Mark Cochrane: Climate Change, Revisited

Mark Cochrane, Professor and Senior Research Scientist at the Geospatial Science Center of Excellence at South Dakota State University, returns to the podcast after a year and a half to update us on what the latest science has to tell us on the (often controversial) topic of climate change.

Mark has been researching the climate for over 20 years, and among his many other accomplishments, moderates what we believe to be the most level-headed, open-minded and data-centric discussion forum on climate change available on the Internet today.

In this week's podcast, Mark updates us on the latest empirical data, separates out what science can and cannot prove today regarding climate change, and provides clarity into closely-related but less well-understood issues, such as ocean acidification:

Ocean acidity levels have gone up by 30 percent in recent decades. It is off the charts compared to the previous baseline of millions of years in terms of the rapidity of this. Have we had really high acid levels before? Yeah, but that was many millions of years ago. It didn't happen over night they way it is now.

What we have is all of the organisms that rely on calcium or calcium carbonate shells, whether it's their external shells or internal systems, they are under increasing amounts of stress, having a harder and harder time making those calcium-based structures.

In a lot of places, we're already losing things. In the coastal areas they're is a lot of carbon that was actually buried back in the '50s and '60s that is now simply of washing ashore in those regions. That is not even as bad as it is going to be. There is an increasing amount of studies looking at this in various ways to try to get a handle on what is happening now. There is just a study out yesterday showing how they can actually look at what the concentrations are going to be like by 2100. See how things will respond. They took some coral. They put them there and just monitored how they responded. It was not just a question of them resolving or having a harder time to grow. They will fight the tide so to speak. They will keep trying. But they are stressed. What they are finding is that they get these worms that start riddling through it; and actually eating it, and not just dissolving it. It is kind of a double whammy for a lot of these systems.

So we know it's ongoing. We can measure it. We can see it. The question is trying to infer what will occur because of it? Now, we know we are losing the base of a lot of food chain items. Therefore, it's harder and harder for other things that are not directly impacted to feed. We also have a variety of other things going on for the coral reefs between the heating causing bleaching, people blowing them up, fishing and other human-based efforts.

Right there, we are losing the food source for about a half a billion people.

This will take time to play out. But it's a major concern right now. It's one that's not on many people's radar because it's the ocean: it's far away and vast. It's been around for a long time.

Well, life will go on. It will just not be the sort of life that we're used to.

Click the play button below to listen to Chris' interview with Mark Cochrane(48m:12s).

This is a companion discussion topic for the original entry at

Thanks for this very important (and long overdue) interview with Mark. We are fortunate to have his expertise on this website.


Chris mentioned both sides talking needs to happen and I agree.Can I suggest there is another side to this argument and it behooves all of us to know it. I have looked very carefully at both sides and frankly find the skeptical side compelling. Trump is in and despite reports he is going to soften on climate change I think that is unlikely. Senator Inhofe will likely be in charge of the senate committee on the environmental again. Polls show the concern about climate change to be at low levels. When it comes to climate change many peoples BS detectors have gone off and it is not hard to see why. For 30 years we have heard over and over there is only 5 years to save the plant, catastrophe, needs urgent action, the arctic ice cap will be melted my 2014, there will be more hurricanes, floods, wild fires,New York will be under 12 feet of water and many more. I cannot name one that is true. I noted Dr. Cochrane suggested wildfires are increasing but I am sorry to disagree, go look at the data, it is just not true.
I have a scientific background though not in climate, still I understand the scientific process. I see corruption of that process in climate science (read climate gate e mails as a start). I believe much of the public though not understanding the detail senses that to. Thus the BS detector. The skeptical side is winning the argument. If you don't believe me just look who will soon be n the white house. Look who the new director of the EPA is. Most people are not concerned about climate change.

If I had an issue I thought was the most important challenge facing the planet and in fact threatening our very existence I would want to debate and crush all those opposed to that view with my overwhelming evidence. Yet those on that side for the most part refuse. Sure there are a few debates mostly years ago. I know for sure the skeptical scientists would like to engage in debate. It is also clear to me the skeptics win most of those debates. They bring data, not antidodal stories of floods in Florida or local effects on oysters.

