Dr. Ricky Rood's Climate Change Blog

Tracking El Niño: Underlying Models

By: RickyRood, 8:13 PM GMT on May 29, 2014

Tracking El Niño: Underlying Models

El Niño and La Niña are names given to frequently occurring patterns of variation that are concentrated in the tropical Pacific Ocean, but that change the average temperature of Earth for about a year. When there is an El Niño the globe is warmer and when there is a La Niña the globe is cooler.

In the last blog I wrote about predictions of a 2014 El Niño and why it is of such interest to climate and climate change. In this blog, I want to write about models that predict El Niño and relation of this type of modeling to climate change and climate modeling. Reaching very far back, I have written a bunch of blogs about modeling. In this blog from 2007, I write about types of models: intuitive or heuristic, statistical and physical. For this blog I will focus on physical models. I have also written about the difference between weather predictions and climate projections, with a simplistic explanation of internal variability versus forced behavior. Finally, I wrote a series to introduce models and modeling to nonscientists and here is a link to a late article in that series.

Here, I focus on the modeling of El Niño and a set of issues that are potentially related to climate change over the next decades and centuries.

Basic Information on El Niño Predictability: It has been recognized from earlier than the 1990s that El Niño might be predictable. El Niño is often stated as the largest source of natural variability, though such a statement depends on how long a time period you are talking about. Someone, who studies ice ages might provide a convincing counterexample of large natural variability. However, if we look at the recent weather and climate that is relevant to humans and society, El Niño is a major cause of variability in, for example, the global average temperature. This is especially obvious when looking at the hot years, for example 1997 and 1998, and even a moderate El Niño this year is likely to lead to the hottest year on record. El Niño also has a big impact on the weather. For the U.S., El Niño is known to affect the precipitation on the West Coast and in the Southeast. There is also a reliable impact on Atlantic hurricanes. Therefore, with an El Niño forecast, we can say something about the characteristics of weather. This is an example of how a forecast or projection that focuses on climate variability provides usable information for planning – a strong El Niño will matter a lot to water managers and emergency managers in California.

Seasonal prediction is feasible if there are slow and predictable variations in measures such as sea-surface temperature, sea-ice, snow cover and soil moisture. The atmosphere and, therefore, the weather is sensitive to these changes. Especially for El Niño, which is first described by a change of sea-surface temperature in the eastern Pacific, there is an atmospheric response. This response has a pattern, which includes more precipitation in California in the winter and fewer hurricanes in the North Atlantic in the summer. Here are a couple of references I use in class if you want to read more (Seasonal Prediction in 2001) and (Seasonal Prediction 12 years later).

One of the interesting pieces of information that comes from these papers is the “springtime barrier.” That is, if the forecast extends through the springtime of the northern hemisphere, then the skill of the forecast declines. One explanation of this characteristic is that the northern springtime signal of El Niño is relatively small, therefore variability that might be construed as noise to an El Niño forecast dominates the projection. There is an obvious consequence of a springtime barrier, a limit of forecasting of about six months. There is an interesting paper Very Early Warning of Next El Niño, which “indicated (in September 2013 already) the return of El Niño in late 2014 with a 3-in-4 likelihood.”

Some Changes in the Climate?: I wrote a long, some would say tedious, series of blogs on the Arctic Oscillation, changes in sea ice and atmospheric blocking (all of those terms defined in that series). Whether or not the changes in the Arctic are having large impacts on weather in middle latitudes or the tropics remains an open question subject to scientific investigation. 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. The same could be said for springtime snow cover. In short, our background environment, on which we have developed what forecast skill we have, is changing. Also in my mind is a project that I participated in back in 2011 and 2012, where we were concerned about La Niña and flooding in the Upper Missouri River Basin. In that project, any sensitivity to La Niña was overwhelmed by the Arctic Oscillation being in its negative phase.

We Can’t Predict Beyond Two Weeks: One of the sacred utterances of the community of the skeptic is that the the description of weather as chaos means that we cannot predict climate. Another statement is that errors in weather forecasting mean that we cannot predict climate. The skill that we have established in seasonal prediction stands as a concrete example of why these utterances are merely rhetorical diversions. A talking point would be that ocean sea-surface temperature can be predicted. We both predict and observe organized patterns of warm and cool regions of the sea. The atmosphere responds to these patterns. The atmospheric response is not random, for example, during an El Niño in winter, California can expect major rainstorms. In the summer, hurricanes are likely to be less frequent in the North Atlantic. The people who place real money on these predictions, emergency managers, insurance companies, farmers and water managers, ultimately, win.

