Climate change is as old as the estimated 4.54 billion years that the Earth has existed. Over the past five hundred million years, global temperatures were too high for persistent polar ice caps. The last fifty million years form an exception to this. During this last colder period, Homo sapiens appeared approximately 300,000 years ago. During this period, Homo sapiens also lived in times when the polar ice caps had shrunk significantly or had even completely disappeared. These warm interglacial periods offered ice-free environments in both hemispheres in which humanity flourished through expansion, technological innovation, and migration. On average, humans can adapt better to moderate heat than to prolonged, severe cold. So, what makes climate change a threat to humanity?
Climate change is defined as a change in global weather patterns resulting from changes in the average temperature of the Earth’s atmosphere over a period of at least thirty years.
Weather is not the same as climate
Weather and climate are not the same. Weather consists of short-term changes in the atmosphere. Climate is the average weather over a period of at least thirty years. Global warming occurs when the average temperature of the atmosphere rises worldwide. That does not mean that some areas of the world have not become colder over the past thirty years, while others have actually become warmer.
Earth system sensitivity
A long-term statistically robust geological estimate of global mean surface temperature (GMST) across the last 485 million years showed that the average Earth’s temperature has varied dynamically, from eleven to thirty-six Celsius degrees, and that climate periods with high levels of greenhouse gases were very warm. During this long time period more time was spent in warmer than in colder climates. Within this period atmospheric carbon dioxide (CO2) seems to be the main driver for climate change showing a consistent apparent Earth system sensitivity: when the global average CO2 level doubles, the global average temperature increases approximately with eight degrees Celsius. In the latest report from the IPPC (Intergovernmental Panel on Climate Change), it is estimated that the average global temperature will rise by 1.4 to 4.4 degrees Celsius between 2081 and 2100, depending on the greenhouse gas emissions scenario assumed.
Although the relationship between CO2 and temperature appears stable over very long geological timescales, regardless of warm or cold periods, hasty conclusions should be avoided, as this reduces the complexity of the sensitivity of the Earth system to just a single number.
Earth’s climate states
Based on research into single-celled marine organisms with calcium skeletons from the deep sea over the past sixty-six million years, the Earth’s climate can be subdivided into distinct climate states, separated by transitions influenced by changes in greenhouse gas levels and the extent of polar ice cap presence. Each climate state is determined by variations in orbital cycles: the shape of Earth’s orbit around the Sun within a cycle of approximately 100,000 years (eccentricity), the variation in the tilt of the Earth’s axis within a cycle of approximately 41,000 years (obliquity), and the change in the direction in which the Earth tilts within a cycle of approximately 26,000 years (precession). Each climate state responds differently to variations in radiative forcing, meaning that, depending on the climate state, solar radiation, greenhouse gases (such as CO2), and aerosols may cause increased warming or cooling. Thus, the same radiative forcing can cause a greater climate effect as a result of the climate state at that specific moment.
Natural and man-made causes of warming and cooling
While solar radiation is a natural phenomenon, greenhouse gases and aerosols can also be man-made. Depending on the source, greenhouse gases such as water vapour (H2O), CO2, methane (CH4), nitrous oxide (N2O) and ozone (O3) can be naturally occurring or man-made. Fluorinated gases are an example of man-made greenhouse gases. Examples of natural aerosols include dust, sea salt, volatile organic compounds from plants, and sulphates from marine phytoplankton emissions and volcanic eruptions. Aerosols from wood and the combustion of fossil fuels (sulphates and organic carbon), incomplete combustion of fossil fuels, biofuels, and biomass (black carbon), agricultural fertilisers and vehicle exhaust (nitrates), and industrial production (mineral dust, fly ash, metal oxides) are examples of man-made aerosols.
Climate change as a natural phenomenon has slowly fluctuated between warming and cooling over the past 900,000 years, in the periods known as ice ages and interglacial periods. Since the agricultural revolution, humanity has been in an interglacial period, characterised by a predominantly stable climate. Since the start of measurements in 1880, the average temperature of the Earth’s atmosphere has risen at an accelerated rate since 1975. Since then, human activities have added greenhouse gases such as CO2 to the atmosphere faster than they can be removed naturally. This intensifies atmospheric warming and thereby strengthens the Earth’s natural greenhouse effect. The rate of climate change can affect the environment both positively and negatively.
