A new study has found that if the Earth continues to warm at current levels over the next 50 years, more than 3 billion people could be living in areas that are too hot for humans to reside in. Humans have lived within a normal climate where the average temperatures are ideal for people to grow food and keep livestock.
However, a group of international archaeologists, ecologists, and climate scientists said that if heat-trapping greenhouse gas emissions continue at the current pace, by the year 2070 there will be billions of people who will be living in hotter areas and it may be impossible for life to flourish. The findings were published in the Proceedings of the National Academy of Sciences.
If this happens, at least 1 billion people will either have to migrate to cooler regions or they would need to adapt to extreme heat conditions. An archaeologist at the University of Washington, Tim Kohler, said that these findings can be seen as a worst-case scenario of what could happen if humans do not do something about the problem today.
Temperatures are changing fast
The researchers used data on historical global temperatures and the distribution of human populations. Using these, they found that humans thrive best within a narrow climatic envelope. Most of the people in the world live in areas with a temperature between 11 and 15 degrees Celsius or 51.8 to 59 degrees Fahrenheit.
In South Asia, a smaller band of between 20 to 25 degrees Celsius or 68 to 77 degrees Fahrenheit can be recorded in areas that are affected by the Indian monsoon, which are the rains that occur yearly and is vital for food production. Scientists stated in the study that humans have lived in these conditions for the past 6,000 years, despite the technological advances in recent years such as air conditioning.
Currently, the Earth is on track of 3 degrees Celsius of warming by 2100. Since the land areas are warming faster than the oceans, temperatures experienced by humans are likely to increase by about 7.5 degrees Celsius by 2070. As the Earth heats up due to the increase in emissions, the temperature experienced by an average person is recorded to change more in the coming years than it has over the past 6,000 years.
Extreme heat areas will expand in future
The Sahara region of Africa is one of the hottest places on Earth, which experiences annual mean temperatures above 29 degrees Celsius or 84.2 degrees Fahrenheit. However, researchers stated that those extreme heat areas may spread to at least 19% of the Earth's surface in the future and it may affect 3.5 billion people by 2070.
The projection in the study that 3.5 billion people will be affected by climate change in the future goes beyond the World Bank estimates, which shows 143 million people across South Asia, Latin America, and Sub-Saharan Africa will be at risk of being displaced due to extreme heat. It is a warning of what could happen if humans do not do something about climate change now.
The scientists say that there is hope since global carbon emissions are rapidly reducing, the number of people that will be exposed to hot conditions in 2070 could be halved. The authors suggested that there are uncertainties with how climate change will fuel displacement and to what extent, and that the study can't be used as a prediction of migration.
