Humans must immediately implement a series of radical measures to halt carbon emissions or prepare for the collapse of entire ecosystems and the displacement, suffering and death of hundreds of millions of the globe’s inhabitants, according to a report commissioned by the World Bank. The continued failure to respond aggressively to climate change, the report warns, will mean that the planet will inevitably warm by at least 4 degrees Celsius (7.2 degrees Fahrenheit) by the end of the century, ushering in an apocalypse.

The 84-page document,”Turn Down the Heat: Why a 4°C Warmer World Must Be Avoided,” was written for the World Bank by the Potsdam Institute for Climate Impact Research and Climate Analytics and published last week. The picture it paints of a world convulsed by rising temperatures is a mixture of mass chaos, systems collapse and medical suffering like that of the worst of the Black Plague, which in the 14th century killed 30 to 60 percent of Europe’s population. The report comes as the annual United Nations Conference on Climate Change begins this Monday [Nov. 26] in Doha, Qatar.

A planetwide temperature rise of 4 degrees C — and the report notes that the tepidness of the emission pledges and commitments of the United Nations Framework Convention on Climate Change will make such an increase almost inevitable — will cause a precipitous drop in crop yields, along with the loss of many fish species, resulting in widespread hunger and starvation. Hundreds of millions of people will be forced to abandon their homes in coastal areas and on islands that will be submerged as the sea rises. There will be an explosion in diseases such as malaria, cholera and dengue fever. Devastating heat waves and droughts, as well as floods, especially in the tropics, will render parts of the Earth uninhabitable. The rain forest covering the Amazon basin will disappear. Coral reefs will vanish. Numerous animal and plant species, many of which are vital to sustaining human populations, will become extinct. Monstrous storms will eradicate biodiversity, along with whole cities and communities. And as these extreme events begin to occur simultaneously in different regions of the world, the report finds, there will be “unprecedented stresses on human systems.” Global agricultural production will eventually not be able to compensate. Health and emergency systems, as well as institutions designed to maintain social cohesion and law and order, will crumble. The world’s poor, at first, will suffer the most. But we all will succumb in the end to the folly and hubris of the Industrial Age. And yet, we do nothing.

“It is useful to recall that a global mean temperature increase of 4°C approaches the difference between temperatures today and those of the last ice age, when much of central Europe and the northern United States were covered with kilometers of ice and global mean temperatures were about 4.5°C to 7°C lower,” the report reads. “And this magnitude of climate change — human induced — is occurring over a century, not millennia.”

The political and corporate elites in the industrialized world continue, in spite of overwhelming scientific data, to place short-term corporate profit and expediency before the protection of human life and the ecosystem. The fossil fuel industry is permitted to determine our relationship to the natural world, dooming future generations. Carbon dioxide (CO 2 ), the main greenhouse gas, increased from its pre-industrial concentration of about 278 parts per million (ppm) to more than 391 ppm in September 2012, with the rate of rise now at 1.8 ppm per year. We have already passed the tipping point of 350 ppm; above that level, life as we have known it cannot be sustained. The CO 2 concentration is higher now than at any time in the last 15 million years. The emissions of CO 2 , currently about 35 billion metric tons per year, are projected to climb to 41 billion metric tons per year by 2020.

Because about 90 percent of the excess heat trapped by the greenhouse effect since 1955 is momentarily in the oceans, we have begun a process that, even if we halted all carbon emissions today, will ensure rising sea levels and major climate disruptions, including the continued melting of the Greenland and Antarctic ice sheets as well as the acidification of the oceans. The report estimates that if warming accelerates toward 4 degrees Celsius, sea levels will rise 0.5 to 1 meter, possibly more, by 2100. Sea levels will increase several meters more in the coming centuries. If warming can be keep to 2 degrees or below, sea levels will still rise, by about 20 centimeters by 2100, and probably will continue to rise between 1.5 and 4 meters above present-day levels by the year 2300. Sea-level rise, the report concludes, is likely to be below 2 meters only if warming is kept to well below 1.5 degrees. The rise in sea levels will not be uniform. Coastal areas in tropical regions will be inundated by sea-level rises that are up to 20 percent higher than those in higher latitudes.

