Thursday, August 30, 2018


We need all the good news we can find these days, and California has just handed us a climate-change bouquet.

On August 28, 2018, the legislature passed a bill that requires 100 percent carbon-free electricity in the state by 2045. This massive change in the way power is produced in or imported to California will keep 70 million metric tons of greenhouse gases from being spewed into the atmosphere every year, equivalent to taking 12 million cars off the road.

California Wind Farm
a rapidly growing source of clean power
Credit: Creative Commons Zero; Max Pixel

If Governor Brown signs the bill into law, as expected, California will become the largest economy in the world to commit to 100% carbon neutral electricity before mid-century. (Yes! Governor Brown signed the bill into law on September 10, 2018).

Of course, much more than this is needed for the world to meet the goals of the Paris Climate Agreement and keep global temperatures no more than 1.5 or at most 2.0 degrees C (2.7/3.6 degrees F) above pre-industrial levels. Still, it's a giant step in the right direction, and one that we hope many more states, cities, countries, companies and industries will follow--and the sooner the better.


You can find the text of California Senate Bill 100 here.

Friday, August 24, 2018


Climatologists have traditionally been leery of linking a specific event--an extended drought, an exceptional run of hurricanes, massive flooding--to climate change. The most they could be coaxed to say was something along the lines that climate change might have increased the odds of the extreme event, often with a comparison to rolling loaded dice or to an athlete on steroids.

Recently, however, some researchers have started to be more specific. For example, Frederika Otto, a climate scientist at Oxford University, and her colleagues recently reported that South Africa's three-year mega-drought, during which Cape Town came nerve-wrackingly close to running out of water, was demonstrably three times as likely as it would have been without human-caused climate change.

This new capability goes beyond just pinning down the increased odds of an extreme event. In three cases recently, researchers have felt confident enough to say that certain events simply could not have happened without human climate forcing. These included devastating heatwaves in Asia in 2016, the global heat record set the same year, and shockingly high sea temperatures in the Gulf of Alaska and the Bering Sea between 2014 and 2016. 

A review of 170 similar attribution studies between 2004 and 2018 found that two-thirds of the extreme weather events studied were more likely or more intense because of human caused climate forcing.

 South Africa's Theewaterskloof Reservoir, nearly empty on March 11, 2018
Credit: Zaian

So the question is, what's changed? Why are climate scientists now able to make such specific attributions of the impacts of human-caused climate change?

In principle, the answer is remarkably simple. Researchers use multiple state-of-the-art computerized climate models to run thousands of simulations with slightly different initial conditions. Some of the simulations run with current levels of greenhouse gas levels while others use pre-industrial levels. The researchers can then see how many times a comparable event shows up in each scenario. A drought as long and intense as the one that drained Cape Town's reservoirs to the brink of catastrophe happened three times more often under current atmospheric greenhouse gas levels than in models using pre-industrial levels.

In practice, it's a bit more challenging. The multiple computer simulations that are needed are costly and need a lot of time even on the fastest supercomputers. Otto and her colleagues got around this by tapping into weather@home, a network of thousands of volunteers who offer up time on their computer to help perform these massive calculations. In addition, current climate models are not fine-grained enough to model smaller events, such as a crop-destroying hailstorm or an outburst of tornadoes.

Still, scientists now have what it takes to specify to what extent many extreme events, such as a drought, massive flooding or a killer heat wave, can reliably be attributed to human-caused climate change. We can expect much more frequent, accurate and meaningful reports of this kind in the near future.

These attribution studies are not likely to convince dyed-in-the-wool climate change deniers, but they are already proving helpful to planners at all levels. For example, Helen Davies, with the Western Cape's Department of Economic Development and Tourism, now knows that the devastating drought was not a once-in-a-lifetime event. "This is an incredibly strong message which we cannot afford to ignore. We may need to work on a radically new approach to water management."

Otto hopes that this approach will soon be fast and accurate enough to be linked to extreme weather events in real time. Germany may become one of the first countries to do this on a regular basis. 'It’s part of our mission to illuminate the links between climate and weather,” says Paul Becker, Vice President of the German Weather Agency. “There is demand for that information, there is science to provide it, and we are happy to spread it.”

One example of real-time attribution is the assessment by scientists at the Lawrence Berkeley National Laboratory that Hurricane Florence is 50 miles wider and will inundate the Atlantic Coast with 50 percent more rain than a comparable hurricane before human-caused climate change.

And a new study using the supercomputers at the Lawrence Berkeley National Laboratory was able to detail the additional rainfall provoked by global warming in 15 hurricanes that took place in the last ten years, and predict even more rainfall and more intense winds if warming continues.

Let's hope that the entrenched climate change denial on the part of the current US president and congress does not keep this important emerging science from being used here at home.


The Nature article from which most of this information comes can be found here.

The article summarizing 170 different studies, including a useful interactive map, can be found at this URL.


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Friday, August 17, 2018


Remember DDT? It's an insecticide that was banned worldwide for most uses more than 30 years ago, but which lingers in the environment and in our bodies to this day. In its heyday, DDT was sprayed massively over farms, forests and cities to control mosquitoes and other insects. I remember as a child swimming in an outdoor pool as a plane flew overhead spraying DDT over the entire city. People accepted it as normal.

