Limiting warming to 2 degrees Celsius

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Now, an equivalent authors have used their tools to ask: What emissions cuts would actually be required to satisfy the goal of two degree Celsius warming, considered a threshold for climate stability and climate-related risks like excessive heat, drought, extreme weather and water level rise?

The University of Washington study finds that emissions reductions about 80% more ambitious than those within the Paris Agreement, or an average of 1.8% drop by emissions per annum instead of 1% annually, would be enough to remain within 2 degrees. The results were published Feb. 9 in Nature’s open-access journal Communications Earth & Environment.

“A number of individuals are saying, particularly within the past few years, that the emissions targets got to be more ambitious,” said lead author Adrian Raftery, a UW professor of statistics. “We went beyond that to invite a more precise way: what proportion more ambitious do they have to be?”

The paper uses an equivalent statistical approach to model the three main drivers of human-produced greenhouse gases: national population, gross domestic product per person and therefore the amount of carbon emitted for every dollar of economic activity, referred to as carbon intensity. It then uses a statistical model to point out the range of likely future outcomes supported data and projections thus far .

Even with updated methods and five more years of knowledge , now spanning 1960 through 2015, the conclusion remains almost like the previous study: Meeting Paris Agreement targets would give only a 5% probability of staying below 2 degrees Celsius warming.

Assuming that climate policies won’t target increase or economic process , the authors then ask what change within the “carbon intensity” measure would be needed to satisfy the two degrees warming goal.

Increasing the general targets to chop carbon emissions by a mean of 1.8% annually, and continuing on it path after the Paris Agreement expires in 2030, would give the earth a 50% chance of staying below 2 degrees warming by 2100.

“Achieving the Paris Agreement’s temperature goals are some things we’re not on track to try and do now, but it wouldn’t take that much extra to try to to it,” said first author Peiran Liu, who did the research as a part of his doctorate at the UW.

The paper looks at what this overall plan would mean for various countries’ Paris Agreement commitments. Nations set their own Paris Agreement emissions-reductions pledges. The us pledged a tenth drop by carbon emissions per annum until 2026, or slightly more ambitious than the typical . China pledged to scale back its carbon intensity, or the carbon emissions per unit of economic activity, by 60% of its 2005 levels by 2030.

“Globally, the temperature goal requires an 80% boost within the annual rate of emissions decline compared to the Paris Agreement, but if a nation has finished most of its promised mitigation measures, then the additional decline required now are going to be smaller,” Liu said.

Assuming that every country’s share of the work remains unchanged, the U.S. would wish to extend its goal by 38% to do its part toward actually achieving the two degrees goal. China’s more ambitious and fairly successful plan would wish only a 7% boost, and also the uk , which has made substantial progress already, would wish a 17% increase. On the opposite hand, countries that had pledged cuts but where emissions have risen, like South Korea and Brazil, would wish a much bigger boost now to form up for the lost time.

The authors also suggest that countries increase their accountability by reviewing progress annually, instead of on the five-year, 10-year or longer timescales included in many existing climate plans.

“To some extent, the discourse around climate has been: ‘We need to completely change our lifestyles and everything,'” Raftery said. “The idea from our work is that really , what’s required isn’t easy, but it’s quantifiable. Reducing global emissions by 1.8% each year may be a goal that’s not astronomical.”

From 2011 to 2015, Raftery says, the U.S. did see a drop by emissions, thanks to efficiencies in industries starting from lighting to transportation also as regulation. The pandemic-related economic changes are going to be short-lived, he predicts, but the creativity and adaptability the pandemic has required may inaugurate an enduring drop by emissions.

“If you say, ‘Everything’s a disaster and that we got to radically overhaul society,’ there is a feeling of hopelessness,” Raftery said. “But if we are saying , ‘We got to reduce emissions by 1.8% a year,’ that’s a special mindset.”

This research was funded by the National Institutes of Health.

Materials provided by University of Washington