Scientist Zeke Hausfather explains a new study showing oceans are warming 40% faster than the IPCC estimated
Story Transcript
DIMITRI LASCARIS: This is Dimitri Lascaris reporting for The Real News Network from Montreal, Canada.
A new study published earlier this month in the journal Science has concluded that the oceans are heating up 40 percent faster on average than the United Nations Intergovernmental Panel on Climate Change, or IPCC, estimated several years ago. The researchers also concluded that ocean temperatures have broken records for several consecutive years. 2018 appears destined to be the warmest year on record for the Earth’s oceans. This year, 2018, follows a record-breaking 2017, which itself followed a record-breaking 2016 for the Earth’s oceans.
Now here to discuss this alarming new study with us is Zeke Hausfather. Zeke is one of the authors of this new study. He’s also a writer for Carbon Brief, he covers research and climate science and energy with a U.S. focus. He has a master’s degree in environmental science from Yale University and he joins us today from San Francisco. Thank you very much for coming on The Real News, Zeke.
ZEKE HAUSFATHER: Pleasure to be here.
DIMITRI LASCARIS: So Zeke, a recent New York Times report on this new study quoted Malin Pinsky, an Associate Professor in the Department of Ecology, Evolution, and Natural Resources at Rutgers University, as stating, “If the ocean wasn’t absorbing as much heat, the surface of the land would heat up much faster than it is right now. In fact, the ocean is saving us from massive warming.” Zeke, how is it that the ocean is saving us from massive warming, as Associate Professor Pinsky indicated?
ZEKE HAUSFATHER: So human emitted greenhouse gases are trapping more heat in the Earth’s atmosphere than is escaping back to space, and most of that is going into the oceans. About 93 percent of all the heat being trapped by greenhouse gases end up in the Earth’s oceans. And the reason for that is because water can hold a lot more heat than air can. So the top two and a half meters, seven feet or so of the ocean, holds as much heat as the entire atmosphere above it.
And so, the top 2000 meters of the ocean holds a truly large amount of heat indeed. And so, if the earth didn’t have oceans, the land would be warming about 50 percent faster than otherwise. And what that means, effectively, is there’s a certain amount of warming in the pipeline. So even if we were to freeze greenhouse gases in the atmosphere at today’s levels, we’d still have another half a degree or so warming as the oceans slowly reach equilibrium with the atmosphere.
DIMITRI LASCARIS: And why should ordinary citizens be concerned that the oceans are warming far faster than the IPCC expected? How, practically speaking, in the decades ahead, if we don’t put a stop to this warming, how is this going to affect life on Earth?
ZEKE HAUSFATHER: Well, the oceans affect life on Earth in many different ways. They’re closely coupled to the atmosphere and the temperatures on the surface, so the warmer the oceans get, the warmer the land and the surface is going to get. But also, they affect a lot of things directly. So sea level rise, for example, which threatens to inundate low-lying areas and many coastal cities, is directly affected by sea level rise. So if you were to heat water in a kettle on your stove, when it’s boiling, it’s going to take up more space in that kettle than when it’s cold.
Now, while it’s hard to notice that difference on your stovetop, when you apply that to the whole ocean of the earth, it makes a big difference. And so, if we keep emitting at today’s levels, by the end of the century, we could have a foot of sea level rise just due to the fact that the oceans are warmer. That’s on top of sea level rise from melting ice caps and glaciers and other land ice.
DIMITRI LASCARIS: So let’s focus for a moment on the question of ocean acidification, you’re talking about thermal expansion and the rise of sea levels. Higher levels of carbon dioxide in the ocean will also cause, I understand, the ocean water to become more acidic. If the oceans are warming far faster than previously anticipated, does this mean that oceans will acidify faster than previously anticipated? And if so, how will this affect marine life?
ZEKE HAUSFATHER: So it doesn’t necessarily mean that the oceans will acidify faster. The ocean acidification is directly related to the amount of carbon dioxide in the atmosphere, because the oceans absorb about 40 percent of the carbon we emit, the rest ends up in the atmosphere. But what is important for marine life is the rate at which the oceans are warming. So a lot of ocean ecosystems are very sensitive to ocean temperatures. Coral reefs, which are an immense source of biodiversity and home to many species, are very, very sensitive to small changes in summer temperatures.
And so, in 2015 and 2016, we saw about 20 to 30 percent of all the coral reefs in the world die because of extraordinarily high ocean temperatures. Now, coral reefs can recover from that sort of event that happens once every decade or two. But the problem is, the 2015 and 2016 extreme heat events in the surface oceans is going to be a typical, if not slightly cool, summer by 2050. And so, it’s hard to see how those sort of ecosystems will survive when they’re bleaching and being exposed to extreme heat stress every single year.
DIMITRI LASCARIS: Now, as I indicated at the top, the study concluded that oceans are warming 40 percent faster on average than the IPCC estimated. I would suggest that this means the IPCC was not just slightly wrong, it was very wrong. How did the IPCC get it so wrong?
ZEKE HAUSFATHER: Well, it’s a lot harder to measure ocean heat content than it is to measure temperatures on the surface. Since 2005 or so, we’ve had this incredible network of robots called Argo. There’s about 4000 of these that drift around the ocean, and every few days they dive down to about 6000 feet and slowly rise up, taking measurements of temperature, acidity, salinity, things like that. And when they get to the top, they send their data up to a satellite. That data means that since 2005, we have a really good sense of what’s happened to ocean heat continent.
The problem is, before 2005, our records are much less reliable, they use instruments that require a lot of calibration. And more importantly, back then, we only really took measurements where ships were sailing. And so, there are large parts of the ocean that have gaps where we don’t have good ocean heat content data. So what’s happened over the last five years or so is a number of different groups around the world have independently updated the corrections for past measurement biases and developed better techniques to fill in the gaps between measurements. And that’s led to a reassessment of ocean heat content and a higher estimate of warming over the last 30 years.
DIMITRI LASCARIS: Nonetheless, to a layperson like myself, it does seem sometimes that the scientific community has repeatedly underestimated the rapidity with which climate change is happening and the severity of its effects on the planet. For example, a 2014 study found that scientists had underestimated Greenland ice melt. Another example is a 2016 study which concluded that scientists had underestimated global sea level rise by as much as 28 percent. Is it fair to say that the scientific community has tended to underestimate the rapidity and effects of climate change? And if so, why do you think that’s the case? What’s going on here?
ZEKE HAUSFATHER: Well, science is, to some extent, an inherently conservative endeavor. We don’t want to go too far out on a limb with what we can’t defend rigorously, and science works slowly and methodically. And so, often the consensus in science lags behind sort of the newest results. But what we can say in the case of ocean warming is it seems to be a case where our models got it right, even if our older observations were wrong.
So the last IPCC report published a number of climate models, which are big physics-based simulations run on the world’s most powerful supercomputers, and those predicted that the oceans would be warming at roughly the rate that we see now. It’s the older observations that were problematic. And so, this is an interesting case of the models getting it right, but the observations, at least at the time, being off because of problems with the measurement instrumentation and data gaps and things like that.
DIMITRI LASCARIS: Well, we’ve been speaking to Zeke Hausfather about a new study showing that oceans are warming, on average, 40 percent faster than had been anticipated by the scientific community. Thank you very much for joining us today, Zeke.
ZEKE HAUSFATHER: Thank you.
DIMITRI LASCARIS: And this is Dimitri Lascaris reporting for The Real News from Montreal, Canada.
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