Scenes from a dry city: The water crisis in Cape Town

 

Global warming has already raised the risk of more severe droughts in Cape Town

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Cape Town residents queuing for water during the water crisis.
Shutterstock

Mark New, University of Cape Town; Friederike Otto, University of Oxford, and Piotr Wolski, University of Cape Town

Between 2015 and 2017 South Africa’s South Western Cape region experienced three of its lowest rainfall years on record. This led to the progressive depletion of water supply reservoirs and by the summer of 2017/18 there was a real danger that – without drastic reductions in water use – the region, and especially the city of Cape Town, would run out of water.

Droughts close to this magnitude have occurred in the past (for example in the late 1920s, early 1970s, and 2003 to 2004) and led to water shortages in Cape Town. But are they getting worse?

The reliable yield of the South Western Cape water system has, until now, been calculated under the assumption of a stationary climate. This is the idea that past rainfall can be used to estimate present day as well as future rainfall, and then also water system yields. A water resource model is used to estimate the frequency of failure under all the known past rainfall conditions – in the case of this region, the last 80 or so years. The water system is then designed to be fairly reliable. The supply system for Cape Town and surround areas was designed to maintain supply without imposing water restrictions 98% of the time, or – on average – 49 out of every 50 years.

It’s known that the climate is going to change in the future, as a succession of international scientific assessments have shown. And many water resource planners are taking climate change into account when upgrading existing or designing new water supply systems.

But has this changing global climate already altered the risk of droughts like the one Cape Town just experienced?

[Read more…]

The climate change lawsuit that could stop the U.S. government from supporting fossil fuels

60 Minutes reports:

Of all the cases working their way through the federal court system none is more interesting or potentially more life changing than Juliana v. United States. To quote one federal judge, “This is no ordinary lawsuit.” It was filed back in 2015 on behalf of a group of kids who are trying to get the courts to block the U.S. government from continuing the use of fossil fuels. They say it’s causing climate change, endangering their future and violating their constitutional rights to life, liberty and property. When the lawsuit began hardly anyone took it seriously, including the government’s lawyers, who have since watched the Supreme Court reject two of their motions to delay or dismiss the case. Four years in, it is still very much alive, in part because the plaintiffs have amassed a body of evidence that will surprise even the skeptics and have forced the government to admit that the crisis is real.

The case was born here in Eugene, Oregon, a tree-hugger’s paradise, and one of the cradles of environmental activism in the United States. The lead plaintiff, University of Oregon student Kelsey Juliana, was only five weeks old when her parents took her to her first rally to protect spotted owls. Today, her main concern is climate change, drought and the growing threat of wildfires in the surrounding Cascade Mountains. [Watch the full report…]

Heatwaves sweeping oceans ‘like wildfires’, scientists reveal

The Guardian reports:

The number of heatwaves affecting the planet’s oceans has increased sharply, scientists have revealed, killing swathes of sea-life like “wildfires that take out huge areas of forest”.

The damage caused in these hotspots is also harmful for humanity, which relies on the oceans for oxygen, food, storm protection and the removal of climate-warming carbon dioxide the atmosphere, they say.

Global warming is gradually increasing the average temperature of the oceans, but the new research is the first systematic global analysis of ocean heatwaves, when temperatures reach extremes for five days or more.

The research found heatwaves are becoming more frequent, prolonged and severe, with the number of heatwave days tripling in the last couple of years studied. In the longer term, the number of heatwave days jumped by more than 50% in the 30 years to 2016, compared with the period of 1925 to 1954.

As heatwaves have increased, kelp forests, seagrass meadows and coral reefs have been lost. These foundation species are critical to life in the ocean. They provide shelter and food to many others, but have been hit on coasts from California to Australia to Spain. [Continue reading…]

With climate science on the march, an isolated Trump hunkers down

The New York Times reports:

New efforts by President Trump and his staff to question or undermine the established science of climate change have created a widening rift between the White House on one side, and scientific facts, government agencies, and some leading figures in the president’s own party on the other.

