Twilight zone near clouds raises warming questions
Photo by Steve0323
Climate scientists have identified what they’re describing as a “twilight zone” around clouds.
And it could complicate predictions of how fast Earth is warming. Physical scientist Lorraine Remer is at the Goddard Space Flight Center.
The twilight zone she describes happens near clouds, where aerosol particles pick up water vapor. About 30 to 60 percent of what was thought to be a cloud-free sky is actually part of this twilight zone of aerosol particles.
Lorraine Remer: If you go outside on a hazy day, you’ll see the twilight zone yourself with your own eyes. You’ll see the clouds, and you’ll see the haze. And if you look around the cloud you’ll see something sort of cloud-like, but not quite cloud-like.
Aerosols cool Earth by reflecting sunlight back to space. Remer said that aerosols from pollution counteract about 20 to 30 percent of greenhouse gas warming.
Lorraine Remer: So as we clean up our industry to produce less particles, it may have an effect we’re not expecting, which is that the fewer particles, the less sunlight goes back to space and the more global warming we could have. In terms of the particles in the vicinity of clouds, it may accentuate that effect also.
But just how much, Remer added, remains unclear.
Our thanks today to NASA: explore, discover, understand.
Our thanks to:
Lorraine Remer
Physical Scientist
NASA Goddard Space Flight Center
Doing a good job
uhhhh…..what? did i just read that by cleaning up the atmosphere we may be damaging the atmosphere we were damaging?..does not compute!!!!does not compute!!! does no…..com…
This illustrates a point that many respected (but ignored) atmospheric scientists keep trying to make. Global warming is happening, as measurements prove. How much is caused by humans (or prevented by humans) and what is in the future have been estimated by various computer models of the atmosphere. These models are our only method of predicting the future.
I do computer modeling of relatively simple systems for a living, and I know that to do a reasonable model, you have to understand what you’re modeling, you have to make assumptions, and you have to ignore elements that would make the model much too cumbersome to use and that you believe can be neglected without harming the accuracy of the conclusions.
The atmosphere is immense and complicated. It has feedback loops and feed-forward loops. It’s called a chaotic system for very good reasons. We not only don’t know that what we’re ignoring is actually negligible, we don’t even know what some of the factors are that we have to consider. So, to base some sort of global policy on the models’ telling us that humans are significant contributors and how they are contributing may be a serious mistake.
Global warming and cooling cycles occurred long before humans were around, and certainly before we had any kind of global presence. To presume that significantly altering the world’s economy would solve the “problem” (which may even be a blessing to many areas of the world) would be foolish. We need more data, and we need scientists to tell us what is in their models and what was left out. Some refuse even to do that.
Ray
hmm. Although I don’t want to write this with a critical eye, I think I should. Really, They always just say about preventing global warming, or Let’s reduce carbon dioxide or something. However, Did someone ever do that? They always says first before acting(is it right? whatever.) well, they don’t even act I think..
I think what Remer – and many scientists – are trying to say is that climate is extremely complicated. That’s why they held off for many years before coming out and saying – as the IPCC did earlier this year – that global warming is real and caused by humans. There are just so many variables. This “twilight zone” around clouds is another variable.
In my opinion, what needs to happen is that people need to take scientists more seriously – and give them more support. If we’re going to make it through this century, we need science!
Deborah
The work of Dr. Remer and her colleague Ilan Koren, among others, is filling in the gap between what is being observed in the atmosphere through satellites and ground-based robotics such as AERONET and the computer models. And the models are constantly improving.
One point Dr. Remer made clear is that we might not be able to count on the cooling from pollution to counteract future global warming. I think anyone who breathes smoggy air on a daily basis would agree that reducing air pollution is the healthy way to go.
You are one hundred percent right, Deborah. But to take them seriously, we need to take both sides seriously. We need not dismiss objective scientists who disagree as “in the pay of the oil companies” or “crackpots.” Some may be crackpots, but many objectors are both legitimate and objective.
We need to take scientists’ work seriously. To me, this means that we need to review what assumptions went into their models, what was left out, how their models handled certain variables, and so on. This is common practice where I work. Right now, all that 99% of the public knows is what politicians and actors have told us. Often, politicians and actors, who DO have an agenda, will quote only extremes, or quote speculation as fact. We need to take motives seriously as well as models.
Newer models project that global warming will be far less than older models predict. These newer, presumably more thorough models, are ignored; because they don’t coincide with the agendas of those who have the public ear.
Right now, we are doing science by concensus. It’s always “No one seriously doubts…” and phrases like that. I say that no one has seriously reviewed the models. Those that have, have doubts; but these doubts are usually not heard.
Deborah, I KNOW that we will make it through this century. A few degrees of global warming will change things, but it won’t wipe out the human race. One way or another, things will change. Let’s do our best to make sure that they change in the best possible way. Let’s be responsible. Let’s support both sides.
Ray
As I’ve said before, Ray, I’ve been left a bit dumbfounded by the global warming controversy. To me, after watching scientists’ understanding of global warming unfold for three decades, it has seemed that the very small minority of scientists who disagree that global warming is both real and, at least in part, caused by humans are – and I don’t mean this to be offensive in any way – new to the discussion.
That doesn’t mean their voices shouldn’t be heard. But it has been surprising to me to hear them speaking up, when all along there was a very careful scientific effort going on – a very conservative effort – to understand global warming, and our human role in it.
There is now, indeed, a consensus on global warming. And I could not disgree more with your suggestion – and the suggestion of others on this website and others – that “science is not done by consensus.” Because science IS done by consensus. Of course, it is! Scientists study things, and write papers about what they study. If other scientists believe their work and reference it, that work becomes part of what we know as “scientific truth.” If other scientists read their work and do not believe it, they do not reference it, and it falls by the wayside.
This is not to say that we know everything there is to know about global warming. We don’t, of course. As Earth & Sky says on its about page, science is not perfect. It’s a process, not a body of facts. When I was new to science writing, I purchased many old science books … from the 19th century and early 20th century. Those books contained a lot of “scientific truth” that has been totally disregarded today, but that, at the time, those 19th and 20th century scientists believed just as fervently as any of today’s scientists believe (or disbelieve) in human-caused global warming. So I’m very clear that science is, indeed, a process.
And I have faith – as you do – that we will make it through this century. However, I fear for those in the developing world and believe that – while we in this part of the world created the lion’s share of the global warming problem – people in places like Africa will suffer from it the most.
Many thanks for this interesting discussion.
Deborah