What scares me about the climate crisis is that we don’t know how bad things really are | Roger Harrabin

OROver the last few decades, climate scientists have made great strides in understanding the future climate. But after the last few weeks of extreme heat and devastating flooding, it’s clear that while climate models have provided good information on rising temperatures overall, they can’t be sure of the level of destruction each notch on the thermometer will bring.

Climate modeling is extremely complex, but its fundamentals are based on basic physics X tons of emissions will lead to Y temperature increase, with some error bars. Supercomputers have been able to take this into account changes in land use that will change the reflectivity of the earth’s surface. Improved temperature records helped verify their results.

But lately, Leading researchers have made a painful confession: Even their most sophisticated models still can’t predict exactly how Earth’s systems will respond to those higher temperatures.

The influential Intergovernmental Panel on Climate Change (IPCC) says raising global temperature by half a degree will bring much more extreme weather, and that it can be more frequent, more intense or prolonged in duration, but exactly how much more it cannot say precisely.

So, for example, we’ve already had a global temperature increase of around 1.2°C – this is in line with the IPCC’s projections. Yet the panel could not warn us of the appalling heat dome that is burning North America. I can’t find the thermal domes mentioned in the climate change bible, the IPCC report. This periodic report inevitably lags behind the new science and under pressure from some governments and industries, as well as the desire not to scare its statements tend to be conservative.

Furthermore, the models have not been able to accurately warn us of the emergence of heat trapped in the deep ocean, which absorbs 90% of the world’s excess heat. In the 35 years I’ve covered the environment for the BBC, I recall the speculation that the heat might linger for decades, perhaps centuries, not that some of it would suddenly burst to the surface off the north coast of Britain.

There are also major uncertainties about precipitation. Good information about the future of monsoon rain would be a godsend for farmers who rely on it not only in India but also in southern China. Unfortunately, good rainfall information is proving a bit hard to come by.

Furthermore, the macro models failed to project the effect of the current high temperatures on the ice at both poles. The former head of the IPCC, Professor Bob Watson, told me: I am very worried. None of the changes observed so far (with a temperature increase of 1.2°C) are surprising. But they are worse than predicted 20 years ago, and worse than predicted five years ago. We probably underestimated the consequences.

That’s a massive admission. He added: Scientists are only now beginning to understand the response from the large ice sheets in Greenland and Antarctica and it is very disturbing.

Professor Jane Francis, director of the British Antarctic Survey, told me a few months ago that the latest science on melting ice was really scary.

A digital billboard displays the temperature in downtown Phoenix.
The United States considered itself less vulnerable. But tell that to the people in Phoenix trapped under that heat dome. Photography: Matt York/AP

Watson said that at current rates the world would almost certainly exceed the agreed maximum temperature rise of 1.5-2°C. We’d be lucky to get away with 2.5C, she said. More likely, they were heading to 3C.

That number positively scares many climate scientists. But, as India begins to stockpile rice with a 1.2°C temperature rise, what helpful advice can scientists offer for a 3°C world? How bad will things get then?

Should holidaymakers avoid buying homes in Greece? China is vulnerable to extremes, how should its economy adapt? The United States considered itself less vulnerable. But tell that to the New Yorkers choking on the smoke from the wildfires, or the people in Phoenix trapped under that heat dome.

While the immediate harm to people is newsworthy, what is it even more destructive may be the impact of heat and humidity on food production for an expanding population. A global shift to a plant-based diet could cut land and water used for agriculture in half and cut carbon emissions in half, but politicians fear anger voters recommending a dietary change.

Dealing with all this darkness means we need imagers as well as climatologists. Watson argued that civilization will still exist in the future, but with much worse living conditions. But what kind of degraded civilization could it be? By then we may even have triggered some natural tipping points that could result in a massive release of trapped methane in the tundra, hopefully not.

What we do know is that so far the effects of global warming are earlier and worse than many scientists predicted (at least publicly). This has political implications. The world has agreed to reduce emissions to zero by 2050, but UN Secretary-General Antnio Guterres says rich countries should aim to reduce the timetable to 2040. But what good is a zero-emissions policy if it relies in part on planting trees that might wither in a future drought or crackle in a fire?

To make matters worse, global warming is one thing in a list of massive environmental problems including air and water pollution, destruction of wildlife habitats, overfishing, insect population decline, bird loss, plastic pollution, nitrates, soil loss, and more.

Watson says we don’t know how these phenomena will interact with each other, but urges politicians to err on the side of caution, as the stakes are very high. Every 0.1°C of warming matters, scientists say: 1.5°C is better than 1.6°C. Which in turn is less negative than 1.7C.

As the barrage of bad news continues, all we can be sure of is that many climate surprises lie ahead. Governments, businesses and individuals urgently need to reduce emissions to insulate us as much as possible from what we may be facing.

#scares #climate #crisis #dont #bad #Roger #Harrabin
Image Source : www.theguardian.com

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