The atmosphere, lithosphere, hydrosphere, and biosphere … all intimately interconnected. In the biosphere is a life-form that is extremely powerful in bringing about accelerated change in all the spheres. Strangely, this life-form knows that it is suffering from this change. Yet, it seems to be unwilling to, or incapable of, taking action to halt the change it is wreaking.

One effect of that is migration of humans … and non-humans.


Anthropo (from the Greek anthropos, meaning ‘human) and genesis (from the Greek for ‘origin’) together give us Anthropogenesis (birth by humans, cause by humans). From this, we get anthropogenic (adjective, meaning ‘caused by humans’).

In the figure from NASA, beginning from the industrial revolution in the 19th century, “[t]he amount of solar energy that Earth receives has followed the Sun’s natural 11-year cycle of small ups and downs with no net increase since the 1950s. Over the same period, global temperature has risen markedly. It is therefore extremely unlikely that the Sun has caused the observed global temperature warming trend over the past half-century. Credit: NASA/JPL-Caltech”

This means that the warming is coming from human activity, hence it is anthropogenic.

Historical changes in the level of carbon dioxide (CO2) in the atmosphere. [Source: accessed on 26 Nov. 2019] Click on the image to see a larger version in a new tab.

Warming and cooling of Earth are parts of natural cycles over the millennia. They occurred over long periods of time. Yes, there were many species that were wiped out. Other species were able to adapt, survive, and continue.

What is different now is that our activities are causing the faster rise in the global temperature. AGW (Anthropogenic Global Warming) is so rapid that neither us nor other species can adapt to it this quickly. Nor can the inorganic components of Earth system.

“But several lines of evidence show that current global warming cannot be explained by changes in energy from the Sun:

  • “Since 1750, the average amount of energy coming from the Sun either remained constant or increased slightly.
  • “If the warming were caused by a more active Sun, then scientists would expect to see warmer temperatures in all layers of the atmosphere. Instead, they have observed a cooling in the upper atmosphere, and a warming at the surface and in the lower parts of the atmosphere. That’s because greenhouse gases are trapping heat in the lower atmosphere.
  • Climate models that include solar irradiance changes can’t reproduce the observed temperature trend over the past century or more without including a rise in greenhouse gases.” (Source)


Solar activity versus temperature: evidence of anthropogenic global warming (AGW). (See text).
[Source: ] Click on image to view larger version in a new tab.


Animation of global warming.(Source:NASA)


One of the phenomena that geographers study is migration. Migration is movement from place to place. Place is involved and this immediately attracts geographers’ attention!

Migration may be short-term or long-term, it may be voluntary or involuntary (forced), and it may be short-distance or long-distance. The causes of migration include push factors (these cause migrants to leave the place of origin), and pull factors (these are the destinations that attract migrants). Basically, migration is a result of complementary set of push (unfavorable conditions at the origin) and pull factors (favorable conditions at a destination).

Geographers recognize different sets of the complementary factors I mentioned above. For example: economic migration, political migration, climate migration, etc.

Of these, we look at climate migration very briefly today.

First, let us recall the difference between climate (long-term average atmospheric conditions) and weather (short-term atmospheric conditions). They are linked. Long-term changes (AGW) in atmospheric conditions are reflected in the short-term changes (extreme weather conditions such as excessive rainfall or drought, etc.).

Environmental migration

People migrating due to climate change have been called climate refugees. A refugee is one who seeks a refuge (safe place) to escape harm. The term climate refugee is not yet clearly defined. This causes problems in identifying people who are displaced due to climate change factors.

The term environmental migrants is now coming into practice. “Environmental migrants are persons or groups of persons who, for compelling reasons of sudden or progressive changes in the environment that adversely affect their lives or living conditions, are obliged to leave their habitual homes, or choose to do so, either temporarily or permanently, and who move either within their country or abroad.” (Source)

In 2018, the World Bank published Groundswell: Preparing for internal climate migration. It paints an alarming picture of migrations happening within countries in various regions of the world. The direst picture is in sub-Saharan Africa (i.e., Africa south of the Sahara). Closer home, South Asia where we are located does not fare all that well either. In South Asia, the report says we are likely to see up to 40.5 million ‘climate migrants’ by 2050! (Source)

A documentary about climate migration in India. (Source: TERI)

Climate migration in Bangladesh. (Source: DW Documentary)>


It’s not just people who are migrating due to climate change. All species face threats. Some die out and others will have to adapt wherever they are (difficult because climate change is occurring faster than the time it takes to adapt). Still others will have to find new habitats (locations for life).

We think of trees as stationary, but they are migrating too. As climate changes, the temperatures and moisture in various latitudes are changing, too. In your geography textbook, you have studied the traditional ‘types of climate’ – torrid zone, temperate zone, and frigid zone. The boundaries between these types are moving further away from the Equator. (For example, read:

With these changes, for example, trees in the temperate zone become vulnerable to new kinds of pests and diseases that were once confined to the torrid zone. Apart from this, the rainfall and temperature patterns (i.e., the seasons) also change. Some trees may be able to adapt quickly, but many may not.

Anthropogenic climate change affects the whole world.


Will your individual action to reduce climate change’s effects make a difference? Why or why not?

Join us for the 6th International Geography Youth Summit, IGYS-2020,
24-26 July 2020, Bengaluru

A version of this article appeared in the Deccan Herald Student Edition on 20 November 2019

Featured image:  [Source:  accessed on 20 Nov. 2019]



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