The world we live in today is in a climate-state that mankind never has experienced before. Overpopulation is a growing factor, which may cause heat-related deaths, unbreathable air, poisoned oceans and a series of other terrifying scenarios.
Increase in global warming:
The rate of global warming is increasing at an alarming rate compared to past global climate changes. Earth has encountered global climate changes before without the assistance from mankind. NASA’s research  about past global climate changes is based on samples from e.g. coral reefs, ocean sediments and ice sections in glaciers.
In Earth’s past, the climate was pending between ice-ages and warm interglacial periods. The climate records show us the time and duration of past ice ages and periods of even warmer climates than today. The findings also reveal, that the current global warming increases at a daunting rate in contrast to past warming cycles.
Predicting models  of the Earth’s warming rate show an accelerated increase of about 0.5 degrees Celsius by the end of the century, which is 15 percent hotter than the previous estimate. The likelihood of temperatures increasing by more than 4 degrees by the 22nd century, taking mankind’s centurial carbon dioxide emissions into account, increased from 62% to 93%. This new analysis proves that the world will have to cut another 800 gigatons of carbon dioxide emission this century in order to achieve the earlier issued warming estimate. Previously, it has usually taken the Earth a period of about 5,000 years to warm approximately 5 degrees . The now predicted rate of warming is at least 20 times faster, and it is an acceleration never seen before. There are still flaws with climate models as the climate is changing faster than the most current models predict. Real-world events may probably occur, that the models do not predict and take into consideration in its calculation, such as the melting of the Arctic sea ice is happening more rapidly than the models can explain. The models that are the most accurate are the ones projecting the highest warming in the future.
Mankind, reason for increasing global warming
Overpopulation causes environmental degeneration. With time the population rises, more land has to be deforested in order to provide space for agriculture and infrastructure for the additional masses. Around 19 million acres of forest are lost each year due to deforestation , which contributes exponentially to the increase in global warming.
People generate pollution, consequently more people generate more pollution. Humans have released enough carbon dioxide emission into the atmosphere to make them the leading cause of global warming . In accordance with the popular website Population Matters : this century, human activity requires more resources than the Earth can provide, and this endangers the health of the natural environment on which we all depend on. Every new human is born into a more competitive society, which means that the more of us there are, the more we are forced to exhaust the Earth’s natural resources, harvest trees in larger proportions and pollute the air more than ever before.
The naturalist, David Attenborough addressed the level of human population on the planet as a multiplier of all other environmental problems in a presentation  to the Royal Society of Arts. He also described humanity in an interview from 2013 as a “plague on Earth,” and it is urgent to get it under control by limiting population growth. Some of our deep ecologists, one of them being the radical thinker Pentti Linkola, sees human overpopulation as a threat to the entire biosphere . And most biologists and sociologists consider overpopulation so serious a threat as putting the quality of human life in jeopardy [9, 10].
The famous biologist Paul Ehrlich of Stanford University in California, said that the rich western countries are now consuming the planet’s resources and destroying its ecosystems at an unprecedented rate. We have desires to build highways across Serengeti in order to have access to more minerals for our cell phones. Fish are pillaged from the seas, coral reefs are ruined and carbon dioxide is pumped out into the atmosphere. Even major extinction events have been triggered as a result of overpopulation.
Global warming shows no empathy
Scientists warn that Earth’s sixth mass extinction event is en route. In a study , this is described as a “biological annihilation” that represents a “frightening assault on the foundations of human civilisation”. The scientists blame overpopulation together with overconsumption for the crisis and warn that it threatens the survival of human civilisation, which leaves us only with a short period of time to act.
They discovered that approximately a third of the thousands of species losing populations are yet not considered endangered and in recent decades up to 50% of all individual animals have been lost. Billions of populations of mammals, birds, reptiles and amphibians have been lost over the planet, which shows that the “sixth mass extinction” has come a lot further than anticipated, e.g. nearly half of the 177 mammal species observed in the study lost more than 80% of their distribution during the previous century up until 2015. The rapid loss of animal species is caused by environmental demolition, polluting of the air and by major shifts in the global climate. The ultimate cause of all these factors is “human overpopulation, continued population growth, and overconsumption, more specifically by the wealthy,” says Prof Paul Ehrlich.
If everyone consumed resources at the same level as the US, which unfortunately is what the world aspires to, then it would require the assets of another four or five Earths. Overpopulation provokes a competitive stress on the basic life sustaining resources, such as clean water, clean air and food, which in turn is leading to a declined quality of life. Therefore, by using resources beyond a sustainable level, the resource becomes inferior and ineffective, which further increases the discrepancy between the demand and the availability. This shows us that to support contemporary human lifestyles, a change in human activity and behaviour must occur in order to provide sufficient recovery time to each one of the resources.
The resources are running lower and lower at a steady rate, species are dying out and as if this was not bad enough of a situation, the overpopulation still continues to grow in magnitude. These are only current major issues and the future holds much worse living conditions according to both Prof James Hansen and Prof Wallace Smith Broecker which have forecasted an apocalyptic conclusion where no plausible program of emissions reduction alone can prevent climate disaster. Permafrost has not been a concerning issue until recently. The Arctic permafrost contains around 1.63 trillion tonnes of carbon , which is more than twice as much than what is currently suspended in the Earth’s atmosphere. When the permafrost thaws and releases this massive amount of carbon into the atmosphere, it may evaporate as methane. The gas methane is 34 times more powerful factor to the greenhouse effect compared to carbon dioxide, when measured on a time period of 100 years, and when measured in 20 years, it is 86 times more powerful. Last time this phenomenon occurred, 97% of all life on Earth died out . It is enough with a rise of 7 degrees to tear on the limits of habitability of some regions, and if the temperature rises with 11 or 12 degrees, more than half of the world’s population would die of direct heat, with today’s current distribution of the population . All of these examples are theoretical meanwhile major natural disasters caused by global warming are happening in contemporary time more frequently and stronger compared to the past. The most obvious effects can be seen for heat waves but also for storms and hurricanes  such as Harvey and Irma, which caused appalling damage both in the Caribbean and the southwestern coast in the US.
As the poles’ ice is melting, it makes a sea-level rise of at least 1.2 meters up to 3 meters a very likely possibility . It could mean large-scale consequences all over the world as a third of the world’s major cities are located on the coast, along with farmlands, power plants, ports, etc. Communities and facilities of great importance that are located above the highest estimate of 3 meters will run a higher risk of being flooded. The loss of land is not the worst consequence compared to increased ocean acidification , which is when carbon is sucked up by the oceans. Up until now, around a third of the world’s carbon has been dissolved by oceans. Coral reefs diminish because of this phenomenon, and the repercussions are weakened support for a quarter of all marine life and less food for almost half a billion of people . Harsher consequences of stronger ocean acidification is that fish populations would decline, oysters and mussels will struggle to grow their shells  and when our blood’s pH value is equal to the oceans’ pH, it may induce seizures, comas and sudden death .
As can be seen, overpopulation is causing mankind major troubles where one is worse than the other, e.g. increased overall environmental pollution, depletion of natural resources, mass species extinctions and consequent global warming.
The well-known astrophysicist Stephen Hawking and the CEO of SpaceX, Elon Musk both agree on that the human species needs to colonise an alternative habitable planet as early as in the next century in order to survive . There is almost no longer any question about if it is necessary anymore, rather if we are capable of accomplishing it before it is too late.
You can read more about the progress for projects concerning the search for another habitable planet here.
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