Humans. They are an interesting species aren’t they? At the time of this production, there are estimated to be 7.7 billion of them roaming around the surface, and that figure is still rising.

There are many reasons why people live in the places that they do. On the coast, or along rivers, for trade. Security in the hills, away from invaders. Occasionally, rulers arbitrarily create new capitals in the centre of their realms.

But the main determinant for human settlement is the availability of clean, fresh water. Because without it, crops cannot grow, livestock cannot be raised. Without those, there is no food. Without food, there is no population.

And what determines the availability of running water? Rainfall and temperature. Too little rain, and you have a desert. Too cold, and you have frozen ground, ice. Too much rain and heat, and you could have disease.

So climate and population are inextricably linked. And if you know a bit about climate classification, then you’ve probably wondered which climate types have the least and most populations. Well it’s time to wonder no more, because after extensive original research and tabulation this data is about to be presented, in this the latest article in my Climate Casebook.

If you’ve viewed any of my other articles then you should be familiar with the Koppen climate system, which breaks down the world into zones of climate types based on temperature and rainfall patterns. If you haven’t, then I recommend you check out my Secrets of World Climate series, or for a quick overview, this summary article.

There are 29 Koppen zones in total, but I’ve grouped most of these into the twelve more distinct categories that formed each chapter in my Secrets of World Climate series. So, let’s get right into which climate zones support what populations. You’re probably wondering which zone has the biggest population, but to keep you in suspense, we’re going to go in reverse order, starting with the most empty of human life.

At number twelve there are no surprises for guessing that the least populated climate zone is the Icecap. Since temperatures never rise above freezing, no self-sustaining settlements are possible, and so research stations make up the “population” here. The number of scientists varies depending on the season with summer being higher than winter, and the vast majority of this population numbering in the thousands is in Antarctica with typically less than one hundred on the Greenland ice sheet at any given time.

Populations in the Tundra

At number eleven, we have the next coldest zone – that of the Tundra. In these bleak, treeless lands, agriculture is impossible, and any settlements here either have to rely on supplies from outside, or on hunting wildlife. Total tundra population worldwide is estimated to be in the hundreds of thousands – a tiny, tiny fraction of the total human population. These populations are scattered worldwide with about half spread along the coasts of the Arctic and the other half concentrated in the southern tip of South America. Some of you may take issue with the inclusion of Tierra del Fuego, since it’s not true tundra in that it does not experience very cold winters like the arctic, and is in fact a slightly cooler version of the Subpolar Oceanic variety where summer temperatures rarely exceed 10°C. But it would be an omission to not mention it.

At number ten, we have the next coldest zone – the vast subarctic band that spreads across northern North America, Europe and Asia. Now we are getting into the millions in terms of population, but still less than a fifth of one percent of humans live in the vast boreal forests that experience warm summers but very cold winters here. This population is mostly found in Russia, which is to be expected as it contains the largest land area under this climate type, including the vast stretches of Siberia. There are a number of Koppen subtypes in the Subarctic. Most people live in the standard Subarctic of cold winters and year round precipitation, with a smaller fraction in the east of Asia where only light snow falls in winter, with more consistent rain in summer. A much smaller fraction live in the area of very cold winters in north-east Siberia.

Subarctic population by countries

Subarctic population by climate sub-type

Populations in the Tropical Rainforest

At number nine, and we switch from the coldest zones to one of the hottest – the year round rain and warmth of the Tropical Rainforest. With a global population of just over a quarter billion, we are at last into an area that is home to a significant percentage of total human numbers. Almost half of them live in just one country – Indonesia, with most of the others also within SE Asia, and significantly fewer numbers in South America and Africa.

At number eight and we head to the mid-latitudes, and the western fringes of the continents under the sway of maritime westerly winds – the Oceanic, characterised by rain year round and relatively mild temperatures between winter and summer. Of the two hundred and seventy million souls