Climate Change Blogs

Climate Change, Engineering, Stationarity and Applied Climate

Published: August 14, 2014
Climate Change, Engineering, Stationarity and Applied Climate


Something New, Something Fantastic

Some years ago there was a Brevity comic strip with a man, John, standing at the supermarket checkout. The caption was, “Suddenly John realized he didn't want paper or plastic. He wanted something new… something fantastic.” You can see it here.

I try in my WU blog to find a niche that is different from other climate and climate-change blogs. I imagine that I synthesize information, and I introduce how climate change fits into the proverbial big picture. The blog started after I had been teaching for a while, and both the blog and my class on climate-change problem solving have evolved over the past 8 years. My research has evolved as well, focusing more and more on the usability of climate knowledge in planning and management – whatever that means. All together, what I do has evolved, and this semester at University of Michigan I am taking on a new role to grow a Masters of Engineering in Applied Climate. This notion has been in a slow yeasty ferment for a few years. It is something new. Hope it will turn into something fantastic.

I have the intention of putting more material online, or in many cases better organizing the material that I have online. My experience, so far, is that massively open online courses (MOOCs) are not so effective in the sort of material and context that I want to teach. I have noticed in the blog comments that some of you have flirted with or taken online courses. I’d be very interested in learning about your experience, and perhaps, even, something of a review.

For the past few weeks I have been preparing for the applied climate venture. One of my goals is to connect our knowledge of climate change with engineering design. Our response to climate change will often be expressed in engineering. Some engineering projects will be direct interventions, perhaps in the spirit of the Thames River Barrier. Other examples of engineering will be in energy systems, water management, roads and seaports. Then there will be pervasive changes in construction materials, codes, standards and practices.

During 2011 and 2012, I was the member of the External Advisory Board of The Partnership for Education on Climate Change, Engineered Systems and Society. This was a research effort of the US National Academy of Engineering. The goal of this effort was to transform engineering education to prepare current and future engineers, policymakers and the public to meet the challenges of climate change. Deliberations of the Advisory Board included the need to better frame climate-change science so that it could be integrated into design and engineering and specifically, how to incorporate changing weather patterns into engineering. In a number of other meetings of engineers, I have carried the banner of climate change. A repeated theme is how to use the knowledge of climate change in, for example, designing water and transportation infrastructure. (By coincidence … National Academy of Engineering just sent out an email on August 15 with two videos from this effort: Climate Change and Infrastructure I: Why does it matter? and Climate Change and Infrastructure II: Who Should Address it?)

A major challenge is how to include non-stationarity into design. I have written a couple of blogs about non-stationarity. In this case, non-stationarity really means that the weather in the future will not have the same characteristics as the weather of the past. I wrote about this from the point of view of farming in this entry and, more recently, with a sea level rise perspective. This week, the weather has offered us an excellent case study in stationarity. Flooding.

As documented in the 2014 National Climate Assessment, in the US Midwest, including the Great Lakes, since 1958 the amount of precipitation occurring in very heavy events (top 1%) has increased by 37%. In the Northeast, the increase has been more than 70%. Even in the drought-stricken Southwest, there has been a 5% increase in extremely heavy rain events. This is an observed trend. Such changes are consistent with the guidance provided by climate models, as well as with the foundational principles from thermodynamics. This convergence of observations, theory and projections provide confidence that we have usable information.

In Southeast Michigan on August 11-12, 2014 a storm surprised Detroit with more than 4 inches of rain and regional flooding. I say surprised because the storm caused far more rain than forecast. On August 13, 2014, the Northeast Regional Climate Center reported a more than 13 inch rainfall total on Long Island, a greater that a 200-year event – a rainfall amount normally associated with tropical storms and hurricanes.

I have referred to the 2012 flood in Duluth, Minnesota a number of times. The magnitude of that flood defied historical precedence, and was classified as greater than a 500-year event. Researching this blog, I am reminded of floods, again, in Minnesota in 2014. In many parts of Minnesota, 2014 is tracking to be the wettest year on record.

These floods have overwhelmed drainage systems, leading to destruction of many roads, structural damage and loss of life. In rural areas, the floods are challenging planting. They have become so regular that new farm machinery is being purchased to accommodate spring floods. The damage caused by these weather events reveals existing vulnerabilities. They compel the need to plan for events that have, previously, occurred less frequently than once a century occurring on the order of decades.

