Consequences of GHG Emissions — Climate’s Troubling Unknown Unknowns

by admin on April 23, 2019

The cause is known & the solution is known

We can’t adapt to perils we can’t foresee — we need to cut greenhouse gas emissions now

From an Article by William B. Gail, PhD, New York Times, April 22, 2019

Donald Rumsfeld famously popularized the term “unknown unknowns” in a 2002 news briefing when describing the challenges of linking Iraq to weapons of mass destruction. Troublingly, climate change may also be strewn with such unknowns, and they pose daunting tests for how we face the future.

One is choosing among policy alternatives. Should we minimize tomorrow’s risks now by reducing greenhouse gas emissions, or save money today and spend it on adapting to the effects of planetary warming once threats emerge more fully, like rising seas or prolonged droughts? The policy debate increasingly tilts toward adaptation. But we can’t adapt to perils from unknown unknowns. In such cases, adaptation will largely fail; only mitigation will be effective.

The National Climate Assessment released last fall provided an updated scientific summary of the “knowns.” The simple version was this: Earth is warming, humans are largely responsible, ecosystems are changing in response, and the impact on societies will be large.

The report also characterized the known unknowns, as Mr. Rumsfeld might put it — those things we know at a fundamental level but about which we seek greater certainty. They include how much Earth will eventually warm, how rapidly oceans will rise, where and when weather extremes and water shortages might occur, and whether potential tipping points (like the collapse of Antarctic ice sheets) will, in fact, occur.

Unsurprisingly, the report carefully limited speculation about unknown unknowns: the many initially small environmental shifts that are potential consequences of the changing climate. What will actually emerge is largely unknowable because of the highly unpredictable nonlinear response to the warming of Earth’s complex and adaptive physical and ecological systems.

Yet credible speculation on climate’s unknown unknowns is sorely needed by policymakers. Future generations will be affected by today’s policy decisions, whether the underlying science is complete or not. The basics are simple: The more we warm our planet, the more likely it is that deeply surprising environmental changes will ensue.

Most of these smaller environmental changes should be manageable, readily addressed through adaptation. Inevitably, however, a rare few will most likely evolve and expand until they threaten our security, health or economy. We lack the ability to predict which are which. This is the curse of unknown unknowns. Nevertheless, things we can credibly imagine should accentuate our concern for what we are unable to imagine.

Perhaps a routinely ice-free Arctic summer, altering polar ocean life in subtle ways, sets off an unpredictable cascade of complex changes throughout the global ocean ecosystem, devastating fisheries. Maybe agricultural pests adapt to climate change stresses by evolving novel and frequently changing abilities to destroy crops, leaving farmers struggling to keep pace and feed populations. One unsettling risk is that mutant diseases — like Zika and Ebola today and the 1918 flu epidemic that killed 50 million people — could emerge more often because of altered evolutionary competition in a changing climate, each a greater medical challenge than the last.

Environmental changes occur regularly; climate change significantly accelerates the process. Should warming progress too far, society risks being overwhelmed by the growing rate at which disruptive events could occur. Each new threat is likely to emerge and proliferate differently, undermining adaptation’s effectiveness.

Some threats might be so startling and strange that our imaginations would struggle to comprehend them even after they arise. Timely response efforts would be frustrated by poor knowledge about what is occurring and how to contain the threat.

Though climate change has yet to produce clearly attributed examples, Zika hints at this dispiriting future. Within a few short years, it transformed from an ignorable rare disease into a medical terror. Nobody saw it coming. Its long-term societal consequences run deep, with childbearing upended for people threatened by the mosquito that carries the virus. Though probably not a direct result of climate change, Zika starkly illustrates the type of inconceivable surprises, and their demoralizing consequences, that threaten to emerge with ever greater frequency should we fail to slow global warming.

Three millenniums ago, Homer foreshadowed our dilemma. He wrote of Odysseus returning by ship across the Aegean Sea, headed homeward to Greece after his great victory over Troy. Odysseus anticipated an arduous sea journey, but was unprepared for what followed: an interminable voyage punctuated by unimaginably difficult experiences one after another, from Sirens to the Cyclops.

Our decisions in the next few years will determine whether our climate journey follows a similar course. Perhaps current policy discussions will navigate society through the journey’s recognized risks. If warming progresses rapidly, however, the known concerns — increasing temperatures, sea level rise, a melting Arctic — will not be the whole story. Nature’s unforeseeable surprises, some unimaginable to us today, could become pivotal to our fate.

Without an aggressive policy commitment to mitigation by rapidly reducing our carbon emissions, our grandchildren could be destined to live in a world with nature’s unknown unknowns around each year’s turn.

>>> William B. Gail is a co-founder of the Global Weather Corporation, a past president of the American Meteorological Society and the author of “Climate Conundrums: What the Climate Debate Reveals About Us.”


