Harvey, Irma, Maria, two massive earthquakes in Mexico and a small one that hit Los Angeles recently, multiple large fires in the West and drought. OMG!! It really does feel like the sky is falling.
Here in Chicago the weather has been wonderful. Dry, sunny, warm. I feel a sense of guilt as I see so many of our fellow citizens suffering so horribly. And it’s not just here. South Asia is suffering massive flooding and related deaths and destruction as well. Small island nations are planning to evacuate their home entirely as the sea level rises.
It feels as if this is just a preview of what is to come as we continue to pump climate warming gasses into the atmosphere. All of a sudden, what was hypothetical is now reality…and it’s not pretty. I grieve for my kids and grandson. What a planet we are bequeathing to them.
It is so easy to become depressed and discouraged by it all. Nevertheless, we ARE achieving progress in making the changes that will limit the worst impacts that could otherwise occur. Not fast enough but faster than thought imaginable just 5 or 10 years ago. What is most encouraging is that despite those in our country and Trump Administration that deny the problem and want to roll back much of the legal and regulatory progress we’ve achieved to encourage and enforce actions that will limit and eliminate the buildup of dangerous gasses in the atmosphere, state and local governments and corporations are moving ahead full speed to limit emissions.
The world is finally recognizing the full cost of doing nothing in terms of both human and economic impact. As I’ve tried to show in these posts, change is coming much faster than the expert “talking heads” have predicted.
Certain aspects of science are quite precise and knowable. We know that there are certain gasses that trap heat in our atmosphere and we can measure the rise in temperature pretty accurately. What isn’t so precise is forecasting the outcome of this phenomenon. How all the additional heat affects the planet is complicated and predicting is an evolving science. Now, there is a new study that provides a little glimmer of hope that maybe, maybe, there is a little more wiggle room than believed up until now.
“A blockbuster new study is challenging a widely held belief that the Paris Agreement’s most ambitious goal — keeping Earth’s temperatures within 1.5 degrees Celsius of their preindustrial levels — is probably unattainable. If it’s right, the target may be within reach after all.”
“Previous estimates suggest that only an additional 200 billion to 400 billion metric tons of carbon dioxide can be put into the atmosphere without overshooting the 1.5 C target. Given that about 40 billion tons of carbon dioxide is emitted each year, that means only five to 10 years are left.”
“According to the new study, which was authored by some of the world’s leading carbon budget experts, the budget is actually larger than previously believed. It suggests that more than 700 billion tons of carbon dioxide can be emitted before global temperatures exceed 1.5 C.
There’s no promise that can happen. It would still require immediate and rapid reductions in greenhouse gas emissions, and the researchers are careful to note that the climate pledges submitted by nations participating in the Paris Agreement are not strong enough. But the study does suggest that there is more leeway than previously thought.”
Keeping Temps under 1.5 C Goes from ‘Impossible’ to Maybe
Chelsea Harvey,
New research suggests the world might have a larger carbon budget than previously thought. Seen here is a surface coal mine in Wyoming. Greg Goebel/Flickr
A blockbuster new study is challenging a widely held belief that the Paris Agreement’s most ambitious goal — keeping Earth’s temperatures within 1.5 degrees Celsius of their preindustrial levels — is probably unattainable. If it’s right, the target may be within reach after all.
The researchers, writing in Nature Geoscience, revisit the question of how much carbon humans can emit and still keep the planet within a given temperature threshold. That’s known as the global carbon budget.
Previous estimates suggest that only an additional 200 billion to 400 billion metric tons of carbon dioxide can be put into the atmosphere without overshooting the 1.5 C target. Given that about 40 billion tons of carbon dioxide is emitted each year, that means only five to 10 years are left.
“In quite widespread belief, it was considered basically impossible because the budget is so small, it’s essentially zero,” the new study’s lead author, Richard Millar of the University of Oxford, told E&E News. “What we’re showing is we still have a reasonably small window where 1.5 degrees remains a geophysical possibility.”