Climate Models Climate Change

Updated: 7:35 PM GMT on May 31, 2014

Permalink

Tracking El Niño: Amongst Other Things

By: RickyRood, 4:13 AM GMT on May 20, 2014

Tracking El Niño: Amongst Other Things

After what seemed a period of climate languidness, there are a number of things I want to write about. There is the compelling news release on West Antarctica and the unbridled melting of glaciers. That’s one I want to think about a while. Almost overwhelmed by West Antarctica is a study on hurricanes creeping northward. And I have a number of entries I’d like to write about the National Climate Assessment. However, I will start tracking El Niño.

El Niño and La Niña are names given to frequently occurring patterns of variation that are concentrated in the tropical Pacific Ocean, but that change the average temperature of Earth for about a year. When there is an El Niño the globe is warmer and when there is a La Niña the globe is cooler.

As Daniel Swain wrote at weatherwest.com, “one of the few things growing more rapidly than the Eastern Pacific sea surface temperature in recent weeks has been the media speculation regarding the future evolution of El Niño conditions in the equatorial Pacific Ocean …” Swain goes on with a nice description of El Niño and its global impacts. Joe Romm talks about a Super El Niño. John Upton at Pacific Standard Magazine writes about a Monster El Niño, a “dinosaurian belch of warm water,” and the potential effects on crops. The Motley Fool discusses El Niño and investment strategies.

Back on February 21, 2014, Michael Ventrice wrote in Jeff Master’s blog, “We are seeing increasing evidence of an upcoming change in the Pacific Ocean base state that favors the development of a moderate-to-strong El Niño event this Spring/Summer.” In March NOAA issued an El Niño watch. Then in May 2014 ocean temperatures reached the threshold that if sustained we would have an El Niño. Currently the NOAA prediction is that with 65% probability there will be an El Niño with its official onset at the end of the summer. At the end of this blog, I provide a list of references.

Enough reporting, now I will wander into whatever it is that distinguishes this blog from the others. For that I will reach back to 2010 and the first two blogs in my series called Bumps and Wiggles (number one and number two). In that blog I used the following figure from Judith Lean’s and David Rind’s 2009 paper “How will Earth's surface temperature change in future decades?




Figure 1 from Lean and Rind (2009), Geophysical Research Letters.

In the Lean and Rind (2009) paper they write about both carbon-dioxide-related warming and internal variability. They investigated the impact of typical events on global averaged temperature, such as volcanic eruptions and El Niño. They considered a “super” El Niño, which was defined as an El Niño similar to the events of 1992-1997. The effect of a “super” El Niño is major warming of the planet. The last strong (dare I say super?) El Niño was 1997-1998, the result of which was a very warm year. 1998 server as fodder for endless ruminations on things like the whole silly warming haitus. Here is a simple graphic of weak and strong El Niños from Golden Gate Weather Services.

One reason there is so much discussion about the possibility of a colossal El Niño is the whole silly warming hiatus. The warming hiatus is the name given to the observation that the global surface temperature has not risen as fast as might be expected. The scientific investigation of the hiatus reveals that there are many things that might be viewed as extreme. Since the 1997-1998 El Niño, the eastern Pacific has remained cool, with strong tropical winds blowing from east to west piling up water in the western Pacific. As discussed in England et al. (2014), and in the blog I referenced above, these extraordinary winds have kept the eastern Pacific and, hence, the planet cool(ish). The amount of water piled up in the western Pacific is enormous and it is natural to imagine an event that might adjust to levels closer to long-term averages. Such a large shift in mass of the Pacific Ocean would be a large El Niño.

If there were such a large El Niño, then there would a large spike in the planet’s temperature. If this proved the end of the warming hiatus, then it would be dramatic in the realm of climate-change news. There are also other possible consequences, such as disruption of the patterns of oceanic and atmospheric heat transport that currently lead to the build up of Antarctic sea ice (see Earth Observatory and Michael Lemonick @ Wunderground News and National Snow and Ice Data Center).

In my 2012 blog Just Temperature, I used this graphic.



Figure 2: Global temperature differences with El Niño (warm) and La Niña (cool) years marked. From National Climatic Data Center.

As pointed out innumerable times by myself and others, the past decade has been historically warm; there is not a convincing warming hiatus. Even the moderate El Niño of 2010, which did not break the larger scale cool pattern of the eastern Pacific, flirted with being a year of record warmth.

