceeding 1.5ºC was recorded for the Amazon basin and Central Brazil, the Central Prairies in the USA and Canada, as well as Eastern Europe. Strong positive departures were also recorded for western China, the Korean Peninsula, and Japan. Different from other years, it presents the reality that high temperature in global agricultural area in 2024 have had a appreciable impact on agricultural production. 

Figure 1.2 Global map of temperature anomaly (as indicated by the TEMP indicator) by CropWatch Mapping and Reporting  Unit: departure of July to October 2024 average from 2009-2023 average (15YA), in °C.

1.5 RADPAR

All of Brazil, Paraguay, Uruguay, the Pampas in Argentina as well as the Andeans from Bolivia to Colombia had above average solar radiation, exceeding the 15YA by more than 3%. Central America, southern and western Mexico as well as the West Coast and Southeast of the USA had average radiation levels. The Midwest in the USA, as well as the Central and Eastern crop production regions of Canada had strong above average radiation levels. Western and southern Europe had below average solar radiation, in the range of -1 to -3% below the 15YA. Drought-stricken Eastern Europa had above average solar radiation. In Africa, radiation levels were below average in its regions north of the equator, while the opposite was observed for its southern regions. Central Asia, Northeast China as well as the Philippines had below average solar radiation. In Southeast Asia, solar radiation was more than 3% above the 15YA. In the crop production regions of Australia, solar radiation was also above average. 

Figure 1.3 Global map of photosynthetically active radiation anomaly (as indicated by the RADPAR indicator) by CropWatch Mapping and Reporting Unit: departure of  July to October 2024 average from 2009-2023 average (15YA), in percent.

1.6 BIOMSS

Biomass is estimated as a function of rainfall, temperature and solar radiation. This was the dry period for South America. Almost all of its regions had estimated biomass production that was more than 5% below the 15YA. Production was average in Central America. In the USA and the crop production regions of Canada, biomass production was also reduced by more than 5%. The only exception was the southeast of the USA. Western Europe benefitted from above average rainfall and temperatures, leading to above average biomass production. In drought-stricken Eastern Europe, biomass production was below average. In West Africa, production was also below average by more than 5%. The regions bordering the Sahel had above average biomass production. This was the dry season for Southern Africa, where conditions were mixed. For Central, South and the Northeast of Asia, including Northeast China and  most of the North China Plain, above average biomass production was estimated. For Southeast Asia and Eastern Australia biomass production was estimated as average. A below average production was estimated for the Murray-Darling basin in Australia. The potential biomass of important agricultural areas in West Australia was above the average 

Figure 1.4 Global map of biomass accumulation (as indicated by the BIOMSS indicator) by CropWatch Mapping and Reporting Unit: departure of July to October 2024 average from 2009-2023 average (15YA), in percent.