The climate change has emerged as the most potent existential threat to the entire world and its awareness along with public pressure has now compelled policy makers to devise effective measures to combat it. It is already manifest that global heating pushes tropical regions towards limits of human livability with rising heat and humidity threatening to plunge much of the world’s population into potentially lethal conditions and causing tremendous harm to all living species.
It is now more than clear that if the governments fail to curb global heating to 1.5C above the pre-industrial era, areas in the tropical band that stretches either side of the equator risk changing into a new environment that will hit the limit of human adaptation. The ability of human race to regulate their body heat is dependent upon the temperature and humidity of the surrounding air. Humans have a core body temperature that stays relatively stable at 37C (98.6F), while human skin is cooler to allow heat to flow away from the inner body. But should the wet-bulb temperature – a measure of air temperature and humidity – pass 35C, high skin temperature means the body is unable to cool itself, with potentially deadly consequences.
If it is too humid human bodies cannot cool off by evaporating sweat – this is why humidity is important when we consider livability in a hot place as high body core temperatures are dangerous or even lethal. This reality is borne out by the high average of fatalities in regions where this kind of climate conditions prevail. It is also observed through various historical data and simulations that how wet-bulb temperature extremes are determined that will change as the planet continues to heat up. Discovering that these extremes in the tropics increase at around the same rate as the tropical mean temperature also is now a proven fact. This means that the world’s temperature increase will need to be limited to 1.5C to avoid risking areas of the tropics exceeding 35C in wet-bulb temperature, which is so-called because it is measured by a thermometer that has its bulb wrapped in a wet cloth, helping mimic the ability of humans to cool their skin by evaporating sweat.
Dangerous conditions in the tropics will unfold even before the 1.5C threshold, however, with the warning that 1C of extreme wet-bulb temperature increase could have adverse health impact equivalent to that of several degrees of temperature increase. The earth has already warmed by around 1.1C on average due to human activity and although governments vowed in the Paris Climate Agreement to hold temperatures to 1.5C, scientists have warned this limit could be breached within a decade. This has potentially dire implications for a huge swathe of humanity as around 40% of the world’s population currently lives in tropical countries, with this proportion set to expand to half of the global population by 2050 due to the large proportion of young people in region.
Various researches are centered on latitudes found between 20 degrees north, a line that cuts through Mexico, Libya and India, to 20 degrees south, which goes through Brazil, Madagascar and the northern reaches of Australia. These researches keep on analysing how rising temperatures can render portions of the tropics uninhabitable in the absence of considerable infrastructure investments. If this limit is breached then infrastructure like cool-air shelters are absolutely necessary for human survival. Given that much of the impacted area consists of low-income countries, providing the required infrastructure will be challenging resulting in widespread fatalities. Theoretically no human can tolerate a wet bulb temperature of above 35C, no matter how much water they have to drink.
Many studies are also warning about severe dangers posed by heat and point out extreme heat-waves could push parts of the Middle East beyond human endurance with rising temperatures also posing enormous risks for parts of China and India. The global number of potentially fatal humidity and heat events doubled between 1979 and 2017 with the coming decades set to see as many as 3 billion people pushed beyond the historical range of temperature that humans have survived and prospered in over the past 6,000 years.
The heat-waves also negatively affect food production as a third of all the world’s man-made greenhouse gas emissions are linked to food, according to new global research that tracked produce from field to fork to landfill. Land clearing and deforestation, fertiliser use, livestock and waste all contribute to the emissions from the system to feed Earth’s 7.7 billion people. While numerous reports have looked to quantify the climate footprint of food researchers have encapsulated all countries and sectors from production, packaging and distribution to disposal of food waste. In wake of the current climate conditions food systems are in need of transformation with emphasis on reducing emissions.
In respect of food production it is reported that during the last few decades it was noted that a decoupling of population growth and food-related emissions are growing slower than the population but it was found that wide variations across the world, with some countries and regions seeing large increases in emissions driven by both domestic demand and exports have also contributed to worsening climate. The estimated range of 25 to 42 per cent was higher than the UN Intergovernmental Panel on Climate Change (IPCC) figure of 21 to 37 per cent, partly due to a more expansive view of the global food system. The new calculations take into account things like cooking as part of consumption, as well as waste disposal. Overall the food-system emissions represented 34 per cent of total greenhouse gas output in 2015.
It was also described that about half of these emissions were carbon dioxide, chiefly from land use –and mainly carbon losses from deforestation and degradation of organic soils as well as energy from steps like packaging, transportation and processing. A further third of emissions were from methane — which is 28 times more potent than CO2 as a greenhouse gas over a 100-year period — released by livestock like cows, sheep and goats, as well as from rice production and in the disposal of bio-waste. The remainder was largely nitrous oxide from fertilisers, although the report said that fluorinated gases often found in refrigeration played a small but growing part.
Contributing to the climate crisis is the food production and the six top food system emitters were China (13.5 per cent of the global total), Indonesia with (8.8 per cent), the United States (8.2 per cent), Brazil (7.4 per cent), the European Union (6.7 per cent) and India (6.3 per cent). The global food system is becoming more energy intensive, with almost a third of its emissions directly from energy consumption. While emissions from distribution are on the rise, the distance food travels is less important than packaging with transportation accounting for 4.8 per cent of total food system emissions compared to 5.4 per cent for packaging. The need is to improve efficiency, reduce emissions in the supply chain, and enable people to access healthier diets.
It is more than clear that future food system emissions, if left unaddressed, would by themselves push Earth above the 1.5 degrees Celsius warming threshold — seen as the guardrail for avoiding devastating climate impacts — by 2050. It is also mentioned that 17 per cent of the food available to consumers worldwide in 2020 — almost one billion tonnes — was thrown away by households, retailers, institutions and the hospitality industry, far more than previously suspected that had already produced emission during production stage hence causing more harm to the climate. TW