Fossil fuels have powered the Industrial Revolution and Green Revolution of the last 200 years, making our lives relatively more pleasant for the time being.
However, the extraction and burning of fossil carbons releases historically unprecedented quantities of steadily accumulating heavy metals, sulfur, nitrogen oxides, particulates, and processing synthetic organic chemicals, along with methane and CO2.
The latter in particular has a dramatic effect on the atmosphere and the oceans.
The pleasantly stable weather pattern of the last ten thousand years of the Holocene – a period which fostered the development of agriculture and subsequent civilizations – are changing rapidly as the burning continues. The changes are serious and irreversible on a relevant human time scale.
On land, it will impair food production, despite the optimistic calls for the imperative to increase it, even for the current 7 billion.
For example, for each degree Celsius rise in temperature above the norm during the growing season, nations should expect as much as 6% to 10% decline in wheat, rice, and corn yields.
Soil conditions, their microbial activity, and thus soil fertility may be under stress as severe droughts and floods become more pervasive. Other ecosystem services will also be hurt. Most crucially, further biodiversity loss is expected as the climate change rate surpasses the capacity of many species to adapt.
Sea level rise along with more violent rainfall and flooding also means that tides and storms will devour prime land property in coastal areas. As those floods push inland, they will threaten freshwater supplies, as saltwater invades the rivers, prompting salinization of coastal groundwater.
Ultimately those changes will force massive human migrations away from the coasts.
Climate refugees will not only come form low-lying island nations.
Bangladesh, situated to a large extent on the Ganges-Brahmaputra delta, is about to lose 11% of its territory (home to over 15 million people and one of the most fertile plains in the world) when the sea level rises by only 1 meter.
The world’s other 32 major low-lying deltas are home to many urban centers. About half the world’s population and much of its wealth is in the proximity of water. For example, the Nile Delta accounts for more than half of Egypt’s economy.
The melting of glaciers and reduced snowpack will ultimately question the viability of many dams in their hydropower generation capacity.
A 1% reduction in river flow can reduce electricity output by roughly 3%. Just the Hindu Kush–Karakoram–Himalayan glaciers – the eastern and central parts of which are melting an accelerated rate – are a steady water flow for energy generation, besides being an important water source for agriculture and urban as well as industrial consumption for a quarter of the world’s population.
The rivers draining from that area include Ganges, Indus, Mekong, Yangtze, Yellow, Brahmaputra, Irrawaddy and Salween.
Of course, the glaciers and snow pack have less impact on areas downstream, which rely on the annual monsoon precipitation. But monsoons are seasonal and from time to time they don’t come. It is then that the glaciers are the key provider of continuous river flow.
For example just Pakistan, a country, which grew from 52 million to 188 million people in 50 years, depends precariously on the Indus River, which in turn depends on glacial waters for up to half of its flow.
Over one third of the CO2 emissions are absorbed by seawater.
This has led to an increase in the oceans’ acidity of about 30% since the beginning of the Industrial Revolution, and the process continues.
The increased acidity decreases the concentration of a key chemical, carbonate ion, in ocean water. These are the building blocks for the skeletons and shells of many organisms – including calcareous plankton, krill, corals.
The acidification has a multitude of other effects that only now are being discovered. These include undermined immune system and orientation abilities of marine animals. Thus the resultant acidification threatens the entire marine food web possibly turning huge swaths of the oceans into dead zones.
These changes will unquestionably impact the human enterprise. More than a billion people worldwide rely on food from the ocean as their primary source of protein, and many economies thrive on fisheries and related industries.