Extreme heat: The new global normal

Climate-related risks to agriculture, food systems in Asia will progressively intensify, UN report says

“In India, rice production can decrease from 10 per cent to 30 per cent, whereas maize production can decrease from 25 per cent to 70 per cent, assuming a range of temperature increase from 1 degree to 4 degrees Celsius,” UN report says.

Extreme climatic conditions are threatening the food security in South Asia with escalated floods and droughts making India and Pakistan the most vulnerable to climate change, cautioned the latest IPCC report.

The second installment of the Intergovernmental Panel on Climate Change (IPCC) Working Group II’s report, titled “Climate Change 2022: Impacts, Adaptation and Vulnerability”, said climate-related risks to agriculture and food systems in Asia will progressively intensify with the changing climate, with differentiated impacts across the region.

“Differential human vulnerability to environmental hazards results from a range of social, economic, historical and political factors, all of which operate at multiple scales. Climate change is expected to have serious impacts for people living within these hotspot areas, as observed from loss of food crop yields to disasters such as floods, fluctuations in seasonal water availability or other systemic effects.

“For instance, in South Asia, extreme climatic conditions are threatening food security, thus agro-based economies like India and Pakistan are the most vulnerable to climate change in this regard,” the report said.

It warned that the major projected impacts of climate change in the agriculture and food sector include a decline in fisheries, aquaculture and crop production, particularly in South and Southeast Asia, a reduction in livestock production in Mongolia, and changes in crop, farming systems and crop areas in almost all regions with negative implications to food security.

The report said temperatures enhance not only ozone production but also the ozone uptake by plants, exacerbating yield and quality damage.We have seen a trend toward extreme heat conditions across the globe in the last number or years.

If greenhouse gas emissions are not significantly curtailed, daily high and low temperatures will increase.Heat waves are more dangerous when combined with high humidity. The combination of temperature and humidity is measured by the heat index.

Extreme heat can increase the risk of other types of disasters. Heat can exacerbate drought, and hot, dry conditions can in turn create wildfire conditions. Buildings, roads, and infrastructure absorb heat, leading to temperatures that can be just a few degrees hotter in urban areas than outlying areas – a phenomenon known as the urban heat island effect. This impact is most intense during the day, but the slow release of heat from the infrastructure (or an atmospheric heat island) overnight can keep cities much hotter than surrounding areas. Rising temperatures across the globe pose a threat to people, ecosystems, and the economy.

Extreme heat is one of the leading causes of weather-related deaths in the United States, killing an average of more than 600 people per year from 1999-2009, more than all other impacts (except hurricanes) combined. The Billion Dollar Weather Disasters database compiled by the National Oceanic and Atmospheric Administration lists heat waves as six of the top 10 deadliest U.S. disasters since 1980.

Heat stress occurs in humans when the body is unable to cool itself effectively. Normally, the body can cool itself through sweating, but when humidity is high, sweat will not evaporate as quickly, potentially leading to heat stroke. High humidity and elevated nighttime temperatures are likely key ingredients in causing heat-related illness and mortality. When there’s no break from the heat at night, it can cause discomfort and lead to health problems, especially for those who lack access to cooling, which are often people who have low incomes. Other groups that are particularly vulnerable to heat stress include older adults, infants and children, people with chronic health conditions, and outdoor workers. Hot days are also associated with increases in heat-related illnesses, including cardiovascular and respiratory complications and kidney disease.

In extreme temperatures, air quality is also affected. Hot and sunny days can increase the production of ground-level ozone, a harmful pollutant that is the main component of smog, which can damage the respiratory system and is particularly harmful for those with asthma. In addition, greater use of air conditioning requires more electricity which, depending on the electricity source, emits other types of pollution, including particulates that have an impact on air quality too. These increases in ozone and particulate matter can pose serious risks to people, particularly the same vulnerable groups directly impacted by heat mentioned above.

High temperatures can be damaging to agriculture. Plant growth is negatively impacted by high daytime temperatures and some crops require cool night temperatures. Heat waves also increase the chances of livestock experiencing heat stress, especially when night time temperatures remain high and animals are unable to cool off. Heat-stressed cattle can experience declines in milk production, slower growth, and reduced conception rates.

Heat waves can exacerbate droughts and wildfires, which can lead to negative impacts on the agriculture sector. For example, the 2021 drought in the West caused North Dakota cattle ranchers to sell their stock due to a lack of feed for the winter. Wildfires in California have burned agricultural land and are raising the cost of insurance for farms and wineries.

Warmer temperatures affect many aspects of the global energy system, including production, transmission, and demand. While higher summer temperatures increase electricity demand for cooling, at the same time, they can lower the ability of transmission lines to carry power, possibly leading to electricity reliability issues like rolling blackouts during heat waves.

Although warmer winters will reduce the need for heating, modeling suggests that total energy use will increase in a warmer future. In addition, as rivers and lakes warm, their capacity for absorbing waste heat from power plants declines. This can reduce the thermal efficiency of power production, which makes it difficult for power plants to comply with environmental regulations regarding the temperature of their cooling water, and could lead to plant shut-downs.While warmer temperatures have recently been experienced in Europe and North America, Africa, Asia and South America have also extremely higher temperatures recently.

Strategies to build resilience to extreme heat include Identifying vulnerable populations and creating heat preparedness plans with all residents in mind, that may include steps like opening cooling centers during periods of extreme heat and adopting workplace heat stress standards. Installing cool and green roofs and cool pavement to reduce the urban heat island effect. Planting trees to provide shade and to cool the air through evapotranspiration. Pursuing energy efficiency to reduce demand on the electricity grid, especially during extreme heat conditions.

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