SEE ALSO: ‘We Are Not Moving Fast Enough’: Study Shows Cost of Melting Permafrost Could Total $70 Trillion

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National Geographic April 23, 2019 at 10:45 am

A warming Arctic could cost the world trillions of dollars —
New science warns that melting ice and permafrost could set off feedback loops that make climate change worse.

From an Article by STEPHEN LEAHY, National Geographic, April 23, 2019

Scientists have long warned that climate change is likely to bring expensive impacts, from rising seas to stronger storms. And a new study comes with a hefty price tag.

A warming Arctic is shifting from white to dark as sea ice melts and land-covered snow retreats, and that means it can absorb even more of the sun’s heat. Plus, the Arctic’s vast permafrost area is thawing, releasing more heat-trapping carbon and methane. These climate-change-driven feedbacks in the Arctic are accelerating warming even faster and may add nearly $70 trillion to the overall costs of climate change—even if the world meets the Paris Agreement climate targets, a new study says.

However, if efforts can be made to keep climate change limited to 2.7 degrees Fahrenheit (1.5C), the extra cost of Arctic warming drops to $25 trillion, new research published in Nature Communications reports. A trillion is a thousand billion. For comparison, the global GDP in 2016 was around $76 trillion.

“Massive changes are underway in the Arctic. Permafrost and loss of sea ice and snow are two known tipping elements in the climate system,” said lead author Dmitry Yumashev of the Pentland Centre for Sustainability in Business, Lancaster University in the United Kingdom.

“We wanted to know what Arctic warming could do to the rest of the world,” said Yumashev.

Download the New Nat Geo App on iOSClimate “tipping elements” are also known as tipping points or feedbacks, where a change in a natural system triggers further warming. Last year, a study documented ten tipping points and noted that these can act like a row of dominoes, one pushing another system over. Once started, these tipping points are nearly impossible to stop and risk what researchers called a “Hothouse Earth” state—in which the global average temperature is 4 to 5 degrees Celsius higher, with regions like the Arctic averaging 10 degrees C higher than today.

The Arctic is warming at least twice as fast as the global average. Sea ice has been in decline since the 1990s, exposing a million square miles of ocean. As more solar energy is absorbed it creates what’s called the surface albedo feedback.

Melting permafrost

Permafrost feedback involves the frozen soils of the permafrost zone that cover nearly a quarter of the land area of the northern hemisphere. These soils, which contain enormous stores of carbon and methane, have been thawing since the 1980s. As Arctic temperatures climb, thawing permafrost releases those warming gases.

The Yumashev study uses the most updated estimates of these feedbacks, which have yet to be included in climate models or carbon budgets. It turns out that permafrost and loss of albedo will cause significant extra warming globally, even if the world meets the 1.5°C and 2°C Paris Agreement targets, the research suggests. This extra warming could result in additional temperature-driven impacts on the economy, ecosystems, and human health, and additional impacts from sea-level rise.

While there may be some economic gains from a warming Arctic—shorter shipping routes and mineral resource extraction—those gains are a small fraction of the additional economic losses. The bulk of these losses are more likely to be incurred in warmer, poorer regions such as India and Africa, the study found.

The $25 to $70 trillion cost of Arctic warming adds four to six percent to the total cost of climate change—which is estimated to reach $1,390 trillion by the year 2300 if emissions cuts are not better than the Paris Agreement. However, the costs of the current business-as-usual path could be more than $2,000 trillion.

Additional feedback loops?

Permafrost and loss of albedo are the only two feedbacks with cost estimates at this point. There are others, including emissions from undersea permafrost and methane hydrates and other unknowns, said co-author Kevin Schaefer of the National Snow and Ice Data Centre in Boulder, Colorado.

Just last week, a new study revealed that thawing permafrost in Alaska appeared to be releasing 12 times more nitrous oxide than previously estimated. Nitrous oxide is another global warming gas but is nearly 300 times more potent at trapping heat than carbon dioxide. It also dissolves ozone in the upper atmosphere. However, the extent and total volumes being released across the permafrost region is unknown.

“With climate change we’re conducting a high-risk experiment where we don’t know what is coming,” Schaefer said. “The most important thing to remember about our study is the greater the warming, the stronger the feedbacks and the higher the costs to society.”

We already experience the impacts and the costs of climate change, he said. Shifting to a low-carbon economy is the biggest business opportunity of the 21st century. “The countries that shift first will be the winners. As an American I’d love to see it happen here first,” he said.

Reply April 25, 2019 at 11:04 am

Deadly Kissing Bug Spreads to Delaware, CDC Confirms – EcoWatch

We know the bugs are already across the bottom two-thirds of the U.S., so the bugs are here, the parasites are here. Very likely with climate change they will shift further north and the range of some species will extend.”


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