It’s the peak of summer in the Southern Hemisphere, and this week historic heat waves have hit both Australia and South America.

On Thursday, January 13, one of the most iconic world weather records was tied when a ferocious heat wave in Western Australia sent the mercury soaring to 50.7 degrees Celsius (123.3°F) in the coastal city of Onslow. This tied the previous all-time heat record for hottest temperature for the entire Southern Hemisphere, set on January 2, 1960, at Oodnadatta Airport in South Australia.

Figure 1. Heatwave situation for Australia for the three-day period January 12-14, 2022. The Western Australia city of Onslow is where the all-time Australia heat record was tied. (Image credit: Australia Bureau of Meteorology)

The heatwave over Western Australia built over the week, aided by sea surface temperatures approximately 2 degrees Celsius (3.6°F) above average, offshore winds, and subsiding upper-level air created by the landfall of Tropical Cyclone Tiffany over north-central Australia.

Three stations in Western Australia exceeded the 50 degrees Celsius mark on January 13. Before this week, the entire nation of Australia had recorded only four instances of temperatures of 50 degrees Celsius (122°F) or more, in records going back to 1910.

The heat wave continued on Friday, January 14, but with slightly less-scorching temperatures. Onslow was again the hottest major airport, topping out with a high of 48 degrees Celsius (118°F). The heat wave is expected to diminish in intensity over the weekend.

The new record will undergo review by the World Meteorological Organization (WMO) before it is certified as being official, perhaps a lengthy process. In an interview with the Washington Post, Randy Cerveny, who leads the World Meteorological Organization’s weather and climate extremes team, said, “Since the creation of the WMO World Archive of Weather and Climate Extremes in 2007, we have never had so many ongoing verification/evaluations as we currently do. We are seeing more frequent extremes in temperature. The climate that we have lived through over the past decades is changing and we must be aware of that — and realize those fundamental changes have consequences to our way of life.”

Extreme heat bakes Argentina’s critical grain-producing region

Extreme heat also cooked South America this week, with multiple stations in Argentina, Uruguay, and southwestern Brazil approaching or beating their all-time highs. Most notably, Uruguay tied its all-time national heat record on Friday, January 14, when the mercury hit 44 degrees Celsius (111.2°F) in the town of Florida; Paysandú, Uruguay, also recorded 44 degrees Celsius on January 20, 1943.

Buenos Aires, Argentina, recorded its second-hottest day in history on Friday, January 14, with 41.5 degrees Celsius (106.7°F). The temperature might have gone even higher, but for smoke from wildfires burning to the north that shrouded the region. The city’s third-hottest day in history was three days earlier, with 41.1 degrees Celsius (106°F) on January 11; their all-time record remains 43.3 degrees Celsius (109.9°F) in 1957. Numerous Argentinian stations broke their all-time hottest temperature on record on January 11, 13, and 14, 2022.

As of January 14, the hottest temperature in Argentina reported during this week’s heat wave by the Servicio Meteorológico Nacional was 45 degrees Celsius (113°F) at Rivadavia on January 12. That reading is not far below the hottest reliably measured South American temperature of 47.3 degrees Celsius (117.1°F) at Campo Gallo, Argentina, on October 16, 1936.

This is the second historic heat wave to affect South America this year. On January 1, Paraguay, which lies along Argentina’s northern border, broke its all-time heat record, with 45.6 degrees Celsius (114.1°F) at Sombrero Hovy.

Concerning extreme weather event for key global grain-producing region

With global food prices currently at a 46-year high, the heat wave and an associated drought in Argentina are cause for concern, as the nation is a key grain-producing breadbasket for the world. Indeed, the greatest threat of climate change to civilization over the next 40 years may very well be climate change-amplified extreme droughts and/or floods hitting multiple major global grain-producing “breadbaskets” in the same year: That situation could trigger significant food price spikes that lead to mass starvation, war, and severe global economic recession. I outlined such a scenario last year, which was published in The Hill. The scenario is similar to one outlined by insurance giant Lloyds of London in a “Food System Shock” report issued in 2015. Argentina – the world’s largest exporter of soybeans, third-largest exporter of corn, and seventh-largest wheat exporter, according to the USDA – played an important role in both scenarios.