At the time of this blog the official Climate Prediction Center Advisory is “Chance of El Niño increases during the remainder of the year, exceeding 65% during summer.” Further, “There remains uncertainty as to exactly when El Niño will develop and an even greater uncertainty as to how strong it may become. This uncertainty is related to the inherently lower forecast skill of the models for forecasts made in the spring.” From Japanese Meteorological Agency, “It is likely that El Niño conditions will develop during the northern hemisphere summer and will continue to autumn.” From the Australian Bureau of Meteorology, “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.” And from the International Research Institute, “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.” Note, none of these centers are predicting, yet, strong, super or monster. I’m not as smart as those others, 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.

r

Here is a list of resources. I will be informally seeing how usable these are over the next few months. If you have some more that you like, please email me. Plus if you want to see which seem best to you, keep score.

Forecast and Analysis Centers

Climate Prediction Center Alert System and the Climate Prediction Center Diagnostic Discussion

International Research Institute Forecast Products and the Quick Look

Japanese Meteorological Agency El Niño Monitoring and Outlook and a nice graph of historical events

Australian Bureau of Meteorology Wrapup

Netherlands Meteorological Institute (KNMI) Forecasts

Information Portals

CLIVAR (Variability and predictability of the ocean-atmosphere system) Forecast Page

World Meteorological Updates

Pacific Marine Environmental Laboratory El Niño Theme Page Forecasts

Climate Prediction Center FAQ

NOAA’s El Niño Page and NOAA’s La Niña Page

Summaries in Blogs

Judy Curry El Niño Watch

NOAA’s ENSO Blog




Figure 3: Ortelius World Map with a Monster in the Eastern Pacific. Go here to get a really big version Wikipedia

Climate Change News Climate Change

Updated: 2:00 PM GMT on May 20, 2014

Permalink

The National Climate Assessment – Thank You

By: RickyRood, 6:54 PM GMT on May 11, 2014

The National Climate Assessment – Thank You

After more than four years of preparation and review, the National Climate Assessment was released last week (May 6, 2014). I was surprised at the attention that it got in the press, especially after following the three recent IPCC assessment reports. The headline on Science Friday was Another Climate report but Who is Listening. Many have treated the report as a one-time event, with the most common headline being that climate change is already here.

Aside from straightforward reporting about the assessment and its content, there was also a strand of political reporting; there is always a political conversation. Climate Progress has a blog entry on cable TV coverage, with Al Jazeera America the outlet with the most coverage. There is also an entry on the worst TV reactions to the National Climate Assessment.

Here we have the standard response to the release of the climate assessment. There is straightforward reporting and the attempt to reach as many people as possible - the effort to get it out there. Aside from the reporting, there is flurry of politicization, claims that the National Climate Assessment (NCA) is a political document, attempts to correct facts about the motivations of the document, a set of statements about the document showing that this is our last chance to avoid the worst effects of climate change and a set of statements that if we do respond to climate change it will be our economic ruin. Then, poof, it’s largely gone.

The National Climate Assessment (NCA) is a review of climate change and its impact on the U.S. – as stated on their website, “The National Climate Assessment summarizes the impacts of climate change on the United States, now and in the future.” With a major focus on “now,” the NCA is largely based on observations. There is a summary of highlights, and within that summary there are short descriptions of observed changes in our climate. There are graphics, many with nice, simple interactive features that clarify the text. There is the capability to find, easily, an url and link directly to the graphics. Here is Arctic Sea Ice Decline comparing September 1984 and September 2012. There are 12 categories in report findings, with a short finding statement for each category, for example, in the infrastructure category, “Infrastructure is being damaged by sea level rise, heavy downpours, and extreme heat; damages are projected to increase with continued climate change.”

Compared with previous assessments there has been remarkable progress in making the document both communicative and web accessible. Here is a figure of Sea Surface Temperature Changes from Average:



Figure 1: Sea surface temperatures for the ocean surrounding the U.S. and its territories have risen by more than 0.9°F over the past century. (Figure source: adapted from Chavez et al. 2011 1). (That's supposed to be a superscript after the date.)

In the online NCA document if you hover over the superscript, then the full reference pops up. If you click on the “Details/Download” below the figure in the original document, then you get brief metadata about the figure. In addition there is a supplemental graphic that shows what is meant by “ocean surrounding the U.S. and its territories.” You can download the figure. Here is the link to go check it out. This information associated with the figure is a great step forward in allowing traceability to the original source of information and supports transparency.

