If one phrase has dominated COP26Cop stands for  Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change, it is "business as usual". Officials and leaders have queued up to denounce progress on climate breakdown, warning of consequences if we do not make changes.

The outlook looks bleak. It has been reported that by 2030, crops in Australia could drop by 50%, Madrid will face droughts and tropical cyclonesA huge, devastating storm. They are also known as hurricanes and typhoons, depending on their location., and Nigeria will be stricken with famine.

But science writer Tom ChiversA freelance science writer who is also Science Editor at heterodox British magazine UnHerd. thinks this is overblown. He argues that all these predictions are based on a worst-case scenario that is not likely to come true.

In 2014, scientists at the Intergovernmental Panel on Climate ChangeA UN body tasked with researching climate breakdown and coming up with recommendations for states to follow. (IPCC) sketched out four scenarios, called Representative Concentration PathwaysA number of potential trajectories that the climate could follow according to our best scientific knowledge. Each pathway tracks the likely consequences of a particular volume of greenhouse gas emissions. (RCPs).

With RCP2.6, each square metre of the planet would be warmed by 2.6 watts by 2100, around 1.8C of heating. To achieve this, global emissions would have had to peak in 2020. Under RCP4.5, emissions need to peak in 2040, keeping heating between 2C and 3C. RCP6 has emissions peaking in 2080.

When newspapers report on the climate emergency, they mostly use the most extreme pathways, RCP8.5. This scenario, which would result in 4.3C of heating, is known as "business as usual", because it assumes no measures are taken.

Some are sceptical. Even when first devised, RCP8.5 was considered unlikely. Every country in the world now has a strategy for reducing emissions, so "business as usual" no longer means inaction. In fact, to achieve the kind of emissions expected under RCP8.5, we would have to increase our coal use per capitaPer person. The phrase came into use in the late 17th Century, but it is originally a Latin phrase meaning "by heads". by around 700%.

It is likely that we end up with 3C of global heating. This could still have catastrophic impacts, but not as terrible as those predicted by RCP8.5.

Part of the challenge of the climate crisis is uncertainty. Chivers notes that the outcomes predicted under RCP8.5 could still come true, because of feedback loops in nature. For example, ice reflects sunlight. When ice melts, less sunlight is reflected and so the amount of heating increases.

On the other hand, he points out, some feedback loops might work in our favour. The more CO2 there is in the atmosphere, the faster plants grow, and they suck some of that CO2 out of the atmosphere.

But some think Chivers is too optimistic. While the world's use of fossil fuels might be on track to meet RCP4.5, deforestationThe removal of a forest in order to use the land on which it stood for some other use, often agriculture or housing. is pushing up emissions. 

And growing conflict between the world's great polluters - the USA, China and India - might cause all of them to stick to cheap fossil fuels rather than risk losing their competitive advantage. RCP8.5 could still happen, even if not in the way scientists predicted.

Yes. The consequences of global heating will be severe. But newspapers are only interested in running the most dire predictions, which is harming our capacity to prepare for the real effects.

No. No-one is suggesting that humanity is going to drown or burn to death. The problem is that our political, economic and social structures are fragile. Extreme weather events could devastate economies, and states may be unable to cope with refugee flows.

Cop26 - Cop stands for  Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change

Tropical cyclones - A huge, devastating storm. They are also known as hurricanes and typhoons, depending on their location.

Tom Chivers - A freelance science writer who is also Science Editor at heterodox British magazine UnHerd.

Intergovernmental Panel on Climate Change - A UN body tasked with researching climate breakdown and coming up with recommendations for states to follow.

Representative Concentration Pathways - A number of potential trajectories that the climate could follow according to our best scientific knowledge. Each pathway tracks the likely consequences of a particular volume of greenhouse gas emissions.

Per capita - Per person. The phrase came into use in the late 17th Century, but it is originally a Latin phrase meaning "by heads".

Deforestation - The removal of a forest in order to use the land on which it stood for some other use, often agriculture or housing.