Marshall Shepherd is hosting a new Weather Channel show called WXGeeks. He has a WU blog on recent urban floods. He writes a simple equation

Urban Flooding =
Increase in intensity of top 1% rain events
+ expanding urban impervious land cover
+ storm water management engineered for rainstorms of "last century"

This equation shows both the role of climate change and how humans change the surface. What becomes obvious is the role of engineering both in solving the problem as well as potentially exacerbating the problem. (Rood’s old blog on Balancing the Budget, Water Resource Foundation on Infrastructure)

I close with a blog from the American Society of Civil Engineers, entitled, Bridging the Gap between Climate Change Science and Civil Engineering Practice. In the piece Richard Wright states that the Society is writing a white paper on climate change with the purpose of

Foster understanding and transparency of analytical methods necessary to update and describe climate, weather and extreme events for planning and engineering design of the built and natural environments.

Identify (and evaluate) methods to assess impacts and vulnerabilities caused by changing climate conditions on the built and natural environments.

Promote development and communication of best practices for addressing uncertainties associated with changing conditions, including climate, weather, extreme environments and the nature and extent of the built and natural environments, in civil engineering practice.

Will be working to make those things happen sooner rather than later,

Categories:Climate Change

Extreme Rains Swamp Baltimore and Long Island

Published: August 13, 2014
An extreme deluge nearly unprecedented in Baltimore history swamped the city in flood waters that closed multiple expressways on Tuesday afternoon. Officially, 6.30" of rain fell at the Baltimore Airport on Tuesday. This was their second wettest calendar day in history, behind only the 7.62" that fell on August 23, 1933 during the Chesapeake-Potomac Hurricane. Remarkably, 3.95" of yesterday's Baltimore deluge fell in just 73 minutes. According to the NOAA Precipitation Frequency server, we would expect such a heavy 2-hour rainfall event to happen only once every 100 years. A 6.30" rainfall in 24 hours has a recurrence interval of once every 25 years.

Figure 1. Flooding in Baltimore, Maryland on Shell Avenue between Curtis Bay and Route 2 on August 12, 2014. Image posted to Instagram by blueagavebalto.

Extreme rains swamp Long Island and Connecticut
Dangerous flash flooding is occurring this Wednesday morning across Central Long Island, New York and Southern Connecticut as a low pressure area centered near New York City brings bands of heavy rain to its east. Rainfall rates as high as 5.34" per hour were observed in Islip, New York, triggering flooding that has forced the closure of multiple freeways, including the Long Island Expressway. Thunderstorms that repeatedly trained over the same point brought Islip 5.34" of rain between 5 - 6 am EDT, then another 4.37" between 6 - 7 am. The NWS reported that 13.20" of rain had fallen in Islip so far this morning, as of 10 am EDT. The record rainfall total for the entire month of August in Islip is 13.78".

Figure 2. Radar-estimated rain in Long Island, New York on August 13, 2014 exceeded 8" along a narrow swath.

Why such heavy rains?
Baltimore and Long Island's deluges comes on the heels of Monday's torrential rains in Detroit, whose roads were virtually shut down when the city's 2nd heaviest 24-hour rain since 1874, 4.57", fell. Portions of four major expressways remain closed in Detroit today due to flood damage, and states of emergency remain in effect for much of Detroit and some of its northern suburbs. All of these floods had two things in common: an unusually high level of water vapor in the atmosphere, and an unusually amplified jet stream. Precipitable water (a measure of water vapor) in Detroit on Monday and near Long Island last night was in the 99th percentile historically. The jet stream was in an unusually contorted configuration, with a strong trough of low pressure over the Eastern U.S., and sharp ridge of high pressure over the West. This allowed colder air than usual to move in aloft, increasing the instability of the atmosphere, causing stronger thunderstorm updrafts and heavier rains.

Figure 3. I-94 East in Detroit at Livernois on August 11, 2014. Image posted to Twitter by Ali B. (@AABaydoun.)

