Texas' odds of Harvey-scale rainfall to increase by end of centuryNovember 13, 2017
CAMBRIDGE, MA -- As the city of Houston continues to recover and rebuild following the historic flooding unleashed by Hurricane Harvey, the region will also have to prepare for a future in which storms of Harvey's magnitude are more likely to occur.
A new MIT study, published online this week in the Proceedings of the National Academy of Sciences, reports that as climate change progresses, the city of Houston, and Texas in general, will face an increasing risk of devastating, Harvey-scale rainfall.
According to the study, the state of Texas had a 1 percent chance of experiencing rainfall of Harvey's magnitude for any given year between 1981 and 2000. By the end of this century, the annual probability of Hurricane Harvey's record rainfall returning to Texas will rise to 18 percent, if the growth of greenhouse gas emissions to the atmosphere continues unmitigated.
If the risk for such an event during this century increased in a steady, linear fashion, it would mean that there was a 6 percent chance of having Harvey's magnitude of rainfall in Texas this year.
"You're rolling the dice every year," says study author Kerry Emanuel, the Cecil and Ida Green Professor of Atmospheric Science and co-director of the Lorenz Center at MIT. "And we believe the odds of a flood like Harvey are changing."
When the past isn't a guide
In the wake of a large disaster, Emanuel says it is natural, and in some cases essential, to ask whether and how soon such an event will occur again.
"Suppose you're the mayor of Houston, and you've just had a terrible disaster that cost you an unbelievable fortune, and you're going to try over the next few years to put things back in order in your city," Emanuel says. "Should you be putting in a more advanced storm-sewer system that may cost billions of dollars, or not? The answer to that question depends upon whether you think Harvey was a one-off -- very unlikely to happen any time in the next 100 years -- or whether it may be more common than you thought."
Looking at historical records of extreme rainfall will not provide much insight into the future, Emanuel says. That's because past measurements have been spotty and difficult to extrapolate across larger regions, and the period over which rainfall data have been recorded is relatively short. What's more, climate change is shifting the odds in terms of the frequency of high-intensity storms around the world.
"If the underlying statistics are changing, the past may not be a good guide to the future," Emanuel notes in the paper.
Instead, scientists are turning to climate models to try and forecast the future of storms like Harvey. But there, challenges also arise, as models that simulate changing climate at a global scale do so at relatively coarse resolution, of around hundreds of kilometers, while hurricanes require resolutions of a few kilometers.
"[Climate models] do simulate slushy hurricane-like storms, but they're very poorly resolved," Emanuel says. "We don't have the computational firepower to resolve storms like hurricanes in today's climate models."
Emanuel and his colleagues had previously devised a technique to simulate hurricane development in a changing climate, using a specialized computational model they developed that simulates hurricanes at high spatial resolutions. The model is designed so that they can embed it within coarser global climate models -- a combination that results in precise simulations of hurricanes in the context of a globally changing climate.
Emanuel used the team's technique to model past and future hurricane activity for both the city of Houston and the state of Texas. To do so, he first embedded the hurricane model in three gridded climate analyses -- simulations of global climate, based on actual data from the past -- to simulate hurricane activity near Houston between 1980 and 2016.
He randomly seeded each climate model with hundreds of thousands of "proto-hurricanes," or early-stage storms, the majority of which naturally peter out and don't grow to become full-fledged hurricanes. Of the remaining storms, he focused on the 3,700 storms that passed within 300 kilometers of Houston between 1980 and 2016. He then noted the frequency of storms that produced 500 millimeters of rainfall or more -- the amount of rain that was initially estimated immediately following Hurricane Harvey.
During this historical period, he calculated that the probability of a Harvey-like storm producing at least 500 millimeters of rain in Houston was around once in 2,000 years. Such an event, he writes, was "'biblical' in the sense that it likely occurred around once since the Old Testament was written."
To get a sense for how this probability, or risk of such a storm, will change in the future, he performed the same analysis, this time embedding the hurricane model within six global climate models, and running each model from the years 2081 to 2100, under a future scenario in which the world's climate changes as a result of unmitigated growth of greenhouse gas emissions.
While Houston's yearly risk of experiencing a 500-millimeter rainfall event was around 1 in 2,000 at the end of the last century, Emanuel found the city's annual odds will increase significantly, to one in 100 by the end of this century.
