House Science Hearing on Climate Science

Background Information

  • Opening statement by Environment Subcommittee Chairman Andy Biggs (R-Ariz.) (text available here)

 

Transcript of some noteworthy, scientifically verifiable statements

From the opening statements and testimonies

 

“The existence of the ‘greenhouse effect’ was first proposed in the early 1800’s. By the late 1800’s scientists began to theorize that increases in carbon dioxide in our atmosphere could lead to global warming. By 1960 scientists had shown that carbon dioxide was in fact increasing in the atmosphere and humans were at least in part responsible for the increase. Scientific evidence for human induced climate change rapidly increased throughout the 1970’s.

Since the early 1980’s when Exxon internally acknowledged the reality of climate change, the scientific evidence confirming human caused climate change has piled up at an incredible rate. The current scientific consensus on human caused climate change is based on thousands of scientific studies conducted by thousands of scientists all across the globe.”

 

“It is an empirical fact that the Earth’s climate has warmed overall for at least the past century. However, we do not know how much humans have contributed to this warming and there is disagreement among scientists as to whether human-caused emissions of greenhouse gases is the dominant cause of recent warming, relative to natural causes”

“Current global climate models are not fit for the purpose of attributing the causes of recent warming or for predicting global or regional climate change on timescales of  decades to centuries, with any high level of confidence.

Concerns about the utility of climate models include:

  • Predictions of the impact of increasing CO2 on climate cannot be rigorously evaluated for order of a century.
  • Failure of climate models to provide a consistent explanation of the early 20th century warming and the mid-century cooling.
  • Inability of climate models to simulate the magnitude and phasing of large-scale ocean oscillations on decadal to century timescales
  • …”

“The climate community  has  worked for more than two  decades to establish a scientific consensus  on human-caused climate  change, prematurely elevating a hypothesis  to  a ruling  theory. The IPCC’s consensus-seeking process and its  links to the UNFCCC emissions reduction policies have had the unintended consequence of hyper-politicizing the science and introducing bias into both the science and related decision making processes.”

 

“When the “scientific method” is applied to the output from climate models of the IPCC AR5, specifically the bulk atmospheric temperature trends since 1979 (a key variable with a strong and obvious theoretical response to increasing GHGs in this period), I demonstrate that the consensus of the models fails the test to match the real-world observations by a significant margin”

“In the next figure, I show the temperature progression from 32 model groups with their average in red of that tropical section. We are interested in the red curve, because that is the consensus upon which claims of future climate change are based. But don’t overlook the wide spread in the dashed lines—they’re all over the place. There is no clear certainty on what the climate might do in the future. I also show observations on this chart of the bulk atmospheric trend […] What is obvious is that the warming hypothesized and claimed by climate models to have already occurred has not. The warming is clearly overstated. When these trends are formally tested, the scientific conclusion is that the consensus of the climate models fails to represent the reality of the actual changes in the bulk atmosphere.”

“the average model trend fails to represent the actual trend of the past 38 years by a highly significant amount” … “the models are simply too sensitive to the extra GHGs that are being added to both the model and the real world.”
“Indeed, I am a co-author of a report in which we used a statistical model to reproduce, to a large degree, the atmospheric temperature trends without the need for extra greenhouse gases. In other words, it seems that Mother Nature can cause such temperature trends on her own, which should be of no surprise.”

 

“human activity is substantially or entirely responsible for the large-scale warming we have seen over the past century”

“the models have been tested vigorously and rigorously in numerous ways, and have passed a number of impressive tests in the past, such as James Hansen’s famous successful predictions from the 1980s and 1990s. Let me take the opportunity to bring your attention to one particular analysis that appears in the latest issue of Nature Climate Change. Back in 1989, legendary climate scientists Ron Stouffer (a graduate of our program at Penn State I’m proud to say) and Suki Manabe made a prediction not just of the average warming of the globe, but of the precise global pattern of that warming. That pattern matches the observed pattern of warming that has ensued remarkably well.”

“Other recent studies have shown the fingerprints of human-caused climate change on extreme events like the fires that devastated America’s Heartland earlier this month, burning cattle alive […] February’s record warmth was made three times more likely by human-caused climate change, and that record warmth fueled the drought that set up these fires.”

