Chapter 1. Global agroclimatic patterns

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 cloud.cropwatch.com.cn.

1.1 Introduction to CropWatch agroclimatic indicators (CWAIs)

This bulletin describes environmental and crop growth conditions over the period from April to August 2024, AMJJ, 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

Global warming continued to cause new record high temperatures. July 2024 was the warmest July on record and July 22 was the warmest day on Earth in recent history. Fortunately, the northern hemisphere was mostly spared from extreme heat waves and prolonged droughts, although pre-monsoon heat waves hit South Asia very hard. In Rajasthan (India) and Sindh (Pakistan), several cities reported maximum temperatures above 50ºC. These extreme temperatures affect not only the people living in the cities but also agricultural production. El Niño has ended, and we are currently in a neutral phase, which implies a generally more regular distribution of rainfall.

1.3 Rainfall

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

In South America, the patterns of rainfall departures from the 15YA were similar to those reported in the previous bulletin: The most severe deficit (<-30%) was recorded in the Cerrado and Mato Grosso in Brazil, both of which are important producers of soybean and maize. A rainfall deficit in the range of -30 to -10% was observed for the Amazon basin and Andes from Bolivia to Columbia. Similarly, a deficit was observed for the western highlands of Mexico, California and the northern Prairies in the USA, Russia west of the Ural, as well as Spain and Southeast Asia. Drought conditions were also recorded for the Rocky Mountains, the Maghreb, the Mediterranean region and almost all of Africa south of the equator. Only a small region in southwest Africa experienced above average rainfall. Rainfall in the Canadian Prairies and the eastern half of the USA was average to above average. It was also favorable for most of the crop production regions of Argentina, Chile and the south of Brazil, Uruguay and Paraguay and western Europe. Above average rainfall was recorded for Central Asia and South Asia. Notably, eastern Australia and most of the crop production regions of China also had above average rainfall, although rainfall in China was not evenly distributed over time. Most of the rainfall occurred in July.

1.4 Temperatures

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

Similar to the global temperature anomaly, temperatures in agricultural areas were generally above average. A few regions reported negative temperature departures: New Zealand, the Murray-Darling basin in Australia, southern Argentina, Chile, and the Peruvian coast. Temperatures were average for most of Canada, southern Brazil, western Europe, Central Asia, southern India, and Indonesia. All other regions experienced above-average temperatures.

1.5 RADPAR

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

Photosynthetically active solar radiation was rather variable within continents. In all crop producing regions of Argentina, Chile, Paraguay, Uruguay and Parana in Brazil, as well as in Texas, Canada, western Europe, Central Asia, southern India, southeast China, the Koreas, Japan, Indonesia and eastern Australia, solar radiation was below the 15YA by more than 3%.  

A small reduction in solar radiation (-1 to -3%) was observed for the northeast of the USA, the Levant and southeast Asia. Strong positive departures were observed for the drought stricken regions of Brazil and southern Africa and the crop production regions of Western Australia.

1.6 BIOMSS

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

Biomass is estimated as a function of rainfall, temperature and solar radiation, comprehensively reflects the impact of agrometeorological conditions on crop production. Positive departures from the 15YA by more than +5% were estimated for Texas, the Midwest and the Northeast of the USA and most of the important crop production regions of Canada. Western Europe, Central Asia and the Ural region of Russia, as well as Kazakhstan, Pakistan, South India and Eastern Australia also had strong positive departures. Due to the rainfall deficit, below average biomass production was estimated for most of Brazil, the Western USA with the exception of California, the Mediterranean basin, parts of Central and southern Africa, Russia west of the Ural, and Southeast Asia.