Climate change helped destroy these four ancient civilisations

Ignorant, malign and evil. This is some of the unapologetically harsh criticism directed at climate change deniers by Mary Robinson, former President of Ireland and UN High Commissioner for Human Rights.

Her point is as simple as it is blunt: “Climate change undermines the enjoyment of the full range of human rights – from the right to life, to food, to shelter and to health. It is an injustice that the people who have contributed least to the causes of the problem suffer the worst impacts of climate change.”

It is widely accepted that the Earth’s climate is in a near-constant state of flux. There have been seven ice age cycles, featuring the expansion and contraction of glaciers, over the last 650,000 years. The last major ice age ended approximately 11,000 years ago, ushering in our modern climate era, the Holocene. Since then, the climate has been mostly stable, although there was a Little Ice Age that took place between 1200 and 1850 CE.

But there’s more to climate change than the spread of glaciers and many once-mighty civilizations have been devastated by the effects of locally changing climate conditions.

The Mayan civilization in Mesoamerica lasted for some 3,000 years. Their empire was spread throughout the Yucatan Peninsula and modern-day Guatemala, Belize, parts of Mexico, and western Honduras and El Salvador. Agriculture was the cornerstone of Mayan civilization, with great cities being built as the population grew. Religion was an important part of Mayan life; sacrifice – including human sacrifice – was a regular ritual, intended to appease and nourish the gods and keep the land fertile.

However, somewhere around 900 CE, things started to go wrong for the Mayans. Overpopulation put too great a strain on resources. Increased competition for resources was bringing the Maya into violent conflict with other nations. An extensive period of drought sounded the death-knell, ruining crops and cutting off drinking water supplies.

They were not the only ancient people catastrophically caught out by climate change.

More than 4,000 years ago in Mesopotamia – the area currently made up of Iraq, north-east Syria and south-east Turkey – the Akkadian empire ruled supreme. Until a 300-year-long drought quite literally turned all their plans to dust. It was part of a pattern of changing climate conditions in the Middle East around 2,200 BCE that was constantly disrupting life and up-ending emerging empires.

When the effects of drought began to be felt, people would leave the stricken areas and migrate to more abundant ones. These mass migration events, however, increased the pressure on remaining resources, leading to yet more problems.

The iconic Angkor Wat temple is a reminder of the prowess of another of history’s lost civilizations – the Khmer empire of south-east Asia, which flourished between 802 and 1431 CE. It too was brought down by drought, interspersed with violent monsoon rains, against the backdrop of a changing climate.

Even the Viking settlers of Greenland, in the far north Atlantic, are believed to have been affected by climate change. Some 5,000 settlers made the island their home for around 500 years. But they may have had their way of life disrupted by climate change. Temperatures dropped, reducing substantially the productivity of their farms and making it harder to raise livestock. They adapted their eating habits, turning their attention to the sea as a source of food. But life on Greenland became unbearably difficult, leading to the eventual abandonment of the island colony.

The natural cycle of climate change is an ongoing and unavoidable part of life. But history seems to be telling us that when past civilizations have overstretched themselves or pushed their consumption of natural resources to the brink, the effects of climate change soon become amplified. With dire consequences for those caught up in it.

Since the advent of the Industrial Revolution, increasing amounts of polluting gases have been pumped into the atmosphere, triggering an unprecedented rate of warming. According to the IPCC, human activity has caused around 1°C of global warming (above pre-industrial levels). The likely range is between 0.8°C and 1.2°C. Between 2030 and 2052, global warming is likely to hit a 1.5°C increase.

That increase of 1.5°C could put between 20% and 30% of animal species on the fast track to extinction. If the planet warms by an average 2°C the damage will be even worse. For the human population, one of the threats climate change poses is rising sea levels and eight of the world’s 10 largest cities are in coastal locations.

Another is the risk of climate-driven drought leading to mass migration events similar to those seen thousands of years ago. The Climate & Migration Coalition has warned that countries caught up in armed conflict or civil war are particularly vulnerable to famine in the event of drought. The Horn of Africa, home to Djibouti, Eritrea, Ethiopia, and Somalia is an area that has been hit hard by both man-made conflict and climate change. Around 13 million people there face serious food shortages.

In volatile parts of the world, it is exceptionally difficult to address the challenges of drought and famine; getting aid to people in a conflict zone is fraught with difficulty and danger. This can make the effects more profound and longer-lasting, which will, in turn, increase the likelihood of large numbers of people uprooting themselves in search of somewhere they can live.

The challenge facing our world due to climate change is something that should not be underestimated. But neither is it cause for despondency. Because unlike the Mayans, the Mesopotamians and other ancient civilizations, here in the 21st century, we are in a position to do something constructive.

The Paris Agreement was one significant milestone in the fight back against climate change. Signed by 195 members of the UN Framework Convention on Climate Change, it has put in place a serious of goals and commitments to keep the increase in average global temperatures below 2°C. Despite a high-profile decision to leave the Paris Accord, there is now a growing movement in the US political sphere to rejoin. There is also talk of the European Union refusing to sign trade deals with countries that are not signatories to the agreement.