We're just now finding out that there's a possible link between DDT and autism, a severe, often disabling developmental disorder estimated to impact more than 25 million people worldwide, and 15 children out of ever thousand in the US (one out of every 42 boys!). Autistic children have difficulties with communication and relating to people, and often repeat certain movements or behaviors such as rocking over and over again.

 Autistic child and his mother
Credit: istock

A long-term study involving over one million mothers and children in Finland found that high levels of DDE--a breakdown product of DDT that ends up in the fatty tissues of animals and humans--in the blood of pregnant women doubled the risk of a child developing autism with intellectual disability. This link remained strong even after controlling for factors such as the mother's age and psychiatric history.

DDT is one of many Persistent Organic Pollutants (POPs), potentially toxic man-made chemical compounds that accumulate in soil, water and air, in the foodchain and in our bodies. Other research has shown that 10 percent of us have high concentrations of 10 or more POPs in our blood, and that high concentrations of POPs in the body are associated with a variety of metabolic abnormalities, including those leading to metabolic syndrome, diabetes and heart disease.

The current research is the first to reveal a link to autism. The authors suspect that DDT and its metabolite DDE may trigger autism because they lead to lower birthweight infants, and by interfering with the proper functioning of androgens, hormones necessary for the development of male characteristics.

"Unfortunately," says Alan Brown, an epidemiologist at Columbia University Medical Center,  "[these chemicals] are still present in the environment and are in our blood and tissues. In pregnant women, they are passed along to the developing fetus. Along with genetic and other environmental factors, our findings suggest that prenatal exposure to the DDT toxin may be a trigger for autism."

Clearly, homing in on the environmental causes of autism can help us find ways to reduce the high and still increasing incidence of this extremely disruptive condition.

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Wednesday, August 01, 2018


Having followed and written about climate change and the science behind it for decades, I've also had to think a lot about climate-change denial. I've come to realize, ruefully, that science, starting with the most basic physics and including the most powerful supercomputer based climate models, has failed to convince many people who, for one reason or another, are wedded to climate-change denial. Neither have appeals to the health and safety of future generations, nor to the plight of the increasing millions of people whose lives are currently being disrupted by climate change (many of whom become the refugees and migrants whom many climate-change deniers fear).


Through all that I've clung to the idea that when climate change comes home, as it inevitably will, when residents of Florida find their homes flooded because of rising sea levels, when Midwest corn farmers lose ten percent of their crop to extreme heat, when Texas see-saws between drought and floods, or when, as happened to my home town of Santa Rosa, California last year, wildfire sweeps through like a blowtorch, it can no longer be denied. Surely, I've thought, first-hand, life-changing personal experience will break through those layers of denial.

But I'm starting to realize that my faith in personal experience to slap people awake, like my earlier faith in the persuasive effect of science and empathy, is simply naive.

What brought this home to me was an article in the Guardian based on interviews with people who have been impacted by the deadly Northern California Carr fire, which happened to hit a staunchly conservative, Republican, Trump-supporting and climate-change-denying area. The Guardian reporter had no trouble finding people, from politicians to men and women on the street, whose ideas were unchanged even in the midst of the smoke and embers of this deadly fire. "It's bull," said one respondent. And even the one respondent who accepted that climate change was real clung to the meme that we humans are too puny to deal with it, leaving how to fix the problem in the hands of "the good Lord."

There's more evidence in a Guardian story speaking to residents of North Carolina in the aftermath of Hurricane Florence, which climate scientists tell us was 50 miles wider and dropped 50 percent more rain than it would have under pre-industrial conditions. Once again, the reporter found plenty of people still in full climate-change-denial mode.

Scholars who study the history of science often point out that for a new paradigm such as plate tectonics or quantum dynamics to replace an older set of ideas, the old guard simply have to be replaced by a new generation. If scientists, who after all are committed to experiment, hard data and putting every idea to the test, are unwilling or unable to let go of outmoded ways of thinking, I suppose I shouldn't be surprised if everyday people also refuse to learn, even if the lesson is right in front of their eyes.

 Perhaps young people will see more clearly than their elders
Credit: TAKVER

There's still room for hope, if younger generations realize that climate change is real, dangerous, and, can only be dealt with through concerted action. Perhaps Greta Thunberg can be the role model. She's a 15-year-old Swedish girl who is staying out of school and sitting in front of the Swedish Parliament to bring the urgency of the climate crisis home to her elders. Given the feeble steps we've managed to take to date, young people like her may be our last, best hope.


Here's a related story involving people who have become committed to the idea that vaccination is some kind of dangerous, evil-minded plot. This couple almost lost their six-year-old son to tetanus, a terrible and potentially deadly disease to which most of us are immune because we've been inoculated against it. Doctors were able to save the boy's life, but only through radical interventions and weeks of intensive care, which racked up a bill of over $800,000. Despite this horrifying experience, the parents refused further vaccinations. It used to be said that there's no force on Earth more powerful than an idea whose time has come. Maybe we need to modify that to reflect that, for many people, there's no force on Earth more powerful than an idea that perfectly matches their preconceived view of the world.


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