28/01/2019

What Is Global Warming, Explained

National Geographic - Christina Nunez

The planet is heating up—and fast.

Causes and Effects of Climate Change

Glaciers are melting, sea levels are rising, cloud forests are dying, and wildlife is scrambling to keep pace. It has become clear that humans have caused most of the past century's warming by releasing heat-trapping gases as we power our modern lives. Called greenhouse gases, their levels are higher now than at any time in the last 800,000 years.
We often call the result global warming, but it is causing a set of changes to the Earth's climate, or long-term weather patterns, that varies from place to place. While many people think of global warming and climate change as synonyms, scientists use “climate change” when describing the complex shifts now affecting our planet’s weather and climate systems—in part because some areas actually get cooler in the short term.
Climate change encompasses not only rising average temperatures but also extreme weather events, shifting wildlife populations and habitats, rising seas, and a range of other impacts. All of those changes are emerging as humans continue to add heat-trapping greenhouse gases to the atmosphere, changing the rhythms of climate that all living things have come to rely on.
What will we do—what can we do—to slow this human-caused warming? How will we cope with the changes we've already set into motion? While we struggle to figure it all out, the fate of the Earth as we know it—coasts, forests, farms, and snow-capped mountains—hangs in the balance.

Understanding the greenhouse effect
The "greenhouse effect" is the warming that happens when certain gases in Earth's atmosphere trap heat. These gases let in light but keep heat from escaping, like the glass walls of a greenhouse, hence the name.
Sunlight shines onto the Earth's surface, where the energy is absorbed and then radiate back into the atmosphere as heat. In the atmosphere, greenhouse gas molecules trap some of the heat, and the rest escapes into space. The more greenhouse gases concentrate in the atmosphere, the more heat gets locked up in the molecules.
Scientists have known about the greenhouse effect since 1824, when Joseph Fourier calculated that the Earth would be much colder if it had no atmosphere. This natural greenhouse effect is what keeps the Earth's climate livable. Without it, the Earth's surface would be an average of about 60 degrees Fahrenheit (33 degrees Celsius) cooler.
A polar bear stands sentinel on Rudolf Island in Russia’s Franz Josef Land archipelago, where the perennial ice is melting. Photograph by Cory Richards
In 1895, the Swedish chemist Svante Arrhenius discovered that humans could enhance the greenhouse effect by making carbon dioxide, a greenhouse gas. He kicked off 100 years of climate research that has given us a sophisticated understanding of global warming.
Levels of greenhouse gases have gone up and down over the Earth's history, but they had been fairly constant for the past few thousand years. Global average temperatures had also stayed fairly constant over that time—until the past 150 years. Through the burning of fossil fuels and other activities that have emitted large amounts of greenhouse gases, particularly over the past few decades, humans are now enhancing the greenhouse effect and warming Earth significantly, and in ways that promise many effects, scientists warn.

Aren't temperature changes natural?
Human activity isn't the only factor that affects Earth's climate. Volcanic eruptions and variations in solar radiation from sunspots, solar wind, and the Earth's position relative to the sun also play a role. So do large-scale weather patterns such as El Niño.
But climate models that scientists use to monitor Earth’s temperatures take those factors into account. Changes in solar radiation levels as well as minute particles suspended in the atmosphere from volcanic eruptions, for example, have contributed only about two percent to the recent warming effect. The balance comes from greenhouse gases and other human-caused factors, such as land use change.
The short timescale of this recent warming is singular as well. Volcanic eruptions, for example, emit particles that temporarily cool the Earth's surface. But their effect lasts just a few years. Events like El Niño also work on fairly short and predictable cycles. On the other hand, the types of global temperature fluctuations that have contributed to ice ages occur on a cycle of hundreds of thousands of years.
For thousands of years now, emissions of greenhouse gases to the atmosphere have been balanced out by greenhouse gases that are naturally absorbed. As a result, greenhouse gas concentrations and temperatures have been fairly stable, which has allowed human civilization to flourish within a consistent climate.
Greenland is covered with a vast amount of ice—but the ice is melting four times faster than thought, suggesting that Greenland may be approaching a dangerous tipping point, with implications for global sea-level rise. Photograph by Michael Melford, Nat Geo Image Collection
Now, humans have increased the amount of carbon dioxide in the atmosphere by more than a third since the Industrial Revolution. Changes that have historically taken thousands of years are now happening over the course of decades.

Why does this matter?
The rapid rise in greenhouse gases is a problem because it’s changing the climate faster than some living things can adapt to. Also, a new and more unpredictable climate poses unique challenges to all life.
Historically, Earth's climate has regularly shifted between temperatures like those we see today and temperatures cold enough to cover much of North America and Europe with ice. The difference between average global temperatures today and during those ice ages is only about 9 degrees Fahrenheit (5 degrees Celsius), and the swings have tended to happen slowly, over hundreds of thousands of years.
But with concentrations of greenhouse gases rising, Earth's remaining ice sheets such as Greenland and Antarctica are starting to melt too. That extra water could raise sea levels significantly, and quickly. By 2050, sea levels are predicted to rise between one and 2.3 feet as glaciers melt.
As the mercury rises, the climate can change in unexpected ways. In addition to sea levels rising, weather can become more extreme. This means more intense major storms, more rain followed by longer and drier droughts—a challenge for growing crops—changes in the ranges in which plants and animals can live, and loss of water supplies that have historically come from glaciers.