I know many of the people involved in the assessment. I have also worked on information technology to improve the usability of climate data and climate knowledge in planning. My first blush is that what has been produced by the team, led through most of the project by Kathy Jacobs, is a huge accomplishment. It is an enormous task to assess the scientific literature, to assemble information and to manage expert and public review. This report also has a great effort in improved communication, an effort which Susan Joy Hassol has earned accolades. On top of that are important advances to place the document online, taking advantage of and facilitating evolving methods of reporting and communication. I also want to mention Ken Kunkel, who I know did an enormous amount of novel analysis and interpretation for the NCA. These and the many other people involved in the NCA deserve tremendous thanks.

I have a proposal that was recently funded and part of that proposal is to evaluate the usability of the NCA in adaptation planning. More than a report at a given moment of the state of the climate in the U.S., the National Climate Assessment is a document that serves as a translation of the observations, projections and literature on climate change. The translation is from the science community to those who need to use climate-knowledge in planning. The NCA focused on the U.S., and there are both regional and sectoral descriptions of the impacts of climate change. Sectoral refers to things like public health, energy and agriculture. In fact, I have already used some of the figures from the technical reports that contributed to the NCA in previous blogs and in the project I worked on for Isle Royale National Park. To me, this document is not simply a press release and a flurry of politicized reporting. It is a document to use, and in its use to improve the usability of climate information and, ultimately, to improve future NCAs.

Climate Change News

Permalink

It seemed a little apocalyptic: Climate Case Study

By: RickyRood, 5:48 PM GMT on May 02, 2014

It seemed a little apocalyptic: Climate Case Study

When I heard that the train carrying crude oil had blown up in Lynchburg, VA yesterday (April 30, 2014), it felt a little apocalyptic. Lynchburg, VA is place that I remember fondly because as a kid riding around the country looking at Mail Pouch Tobacco barns, Lynchburg had this big billboard on the edge of town proclaiming it the home of Chapstick. (Here is a set of historical pictures from Lynchburg.)

The burning train in Lynchburg immediately brought to mind the Lac-Megantic Quebec disaster in July of 2013. There have been several train wrecks and fires in the last year. They are all carrying petroleum products. This is an issue that I mentioned in my blog on No Energy Policy and the Keystone Pipeline. It is, therefore, part of climate change and our response.

Earlier in the day I had been asked by my favorite climate policy friend whether or not there was any new information about climate change and tornadoes. The question was in response to the tornadoes in Arkansas, Mississippi and Alabama. My response was to steer away from attributing the tornadoes to climate change, especially if any public statements were to be made. The special circumstances that lead to tornadoes are complicated, and how tornadoes will change in our warming and moistening planet is far from certain. A likely change in the characteristics of tornadoes would be the timing of tornadoes, occurring, perhaps, earlier in the year. I said that if there was something to talk about policy wise, then it would be the quality of forecasts and warnings. Alas, even this is politicized, as Rep. Jim Bridenstine (R-OK) gave NOAA Director Dr. Kathryn Sullivan grief over forecast deficiencies and stated that NOAA was compromising weather forecasting by placing money in climate research rather than forecasting.

What did catch my climate sensor, however, was that rather than more Alabama tornadoes on the afternoon of April 29, 2014, there was more than 15 inches of rain in Pensacola, FL (NWS Historic Flash Flood). What struck me first was that all of this rain was not very far east of where the tornadoes had struck the day before. I immediately thought of the jet stream and the blogs I’ve written on the research about weather systems moving more slowly. There was all of this rain in Florida, and here in Colorado where I am, there has been a persistent and unpleasant north wind. In California, it’s hot, chronically dry, with unusual Santa Ana winds and wildfire. (More on Santa Ana winds)

With all of this I hunted down a weather map at the European Center for Medium-range Weather Forecasts, which I reproduce in this figure. This map is of North America and shows the sea level pressure and the wind speed (colors). The wind field is at an altitude about 1.5 km above sea level (850 hecto-Pascals (hPa), nice discussion of 850 hPa). I have marked the low, high, low pattern extending from the eastern half of the U.S. into the Atlantic Ocean. This is a distinct and unusual pattern that has been slow moving, perhaps pretty close to stuck.




Figure 1: Sea level pressure and 850 hPa wind speed (about 1.5 km above sea level) from ECMWF. See text for description.