The ocean cannot becomes acidic. This is clearly a term to induce fear and is not scientific. The ocean maybe able to become less alkaline but it is far from clear this is happening as the data does not exist.

Dr. Patrick Moore's recent assay"There is no solid evidence that ocean acidification is the dire threat to marine species that many researchers have claimed. The entire premise is based upon an assumption of what the average pH of the oceans was 265 years ago when it was not possible to measure pH at all, never mind over all the world’s oceans. Laboratory experiments in which pH was kept within a range that may feasibly occur during this century show a slight positive effect on five critical factors: calcification, metabolism, growth, fertility and survival."

I challenge Chris to bring someone on like Dr Moore. There is another side to this story and as you would expect when challenging the prevailing scientific point of view, it is well reasoned. History is full of scientific truthes turning out to be wrong. Open your mind on this one. The science if far from settled.


PS in my view satellites  are clearly the best way to measure the temp of the earth and not too many years ago used to agree fairly closely with the surface temperature records. Perhaps get Dr. Roy Spencer to explain why.


I noted Dr. Cochrane suggested wildfires are increasing but I am sorry to disagree, go look at the data, it is just not true.
Not in number, in area burned.

In case you are wondering, it costs money to try to fight those fires.

As for the rest, please come over to the Definitive Global Climate Change Thread where your talking points have been dealt with and explained multiple times.


Here is an article that addresses his particular version of reality

Ask the real experts about ocean acidification, not climate science deniers

  • Ocean acidification was “invented” in 2005 by climate scientists because global warming wasn’t bad enough.
  • Because corals and shellfish have been around for millions of years they’ll be fine if the ocean keeps soaking up all the extra CO2.
  • The oceans have a built-in natural “buffer” that stops the water from swinging around the pH scale (the scale used to measure acid and alkaline states).
  • People who keep saltwater aquariums at home sometimes add CO2 to the water to make plants grow – therefore, CO2 is great for the oceans.
There are two things to know about these points.

The first is that they were all made by Canadian climate science denier Patrick Moore, who has not written a single peer-reviewed scientific paper on the subject of ocean acidification (or on anything else in the recent past, as far as I can tell. He got his ecology Ph.D in 1974).

The second thing to know (not surprising when you know the first thing) is that all Moore’s statements are wrong, irrelevant or misleading.

How do I know?

Because I asked some actual experts to review Moore’s column - well respected scientists at universities who have researched and published papers on ocean acidification in the world’s leading journals.

Apparently Moore also moonlights as "an adviser or advocate for industries including mining, forestry and pulp and paper. He has been a vocal supporter of the nuclear energy and GM foods industries."
In an interview earlier this year, Moore defended the herbicide glyphosate, a “probable carcinogen” according to the World Heath Organisation. Moore claimed that you could “drink a whole quart” and it would not harm you. When the interviewer offered a glass of it to drink, Moore refused, saying “I’m not an idiot”.
I stopped reading at that point but the article goes on at some length detailing the numerous ways in which Dr. Moore's talking points on ocean acidification are misleading or plain wrong.

For people looking for confirmation bias there is always a shill out there willing to provide the snake oil.

i remember last year there was a 45 second clip of that interview posted on youtube, it was quite entertaining:


Hello John, Here's a quick sample of dozens of sites, most of them associated with a university or association of scientists. Are they all somehow completely mistaken then? They just don't know chemistry?

I live in forested mountains. Our glaciers have retreated markedly (like glaciers everywhere) since I was a child.

We get rain in January when the lakes used to freeze. Now it's late November, and snow should be 2' deep, but it's only rained, non-stop, for 2 months. In summer, forest fires rip through the mountains. Last summer we got a reprieve. Next summer?

I simply don't accept that all the footage of polar ice melting/shrinking/thinning is tampered with. Polar ice-fields are disappearing and there is visual evidence of it.

