Climate Crisis Explained, at the American Museum of Natural History

The American Museum of Natural History is one of the nation's most well-known, mainstream bastions for educating the public about the sciences. It's also one of New York City's major tourist draws.

Thus, it's telling that the museum has opted to open "Climate Change: The threat to life and a new energy future" right before New York's holiday tourist season. This suggests to me that the museum deems the science of human-caused global warming uncontrovertable...and that global warming's ongoing frisson of political controversy will not upset the fiscal apple cart of the crucial Thanksgiving-to-New Year's visitor season.

Translation of that last: The AMNH expects this show to be a blockbuster.

I got a pre-opening peek at the exhibit last week (and so did a lot of other journalists and bloggers).

What the exhibit does especially well -- and no surprise, given that it's the AMNH -- is to take what could have been an info overload and assemble it attractively into a coherent progression, building fact upon fact to help the visitor gain understanding.

Since most Stop Global Warming readers probably already know quite a bit about global warming, writing up the blow by blow of that information (as most other reviewers have done) seems unnecessary.  But if you're in or near New York City, or will be some time in the coming year, take advantage of this great opportunity to share your passion for this issue with friends and family -- it even comes complete with one of AMNH's signature, high-drama wild animal dioramas.  (See image above: The downbeat-but-important message of this diorama is that melting polar ice means no wild habitat for polar bears, which will increasingly force them into probably-fatal confrontations with humans. And yet, I really like the sci fi-esque, post-nature quality of the great white bruin foraging in a dump.  Apocalypse -- or more accurately, terriblisma -- can be so visually compelling.)

And you'll probably pick up some new knowledge yourself in the process.

The exhibit ends on an accurately optimistic note: that we already have most of the knowledge and tools we need to create a best-case-scenario future.  And it also ends on the appropriately disturbing note that despite the depth of the crisis, we have yet to muster the political will to make that future likely.

At the preview, I had the pleasure of speaking with the exhibit's co-curators. Here's some question and answer with co-curator Edmond Mathez, of the museum's Department of Earth and Planetary Sciences.

Change.org: What do people mean when they say that there is a scientific consensus that human-caused greenhouse gases are causing global warming?

Edmond Mathez: There is a scientific consensus based on the observations that we make. Certain observations are very clear, for example, that the climate is warming. These are things that we observe in many, many different kinds of measurements. So that's perfectly obvious.

There are things that we can't say with absolute assurance -- in particular, we can't say with absolute assurance that the buildup of greenhouse gases in the atmosphere is causing global warming. But we can say that this is by far the most probable cause. The IPCC said that the probability of this being true is over 90%. My own feeling is it's much larger than that, and there are several reasons for that.

First of all, there's no other competing hypothesis. There's no other conceivable explanation that we can think of at this point to account for the observations.

Secondly, there are numerous observations in the climate system itself that are consistent with warming due to buildup of greenhouse gases.

You hear skeptics sometimes say that an increase in the sun's output could be causing the warming. But you know, we're looking at the sun, first of all, and we don't see any long-term changes, at least since we've been looking at it from satellite. We see the 11-year sunspot cycle, but we don't see any long-term changes beyond that.

Also -- I'm using this as an example because that's what you commonly hear about -- if changes in solar output were causing this, we would expect different kinds of changes in the atmosphere. In particular, and not to get too technical, we would see warming in the stratosphere. But in fact we see cooling in the stratosphere. The reason of course is that more thermal radiation that is coming off the surface of the earth is being absorbed by the troposphere: the layer of the atmosphere below the stratosphere. So there are these observations that are only consistent with greenhouse gas warming, and inconsistent with any other idea that we can think of.

C: Do you think that we could hit a tipping point, where we could see very rapid changes in the climate?

EM: It's feasible. The scary thing is that we don't know. I can't answer that; No one can answer that. We just don't know enough about the climate system to know if we are approaching a tipping point. I think this is one of a number of things that concerns the climate community.

We've seen tipping points in the past, so we know that the climate system experiences those.

C: What's an example of a climate tipping point from the past?

EM: There's an event known as the Younger Dryas, that affected especially the North Atlantic. It was a cold period, a 13,000-year span of very cold temperatures that affected Greenland and northern Europe and North America -- basically, the regions around the North Atlantic. It had something to do with change ocean currents.

So that is a good example of a tipping point. It had an enormous effect on the climate of that region. Whether or not it affected the entire globe is still not clear.

C: Some people are theorizing that this could happen in the present, if the North Atlantic current slowed or stalled -- say due to a big influx of fresh water from melting glaciers changing the water's density.

EM: I don't think anyone believes that there would be a tremendous drop in temperature by disturbance of the so-called "ocean conveyor belt" today. The climate is far warmer now. What you see in models is that the conveyor belt slows, the temperature increase in the North Atlantic is less than it would be otherwise, perhaps less than elsewhere on the planet.

I don't think anyone believes that in and of itself could cause a tipping point. But again, we just don't know the workings of the climate system well enough to know if we're going to be facing a tipping point. And that is a risk.

Image: Courtesy of the American Museum of Natural History