I put a big red arrow crossing the coast at the Florida panhandle. This is where very moist air is flowing, persistently, into the East Coast of the U.S. This is the source of the water for the extreme rain. Here we have two important characteristics, the weather pattern is moving slowly, and moist and warm air resupplies water as it rains out of the atmosphere. I put another red arrow in the center of the continent, showing those north winds in Colorado. They’re just the other side of the low that caused the rain in Florida and Alabama. In the western side of the U.S. and Canada, there is a broad region of high pressure (dashed red arrow), which keeps California hot and dry and is also the condition that sets up Santa Ana winds.

Let’s return to Pensacola. The Pensacola News Journal has many stories and pictures of the flood. Here’s another story on the flood from the Tallahassee Democrat. Also I have learned about NWSMobile, which has many snippets about the flood along the Alabama – Florida shore. Here is an entry with rainfall totals that shows a total, at 7:40 AM on April 30, of 17.70 inches of rain in Pensacola. The pictures show collapsed roads, flooded cities and overwhelmed sewers.

Later in the day I got an email from a friend entitled “The near future is clear.” The first sentence is “We got about 8-10 inches of rain over the past day and a half.” This is up in Maryland. There is this amazing video in the Baltimore Sun of a road collapsing in Baltimore - you need to make it to about 1:18 in the video.

In my last blog I wrote about the impacts of climate change. One of the most robust signals that has already emerged as the climate warms is the increase of extreme precipitation events. For example Groisman et al. 2012 state that, “Analyses show that for the central U.S., a statistically significant redistribution in the spectra of intense precipitation days/events during the past decades has occurred. Moderately heavy precipitation events (within a 12.7–25.4 mm per day range) became less frequent compared to days and events with precipitation totals above 25.4 mm.” This observation is not limited to the Central U.S. or even the U.S.; it is a global observation. Figure 2 shows changes observed in the continental U.S.



Figure 2: From Jeff Master’s blog on 2011 extreme spring: Percent increase in the amount falling in heavy precipitation events (defined as the heaviest 1% of all daily events) from 1958 to 2007, for each region of the U.S. There are clear trends toward more very heavy precipitation events for the nation as a whole, and particularly in the Northeast and Midwest. Climate models predict that precipitation will increasingly fall in very heavy events, similar to the trend that has been observed over the past 50 years in the U.S. Image credit: United States Global Change Research Program. Figure updated from Groisman, P. Ya. et al., 2004: Contemporary changes of the hydrological cycle over the contiguous United States, trends derived from in situ observations. Journal of Hydrometeorology, 5(1), 64-85.

Anecdotally, in the problems that I work with on climate planning for cities, the issue that is most discussed is extreme rain and the impact on cities. The Duluth, Minnesota flood of 2012, caused by a slow moving weather system, overwhelmed the storm sewers and water management systems. The floods in Duluth and Pensacola demonstrate vulnerabilities. From the Glossary of the IPCC Working Group II vulnerability is defined as “The propensity or predisposition to be adversely affected. Vulnerability encompasses a variety of concepts including sensitivity or susceptibility to harm and lack of capacity to cope and adapt.” My colleagues and I find that people understand vulnerability, especially when made real to them by streets collapsing, municipal sewer plants overflowing, cars sliding into the abyss, buildings flooding and people suffering physical and financial harm. When this vulnerability aligns with observations, such as those, highlighted above, of increasing extreme precipitation, then the links between weather, climate and new types of risk become real. When the observations of change, the predictions of models, the relation between weather and climate, and the need to rebuild infrastructure to last for fifty years come together, then inclusion of climate change into planning and development becomes desirable and substantive.

The weather events of this week are part of our evolving climate. The extreme rains, the drought and fires are too closely aligned to what we expect from climate change to ignore. They provide us with examples of weather, climate, vulnerability and impacts. They demand our short-term and long-term response. Looking at the cars crashing into the ravine in Baltimore, we are reminded that neglect of infrastructure will become more vulnerable to extreme weather events. And, if weather events that are extreme relative to weather for which infrastructure is designed are becoming more frequent, then separation of climate, climate change and vulnerability into their own little cubbyholes of cause and effect denies how we are intertwined with our climate and climate change.

r

Climate Impacts and Risks Climate Change News

Updated: 10:40 PM GMT on May 02, 2014

Permalink

About RickyRood

I'm a professor at U Michigan and lead a course on climate change problem solving. These articles often come from and contribute to the course.