Top corn exporting nations

  1. U.S.                  31%
  2. Brazil               21%
  3. Argentina    19%
  4. Ukraine           16%
  5. E.U.                  2%

Top soybean exporting nations

  1. Argentina    41%
  2. Brazil               24%
  3. U.S.                  18%
  4. India                3%
  5. Paraguay         3%
Figure 2. Warming-induced changes in mean corn yield (in percent) for global warming of 2.5 degrees Celsius (4.5°F) above pre-industrial levels (or two degrees Celsius above the global average temperature from 1980-1999). Argentina (at lower left) is predicted to see 0-40% declines in corn yield. (Image credit: Tigchelaar et al., 2018, Future warming increases probability of globally synchronized maize production shocksProceedings of the National Academy of Sciences, Jun. 2018, 115 (26) 6644-6649; DOI: 10.1073/pnas.1718031115)

Crops don’t like heat

Generally, crops have an optimal temperature for performance, and hotter temperatures result in a steep decline in yields. For every degree Celsius increase in global mean temperature, yields are projected to decrease, on average, by about 7% for corn, 6% for wheat, 3% for rice, and 3% for soybeans. These losses do not take into account additional losses from the drought conditions that typically accompany extreme heat. However, the losses will be offset modestly by gains in plant growth as a result of increased carbon dioxide in the air that will stimulate plant growth (the CO2 fertilization effect).

A 2021 study led by Ariel Ortiz-Bobea, Anthropogenic climate change has slowed global agricultural productivity growth, found that the optimum global temperature for growing crops is quite cool, and occurred prior to 1961. Since that year, global agricultural productivity has roughly doubled as a result of improvements in technology and practice, but climate change has cut into those benefits by around 21% – the equivalent of losing the past seven years of advances in agricultural technology (Figure 3). The climate-change losses have been greatest across the tropics and the southern midlatitudes, including Argentina.

Figure 3. Country-level impacts of human-caused climate change on agricultural productivity from 1961-2015. Argentina (lower left) suffered approximately a 20% loss during that period. (Image credit: Ortiz-Bobea, A., Ault, T.R., Carrillo, C.M. et al. Anthropogenic climate change has slowed global agricultural productivity growthNat. Clim. Chang. 11, 306–312 (2021), https://doi.org/10.1038/s41558-021-01000-1)

Drought interferes with shipping

Not only is the Argentina drought and heat wave hurting crops, it is also interfering with transportation of grain to foreign markets. Argentina has experienced widespread drought, with rains 2-4 inches below average over the past two months, in the northeastern portion of the country where most of its crops are grown. According to Reuters, drought conditions in January resulted in 30% less grain being loaded onto grain-carrying vessels because Argentina’s main grain-shipping superhighway, the Parana River, was near record-low levels. There is little prospect for improved water levels in January, according to the Argentina National Water Institute.

Figure 4. Though global food prices in December fell 0.9% compared to November, for the year 2021 as a whole, after adjusting for inflation, prices were up to 28% higher than in 2020, the FAO said in its Jan. 6 monthly report. Food prices were at the highest in 46 years, leaving us highly vulnerable to extreme weather shocks in 2022.

How much might Argentina’s grain production suffer?

Drought is more likely in Argentina during La Niña conditions, as are currently present. After a devastating La Niña-linked summer heat wave and drought hit the nation in late 2017 and early 2018, corn production in Argentina fell 22%, and soybean production fell 14% from the previous year’s harvest. The drought cost $3.8 billion (2021 USD), making it Argentina’s most expensive weather-related disaster in history. Corn prices in the U.S. rose 14% between December 2017 and February 2018, as U.S. exports covered the demand that Argentina could not satisfy; global food prices (as measured by the U.N.’s FAO Food Price Index) increased by 1.7% from January to February 2018. Fortunately, international soybean prices did not increase significantly because of a large harvest in Brazil.

As in 2017-2018, the current heat wave and drought has the potential to cause significant crop losses, but with summer in the Southern Hemisphere only half complete, it is unclear how the rest of the growing season will play out. Cooler temperatures and beneficial rains of 1-3 inches are predicted for much of the grain-producing area of Argentina during the week of January 16-22, as a strong cold front pushes northward. And long-range model forecasts do not show unusual heat developing over Argentina during the latter part of January, giving hope that this year’s drought will be less severe than that in 2017-2018.

But with the ongoing pandemic likely to keep global food prices very high in 2022, the hit Argentina’s agriculture is taking from the current historic heat wave and drought is worrisome. We’re going to need good harvests during the coming growing season in the Northern Hemisphere. If the current drought in Argentina turns out to be as bad as the drought of 2017-2018, and two other major global breadbaskets are hit by exceptional 1-in-50-year droughts this summer, we could see dangerously high global food prices capable of causing a global emergency.

Bob Henson contributed to this post.

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Jeff Masters

Jeff Masters, Ph.D., worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. After a near-fatal flight into category 5 Hurricane Hugo, he left the Hurricane Hunters to pursue a...