DON’T UNDERESTIMATE GLOBAL WARMING

For three decades, environmentalists have been claiming that if we don’t do something to fight global warming, we’ll all turn into pumpkins by the end of the century or so. Yet they’ve made very little headway in getting humanity to act on their suggested remedies.

The amount of Global Warming is often measured relative to the late 19th century even though this is about 100 years after the start of the industrial revolution, when humans started burning large amounts of fossil fuels.

According to the Paris Agreement on climate change, the world should try to limit global warming to as close to 1.5C as possible to avoid its worst effects, such as deadly heat waves, sea level rise that threatens coastal cities and more violent storms.

One of the researchers, Professor Michael Mann, said the Intergovernmental Panel on Climate Change (IPCC) had been using a definition of pre-industrial “that is likely underestimating the warming that has already taken place”.

“That means we have less carbon to burn than we previously thought, if we are to avert the most dangerous changes in climate,” he said.

“When the IPCC says that we’ve warmed 1C relative to pre-industrial, that’s probably incorrect. It’s likely as much as 1.2C.”

Meeting a 1.° C target is obviously more difficult if the change already experienced is 1.2 degrees rather than the 1.0 that had been broadly accepted. The new information doesn’t make the world any warmer, but it could have an effect on programs designed to meet the 1.5 degree goal. Either the total change allowed under agreements needs to go up to adjust for this early change, the definition of the allowed change needs to be redefined to make it clear it’s relative to 1880, or programs will have to be rapidly accelerated to try and hold off that final bit of change.

The study, described in the journal Natural Climate Change, found that anything from 0.02C to 0.21C of warming could already have taken place before the late 19th century.

The lower end of that range would mean the current use of the late 19th century is reasonably accurate, but the upper end would be a substantial change.

Professor Mann, of Pennsylvania State University, said that either the Paris targets “have to be revised” or the world could simply decide that they only wanted to restrict warming relative to the 19th century.

The new information doesn’t make the world any warmer, but it could have an effect on programs designed to meet the 1.5 degree goal. Either the total change allowed under agreements needs to go up to adjust for this early change, the definition of the allowed change needs to be redefined to make it clear it’s relative to 1880, or programs will have to be rapidly accelerated to try and hold off that final bit of change.

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