I'm NOT a scientist, but do I need to be?  I think there is a profound confusion afoot about the timing of events.  If some folks got hysterical and expected global floods in 6 months, it doesn't disappear what's actually happening.  Melting ice, everywhere.  Weird weather every year, right where I live. 

Well, we don't have to agree. 


I have spent an unreasonable amount of time delving into this topic, not just reading both sides claims, but also analyzing some of the easier datasets available.  All I really gained from the exercise is that there are  both honest and confused people on each side of this issue.  I came away from the exercise largely skeptical of the IPCC as an organization, and yet…
It is impossible to ignore the changes I am personally witnessing.  Where I have lived for the last 32 years has become consistently warmer, a lot warmer.  Witness the fact that the USDA hardiness zones have moved North 150 miles in the last 10 years.  Our growing seasons have become reliably longer.  

Regardless of their size, I can confirm dramatic changes to the Great Lakes and the worlds oceans that are a direct result of human activity.  If I can see that we are causing detrimental changes to Earth's largest bodies of water, why would I dismiss out of hand the possibility that we could be changing our atmosphere and weather as well?

Global warming is either happening or it's not.  If it's happening, it's either anthropogenic or it's not.  Those statements are 100% independent of the science and claims.

My senses tell me it would be foolish to ignore climate change as a possible, dare I say probable predicament humanity faces.

Quite a while back, I significantly reduced my carbon footprint, specifically to address my conviction that peak energy is an undeniable reality.  If you believe in peak energy, then the climate change debate becomes a far more academic exercise.  The personal changes necessary to mitigate both predicaments are largely the same.

Re Wildfires.I note the data in your graphs starts n 1985. There is data gong back over 100 years.

Yes of course the climate is changing, it always has. How do explain the tree line in California being hundreds of feet higher than now 1000 years ago. Viking's farming in Greenland on land that is now permafrost. The evidence shows the earth was much warmer for most of the last 10,000 years than it is right now. Yes the earth is warming at a fairly steady rate for the last few hundred years.

There has been warnings of the antarctic ice sheet breaking off for 100 years.

Re Patrick Moore a "Denier". I have noted that but I have also noted all scientist who oppose this are deniers and work for big oil. Funny about that. He was a co founder of Green Peace but then turned to the dark side for the money I guess. 

There is another point of view. I try listened to both with an open mind.

Mark mentioned clearly that change by itself is not the problem. The pace of change is the real issue. When the climate changes naturally, colder or hotter, without human super-charging it, over a large period of time, all species have plenty of time to adapt (except may be one or two). But when the change is fast (decades, few centuries) AND important, then everyone and everything is screwed. On top of that if you add the fact that CO2 changes the PH of oceans, then you double up the stress on all the tiny organisms at the bottom of the chain food. A nasty chain on consequences are unfolding before our eyes.
This is how I understand it.

Quebec's climate changed during the last 20 years: We are getting more ice storms in January and February (Side story: in winter 2010, my car got crushed by a truck on a iced road, at low speed, but, man, impressive to see this beast coming at you and craouch! flattening your much loved carbon producing and polluting car and pushing it all the way in the ditch). While having a little bit more annual precipitation, we are getting more heavy rains and longer dry periods in between (This year the honey harvest was bad because of no nectar in flowers - too dry). Deciduous trees are growing more north. Some insects are also moving north. Coyotes are also moving north and interbreeding with wolves.

One day Quebec will grow pineapples and bananas year round… wink


Let me try to explain based on some basic understanding of fire history in the Adirondack Mountains as well as some educated guesses.

  • The peak in the 1930s was a result of massive clear cutting over the previous 50 years with really poor practices: leaving the slash (branches) in place to dry and become a huge fuel source, no replanting, plus sparks from the new railroad lines.
  • The decline after that was from all of the excess fuel burning or rotting, better fire fighting technology and aggressive fire suppression.
  • The recent increase was from fuel build up due to regrowth of forests, less aggressive fire suppression policies and drying/stress on trees from a warming and drying climate.

