With war in Ukraine, energy and food security have shot up the political agenda, and some are arguing that we need to increase fossil fuel extraction, including in Scotland. But climate change is already biting harder as the world heads towards multiple tipping points.

We are now pushing 1.3°C of global warming and 1°C of that has happened in my lifetime. That has put the world in the danger zone for

passing five large-scale climate tipping points: We are risking irreversible loss of the Greenland and West Antarctic ice sheets – which together hold enough water to raise sea levels by over 10 metres. We are risking abrupt loss of tropical coral reefs which support the livelihoods of 500 million people. We are risking abrupt thawing of the boreal permafrost which releases massive amounts of carbon amplifying global warming. Then there is a risk you have probably never heard of: the collapse of deep convection in the Labrador Sea.

The last time that tipped it started the Little Ice Age in Europe, and it can tip within a decade. The Scottish skiing industry may rub its mittened hands in glee at the thought of intense winter storms suddenly becoming the norm, but our national infrastructure is just not built for a radical increase in seasonality. Across the Atlantic it would raise sea levels by up to 30 centimetres along the northeast seaboard of the US and Canada – meaning widespread flooding when a storm surge hits Boston or New York. Further afield it would seriously disrupt the monsoon in West Africa triggering famine in the Sahel region.

If we miss the goal of the Paris Agreement and exceed 1.5°C global warming, passing these climate tipping points becomes likely and five more are put at risk, including the big one: a collapse of the Atlantic ocean’s great overturning circulation. If that happens it will dramatically dry out the UK and Europe and disrupt monsoons all around the tropics. By our calculation, the double whammy of global warming and that tipping point will halve the viable area for growing wheat worldwide.

Meanwhile in the tropics, if warming exceeds 1.5°C, the number of people exposed to potentially fatal extreme heat and humidity will escalate radically to hundreds of millions. If I was one of those people, and could afford to, I would be looking to move. As one friend put it at COP26 “they will be coming to live with us”. I hope we are ready to welcome them with open arms and a wee dram. But we are talking about a scale of human migration across the planet that is hundreds of times larger than that triggered by the wars in Syria and Ukraine.

In short, it would be unethical madness to increase fossil fuel extraction now and knowingly trigger such harm – and it would be impossible for Scotland, the UK or anywhere else to insulate itself from the consequences. The world is far too interconnected – both the climate world and the human world – to escape the consequences of our energy decisions now. Yes, we are suffering a cost-of-living crisis, but the way out of that is not backwards to fossil fuels, it is forwards – embracing the positive tipping point to renewable energy.

We are risking irreversible loss of the Greenland and West Antarctic ice sheets – which together hold enough water to raise sea levels by over 10 metres, writes Professsor Tim Lenton.

What doesn’t seem to have registered on the collective radar is that we are reaching peak fossil fuel use globally, because the exponential growth of renewable energy is about to exceed the increase in global demand for energy. Things are even better in the power sector – where growth in renewables has already outstripped growth in electricity demand in 2022. This has produced a 1% global reduction in fossil-fuel based power generation and associated emissions. A modest start for sure, but that change is accelerating exponentially as renewable power generation is increasing at well over 10% per year.

In short, renewables are now displacing fossil fuels globally, and they have been doing so in the UK for over a decade. Renewables are already the cheapest form of power generation in most of the world and cheaper than fossil fuel power has ever been. They are only going to get cheaper – thanks to phenomenal economies of scale: The more solar or wind power that gets installed, the cheaper the next unit is to install. Over the last decade solar and wind have fallen in price by around 90% and 70% respectively.

Currently the UK has about 25 gigawatts of installed wind power capacity – 14 on land and 11 offshore – supplying about 25% of our electricity needs. Our latest national target is 50 gigawatts of offshore wind power by 2030. That means renewables will be supplying most of our electricity by the end of this decade.

Meanwhile electric vehicle uptake has passed a tipping point in the UK which is going to radically reduce our demand for oil. As the EV market expands, ever-cheaper batteries will provide cheap energy storage reinforcing the transformation to renewable power.

This means positive tipping points could cascade across the economy. Ever cheaper renewable power will reduce the costs of running heat pumps to decarbonise buildings, and of running electrolysers to make green hydrogen and green ammonia. Green ammonia is already cost competitive with fossil-fuelled fertiliser production, and as it displaces that, it will trigger further economies of scale. That will open the niche for green ammonia to replace fossil fuels in shipping, triggering further economies of scale, which will in turn enable green hydrogen to replace fossil fuels in steel production.

We are at a tipping point where we can choose to commit to a green energy future and save ourselves from the worst ravages of climate tipping points, or we can cling to fossil fuelled oblivion.

COP27: We are heading towards multiple tipping points on climate change - further fossil fuel extraction is simply unethical - Professor Tim Lenton

Professor Tim Lenton is director of the Global Systems Institute at the University of Exeter