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New Review Paper in Science This Week

Chris Field and I have a new Review paper in the journal Science this week. The Review is part of a Special Section on Natural Systems in Changing Climates. Our review is focused on changes in climate conditions that are known to have impacts on terrestrial ecosystems. We also review sources of inertia and uncertainty in climate change over the coming decades. The image (from Figure 1 in the Review) shows the change in annual temperature projected for the late-21st-century using 27 global climate models developed by research centers around the world, using a scenario for the 21st century that has been similar to the emissions of the last decade.

I had a great time discussing the paper during our Hangouts On Air when the paper was released on Thursday. Thank you to +som dutta , +Euro Maestro , +Carlos Ochoa , +Dale Lanan , +Dawn Hardin  and the others who were able to join the Hangout. The video of the Hangout is available here:
HOA with Stanford Professor Noah Diffenbaugh: Release of New Climate Paper in Science (Aug 1, 2013)

The special issue is available from the Science website here:

There is also a news story by +Bjorn Carey  from +Stanford University (which I have also pasted below):

#climatechange   #globalwarming   #science   #sciencecommunication   #hangoutsonair   #noahclimatehangouts  

Stanford Report, August 1, 2013

Climate change on pace to occur 10 times faster than any change recorded in past 65 million years, Stanford scientists say

Not only is the planet undergoing one of the largest climate changes in the past 65 million years, Stanford climate scientists Noah Diffenbaugh and Chris Field report that it's on pace to occur at a rate 10 times faster than any change in that period. Without intervention, this extreme pace could lead to a 5-6 degree Celsius spike in annual temperatures by the end of the century.


The planet is undergoing one of the largest changes in climate since the dinosaurs went extinct. But what might be even more troubling for humans, plants and animals is the speed of the change. Stanford climate scientists warn that the likely rate of change over the next century will be at least 10 times quicker than any climate shift in the past 65 million years.

If the trend continues at its current rapid pace, it will place significant stress on terrestrial ecosystems around the world, and many species will need to make behavioral, evolutionary or geographic adaptations to survive.

Although some of the changes the planet will experience in the next few decades are already "baked into the system," how different the climate looks at the end of the 21st century will depend largely on how humans respond.

The findings come from a review of climate research by Noah Diffenbaugh, an associate professor of environmental Earth system science, and Chris Field, a professor of biology and of environmental Earth system science and the director of the Department of Global Ecology at the Carnegie Institution. The work is part of a special report on climate change in the current issue of Science.

Diffenbaugh and Field, both senior fellows at the Stanford Woods Institute for the Environment, conducted the targeted but broad review of scientific literature on aspects of climate change that can affect ecosystems, and investigated how recent observations and projections for the next century compare to past events in Earth's history.

For instance, the planet experienced a 5 degree Celsius hike in temperature 20,000 years ago, as Earth emerged from the last ice age. This is a change comparable to the high-end of the projections for warming over the 20th and 21st centuries.

The geologic record shows that, 20,000 years ago, as the ice sheet that covered much of North America receded northward, plants and animals recolonized areas that had been under ice. As the climate continued to warm, those plants and animals moved northward, to cooler climes.

"We know from past changes that ecosystems have responded to a few degrees of global temperature change over thousands of years," said Diffenbaugh. "But the unprecedented trajectory that we're on now is forcing that change to occur over decades. That's orders of magnitude faster, and we're already seeing that some species are challenged by that rate of change."

Some of the strongest evidence for how the global climate system responds to high levels of carbon dioxide comes from paleoclimate studies. Fifty-five million years ago, carbon dioxide in the atmosphere was elevated to a level comparable to today. The Arctic Ocean did not have ice in the summer, and nearby land was warm enough to support alligators and palm trees.

"There are two key differences for ecosystems in the coming decades compared with the geologic past," Diffenbaugh said. "One is the rapid pace of modern climate change. The other is that today there are multiple human stressors that were not present 55 million years ago, such as urbanization and air and water pollution."

Record-setting heat

Diffenbaugh and Field also reviewed results from two-dozen climate models to describe possible climate outcomes from present day to the end of the century. In general, extreme weather events, such as heat waves and heavy rainfall, are expected to become more severe and more frequent.