One of the unfortunate aspects of the PP forum is that we have a certain predilection, amongst contributors, to drone on about what's wrong and who's at fault for many of the predicaments we find ourselves in. I find myself continually asking, "so what can I do about it". Mark's contribution is always data based and implies a recognition that we should be directing our efforts towards solutions and not whether the observable facts exist. Gary Larson's observations of this are on the mark, but we mustn't let ourselves off the hook by acknowledging "original sin". Here's my current suggestion to address this malaise:

The reason the presented data start in 1984 is that this is when useable annual Landsat data (30m resolution) became available for the world. Overpass periods are nominally every 16 days but clouds make useable data less common. Burned area mapping requires substantial amounts of processing of satellite imagery.

The records from earlier times are a combination of aerial imagery and best guesses. That said, there certainly was more area burned because of a variety of reasons. In the west it was mostly because more of the land was allowed to burn naturally. In the east and parts of the west it was the result of ramifications from massive logging early in the century. After the catastrophic fires of 1910, the Forest Service entered into the era of fire suppression where they actively worked to put fires out by 10am each day.

They got better and better at this and with the return of people and equipment after WWII (e.g. repurposed aircraft) they became wildly successful at putting out the majority of wildfires across the country. For some ecosystems (e.g. Ponderosa Pine) they have become a victim of their own success as these formerly open forests that burned frequently but at low intensity that did not kill the large trees have grown in thickly and now burn in severe crown fire regimes that destroy the forest cover.

In part because of the success of wildfire suppression, people forgot how the landscape used to burn and have moved into more and more flammable landscapes. The Forest Service has fought valiantly to suppress wildfires but it has become increasingly obvious that this is ecologically destructive (e.g. Giant Sequoia don't regenerate) and a losing battle because of both climate change and the impacts of past management decisions.

We have recently shown how fire weather conditions have increased fire danger across much of the vegetated surface of the planet (not all of it) in the last 35 years (Jolly, Cochrane, et al. 2015 Nature Communications). This year (just last week!), we have further been able to show that the regions in the US with greater fire danger do in fact burn more frequently and, importantly, at greater intensity, consuming more biomass (Freeborn, Jolly and Cochrane. 2016). A more popularized reporting of our paper is "Fighting Fire with Satellite Data". Note, we use MODIS data and that has only been useable since 2001.

The take home message with the recent decades of increasing area burned is that it is growing rapidly despite our fire suppression efforts. More and more fires are growing large no matter how hard we try to control them. We are spending more and more in a losing battle. We are going to have to adapt to having more fire burning across landscapes (e.g. The Science of Firescapes: Achieving Fire-Resilient Communities, Smith et al. 2016).


Chris invited Mark to comment on the changes that a Trump administration might bring to the public consideration of global warming and climate change. In view of Mr. Trump's previous statements, it will likely require some convincing evidence to induce him to take actions that might significantly reduce fossil fuel consumption. I think that it is clear that the earth is warming and likely due in part to human activities, but the rate is not beyond that of natural variability shown in older climate records. The questions are what fraction of the warming is due to humans and how much warming is in store for the future. The actions that should be taken depend crucially on answers to these questions.
At the present time the UN IPCC estimates that the humans have contributed about half the warming of the last fifty years, but no one really knows. It might be nearly all or nearly none. Our answer to the second question is dependent on climate models. The current trend of warming is on the order of 1C per century, but, as is well known, the models generally project a lot more. Both older models and more current ones are in good agreement when their projections are started at the same point in time. For example, the graph below shows Hansen's 1988 model projections for three scenarios of CO2 emissions. Scenario A corresponds reasonably well with actual emissions since 1988, but the projected temperature increase since then is double what actually occurred. Scenario B corresponds to CO2 emissions held constant after 2000. In Scenario C, CO2 emissions would cease entirely after 2000. Now imagine that you are Mr. Trump and dependent upon the models in formulating a climate policy. What do you do?


I think that it is clear that the earth is warming and likely due in part to human activities, but the rate is not beyond that of natural variability shown in older climate records.
Please elaborate, when was this? Source? Did it happen during the time of human civilization with its dependence on agriculture?