When he performed the same set of analyses for Texas as a whole, he found that, at the end of the 20th century, the state faced a 1 percent risk each year of experiencing a Harvey-scale storm. By the end of this century, that annual risk will increase to 18 percent. If this increase happens linearly, he calculates that this year, the state's odds were at about 6 percent -- a sixfold increase since the late 20th century.
"When you take a very, very rare, extreme rainfall event like Hurricane Harvey, and you shift the distribution of rain toward heavier amounts because of climate change, you get really big changes in the probability of those rare events," Emanuel says. "People have to understand that damage is usually caused by extreme events."
Emanuel hopes that the study's results will help city planners and government officials to decide where and how to rebuild and fortify infrastructure, as well as whether to recode building standards to stand up to stronger storms and more damaging floods.
"We're seeing for Texas an event whose annual probability was 1 percent at the end of the last century, and it might be 18 percent by the end of this century," Emanuel says. "That's a huge increase in the probability of that event. So, people had better plan for that."
Massachusetts Institute of Technology
Related Climate Change Articles:
Silver and Douglas firs could replace Norway spruce in the long run due to their greater resistance to droughts.
A highly granular assessment of the impacts of climate change on the US economy suggests that each 1°Celsius increase in temperature will cost 1.2 percent of the country's gross domestic product, on average.
A new Cornell University study finds that labels matter when it comes to acceptance of climate science.
A new four-step 'framework' aims to test the contribution of climate change to record-setting extreme weather events.
Accurately modeling climate change and interactive human factors -- including inequality, consumption, and population -- is essential for the effective science-based policies and measures needed to benefit and sustain current and future generations.
Climate change can have a different impact on male and female fish, shellfish and other marine animals, with widespread implications for the future of marine life and the production of seafood.
A new University of Washington study finds that one of Alaska's most abundant freshwater fish species is altering its breeding patterns in response to climate change, which could impact the ecology of northern lakes that already acutely feel the effects of a changing climate.
Climate engineering refers to the systematic, large-scale modification of the environment using various climate intervention techniques.
There are gaping divisions in Americans' views across every dimension of the climate debate, including causes and cures for climate change and trust in climate scientists and their research, according to a new Pew Research Center survey.
In a new thesis in psychology, Kirsti Jylhä at Uppsala University has studied the psychology behind climate change denial.
Related Climate Change Reading:
This Changes Everything: Capitalism vs. The Climate
by Naomi Klein (Author)
The most important book yet from the author of the international bestseller The Shock Doctrine, a brilliant explanation of why the climate crisis challenges us to abandon the core “free market” ideology of our time, restructure the global economy, and remake our political systems.
In short, either we embrace radical change ourselves or radical changes will be visited upon our physical world. The status quo is no longer an option.
In This Changes Everything Naomi Klein argues that climate change isn’t just another issue to be neatly filed between taxes and... View Details
Climate Change: What Everyone Needs to Know®
by Joseph Romm (Author)
Climate change will have a bigger impact on humanity than the Internet has had. The last decade's spate of superstorms, wildfires, heat waves, and droughts has accelerated the public discourse on this topic and lent credence to climatologist Lonnie Thomson's 2010 statement that climate change "represents a clear and present danger to civilization." In June 2015, the Pope declared that action on climate change is a moral issue.