According to the new study, which was authored by some of the world’s leading carbon budget experts, the budget is actually larger than previously believed. It suggests that more than 700 billion tons of carbon dioxide can be emitted before global temperatures exceed 1.5 C.
There’s no promise that can happen. It would still require immediate and rapid reductions in greenhouse gas emissions, and the researchers are careful to note that the climate pledges submitted by nations participating in the Paris Agreement are not strong enough. But the study does suggest that there is more leeway than previously thought.
The finding is already stirring debate among climate scientists, some of whom have expressed concerns about the new study’s methods and assumptions. And the controversy raises broader questions about the definition of the carbon budget and how it should be calculated.
The carbon budget is a relatively new concept, according to Glen Peters, a senior researcher at the Center for International Climate and Environmental Research in Oslo, Norway, who was not involved with the new study. It first came to the forefront of scientific attention in a 2009 paper, co-authored by Myles Allen of Oxford, who also co-authored the new study, Peters said.
In 2013, the Intergovernmental Panel on Climate Change (IPCC) issued a report suggesting that humans could only emit another trillion tons of carbon dioxide and remain under a 2 C rise.
Since then, the concept has come to carry immense importance from a policy perspective, helping governments and the international community estimate the rate at which they should be reducing their emissions.
“Of course, it’s a brilliantly simple concept,” Peters told E&E News. “One number encompasses the whole climate problem, so it’s a very easy concept to take on to explain to people.”
But the calculations are far more complex. A variety of factors must be taken into account, from the timeline used to calculate “preindustrial” temperatures to how the Earth’s climate actually responds to carbon emissions. Scientists sometimes disagree on these factors, and altering them can significantly change the estimated carbon budget.
The new study is a prime example. According to the authors, the earth system models used to inform the original IPCC estimates tend to overstate the amount of historical warming the Earth has experienced. When they adjusted for these discrepancies, they arrived at a much more generous carbon budget.
However, some scientists have suggested that correcting for certain biases in the comparisons between models and observations resolves the discrepancy. Such studies “show no discrepancy between observed vs. modeled warming,” Michael Mann, an atmospheric scientist at Pennsylvania State University who was not involved with the new paper, said in an emailed comment.
Mann also pointed out that the baseline used to define Earth’s preindustrial temperatures — the baseline against which the 1.5 C temperature threshold is compared — makes a big difference. The new study uses approximately the same baseline period as the IPCC, beginning in the mid-19th century. However, another recent paper, which Mann co-authored, suggests that human activities had already been affecting the climate for at least 100 years before this point. They found that moving the baseline period back to the 18th century significantly reduces the carbon budget.
Where the baseline should actually fall remains an open question among scientists, according to Millar. He noted that the baseline used in the new study was specifically chosen to correspond to the baseline used in the IPCC report, in order to make the two estimates more easily comparable.
And according to Stefan Rahmstorf, a scientist at the Potsdam Institute for Climate Impact Research in Germany, the very definition of a carbon budget — that is, whether it’s defined as the amount of carbon needed to exceed a given temperature threshold or to avoid it — is also important. The new study, he noted, “is based on model scenarios that exceed the limit of 1.5 degrees C, which is exactly what we want to avoid.”
Peters noted that the carbon budget for a world that never exceeds a given temperature threshold — even if global temperatures peak and fall later on — should be smaller than the budget used to calculate the point at which average global temperatures exceed that limit.
Some scientists are viewing the research as a rare bit of good news for the climate. Peters suggested in a recent blog post that the new budget may make more sense than previous estimates, given the amount of warming the Earth has already experienced since the 19th century and would still need to undergo to reach the 1.5 C target.
And Cristian Proistosescu, a climate researcher at the University of Washington, told E&E News that “the paper is great news and should be cause for optimism, but of the cautious variety,” noting that there are still uncertainties about the Earth’s future climate response.
Scientists are still debating some of the finer details associated with calculating carbon budgets in general — and future estimates may change the conversation again and again.
“It’s very much an evolving concept,” Peters said.