I am not sure of the source of your graphic so can't really address it. Any future projection (not prediction) of climate change comes down to what humanity's future greenhouse gas emissions rates will be. If we follow the current model of exponential growth in fossil fuel use then it is simply a question of how fast the doubling time will be, just like every other exponentially growing system (see our debt for example). The end result for climate will not be linear changes in temperature — and temperature is the least of our problems where climate is concerned.

There is no easy 'solution' for President-elect Trump or any of us, only actions (inactions?) to balance present and future tradeoffs. It used to be a question of how much we valued the viability of future generations against our own comfort. At this point it has become a question of how much we value our children's futures, and even our own, for the younger members amongst us.



If climate change is in fact anthropogenic, then it stems mostly from the burning of fossil fuels. The human race is now entirely addicted to cheap energy from abundant oil, so any proposal to cut consumption is futile. The political will and economic incentives simply do not exist.


However, the problem will soon solve itself. We have already consumed half of the oil which ever existed on the planet in the last 50 years. What is left is becoming ever more difficult to extract, so will become increasingly expensive until it become unaffordable, except for very specialized applications. Therefore, burning of fossil fuels will inevitably decline precipitously over the next fifty years, regardless of the demand or the action (or inaction) of our political 'leaders'.


Popular alternative energy sources, such as wind and solar, will never make up the shortfall but, hopefully, entirely new sources of clean energy, such as the Liquid Flouride Thorium Reactor will emerge to keep us all warm and mobile.


As Chris has repeatedly explained, exponential growth on a planet with finite resources cannot continue indefinitely. So one way or another this problem is going to be resolved within the next few decades.


In the meantime we should beware of people proposing solutions such as carbon credits, which will do absolutely nothing to slow climate change but will accelerate the flow of riches to the banksters.

All great questions and comments from everyone. Certainly wildfires much more complex than just a graph as are oysters and local flooding. This is not really a good form to argue this complex issue
All I am saying is there is another well reasoned point of view and you can either try to understand it and refute it or live with a climate denier in the white house elected by deplorables. It is clear to me the scientific process has been corrupted in climate science and it is now more of a political issue than scientific. 

Judith Curry

Roy Spencer

Richard Lindzen

The Right Climate Stuff ( large group of retired NASA engineers and scientist that really did put man on the moon)

Joanne Nova

Bjorn Lomborg

These are not dumb people and I am sure would much rather not face the ridicule and being ostracized by their others in  their field. My challenge to Chris is have anyone of them on a pod cast. If nothing else destroy them with the overwhelming evidence of global warming/climate change. I like to look at data, I started coming to this sight just because of that reason. When you look at the data and not what someone who sees with local climate change you will likely come away with a different point of view as I have. I have no financial interest in oil unless I buy the odd stock or am short crude as I am now. I used to believe in the theory of climate change by changed that point of view say 5 or 10 years ago, I don't remember exactly 

I am very concerned we are looking at spend many trillions of dollars on a issue that is really only a minor problem and even if catastrophic climate change is real, these efforts will not work.Trillons of dollars that could be spent on other things like bringing Africa out of poverty or cure for cancer etc. See Bjorn Lomborg who would agree with Dr Cochrane on the main issues of climate change but not the solutions. 

It seems there is a very narrow tolerable point of view and deviation is not allowed. See Roger Pielke Jr. who was outcast and threaten for simply saying the data does not show increases in several weather from climate change, despite the fact this is right in the IPCC report. 


John H




I have always been highly skeptical of the ACC position - but it hasn't been a data driven belief.  I have a deep distrust in lots of things that are presented to me as a "consensus" - like 9/11 for example.  Without going into why I don't believe, I wish to ask Mark this earnest question:
If you had all the power in the world, what laws would you change or steps would you take to correct the problem?  What exactly would be required of everyone on the planet to "fix" the problem, and how long would it take?

Please don't flame me, I am seriously asking this question.  Assuming that it is all true, and caused by man, what does it take to fix it?