Climate change effects on the natural environment
Positive effects of climate change on the natural environment are usually considered local and short-term. Higher temperatures can lead to longer growing seasons in some cool and temperate regions. It may increase the productivity of certain crops and fast-growing species. It may reduce cold-related mortality in certain animal and plant species. It may also temporarily increase biodiversity through the expansion of certain species. However, the negative effects of climate change are more often perceived as widespread and far-reaching: an increase in extreme weather, biodiversity that cannot keep pace with climate change, which may lead to the extinction of certain species, a decrease in freshwater storage capacity due to the melting of glaciers and snowpack, longer fire seasons, ocean acidification, and a rise in sea level.
Climate change effects on humans
Studies of nearly a thousand weather events and trends show that eighty-five percent have been negatively (seventy-seven percent) and positively (eight percent) influenced by man-made climate change. It is estimated that the European heatwave in the summer of 2003 caused 70,000 additional deaths on the European continent. Nevertheless, milder climate periods can make it easier for humans to survive.
However, the negative effects of climate change for modern humans often seem to outweigh the positive ones. While longer growing seasons can increase crop productivity and the urgency to address climate change can stimulate a sustainable economy, climate change can also increase human health risks, food and water insecurity, and economic instability.
Hunter-gatherer’s adaptive lifestyle
Although human activities nowadays contribute to the acceleration of climate change, climate change itself is not new and may have initially even increased our human resilience to natural phenomena. Throughout human history, the natural environment, which was heavily influenced by climate fluctuations, has usually determined where people settled. As hunter-gatherers, humans survived through mobility and adaptation to changes in the food supply. They survived climate change by developing new tools that made hunting and gathering more effective, altering their diets to changing food sources, and migrating to environments that were more favourable for human survival. They also depended on egalitarianism and the sharing of ecological knowledge for their survival. Unlike modern man, they were optimally adapted to the continuous natural changes in order to survive.
Decline in human natural resistance as a result of industrialisation
The agricultural revolution introduced a sedentary human lifestyle. With the start of industrialisation in Britain at the end of the 18th century, humanity gradually lost more and more of its natural resilience at an accelerating speed due to this continuously increasing passive sedentary lifestyle. Today, the majority of humanity no longer has access to the ecological knowledge needed to remain physically and mentally healthy, build healthy social relationships, and safeguard a healthy natural environment.
Although some borders already existed before the start of industrialisation, most international borders were established in the twentieth century. This made it easier to prevent conflicts, organise territories, establish political sovereignty, and regulate economic, social, and legal interactions between nations. However, this also limited human adaptability to changes such as climate change. These borders provided a framework and stability that were favourable for the acceleration of industrialisation. Industrialisation, in turn, also accelerated the growth of governance worldwide, as more governance made it possible to manage industrial societies more effectively. Although the effects may be uneven at a global scale, industrialisation fostered population growth and stimulated urbanisation, democratisation, capitalism, and globalisation, enabling more and more people to survive and live longer. Nevertheless, while chronic diseases were rare or even absent during the time when humanity lived as hunter-gatherers, risk factors and some chronic diseases have increased today among the world’s population, especially in younger age groups in some countries and/or communities, causing people to live shorter, healthy lives than before.
Can humanity still adapt to natural climate change?
Thus, although climate change may increase the intensity and frequency of hazards, it is primarily the degree of human resilience, the extent to which modern societies are able to adapt to (climate) change, and the presence and resilience of natural ecosystems that determine how severe the impacts of climate change are. The degree of connectedness with oneself, and with the social and natural environment, largely determines the extent to which humanity can still adapt to climate change. Whether climate change is natural and/or human-made, is humanity still capable of adapting to natural climate change, or is it time to reshape industrial societies with the naturally necessary human connectedness at their centre, so that humanity’s adaptability increases again? This entails, among other things, a re-evaluation of how the world is governed, how land is divided and organised, how human settlements of all sizes are formed and organised, and how human livelihoods and health are ensured. However, this re-evaluation thereby also entails questioning modern cultures and belief systems. As long as the importance of a connected life with ourselves, each other, and our natural environment is not recognised, it will remain impossible to increase human resilience to (climate) change and reduce man-made climate change.
Vicki Van Lommel
founder Free People Media
©FPM
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This is the first article in a series of thirteen articles on climate change on FPM blog.
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