“In particular, the melting of the ice sheets will reduce the gravitational pull on the ocean toward the ice sheets and, as a consequence, ocean water will tend to gravitate toward the Equator,” the report reads. “Changes in wind and ocean currents due to global warming and other factors will also affect regional sea-level rise, as will patterns of ocean heat uptake and warming. Sea-level rise impacts are projected to be asymmetrical even within regions and countries. Of the impacts projected for 31 developing countries, only 10 cities account for two-thirds of the total exposure to extreme floods. Highly vulnerable cities are to be found in Mozambique, Madagascar, Mexico, Venezuela, India, Bangladesh, Indonesia, the Philippines, and Vietnam. For small island states and river delta regions, rising sea levels are likely to have far ranging adverse consequences, especially when combined with the projected increased intensity of tropical cyclones in many tropical regions, other extreme weather events, and climate change-induced effects on oceanic ecosystems (for example, loss of protective reefs due to temperature increases and ocean acidification).”

“By the time the concentration reaches around 550 ppm (corresponding to a warming of about 2.4°C in the 2060s), it is likely that coral reefs in many areas would start to dissolve,” the report reads. “The combination of thermally induced bleaching events, ocean acidification, and sea-level rise threatens large fractions of coral reefs even at 1.5°C global warming. The regional extinction of entire coral reef eco-systems, which could occur well before 4°C is reached, would have profound consequences for their dependent species and for the people who depend on them for food, income, tourism, and shoreline protection.” The report projects that the rates of change in ocean acidity over the next century will be “unparalleled in Earth’s history.”

The global production of maize and wheat has, because of rising temperatures, been in steady decline since the 1980s. But these crop declines will be vastly accelerated in the coming years, with rising temperatures resulting in widespread malnutrition and starvation. It will mean that the poor, and especially children, will endure chronic hunger and malnutrition. There will be an increase in a variety of deadly epidemic diseases. Persistent flooding will contaminate drinking water, spreading diarrheal and respiratory illnesses. The 2012 drought, which affected 80 percent of the agricultural land in the United States, will become the norm. Tropical South America, Central Africa and all tropical islands in the Pacific are, the report says, likely to regularly experience heat waves of unprecedented magnitude, making human life in these areas difficult if not impossible to sustain.

“In this new high-temperature climate regime, the coolest months are likely to be substantially warmer than the warmest months at the end of the 20th century,” the report reads. “In regions such as the Mediterranean, North Africa, the Middle East, and the Tibetan plateau, almost all summer months are likely to be warmer than the most extreme heat waves presently experienced. For example, the warmest July in the Mediterranean region could be 9°C warmer than today’s warmest July.” It notes that these changes “potentially exceed the adaptive capacities of many societies and natural systems.”

The stress and insecurity caused by the breakdown in the climate will, the report says, “have negative effects on psychological and mental health.” It will lead to an increase in “levels of conflict and violence.” These changes “will have ramifications for national identification and alter the dynamics of traditional cultures.”

The report calls on the leaders of the industrial world to immediately institute radical steps — including a halt to the dependence on fossil fuels — to keep the global temperature rise below 2 degrees C, although the report concedes that even an increase of less than 2 degrees would result in serious damage to the environment and human populations. Without a massive investment in green infrastructure that can adapt to the heat and other new extreme weather, and in the building of efficient public transportation networks and renewable energy systems to minimize carbon emissions, we will succumb to our own stupidity.

A failure to respond will assure an ecological nightmare that will most probably be accompanied by an economic, social and political breakdown. The human species, the report says, will cross “critical social system thresholds,” and “existing institutions that would have supported adaptation actions would likely become much less effective or even collapse.” The “stresses on human health, such as heat waves, malnutrition, and decreasing quality of drinking water due to seawater intrusion, have the potential to overburden health-care systems to a point where adaptation is no longer possible, and dislocation is forced.”

“There is also no certainty that adaptation to a 4°C world is possible,” it goes on. “A 4°C world is likely to be one in which communities, cities and countries would experience severe disruptions, damage, and dislocation, with many of these risks spread unequally. It is likely that the poor will suffer most and the global community could become more fractured, and unequal than today. The projected 4°C warming simply must not be allowed to occur — the heat must be turned down.”