The president’s senior advisers are exploring the idea of creating a panel aimed at questioning the National Climate Assessment. According to a White House memo, the group would include William Happer, a Princeton physicist who has asserted that carbon dioxide — a greenhouse gas that scientists say is trapping heat and warming the planet — is beneficial to humanity.

The climate assessment, a sweeping report issued by the White House itself in November, concluded decisively that the burning of fossil fuels was warming the atmosphere, leading to a raft of harmful effects across the United States and the world.

And Mr. Trump announced last week on Twitter that he would nominate Kelly Knight Craft to be his ambassador to the United Nations. Ms. Craft said in a 2017 television interview that, on the issue of climate change, she believes there are “scientists on both sides that are accurate.”

“There is no precedent for something like this,” said Douglas Brinkley, a historian who has written books on five former United States presidents. “Other presidents have attacked policy initiatives, but not science.” [Continue reading…]

The 2020 election now has a climate-action candidate

 

In January, The Atlantic reported:

If there is a new Democratic president come 2021, he or she will get pulled in all sorts of policy directions. [Washington State Governor, Jay] Inslee [who announced his presidential candidacy today] says he has one priority: global warming. It’s not theoretical, or a cause just for tree huggers anymore. Putting off dealing with it for a year or two or kicking it to some new bipartisan commission won’t work, he says. He plans to focus on the threat that climate change poses to the environment and national security—the mega-storms and fires causing millions in damages, the weather changes that will cause mass migrations, the droughts that will devastate farmers in America and around the world.

Even more so, he wants to talk about the risk to American opportunity. “We have two existential threats right now: one is to our natural systems, and one is to our economic systems,” he said.

As he did in Washington State, Inslee would propose a mix of government investments and incentives to spur other investment, restrictions on power plants and emissions, and programs to promote R&D and job growth. An endless number of jobs can be created in the climate arena, Inslee says. It’s the way to make a real dent in income inequality and have the Democratic Party bring tangible solutions to communities in rural America that have been left behind. With his inaction, President Donald Trump—Inslee calls him “the commander in chief of delusion”—is engaged in a “disgusting selling-out of the country,” a “crime” against the aspirational optimism of America. [Continue reading…]

CNN reports:

White House economic adviser Kevin Hassett said Friday that he believes climate change could threaten economic growth.

It’s a position that puts him at odds with the Trump administration and the President himself, who has openly questioned whether the climate is warming at all.

“It’s something people should take seriously and think about,” Hassett said in an interview with CNN’s Poppy Harlow.

Hassett, an economist long involved in conventional Republican political circles, has in the past expressed support for instituting carbon taxes to curb pollution.

“I was one of the first economists writing theoretical papers about carbon taxes,” he said on Friday. “It’s literature I have been involved in for a really long time.” [Continue reading…]

The ocean is running out of oxygen, scientists warn

Laura Poppick writes:

Escaping predators, digestion and other animal activities—including those of humans—require oxygen. But that essential ingredient is no longer so easy for marine life to obtain, several new studies reveal.

In the past decade ocean oxygen levels have taken a dive—an alarming trend that is linked to climate change, says Andreas Oschlies, an oceanographer at the Helmholtz Center for Ocean Research Kiel in Germany, whose team tracks ocean oxygen levels worldwide. “We were surprised by the intensity of the changes we saw, how rapidly oxygen is going down in the ocean and how large the effects on marine ecosystems are,” he says.

It is no surprise to scientists that warming oceans are losing oxygen, but the scale of the dip calls for urgent attention, Oschlies says. Oxygen levels in some tropical regions have dropped by a startling 40 percent in the last 50 years, some recent studies reveal. Levels have dropped more subtly elsewhere, with an average loss of 2 percent globally.