Monday's rains meant that four of Detroit's top ten rainiest days since 1874 have occurred in the past seventeen years. Yesterday's rains in Baltimore means that three of Baltimore's top ten rainiest days since 1871 have occurred during the past five years, and four of the top ten rainiest days have occurred in the past 15 years:

1) 7.62" August 23, 1933 (the great Chesapeake-Potomac Hurricane
2) 6.30" August 12, 2014
3) 6.02" September 30, 2010
4) 5.97" September 24, 1912
5) 5.85" July 8, 1952
6) 5.51" October 29, 2012 Hurricane Sandy)
7) 5.02" September 16, 1999 (Hurricane Floyd)
8) 5.00" September 27, 1985 (Hurricane Gloria)
9) 4.91" August 12, 1955 (Hurricane Connie)
10) 4.76" September 5, 1895

Figure 4. Percent changes in the amount of precipitation falling in very heavy events (the heaviest 1%) from 1958 to 2012 for each region. There is a clear national trend toward a greater amount of precipitation being concentrated in very heavy events, particularly in the Northeast and Midwest. Image credit: NCA Overview, updated from Karl et al. 2009.

If these numbers make you suspect that record heavy rains may be occurring more frequently in these cities due to a changing climate, then you're in good company. The U.S. National Climate Assessment, issued every four years by NOAA, is an effort by more than 300 U.S. scientists to assess how the climate is changing in the U.S. The just-released 2014 report said: “Heavy downpours are increasing nationally, especially over the last three to five decades. Largest increases are in the Midwest and Northeast. Increases in the frequency and intensity of extreme precipitation events are projected for all U.S. regions.” Fundamentally, a warmer atmosphere will evaporate more moisture from the oceans, resulting in more days with 99th percentile water vapor in the atmosphere, and increased chances of very heavy rainfall events like this week's deluges in Detroit, Baltimore, and Islip.

Quiet in the Atlantic
There are no tropical cyclone threat areas in the Atlantic to discuss today, and none of the reliable models for tropical cyclone formation is predicting development during the coming five days.

Jeff Masters
Categories:Flood Climate Change

Climate Change May Increase the Number of Hawaiian Hurricanes

Published: August 6, 2014
The Eastern Pacific is a busy place for tropical storms and hurricanes, with an average of 15 named storms, 8 hurricanes, and 3 intense hurricanes forming each year. However, these plentiful storms rarely affect Hawaii. The predominant storm track is well to the south of the Hawaiian Islands, and the air tends to be dry and ocean temperatures relatively cool near the islands, making it difficult for a storm to make it there intact. But with two tropical storms potentially threatening the islands in the coming week, and Tropical Storm Flossie having passed with 100 miles of the islands in 2013, it is fair to ask, could climate change be increasing the odds of tropical storms and hurricanes affecting the Hawaiian Islands? A 2013 modeling study published in Nature Climate Change, "Projected increase in tropical cyclones near Hawaii", found that global warming is expected to increase the incidence of tropical storms and hurricanes in Hawaii. Lead author Hiroyuki Murakami, from the International Pacific Research Center at the University of Hawaii at Manoa, commented in a press release accompanying the paper: "In our study, we looked at all tropical cyclones, which range in intensity from tropical storms to full-blown Category 5 hurricanes. From 1979 to 2003, both observational records and our model document that only every four years on average did a tropical cyclone come near Hawaii. Our projections for the end of this century show a two-to-three-fold increase for this region."

Figure 1. Projected change in number of tropical cyclones per year by the last quarter of this century in the 2013 Murakami et al. modeling study published in Nature Climate Change, "Projected increase in tropical cyclones near Hawaii" (in this study, tropical cyclones were defined as only tropical storms and hurricanes, though the general term "tropical cyclones" usually includes tropical depressions as well.) The frequency of a tropical cyclone in a 5°x5° area over the Hawaiian Islands increased from about 0.7 - 1.2 storms per year to about 2 - 3 storms per year. Note that the research projects that the heavily populated Mexican Pacific coast will see a decrease in tropical storms and hurricanes--about one less storm per year. The green stippling indicates statistical significance at the 99 percent confidence level. Image credit: Press release from the University of Hawaii, Hiroyuki Murakami, and Nature Climate Change (2013).

Why an Increase for Hawaii?
Even though their model predicted that fewer tropical cyclones would form in the Eastern Pacific in a future climate with global temperatures 2°C (3.6°F) warmer than at present, more of these storms made their way to Hawaii. This occurred because of three factors:

1) A shift in the upper air steering currents, caused by movement of the upper-level westerly subtropical jet poleward so that the mean steering flow near Hawaii became more east-to-west.