For example, the researchers note that, with continued emissions of greenhouse gases at the high end of the scenarios, annual temperatures over North America, Europe and East Asia will increase 2-4 degrees C by 2046-2065. With that amount of warming, the hottest summer of the last 20 years is expected to occur every other year, or even more frequently.

By the end of the century, should the current emissions of greenhouse gases remain unchecked, temperatures over the northern hemisphere will tip 5-6 degrees C warmer than today's averages. In this case, the hottest summer of the last 20 years becomes the new annual norm.

"It's not easy to intuit the exact impact from annual temperatures warming by 6 C," Diffenbaugh said. "But this would present a novel climate for most land areas. Given the impacts those kinds of seasons currently have on terrestrial forests, agriculture and human health, we'll likely see substantial stress from severely hot conditions."

The scientists also projected the velocity of climate change, defined as the distance per year that species of plants and animals would need to migrate to live in annual temperatures similar to current conditions. Around the world, including much of the United States, species face needing to move toward the poles or higher in the mountains by at least one kilometer per year. Many parts of the world face much larger changes.

The human element

Some climate changes will be unavoidable, because humans have already emitted greenhouse gases into the atmosphere, and the atmosphere and oceans have already been heated.

"There is already some inertia in place," Diffenbaugh said. "If every new power plant or factory in the world produced zero emissions, we'd still see impact from the existing infrastructure, and from gases already released."

The more dramatic changes that could occur by the end of the century, however, are not written in stone. There are many human variables at play that could slow the pace and magnitude of change – or accelerate it.

Consider the 2.5 billion people who lack access to modern energy resources. This energy poverty means they lack fundamental benefits for illumination, cooking and transportation, and they're more susceptible to extreme weather disasters. Increased energy access will improve their quality of life – and in some cases their chances of survival – but will increase global energy consumption and possibly hasten warming.

Diffenbaugh said that the range of climate projections offered in the report can inform decision-makers about the risks that different levels of climate change pose for ecosystems.

"There's no question that a climate in which every summer is hotter than the hottest of the last 20 years poses real risks for ecosystems across the globe," Diffenbaugh said. "However, there are opportunities to decrease those risks, while also ensuring access to the benefits of energy consumption."
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The next step will be to apply a ROC and lift curve analysis in order to quantify the optimum confidence threshold probability and its cost, which will basically represents the ultimate and optimal cost of global warming for each location.
The cool option will be to propose a dynamic analysis depending on the time when actions are taken and the cost every year for mitigating (as prevention is not anymore possible) global warming.
I wrote already a paper on similar analysis on some geological problems encountered in oil and gas production. That's why I see some potential for this.
+Olivier Malinur Thanks for the suggestion! One challenge is quantifying all of the potential impacts at each location (since the value of mitigating is linked to the avoided damage). 
Yes. This is very difficult. As well as quantifying cost and probability for false positive (we diagnosed x degree of temperature change and it didn't happen) and the cost of false negative ( we didn't think temperature will raise of x degree but it happened).
You put the finger on the tough part of the game., wait...smokin!....

Ok, we're all gonna die!  Got it.  Can we start building starships and lunar colonies now?
Haven't you guys seen the latest data? Its been cooling for over a decade. Face it climate change is dead. You can stop trying to scare people for there tax dollars. 
+Rich White +Warren Tarbat The instrumental observations show very clearly that the global mean surface air temperature and global ocean heat content have been increasing. Hence, "global warming". 
+Warren Tarbat and +Rich White Since you two are apparently experts in the field, please do link us to the studies illustrating information contrary to the original post.

+Noah Diffenbaugh great stuff as always; keep up the good work! 
+Warren Tarbat you have to be objective about the research that's been conducted on the topic and not dismiss it because the findings may, or may not, affect your personal feelings about capitalism. 
+Carlos Ochoa it has nothing to do with that. However most of the people who agree with global warming are anti capitalist. The fact is all this research is biased and coming from government contracts. If government agencies did not subsidize climate change research climate change would not be a problem. The problem is because of the subsidies not the climate. 
+Rich White a quick glance at +Warren Tarbat's profile indicates his staunch support of lassaez-fair capitalism. Climate change sciences may, or may not, have serious implications for the way capitalism operates as the predominant mode of commerce. This makes people like +Warren Tarbat and other capitalists nervous because industries are so reliant on fossil fuel technologies to operate.
Can you people see that +Warren Tarbat is trolling.  Just another brain dead climate denier that probably believes the earth is only 9000 years old and gets his "facts" from the retards over at Fox "News" or Glen Beck.  Clearly a science hater unable to engage in critical thought.  LOL at the lamer.
Climate change deniers, we'll have to save a few of those for fresh meat once the crops have died, they'll no doubt be fat, and a bit whiny.

