Study suggests Earth to warm more than 2 C this century

A new study from the University of Washington suggests that there is a 90 per cent chance Earth will warm anywhere between 2 C and 4.9 C above pre-industrial levels by the end of the century.

The researchers of the study published in Nature Climate Change used statistical tools which found only a five per cent chance the planet will warm by 2 C or less by the end of the century. There was only a one per cent chance it would warm below 1.5 C, a target set out by almost 200 countries in the Paris climate agreement.

In order to run the model, the researchers collected data from the past 50 years from 150 countries that account for 99 per cent of the world's population. They included population, gross domestic product (GDP) and carbon usage as well as trends, such as declining CO2 production.

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They found that carbon intensity has been decreasing over the past 50 years. That, lead author Adrian Raftery said, is because the global climate has been an issue for more than 30 years and technological advancements have helped reduce emissions.

I think our work puts into sharper focus that we're not very likely to make those targets and we could be going for much higher numbers.- Adrian Raftery, University of Washington

Despite that, however, Earth will continue to warm. And that's largely due to the carbon that has already been produced. Essentially, there's a game of catch-up when it comes to the planet's temperature.

Another reason is the improvement in living conditions, seen in terms of gross domestic product (GDP).

"The rate at which GDP has been increasing is very similar to the rate at which carbon intensity has been going down," Raftery told CBC News. "So they're fairly close to cancelling one another out. In terms in carbon efficiency, we're running fast to stay in the same place. And that's kind of a frustrating perspective."

Consequences

The models also predicted a global population of 11 billion by 2100. But that didn't play a significant role in CO2 production and rising temperatures. That's because three quarters of the population increase will occur in sub-Saharan Africa, where emissions are low and will continue to be low. 

The United Nations Intergovernmental Panel on Climate Change (IPCC) provided four scenarios in Earth's warming. While not forecasts, the consequences are dire for a temperature increase such as the one forecast in this new study. Depending on the geographic location, they include droughts, floods, increasing forest fires, rising sea levels, a change in migration patterns, and food shortages. 

"It's more urgent to address the issue, because up until now it's been couched in terms of a target of 1.5 degrees or 2 degrees which would already have consequences," Raftery said.

"I think our work puts into sharper focus that we're not very likely to make those targets and we could be going for much higher numbers. If they're realized, the consequences would be much more severe."

Raftery said that the world should look to countries like France which has a low-carbon infrastructure, including carbon-efficient public transportation, high gas tax and nuclear power. 

As for the Paris agreement, signed by almost 200 countries in an effort to prevent Earth from warming 2 C above pre-industrial levels, Raftery said it's disappointing to see the U.S. — a major contributor of CO2 emissions — pull out. 

"The U.S. pulling out of the Paris agreement is extremely unfortunate. And I think it will definitely make it harder to limit the amount of warming," Raftery said. However, he added that individual states have stepped up their efforts to reduce emissions, which may mitigate the effects. 

While some may believe we're already doomed and should give up, Raftery said that's not the case.

"I think it's exactly the opposite, because 2.5 [C] is much better than 3.2 [C]."