2) A tendency for storms near Hawaii to be stronger (stronger hurricanes tend to move more to the northwestward in the Northern Hemisphere, due to a phenomenon known as beta drift, caused by the variation in the Coriolis parameter across the width of the storm.)

3) A northwards shift in the genesis location where Eastern Pacific tropical storms formed, due to warming of the ocean waters.

"Our finding that more tropical cyclones will approach Hawaii as Earth continues to warm is fairly robust because we ran our experiments with different model versions and under varying conditions. The yearly number we project, however, still remains very low," reassured study co-author Wang in the press release. Only three tropical storms or hurricanes have made landfall in the islands since 1949, an average of one every 27 years, so an increase by a factor of 2 - 3 would imply a landfall every 9 - 14 years. With such a low incidence of storms, it will be very difficult to determine if they are indeed changing due to a changing climate without several decades of data, though.

Figure 2. Double trouble for Hawaii? True-color MODIS image of Hurricane Iselle (left) and Tropical Storm Julio (right) approaching Hawaii, taken between 3 - 6 pm EDT August 5, 2014. At the time, Iselle was a Category 2 hurricane with 110 mph winds, and Julio had 65 mph winds. Image credit: NASA.

I'll have a new post Wednesday morning.

Jeff Masters

Tracking El Niño: Summertime Update

Published: August 1, 2014
Tracking El Niño: Summertime Update

Back in May 2014, I wrote a couple of blogs about El Niño predictions for this year (Tracking El Niño and Underlying Models). For those who need it, there are links to basic information such as definitions of terms in those blogs. This entry is an update.

One quote I want to bring forward from the May 20, 2014 entry, “Note, none of these centers are predicting, yet, strong, super or monster. I’m not as smart as those others [predicting the super and the monster], so right now I am steering away from “monster,” and looking forward to what we learn about prediction, the climate as a whole and, of course, how we communicate our science.”

I had three reasons to avoid going along with the “super” and the “monster.” First, reading the dispassionate words of several forecast centers, there was little suggestion of an extraordinarily strong event. Second, it’s usually not wise to predict extraordinary extremes without a lot of evidence, because extremes are rare. Finally, as was the case in my cranky response to the return of the polar vortex, the increasing exaggeration and personification of weather events and their implications for climate change are distinctly negative contributions. Of course, it probably costs me readers.

I’m not very good with search engines and analytics, so forgive my shortcomings in actually providing meaningful numbers. I used the Search Tools in Google and looked at the last three months. I’m just going to take a few titles and links from the first page of the results.

May 2014:

El Niño is coming: Epic event ahead? - The Weather Network

We Are heading for the Most Powerful Super El Niño Event

Are We Heading for a Worrying Super El Niño?

Real Climate: El Niño or Bust (thank goodness)

June 2014:

Odds Against Formation of a 'Super El Niño,' Experts Say

Looks like yet another false alarm. Probably no super monster El Niño coming this year

El Niño 2014: Early strength fades

Warmist Year Of Disappointment? Likelihood Of “Super El Niño” Rapidly Fading…Arctic Set For Impressive Rebound

July 2014:

El Niño plays coy with forecasters in 2014

While a 'super' El Niño looks to be off the table, what does develop this year might not deliver what many Canadians are hoping for

The 2014 El Niño is looking more and more like a bust

What’s the three month arc there? From super and monster to yet another false alarm and bust. What was the evidentiary information for super and monster as adjectives back in May? How did super and monster enter into and flash to the top of headlines? Worth studying and thinking about.

In my entry from May 29, 2014 I wrote, “even a moderate El Niño this year is likely to lead to the hottest year on record.” My rationale for this statement is that we are living in the hottest decade since we have had easily defended direct temperature measurements. We have remained warm, globally, despite relatively cool temperatures in the eastern Pacific. Given the importance of the eastern Pacific to the global picture, even a small break in the cool pattern is likely to lead to globally historic highs. Though too early to declare 2014 as warmest, as summarized in Jeff Master’s July 24, 2014 entry, June 2014 was the warmest June since modern temperature records began in 1880, May 2014 the warmest May, April 2014 the warmest April.

OK what’s happening with El Niño? I want to trace this through the prediction centers and the last three months. Also it’s an exercise in the organization and usability of web-based information.

From the Climate Prediction Center

May 8, 2014, Diagnostic Discussion (and my blog)

“Chance of El Niño increases during the remainder of the year, exceeding 65% during summer.”

