There is no legitimate doubt that human activity is accelerating the greenhouse effect, which results in global warming. This was acknowledged in the UN Framework Convention on Climate Change (UNFCCC), which was adopted at the Earth Summit in Rio de Janeiro in 1992 and has since has been ratified by 197 countries. This nearly universal membership gives legitimacy to its main aim of mitigating the human effect on climate change. However, it was not until the Paris Agreement of 2015, that signatories to the UNFCC set targets, promising to hold global warming well below 2°C above pre-industrial temperatures and to try to limit the temperature increase to 1.5°C.

Sadly, we are currently too slow in taking action to meet these targets – greenhouse gas emissions continue to increase. This year’s Emissions Gap Report, issued by the UN Environment Programme (UNEP), has concluded that there is a huge and growing gap between what needs to be done to tackle climate change and what we are actually doing. The challenge is enormous: the report concludes that greenhouse gas emissions must be reduced by 7.6 per cent every year for the next ten years if we want to limit warming to 1.5°C.

Ahead of the COP25 meeting, U.N. Secretary-General Antonio Guterres said that, so far, the world’s efforts to limit global warming have been “utterly inadequate”. He warned that “the point of no return is no longer over the horizon; it is in sight and hurtling toward us.”

We do not have the luxury to postpone effective climate action any longer. Moreover, we need to start preparing for life in a drastically different world, where climate change and related global environmental degradation will impact human security and international security.

It is hard to imagine what the combined consequences of the geophysical and societal changes could mean for us. Scientists warned in the early seventies of “The Limits to Growth” and many of their concerns have since been vindicated. The exponential growth in resource extraction, use of fossil fuels, production, consumption and waste has contributed to the rise in CO2 emissions, extensive pollution, and loss of biodiversity, impacting all kinds of other processes on the planet. Increasingly, Earth’s interacting physical, chemical and biological processes will pass tipping points, and feedback loops will further impact the environment.

‘Planetary security’ therefore captures the new security challenges of our century better than the phrase ‘climate security’, or even the wider concept of ‘environment and security’. The scale of these challenges could easily be underestimated. All the media attention on the 2018 Intergovernmental Panel on Climate Change (IPCC) special report on the impacts of global warming of 1.5°C may have given the impression that only two possibilities lie ahead: a temperature rise of 1.5°C or 2°C. Unfortunately, the future could have much more extreme scenarios in store for us.

As Petteri Taalas, Secretary-General of the World Meteorological Organization (WMO) stated upon the release of the WMO provisional Statement on the State of the Climate in 2019: “If we do not take urgent climate action now, then we are heading for a temperature increase of more than 3°C by the end of the century, with ever more harmful impacts on human wellbeing.”

While we should do the utmost to mitigate climate change, it would be naive not to think about how to prepare for the security consequences of a much warmer world, where a drastically changed environment will contribute to new security challenges. Given the complexities of the planet’s interacting processes, it is difficult to predict exactly what will happen at different mean temperatures –but basically the hotter it gets, the greater the disruption will be to weather patterns, ecosystems and sea levels.

Humidity and heat could make large parts of the tropic zones uninhabitable for at least part of the year. Many of the glaciers in the Himalaya that provide a reliable source of water for more than a billion people are likely to disappear. Many coastal cities risk being submerged. Billions of people may be faced with high levels of water stress or food scarcity, and many may migrate towards more habitable parts of the planet.

Already we are seeing signs of what lies ahead: heatwaves, forest fires and increased destruction by hurricanes, floods and other forms of extreme weather. In the decades to come, and certainly in the second half of this century, climate change will become the biggest challenge humankind has ever faced…