At least they'll have a use.
+Warren Tarbat No idea, I'm capable of forming an opinion based on demonstrable facts, the planet is warming, that's a fact, it has continued to warm, that's a fact, human activity is accepted to be to blame, that's a fact, cooling is a lie fostered by corporate vested interests, that's a fact.

So many facts, deny all you like, when the food is gone and people turn on each other, don't say it's not happening.

And what's wrong with cannibalism, meat is meat when there is no other food to be had, better start considering the implications of climate change and warming, because unless something is done, it will just accelerate.

And do try leaving the insult labelling behind, it makes no difference to me what you think of my politics, I am not here to meet your standards, you're here to fail to meet mine.
+Warren Tarbat It's simple, you're wrong, enjoy finding that out as you get older.

I'm not going to bother educating you, life will do that for me, enjoy your money, and remember it has little nutritional value, especially when it cannot buy food.
This global warming deniers are very strange.
I think they could be like the man who cut the last tree on Easter Island.
He was probably sure that trees are spontaneously generating.
+Noah Diffenbaugh  The paleo climate record isn't high enough resolution to support the statement "Climate change on pace to occur 10 times faster than any change recorded in past 65 million years
"  So isn't it deceptive to make it, assuming you were aware of the issue?
I wonder, among the people who posted comments here, how many did actually read the paper ? It is a pretty simple and powerful demonstration.
+Warren Tarbat , before trying to profile me, read my profile. I definitely don't go to Starbucks, I have no macbook. I work as expatriate in west Africa for a major oil and gas service company and try to do all I can with people and governments to make this world a bit better. For example, today I will be working with an african university on a donation of high tech for their students. Education is a priority. Anyway, I found it very interesting how you shifted the debate from scientific facts to politics and ad hominem attacks.
Good luck with your beliefs.
Thanks +Noah Diffenbaugh , I tried to give an introduction to risks and uncertainties analysis in geosciences to students. Very difficult as, culturally in west Africa, uncertainties are perceived as risks. Additionally, uncertainties are perceived as "God's will" and thus can only be, at best, mitigated.
But for this latest point, I think we have similar opinions among the ultra conservative fringe of climate change denier in the USA, isn't it ? 
+Olivier Malinur In the USA it is the progressive environmentalist norm to perceive uncertainties as risks, e.g., the precautionary principle.  This of course means that they are further inclined to insist the risks be acted upon as if they are certain, because, well,  they might be and we just don't know it, and it would be too late once we found out.  They then progress to denying any uncertainty in the risks, they fail to consider the impact of known model diagnostic issues on their range of projections. For instance, even though whether the net feedback to CO2 forcing is positive or negative remains an open scientific question, they cite model projections based upon high positive feedback without qualification.  The cultural differences between west Africa and the USA are, well ..., different.
+Martin Lewitt As is clearly noted in the Steffensen et al. (2008) paper (which we cite - see Ref. 114), the deuterium excess is "a proxy of Greenland precipitation moisture source". The authors argue that their record tracks rapid shifts in atmospheric circulation patterns, which are associated with changes in Greenland temperature.
+Noah Diffenbaugh The interpretation accepted by the peer reviewers is that these warming events associated with the younger dryas were abrupt.  Climate is more than just temperature,  the Younger Dryas is characterized by comparable temperature change elsewhere, and there is plenty of literature suggesting it was a global phenomenon.  The hypothesized shifts in the climate system including the ITZ are significant and the timescales shorter than those in the recent "climate change"    Could the recent climate change just be in the top 4 or 5 in rapidity during the last 15000 years?
I'm still curious about what that 2000 is in figure S1.  Is that the rate for a single year?
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