 

“There is little scientific basis in support of claims that extreme weather events – specifically, hurricanes, floods, drought, tornadoes – and their economic damage have increased in recent decades due to the emission of greenhouse gases. In fact, since 2013 the world and the United States have had a remarkable stretch of good fortune with respect to extreme weather, as compared to the past.”

“That human activities have led to changes in the earth system is broadly accepted. So too is the possibility that such changes could lead to undesirable outcomes in the future.”

 

From the Q&A

 

  • Dr. Judith Curry

[Asked to list key areas of uncertainty in climate science] “Climate models have a large amplifying effect from clouds and water vapor. The magnitude of this amplifying effect, and even the sign, are in dispute. A lot about the oceans that we don’t understand, how the ocean transports heat and carbon in the vertical is not well represented in the climate models. We also have these very large-scale, long-term ocean oscillations, which play a huge role in determining our climate. These are not well simulated and we don’t have good documentation of the really long time period oscillations. The effects of the Sun on climate, particularly the indirect solar effects.”

 

  • Dr. John Christy

[Asked to explain reason for model-observation temperature mismatch he showed] “the models tend to be too sensitive to greenhouse gases, likely related to the fact the models tend to shrink clouds more than in reality, so that more sunlight gets in and heats up the Earth more. … The Earth has a way to release the heat that greenhouse gases try to build up.”

 

  • Mr. Brooks:

“What we generally see in the news media is that if there is global warming, and it makes sense at first blush, well you’re going to see ice melt and you’re going to see the sea levels rise, so we are going to have all sorts of damage to our coastal areas as a consequence. But while I was here in Antarctica, I met with a number of National Science Foundations that all contended that there was some degree of global warming but they added that if there was a slight or modest global warming that the sea levels would fall not rise. Let me emphasize that: that the sea levels if there is slight or modest global warming will fall not rise.”

“First that the principal amount of ice on the planet is here in Antarctica. Roughly 85% more or less of the total amount of ice on the planet. Second that if the temperatures rise a little bit, it is going to carry more moisture which in Antarctica is going to be deposited over huge land mass that is larger than the size of the United States of America, by way of examples some level of ice I think that the mean is around 6000 feet deep, South Pole is more than that and some some places there in Antarctica it’s as much as 3 miles thick and that it takes hundred of years for that ice that is fallen in Antarctica to actually reach the coast line. Which means that if temperatures goes up a little bit because of this effect you are actually looking at more snow and ice being deposited on in Antarctica and water being taken from the oceans more than offsetting whatever melt there may be in Greenland or the Arctic. So what are your thoughts on that theory or argument that they were raising to us in Antarctica?”

 

  • Dr. Judith Curry

“The idea of warmer oceans translating into more snowfall seems to be a real one but then there is glacier dynamics, it’s a very complex situation.”…

“It’s really only the last decades or so that have had really really good measurements of glacier topography and we can really track the mass balance so we do need the observations from satellites and also field experiments to sort out this issue.”…

“There is uncertainty but you are seeing  the accumulation over East Antarctic whereas on the West Antarctic Ice shelves you are seeing net melting so there is some spatial variability. And there is significant uncertainties in our estimates of all this particularly the further back you go.”

 

  • Dr. Michael Mann:

“We have widespread measurements now from satellites, direct measurements of the total ice mass contained in the ice sheet, and there is no question that the 2 main potential contributors to global sea level rise, the Greenland ice sheet and the west Antarctic Ice sheet are losing ice. And we know that that loss of ice means that the ice sheet are contributing to sea level rise already. Now we hear so much about uncertainty as if uncertainty is a reason for inaction but in this case the uncertainties are breaking against us because we are actually seeing more rapid loss of ice from these ice sheets than the climate models that many here criticize had predicted in the past. That means that we are going to see more sea level rise in the near term than the models had predicted.”

