Global heating is the effect of greenhouse gases—carbon-based compounds that have an effect similar to glass in a greenhouse, trapping heat in while allowing light to reflect back into space. In 2015, 196 nations asked the Intergovernmental Panel on Climate Change (IPCC) to study global warming of 1.5ºC. In 2018, that report found that warming of 1.5ºC would have dangerous, destabilizing, and prohibitively costly consequences.

Now, the United Nations Environment Programme (UNEP) reports that “Global temperature rise is set to cross 1.5°C, likely within the next few years, pushing climate risks and impacts to increasingly dangerous heights…” The report, Limiting Overshoot, also finds that it is possible to reverse excess heating and return to temperatures below 1.5ºC, describing:

an ‘overshoot, peak, and decline’ pathway as the best remaining option to minimize the magnitude and duration of this overshoot and try to return to below 1.5°C as soon as possible.

If we fail to slow, stop, and reverse global heating, the consequences for human security and wellbeing will be severe, costly, and destabilizing. The Limiting Overshoot report highlights as the top message that “Risks and impacts above 1.5°C intensify with every fraction of a degree.”

Major impacts “can either grow with time or emerge suddenly”. In a world of sustained Overshoot, destabilizing impacts can be expected to include:

• Intensified extreme weather, ecosystem loss, and submersion of Small Island Developing States (SIDS) and low-lying coastal cities.
• Severe damage to human health, food security, water supplies, nature, cities, infrastructure and economies.
• Crossing thresholds that become difficult or impossible to reverse on human timescales.

The report cites evidence that “global food production could decline by up to 14 per cent by 2050 in the absence of effective adaptation,” which means ongoing price rises would become far more extreme, whole economies could go into prolonged depression, and conditions for armed conflict would become much more urgent and pervasive.

Sustained Overshoot also could also become irreversible if the polar ice caps are depleted to where thousands or tens of thousands of years of cooling would be required to restore them or if the major Atlantic ocean current (AMOC) or the Amazon rainforest were to collapse.

The two most important contributors to reversing Overshoot and its far-reaching impacts will be:

• Eliminating pollution that causes global heating;
• Restoring Nature, so ecosystems on land and in the ocean can absorb and contain sufficient carbon to lower atmospheric levels of the compounds that cause global heating.

Restoring Nature means protecting ecosystems, improving the chances for natural biodiversity to survive and thrive, and supporting robust and resilient watersheds. All of that means there will need to be significant upgrading of standards and practices across numerous industries. Those upgrades will provide significant opportunities for diversification of local economies and improved livelihoods.

In rural areas, new work related to Earth science observation, data scaling and translation, and to managing co-investments and results-based financing will provide new opportunities for good incomes and enhanced locally rooted small business development. Such diversified rural economies can improve farmer incomes, while bringing new investment to communities and restoring ecosystems and watersheds.

In its press release, UNEP notes:

Strong political will and multilateralism, effective policies, inclusive governance, and finance are all important enabling conditions for action – and equity and justice must underpin all responses. Countries with greater responsibility for climate change should act the fastest with the greatest ambition.

While this would seem to push against the recent trend, in which rogue actors seem to reject international cooperation and rule of law, all of the math balances out on the side of constructive cooperation. To avoid deep and pervasive economic unraveling, cities and villages will need mainstream economies that benefit from climate-aligned trade and policy.

So, we will need:

• Strong political leadership;
• Constructive international cooperation;
• Sound, evidence-based policy to drive sustainable development;
• The elimination of global heating pollution;
• Activities that restore Nature and protect ecosystems and watersheds;
• Investment, finance, and trade that support success.

Chris Bowen, Australian Minister for Climate Change and Energy, and President of Negotiations for COP31, acknowledges “our Pacific family standing on the frontlines” and says:

“The recent energy crisis has reminded the world of the need to reduce our dependence on fossil fuels, accelerate the transition to renewable energy and bolster climate cooperation.”

H.E. Murat Kurum, COP31 President-Designate, called for a major upgrade of cooperative climate action, saying:

“We need to accelerate global electrification, reduce methane emissions from waste, strengthen the climate resilience of cities, and enhance the resilience of marine and coastal ecosystems.”

The upcoming meetings of the UN General Assembly will need to take stock of this report and begin urgently to act on its recommendations. Multilateral climate cooperation is a centerpiece of the Paris Agreement, and connects to all of the Sustainable Development Goals.

The best future for humankind is one in which we limit Overshoot, bring heating back to below 1.5ºC, and promote inclusive sustainable development through climate-smart everyday economies. To get there, we will need science-informed investments that support resilience-building innovations and outcomes.

And, we need to honor the role of science in providing the basis for informed decision-making, at all levels.