June 5, 2014, Diagnostic Discussion

“The chance of El Niño is 70% during the Northern Hemisphere summer and reaches 80% during the fall and winter.”

July 10, 2014, Diagnostic Discussion

“The chance of El Niño is about 70% during the Northern Hemisphere summer and is close to 80% during the fall and early winter.”

July 28, 2014 (Update)

“ENSO-neutral conditions continue. // Sea surface temperatures (SST) are above-average in the eastern equatorial Pacific Ocean. // Tropical rainfall is slightly enhanced over Indonesia and in the western equatorial Pacific. // Chance of El Niño is about 70% during the Northern Hemisphere summer and is close to 80% during the fall and winter.”

From the Japanese Meteorological Agency

May, 2014, El Niño Outlook (from my blog, can’t find archive on JMA page)

“It is likely that El Niño conditions will develop during the northern hemisphere summer and will continue to autumn.”

July 10, 2014, El Niño Outlook

“El Niño conditions did not form in June, though the NINO.3 SST deviation from normal increased from May to June. // The possibility of development of El Niño conditions in this summer is lower than previous forecasts. // It is likely that El Niño conditions will develop during the northern hemisphere autumn.”

From the Australian Bureau of Meteorology

May 6, 2014, ENSO Wrap-Up (and my blog)
“Climate models surveyed by the Bureau suggest El Niño development is possible as early as July. These factors indicate that while El Niño in 2014 cannot be guaranteed, the likelihood of an event developing remains at least 70% and we are at El Niño ALERT level.”

June 3 2014, ENSO Wrap-Up

“The tropical Pacific Ocean remains on track for El Niño in 2014, with just over half of the climate models surveyed by the Bureau suggesting El Niño will become established by August. An El Niño ALERT remains in place, indicating at least a 70% chance of an El Niño developing in 2014.”

July 1, 2014, ENSO Wrap-Up

“While the tropical Pacific Ocean surface temperature is currently at levels typically El Niño ALERT associated with a weak El Niño, waters below the surface have cooled and atmospheric patterns continue to remain neutral.

However, over the past fortnight changes have occurred in the atmosphere that may be a response to the warm surface waters–the Southern Oscillation Index has dropped by over 10 points, and weakened trade winds have re-appeared.

These changes would need to persist for several weeks in order for an El Niño to be considered established, and it remains possible they are simply related to shorter term weather variability.

Climate models surveyed by the Bureau continue to indicate that El Niño is likely to develop by spring 2014. The Bureau's ENSO Tracker remains at El Niño ALERT, indicating at least a 70% chance of El Niño developing in 2014.”

July 29, 2014, ENSO Wrap-Up

“Despite the tropical Pacific Ocean being primed for an El Niño during much of the first half of 2014, the atmosphere above has largely failed to respond, and hence the ocean and atmosphere have not reinforced each other. As a result, some cooling has now taken place in the central and eastern tropical Pacific Ocean, with most of the key NINO regions returning to neutral values.

While the chance of an El Niño in 2014 has clearly eased, warmer-than-average waters persist in parts of the tropical Pacific, and the (slight) majority of climate models suggest El Niño remains likely for spring. Hence the establishment of El Niño before year's end cannot be ruled out. If an El Niño were to occur, it is increasingly unlikely to be a strong event.”

From the International Research Institute,

2014 May Quick Look (and my blog)

“During April through mid-May the observed ENSO conditions moved from warm-neutral to the borderline of a weak El Niño condition. Most of the ENSO prediction models indicate a continued warming trend, with a transition to sustained El Niño conditions by the early northern summer.”

2014 June Quick Look

“During May through mid-June the observed ENSO conditions remained near the borderline of a weak El Niño condition in the ocean, but the atmosphere so far has shown little involvement. Most of the ENSO prediction models indicate more warming coming in the months ahead, leading to sustained El Niño conditions by the middle of northern summer.”

2014 July Quick Look (There are some confused links on IRI page, that I will need to fix in the future.)

“During June through early-July the observed ENSO conditions remained near the borderline of a weak El Niño condition in the ocean, but the atmosphere so far has shown little involvement. Most of the ENSO prediction models indicate more warming coming in the months ahead, leading to sustained El Niño conditions by the middle or late portion of northern summer.”