 

  • Ms. Suzanne Bonamici:

“We know that human contributions to climate change have vast and alarming effects including rising sea levels, ocean acidification, melting glaciers, we just got the alarming report recently about the great barrier reef, climate change is damaging our environment, our economy, our food sources and fossil fuels emissions also contribute to higher rates of asthma, lung and heart diseases, threatening the lives of our children and grandchildren…”

 

  • Dr. Michael Mann:

“The surface and near surface temperature records (in fact if we could show exhibit A from my written statement here) shows that all the surface and near surface temperature records agree that there is a steady long term pattern of warming. That’s true for the temperatures measured by thermometers at the surface, the balloon measurements in the lower atmosphere, and both John’s satellite dataset and other estimates from the same satellite data.”

“In global warming the lower part of the atmosphere, including where we live, the troposphere warms, and the stratosphere cools. His [Christy’s] satellites estimates actually smear some of that cooling stratosphere into that he is calling the upper troposphere and that is the reason for the discrepancy. If he was right that it was warming less quickly than the models predict, …, it would imply a higher climate sensitivity.”

 

  • Dr. John Christy:

“The satellites, balloons and reanalyses, 10 different measurement systems show the same thing, all include the stratosphere portion which is very tiny in the tropics, the models included it as well. And so it was an apples to apples comparison. What I showed was a legitimate scientific test. And I would like to just say one other thing, science is not done by polling, it’s done by numbers …. We see that climate models do fail when compared against real data.”

 

  • Mr Higgins:

“Can you explain why some would say with such certainty that extreme weather events will increase given the fact that they have not.”

  • Dr Pielke:

“Well they may increase yet in the future. And there is a number of projections made by the IPCC that suggest that they might. And that’s part of the uncertainty associated with science.

“If you look at the IPCC and mainstream science, we shouldn’t expect to see the signal in human caused climate change in increasing extreme events for decades, and many decades into the future.”

 

 

  • Dr Curry:

“My main point is that I think there are a lot of uncertainties and that the climate models and the data etc. are not fit for the purpose for drawing highly confident conclusions about what has been causing the recent warming. It’s been warming for hundreds of years! And we can’t explain all of that, you know, due to human causes.”

 

  • Jerry McNerney

“And these are measurements in the ocean, in the atmosphere, all over the whole planet?”

  • Dr. Michael Mann

“That is right. And to people who say they don’t trust the surface temperature record, well we have got measurements from the ocean surface, we have measurements from the land, on all the continents, we have got the southern hemisphere, the northern hemisphere. They all point in the same direction. We have got lots of independent information from holes in the ground, bore holes, an independent way of estimating surface temperatures back in time. Dozens of independent lines of evidence that all come together telling us the same thing. That is how science works. That is why there is a consensus. Not because we are standing around holding hands. Because independent teams of scientists coming at the problem from different angles arriving at the same consistent answer over and over again.”

 

  • Jerry McNerney

“Thank you. This is from testimony. Dr Pielke. He asserts that since 2013 the world and the United States have had a remarkable stretch of good fortune with respect to extreme weather as compared to the past. Would you respond to that please?”

  • Dr. Michael Mann

“Yeah. So Roger is pointing to outdated reports, to outdated data. Three years ago he actually posted the following on his blog: He said, ‘I am no longer conducting research or academic writing related to climate…’ That is what he said back in 2015. Well that is three years ago. There has been a lot of progress over the past three years. We just published an article in the Journal Scientific Reports a few days ago that reaffirms what scientists are now finding. There are whole teams of scientists now that when there is an extreme weather event they can use what is known as detection and attribution. They can actually compare models and observations and estimate how much more likely that event might have been made by human caused climate change and in many of the extreme droughts and flooding events that we have seen in recent years those groups have positively attributed those events. They have said that those events were sufficiently unlikely to have happened without human caused global warming so that we can say at a relatively high level of certainty that climate change did impact that event. Not that it created the event. It made it worse. It made it bigger.

 

  • Lamar Smith:

“I will put in the record an oped from The Wall Street Journal called “Keeping cool” about hot temperatures which points out that even though it is claimed that 2016 was the hottest year on record and 2015 was the hottest year on record before that 2014 the hottest year before that–all three instances the temperatures were within the margin of error and that in fact in 2014 NASA admitted that they were only 38 percent confident of that temperature. That is less than half.”

