According to new reports published by CNN.com, the global temperature is likely to rise more than 2 degrees Celsius or 3.6 degrees Fahrenheit by the end of the century.
The ominous prediction is the conclusion reached by two different studies using entirely different methods published in the journal Nature Climate Change on Monday.
One study used statistical analysis to show that there is a 95% chance that Earth will warm more than 2 degrees at the century’s end and a 1% chance that it’s below 1.5 C.
The author of the study, Adrian Raftery explains, “the likely range of global temperature increase is 2.0-4.9 [degrees Celsius] and our median forecast is 3.2 C. Our model is based on data that already show the effect of existing emission mitigation policies. Achieving the goal of less than 1.5 C warming will require carbon intensity to decline much faster than in the recent past.”
The second study analyzed past emissions of greenhouse gases and the burning of fossil fuels to show that even if humans suddenly stopped burning fossil fuels now, Earth will continue to heat up about two more degrees by the end of the century (2100). It was also concluded that if emissions continue for 15 more years, which is expected, Earth’s global temperature could rise as much as 3 degrees.
“Even if we would stop burning fossil fuels today, then the Earth would continue to warm slowly,” said Thorsten Mauritsen, author of the second study. “It is this committed warming that we estimate.”
When evaluated together, the consistency in the results presents a grim reality.
“These studies are part of the emerging scientific understanding that we’re in even hotter water than we’d thought,” said Bill McKibben, an environmentalist not affiliated with either study.
“We’re a long way down the path to disastrous global warming, and the policy response — especially in the United States — has been pathetically underwhelming.”
Because both studies were completed before the United States left the Paris Agreement under President Trump earlier this year, that has not been accounted for in either study.
“Clearly the US leaving the Paris Agreement would make the 2 C or 1.5 C targets even harder to achieve than they currently are,” said Raftery.
So, what’s with the 2-degree mark?
The 2-degree mark — a rise of 3.6 degrees Fahrenheit in global temperature — was set by the 2016 Paris Agreement. It was first proposed as a threshold by Yale economist William Nordhaus in 1977. The climate has been warming since the burning of fossil fuels began in the late 1800s during the Industrial Revolution, researchers say.
If we surpass that mark, it has been estimated by scientists that life on our planet will change as we know it.
What changes will we see?
- Rising seas
- Mass extinctions
- Super droughts
- Increased wildfires
- Intense hurricanes
- Decreased crops/freshwater
- Melting of the Arctic
All scientists have predicted that the above would have a profound impact on human health.
Rising temperatures and shifts in weather would lead to reduced air quality, food, and water contamination, more infections carried by mosquitoes and ticks, and stress on mental health, according to a recent report from the Medical Society Consortium on Climate and Health.
Currently, the World Health Organization estimates that 12.6 million people die globally due to pollution, extreme weather, and climate-related diseases. Climate change between 2030 and 2050 is expected to cause 250,000 additional global deaths, according to the WHO.
The first study used population, carbon emission, and gross domestic product data from 152 countries (accounting for 98.7% of the world’s population as of 2015) over the past 50 years to develop a new statistical model, said Raftery, a professor of statistics and sociology at the University of Washington.
Many studies come from the Intergovernmental Panel on Climate change and use climate model scenarios — not forecasts — to use as examples of what might happen, based on specific assumptions about economics, population, and carbon emissions in the future.
“This leaves open the question of how likely they are, or whether they cover the range of possibilities,” Raftery said. “In contrast, our results are statistically based and probabilistic, in that they aim to cover the range of likely outcomes.”
What Raftery and his colleagues discovered is that population is not a factor.
“This is due to the fact that much of the expected future population growth will be in Africa, in countries whose carbon emissions are currently very low,” Raftery said.
Director and senior scientist of nonprofit Climate Analytics, Bill Hare, says that these findings confirm the conclusions of many other studies.
“This interesting paper confirms the conclusion about where the world is headed unless there is a major increase in the ambition of climate and energy policies,” Hare said.
The other finding of the study suggests that achieving a goal of less than 1.5 Celsius warmings would require carbon intensity to decline faster than it has in the past.
“The whole purpose of climate and energy policy is to accelerate decarbonization and this will necessarily be faster than what we have seen globally,” Hare said.
Mauritsen, the author of the second study and climate researcher at Max Planck Institute for Meteorology, also shared thoughts on Raftery’s findings.
“It seems interesting in that it uses an economic statistical model that accounts for increased energy efficiency as societies develop,” Mauritsen said. “It shows that the 1.5 to 2 degrees targets will not be met without additional mitigation, and suggests that a focus on energy efficiency is the best way forward.”
How our past is impacting our future
By combining observations of past global warming and how much heat and carbon is being captured and taken in by the ocean, Mauritsen and his co-author, Robert Pincus, found that even though CO2 has an incredibly long lifetime in the atmosphere, the ocean’s absorption capacity may reduce estimates of global warming by 0.2 degrees Celsius.
Based on their research, they concluded that we can expect a warming of 1.3 Celsius by 2100, and the estimate including the ocean factor is 1.1 degrees Celsius (still nearly 2 degrees Fahrenheit).
“What the study is not concerned with is how future emissions might develop,” Mauritsen said. “This is a societal problem where we as physical scientists have fairly little to add. These future emissions will, however, add warming on top of the already committed warming and so our study can act as a baseline for estimating how far we are from reaching various temperature targets.”
Hare said he found this study to be consistent with previous papers on rising global temperatures.
“It shows, in effect, that unless we start reducing emissions quickly — soon there is a risk that we will overshoot temperature limits like 1.5 or 2 degrees C,” Hare said. “It is just another confirmation of how dangerous the present situation is unless CO2 emissions, which have flatlined in the last few years, really start dropping.”
“This addresses a somewhat different question, namely how much warming should we expect if fossil fuel emissions were to suddenly cease,” Raftery said. “In contrast, our study tries to assess how much warming we should expect given realistic future trajectories of emissions. Thus the other study provides a lower bound on expected emissions and warming, and this is indeed lower than the likely range we find, as we would expect.”
Protecting our future
Researchers warn that if there is any hope of preventing the outcomes they include in their findings, changing public policy is key.
“The next few years are going to be key in the fight against global warming,” said Dargan Frierson, co-author of the first study. “Are we going to get to work installing clean energy, or stick to old polluting sources? If we don’t act quickly, we better get to work preparing for many severe consequences of a much hotter world.”
Economist and co-author of the second study, Dick Startz, said, “there are only two realistic paths toward avoiding long-run disaster: increased financial incentives to avoid greenhouse gas emissions and greatly increased funding for research that will lead to at least partial technological fixes. Neither is free. Both are better than the catastrophe at the end of the current path.”
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