This book offers the most up-to-date examination of climate change's foundational science, its implications for our future, and the core clean energy solutions.... View Details
Climate Change: The Facts
by J.Abbot (Author), J.S. Armstrong (Author), A.Bolt (Author), R.Carter (Author), R.Darwall (Author), J.Delingpole (Author), C.Essex (Author), S.Franks (Author), K.Green (Author), D.Laframboise (Author), N.Lawson (Author), B.Lewin (Author), R.Lindzen (Author), J.Marohasy (Author), R.McKitrick (Author), P.Michaels (Author), A.Moran (Author), J.Nova (Author), G.Paltridge (Author), I.Plimer (Author), W.Soon (Author), M.Steyn (Author), A.Watts (Author), Alan Moran (Editor)
Tirelessly promoted by princes, presidents, actors and activists, "climate change" has become a dominant theme of global politics. But what's really going on as the "pause" in global warming prepares to enter its third decade? In this new anthology, leading scientists and commentators from the United States, the United Kingdom, Canada and Australia consider the climate from every angle - the science, the policy and the politics. View Details
A Global Warming Primer: Answering Your Questions About The Science, The Consequences, and The Solutions
by Jeffrey Bennett (Author)
2017 NSTA, Outstanding Science Trade Books
2017 Children's Book Council, Best STEM Books
Nautilus Book Award, Silver, Ecology and Environment
Is human-induced global warming a real threat to our future? Most people will express an opinion on this question, but relatively few can back their opinions with solid evidence. Many times we’ve even heard pundits say “I am not a scientist” to avoid the issue altogether. But the truth is, the basic science is not that difficult. Using a question and answer format, this book will help readers achieve three major... View Details
Climate Change: The Facts 2017
by Jennifer Marohasy (Editor)
Climate Change: The Facts 2017 contains 22 essays by internationally-renowned experts and commentators, including Dr Bjorn Lomborg, Dr Matt Ridley, Professor Peter Ridd, Dr Willie Soon, Dr Ian Plimer, Dr Roy Spencer, and literary giant Clive James. The volume is edited by Dr Jennifer Marohasy, Senior Fellow at the Institute of Public Affairs. Fourteen of the contributors currently hold or have held positions at a university or a scientific research organisation.
Dr Jennifer Marohasy said, "Climate Change: The Facts 2017 presents the case for climate change policies... View Details
Climate Change and the Health of Nations: Famines, Fevers, and the Fate of Populations
by Anthony McMichael (Author)
When we think of "climate change," we think of man-made global warming, caused by greenhouse gas emissions. But natural climate change has occurred throughout human history, and populations have had to adapt to the climate's vicissitudes. Anthony J. McMichael, a renowned epidemiologist and a pioneer in the field of how human health relates to climate change, is the ideal person to tell this story.
Climate Change and the Health of Nations shows how the natural environment has vast direct and indirect repercussions for human health and welfare. McMichael takes us on a tour of... View Details
Climate Change: A Wicked Problem: Complexity and Uncertainty at the Intersection of Science, Economics, Politics, and Human Behavior
by Frank P. Incropera (Author)
Under one cover, Frank Incropera provides a comprehensive, objective and critical assessment of all issues germane to the climate change debate: science, technology options, economic ramifications, cultural and behavioural issues, the influence of special interests and public policy, geopolitics, and ethical dimensions. The underlying science is treated in depth, but in an approachable and accessible manner. A strong case is made for the reality of anthropogenic climate change, while confronting the range of issues that remain uncertain and deconstructing opposing views. Incropera assesses... View Details
Enviromedics: The Impact of Climate Change on Human Health
by Jay Lemery (Author), Paul Auerbach (Author)
Many of us have concerns about the effects of climate change on Earth, but we often overlook the essential issue of human health. This book addresses that oversight and enlightens readers about the most important aspect of one of the greatest challenges of our time.
The global environment is under massive stress from centuries of human industrialization. The projections regarding climate change for the next century and beyond are grim. The impact this will have on human health is tremendous, and we are only just now discovering what the long-term outcomes may be.
By... View Details
The Sixth Extinction: An Unnatural History
by Elizabeth Kolbert (Author)
WINNER OF THE PULITZER PRIZE
ONE OF THE NEW YORK TIMES BOOK REVIEW'S 10 BEST BOOKS OF THE YEAR
A NEW YORK TIMES BESTSELLER
A NATIONAL BOOK CRITICS CIRCLE AWARD FINALIST
A major book about the future of the world, blending intellectual and natural history and field reporting into a powerful account of the mass extinction unfolding before our eyes
Over the last half-billion years, there have been Five mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Scientists... View Details
Climate Change: The Science of Global Warming and Our Energy Future
by Edmond Mathez (Author), Jason Smerdon (Author)
Climate Change is geared toward a variety of students and general readers who seek the real science behind global warming. Exquisitely illustrated, the text introduces the basic science underlying both the natural progress of climate change and the effect of human activity on the deteriorating health of our planet. Noted expert and author Edmond A. Mathez synthesizes the work of leading scholars in climatology and related fields, and he concludes with an extensive chapter on energy production, anchoring this volume in economic and technological realities and suggesting ways to reduce... View Details