 

  • Daniel Webster:

“I would like to ask Dr. Curry, What caused the ice age?”

  • Dr. Judith Curry:

“The big ice ages? Well it has to do with the orbital … variation, changes in the tilt of the earth’s axis, and then there are complex feedbacks with the ocean’s circulation and the carbon cycle. So are we at a point where we have complete predictive understanding of the ice ages? The answer is no. But that is our current understanding relates to earth sun geometry long-term deep circulations in the ocean and the carbon cycle….If you look at the climate of the twentieth century you saw a pretty steep warming trend in the early part of the century up until about 1940, 1945. And this was at a time when there was very little human input of carbon dioxide. And then we saw a cooling trend from the mid-40s to the mid-70s. And this is what I guess triggered concerns about the ice age. And then there was a massive reorganization of oceans circulations in the Pacific in the mid-1970s — the so-called great climate shift — and then we saw increasing temperatures following that. And so trying to sort out what caused the early warming period and then the mid-century cooling period, I have argued that we need to understand this before we have highly confident attribution arguments about the warming since the mid-1970s.”

 

  • Donald S. Beyer

“If the vast majority of scientists are right about the human impact on global warming of you have 55 million people in Bangladesh that will be displaced. Or many countries including the Maldives that disappear from the Planet.”

 

  • Bill Foster

“So you all agree that it is more likely than not that this is a big problem if we continue business as usual?

  • Dr. Judith Curry:

“I would say as likely as not.”

 

  • Bill Foster:

Dr. Mann?

 

  • Dr. Michael Mann:

She [Curry] has argued that we might be responsible for less than 50 percent of the warming that we have seen. The IPCC has assessed that. They have actually estimated the likelihood that that could be true. It is one in 10 thousand. One in ten thousand is the likelihood of something she claims to be true. That is a rejection of basic climate science.

 

  • Dr. Judith Curry:

Based on Climate models, I have argued that the climate models are not fit for that purpose. It is a rejection of a manufactured consensus. That is what I reject….. Our understanding of the ecological impacts of ocean acidification is in its infancy and how this relates to ecosystems. We don’t know very much about how slow rates, highly variable ocean acidification impacts ecosystems.

 

  • Barry Loudermilk

“Do you believe that the climate is changing?”

 

  • Dr. Judith Curry:

“Absolutely. Climate has always changed.”

 

  • Barry Loudermilk:

“Do you believe human activity could be a cause?”

 

  • Dr. Judith Curry:

“Of course. It is a cause. It does contribute.The question is whether it is the dominant cause. And even the IPCC says more than half. That’s from 51 percent to 99 percent. That is a big interval… I just don’t know how much is human vs. how much is natural and I think there is a great deal of uncertainty and it is very difficult to untangle it…. Our understanding of climate dynamics on decades to century to millennial time scales is far from complete.

 

  • Dr. Michael Mann:

I believe what the IPCC has said about this. That the proposition that we are responsible for less than 50 percent of the warming can be dismissed as a one in ten thousand. I accept the world scientists’ consensus… We understand at a great level of detail the workings of the atmosphere the working of the oceans and the ice sheets and the way they interact. Thousands of scientists have been studying these things for decades. We understand the science of climate just about as well as the science of any other field.

 

  • Dr. John Christy:

I would just like to add that when we understand other fields of science, we can predict the behavior. I have demonstrated that we cannot predict the behavior of climate.

 

  • Barry Loudermilk:

The National Academy of Science agrees with you. At least they did in the 1970s when they said, ‘We do not have a good quantitative understanding of our climate machine and what determines its course. Without the fundamental understanding it does not seem possible to predict the climate.” Why did we have a ban on sulfuric dioxide in the 1970s? Dr. Mann?

 

  • Dr. Michael Mann:

So you are right that more than 40 years ago we did not have nearly the understanding that we have today. In 1975 the National Academy of Science actually said they didn’t know what was going to win out. They didn’t say that global warming isn’t caused by greenhouse gasses. What they were saying in that report was that we don’t know what is going to win out. The warming effect of increasing greenhouse gasses or the cooling effect of these particulates that we are producing.