Ocean animals large and small, however, respond to even slight changes in oxygen by seeking refuge in higher oxygen zones or by adjusting behavior, Oschlies and others in his field have found. These adjustments can expose animals to new predators or force them into food-scarce regions. Climate change already poses serious problems for marine life, such as ocean acidification, but deoxygenation is the most pressing issue facing sea animals today, Oschlies says. After all, he says, “they all have to breathe.” [Continue reading…]

Concrete is tipping us into climate catastrophe. We need to tax it, now

John Vidal writes:

Cement, the key component of concrete and one of the most widely used manmade materials, is now the cornerstone of global construction. It has shaped the modern environment, but its production has a massive footprint that neither the industry nor governments have been willing to address.

Because of the heat needed to decompose rock and the natural chemical processes involved in making cement, every tonne made releases one tonne of C02, the main greenhouse warming gas.

Including the new Crossrail line through London, the building of Britain’s four largest current construction projects will, if completed, together emit more than 10m tonnes of CO2 – roughly the same amount as a city the size of Birmingham, or what 19 million Malawians emit in a year.

Nearly 6% of all UK greenhouse gas emissions, and up to 8% of the world’s, are now sourced from cement production. If it were a country, the cement industry would be the third largest in the world, its emissions behind only China and the US.

So great is its carbon footprint that unless it is transformed and made to adopt cleaner practices, the industry could, on its own, jeopardise the whole 2015 Paris agreement which aims to hold worldwide temperatures to a 2C increase. To bring it into line, the UN says its annual emissions need to fall about 16% in the next 10 years, and by far more in the future. [Continue reading…]

A world that neglects to save its children can’t hope to be saved by its children

 

The New York Times reports:

It’s complicated being Greta.

Small, shy, survivor of crippling depression, Greta Thunberg, the 16-year-old Swedish girl skipping school to shame the world into addressing climate change, drew a parade of fans one Friday in February on a frozen square in Stockholm.

Six Swiss students had traveled 26 hours by train to seek her support for their petition for a tougher Swiss carbon emissions law. An Italian scientist told her she reminded him of his younger, activist self. A television news crew hovered around her. Women from an antismoking group came to give her a T-shirt.

Greta nodded, whispered, “Thanks,” posed for pictures. Made exactly zero small talk.

All this attention, she said out of earshot of the others, is great. It means “people are listening.” But then, a knife-blade flash of rage revealed itself.

“It’s sometimes annoying when people say, ‘Oh you children, you young people are the hope. You will save the world’” she said, after several grown-ups had told her just that. “I think it would be helpful if you could help us just a little bit.” [Continue reading…]

Feedback loop between global warming and cloud loss may push Earth’s climate past a disastrous tipping point

Natalie Wolchover writes:

Clouds currently cover about two-thirds of the planet at any moment. But computer simulations of clouds have begun to suggest that as the Earth warms, clouds become scarcer. With fewer white surfaces reflecting sunlight back to space, the Earth gets even warmer, leading to more cloud loss. This feedback loop causes warming to spiral out of control.

For decades, rough calculations have suggested that cloud loss could significantly impact climate, but this concern remained speculative until the last few years, when observations and simulations of clouds improved to the point where researchers could amass convincing evidence.

Now, new findings reported today in the journal Nature Geoscience make the case that the effects of cloud loss are dramatic enough to explain ancient warming episodes like the PETM [the Paleocene-Eocene Thermal Maximum, a cataclysmic hot spell 56 million years ago] — and to precipitate future disaster. Climate physicists at the California Institute of Technology performed a state-of-the-art simulation of stratocumulus clouds, the low-lying, blankety kind that have by far the largest cooling effect on the planet. The simulation revealed a tipping point: a level of warming at which stratocumulus clouds break up altogether. The disappearance occurs when the concentration of CO2 in the simulated atmosphere reaches 1,200 parts per million — a level that fossil fuel burning could push us past in about a century, under “business-as-usual” emissions scenarios. In the simulation, when the tipping point is breached, Earth’s temperature soars 8 degrees Celsius, in addition to the 4 degrees of warming or more caused by the CO2 directly.

Once clouds go away, the simulated climate “goes over a cliff,” said Kerry Emanuel, a climate scientist at the Massachusetts Institute of Technology. [Continue reading…]