Returning here to some of the details in the Climate Prediction Center’s Diagnostic Discussion.

“Over the last month, no significant change was evident in the model forecasts of ENSO, with the majority of models indicating El Niño onset within June-August and continuing into early 2015. The chance of a strong El Niño is not favored in any of the ensemble averages for Niño-3.4. At this time, the forecasters anticipate El Niño will peak at weak-to-moderate strength during the late fall and early winter (3-month values of the Niño-3.4 index between 0.5oC and 1.4oC). The chance of El Niño is about 70% during the Northern Hemisphere summer and is close to 80% during the fall and early winter.”

Analysis at the end of a blog

The forecast summaries from these four centers are consistent in the sense that none of them are calling for a strong El Niño, much less a super or monster El Niño. It is also true, that the forecast centers summaries NEVER called for a strong El Niño in their public releases of information.

All of the centers are maintaining that it is more likely than not that the criteria for an El Niño will be met. The onset, originally predicted for the middle of northern hemisphere summer, keeps moving into the future. The strength of predicted El Niño is projected to be from weak to moderate.

Looking at the press and blogs reports, I would be interested to see in the blog comments how people think “super” and “monster” entered into the discussion. There is a burst of the adjectives in the press and blogs in May, followed quite quickly in June by people distancing themselves from the extreme description. Accompanying this distancing is the growth of commentary in the press and blogs about exaggerated claims and failed models. I point out explicitly, there is no language of exaggeration in the summaries from the prediction centers, which should be viewed as the basic knowledge-based information. Therefore, there is no foundation to say these models have failed in any fundamental sense.

Looking more deeply at the discussions that are only summarized above, the models originally anticipated an atmospheric response to the changes in the sea surface temperature. These responses are not being realized, which is summarized a couple of places above as “atmosphere so far has shown little involvement.” This does, to perhaps only me, raise the question about the state of the atmosphere going into the beginning of the El Niño event. As noted in my previous blogs, there are a couple of documented and persistent extremes, the changes in the Arctic and the very strong trade winds in the eastern Pacific. This brings me back to my conjecture “From the point of view of predicting El Niño, during this prediction cycle we have levels of sea ice that are far lower than in previous El Niño cycles. This changes the heat exchange between the atmosphere and ocean in the Arctic. This is outside of the range of previous variability, which intrinsically increases the uncertainty in the forecast.” Might be a good idea for a proposal.

I close with a mention of NOAA’s ENSO Blog. Michelle L’Heureux wrote an entry on July 25, 2014 entitled What’s the hold up, El Niño? Michelle L’Heureux also wrote Real Climate: El Niño or Bust, where I put the “thank goodness” above. Perhaps that’s the name to look for El Niño news this summer.


I like the effort from the Australian Bureau of Meteorology to summarize the criteria for El Niño and La Niña watches, alerts and existence, in addition to the neutral phase.

Figure 1: ENSO Tracker indicating an El Niño WATCH (left) and El Niño ALERT (right). Far more details from Australian Bureau of Meteorology. In the July 29, 2014 update, the Australian Bureau of Meteorology shifted from Alert to Watch

Models and Planning for Climate Change

Published: July 25, 2014
Models and Planning for Climate Change

I have written many blogs about models and modeling of climate. My collection includes a 2012 tutorial approach where I show that climate modeling is the process of calculating a budget, with many similarities to keeping the balance of a checking account (Introduction and end). In 2012, I wrote a piece on uncertainties in models and a number of ways to evaluate and to place model uncertainty in decision making. In 2011, I wrote a piece about the controversial subject of validation of climate models.

There is regular publication of papers about models, their evaluation and their potential usefulness in planning for climate change. I want to mention a couple of them in this blog. The first is a paper by Elisabeth Lloyd, who is a philosopher at the University of Indiana. ”In Confirmation and Robustness of Climate Models”, Lloyd investigates the robustness of climate models in a formal way. Robustness is related to a set of common outcomes that follow from model simulations. In this case the common outcome is that given an increase in greenhouse gases, then the set of models determine that the average surface temperature of the Earth will rise. Underlying this determination of robustness is the fact that all of the climate models are designed to represent the laws of physics that represent the balance of energy (see the tutorial series). There is a requirement that “greenhouse gases relate in a law-like interaction with the energy budget of the earth.” Then, given the fact that the representation of these laws by a number of models from independent research organizations leads to the same outcome, that the planet will warm, then it is very likely that these models are a robust representation of what will happen in the real world. The size of the temperature increase has meaningful uncertainty; however, that there will be significant heating is of little doubt.

Lloyd’s arguments are not simply based on the fact that all climate models say that the Earth will warm as greenhouse gases increase. Lloyd lays out three fundamental ways to confirm the performance of climate models. The first line of confirmation is how well do the models fit the observations? This is the most common, most natural way of confirming model performance. How well a model fits the observations is, however, always open for arguments. There is always some difference between model simulations and observations. This difference fuels the arguments about whether or not the models are correct enough to provide actionable information (telescope simile in this blog). The other lines of confirmation that Lloyd relies on are varieties of evidence and independent support. Independent support is, basically, that sources of information that are fundamentally unrelated lead to the same conclusion. It is the convergence of all of these pieces of information with the fact that many models give the same basic outcome that supports Lloyd’s conclusion that robustness is a positive virtue in assessing the quality of climate models.

Lloyd’s conclusion is a formalized statement that if models consistently represent an outcome then we have more confidence that the model is correct, than if the models are inconsistent. As the regional details of model simulations are considered, for example what will happen to the water levels in the Great Lakes, models are often more inconsistent in their behavior. This inconsistency is a flag of uncertainty, or a lack of robustness. There are many lines of scientific and experiential evidence that increasing greenhouse gases will lead to warming of the Earth’s surface, the melting of water stored as ice and the rising of sea level. These conclusions are highly robust.

The other paper I describe is an opinion piece, ”Can We Trust Climate Models,” by J. C. Hargreaves and J. D. Annan. In this piece are a number of elements in common with the Lloyd piece, namely the discussion of the independence of models and information. They conclude that the broad predictions of surface warming, melting ice and rising sea level are robust because of their consistency with underlying physical principles. They also state that the models are not robust on regional scales.

Hargreaves and Annan add to the argument the idea of posing alternative descriptions, hypotheses and theories to describe observations of the climate. Climate models can be viewed in many ways. They are a mathematical description of our knowledge of the climate. They are also a way to organize and manage the complexity of describing the Earth’s climate and how it will evolve. What Hargreaves and Annan pose is that if the errors and uncertainties of climate models were too grievous, then they would invite alternative descriptions. Indeed, some of the pieces that make up a climate model do invite alternative descriptions, which is what drives model development and improvements. Observation-based, rational pursuit of alternative descriptions frequently lead to new insights about processes, for example, the partitioning of water in clouds between vapor, liquid and ice. However, the underlying principles of the model the conservations of energy, mass and momentum have proved to be quite robust. The observable and resolvable attributes of the climate, for example the fluid flow that describes the motion of the atmosphere and the oceans, which provide the connections between the pieces, have proved to be resilient against alternative descriptions.

Given the vast amount of observations of the climate and the thousands of researchers who have invested their competitive personalities in exploration and investigation of the climate, it is unlikely that fundamentally different quantitative descriptions of the Earth’s climate will be found. This assertion is supported by the successes of climate models, which have been confirmed in several independent ways. Affirming the successes of climate models is the ability of the models to present complex patterns of behavior that have been simulated, predicted and observed, making it highly unlikely that alternative explanations will be found of the changes being observed in the Earth’s weather and climate.

Is this actionable knowledge? The answer for many is an, obvious, yes, because people, corporations and governments are taking actions. What is missing in action is any rational, national or global approach to reduce emissions and, therefore, to bound the changes to our weather and climate as incremental changes to our history of the past few centuries. This leads to a situation where the actions that we take are in many ways temporary patches, because over decades and the next few centuries, we will be reliably warming up and sea level will relentlessly rise. There is much more difficultly predicting changes to ecosystems, agriculture, pathogens, political systems and nations. This will require anticipation, to which models will contribute, and the willingness and flexibility to spend on adaptive strategies if we are to obtain societal stability. Those who view models as providing actionable knowledge are more likely to succeed. Otherwise, we will be like those who lived on the shore of modern Turkey at the end of last glacial period, chasing the retreating glaciers and their water into the mountains with their goats and sheep (Sagalassos).

About the Blogs
These blogs are a compilation of Dr. Jeff Masters,
Dr. Ricky Rood, and Angela Fritz on the topic of climate change, including science, events, politics and policy, and opinion.