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Imagining A Davos For The Many That Was Actually Serious About Climate Change

The Conversation - 

The World Economic Forum: in need of a refresh? Gian Ehrenzeller / EPA
From the moment world leaders claiming to want to fight climate change arrived in private jets, the 2019 World Economic Forum in Davos attracted controversy. With global inequality growing and the threat of environmental destruction looming ever larger, the jets are getting larger and more expensive. The director of one private charter company says surging demand for his planes is partly down to “business rivals not wanting to be seen to be outdone by one another”.
This contradiction between rhetoric and action goes far beyond the use of private aircraft. It reveals the broader problems of allowing billionaires to not only control a disproportionate amount of the world’s wealth but also shape its political and economic agenda. While recognising the need for change, their solutions will almost always lead to a defence of the status quo from which they profit so handsomely.
Davos is just the tip of the iceberg of the more pervasive problem of “charitable billionaires”. On the surface, it would appear that having “the 1%” direct their wealth toward worthy causes is both laudatory and necessary. But such philanthrocapitalism promotes market-friendly policies and devalues the ability of democratic governments to provide social welfare or meet the needs of their citizens. As one critic noted:
the problems capitalist philanthropists claim to be solving are rooted in the same economic system that allows them to generate such enormous wealth in the first place.
An obvious answer may then be to simply dismiss the World Economic Forum and Davos altogether. Stopgap solutions such as seeking to address economic insecurity through employee “mindfulness and well-being” could be mocked, at best.

An alternative and sustainable Davos?
However, the ethos of Davos still has much to offer. It represents an effort to bring together global leaders and influencers to address problems that go beyond national borders. If anything, it would appear that we need more of these trans-national spaces for discussing technological innovation and social transformation.

In orbit: Al Gore talks climate change at Davos. But what about system change? Gian Ehrenzeller / EPA
For Davos to truly be effective though, it must stop serving as a space for elites to defend their status and power. It must no longer be a forum, for instance, for CEOs like Tim Cook of Apple to defend his company and his executive allies from the legitimate “big tech backlash”. Rather, it should be an opportunity to force billionaires to invest in ambitious progressive solutions for solving the very problems they are primarily responsible for causing.
Climate change is a crucial place to start. At the moment, the most that pro-environmental voices such as New Zealand PM Jacinda Ardern can do is plead with elites to “get on the right side of history and embrace ‘guardianship’ of the earth”. Alternatively, Davos could be used to promote a more ambitious green agenda and directly challenge the power of the billionaire class and the politicians who continue to prop them up.
Leading up to Davos, US congresswoman Alexandria Ocasio-Cortez made headlines by calling for a “Green New Deal”. It proposes to have the US become a global leader in “decarbonising” its economy within ten years. Further, it will achieve these aims through massive public investment, a federal jobs guarantee, and a dramatic increase in the taxing of high income. The growing public support for this plan has also been a platform for progressive lawmakers to question the huge US military budget and tax cuts. Why, they ask, are war and wealth being prioritised over the housing, healthcare or the environment?

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Link: FINAL Select Committee for a Green New Deal
This is a good beginning. Yet it would benefit from having the support of global movements and the capital of global elites. In an alternative world, Davos could be just such a venue for an international commitment to innovation and progressive change. Rather than just having countries fight to tax their richest citizens and corporations, they could also mandate that they have to invest a percentage of their profits in the ideas and agenda proposed by leading experts and activists around the world every year. In this case, it would be for helping to fund countries and communities to put in place a “green new deal”.
The roots of such an alternative are already growing in events like the “World Social Forum” which is an attempt to bring together community and political leaders with leading thinkers to imagine a different “world” to the corporate-friendly one supported by the World Economic Forum. Critically, it advocates “glocal” solutions, customised to local conditions. Davos, in this regard, could be a yearly corrective where those most affected by elite policies could put forward the specific solutions for them to rectify it.
For this to happen it would mean transforming the very ethos of Davos from one of “idea sharing” to that of democratic accountability and justice. It entails delinking social value and influence from economic wealth and the political influence it buys. Instead, Davos could be an annual opportunity for experts and “the people” to propose the best and most cutting edge ideas for redistributing this wealth to where it is truly needed and can do the most good. Scientists warn that we have only 12 years potentially left to avert a “climate change catastrophe”. It is why we need to create an alternative Davos “for the many, not the few” as soon as possible.

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2018 Was The Fourth Warmest Year On Record -- And More Evidence Of A ‘New Normal,’ Scientist Group Reports

Washington Post - Chris Mooney

The year was one in a string that have been a full degree Celsius, or 1.8 degrees Fahrenheit, warmer than temperatures in the late 19th century, the report found.
In this photo taken on November 10, 2018 Flames from the Camp fire burn near a home atop a ridge near Big Bend, California. JOSH EDELSON/AFP/Getty Images (Josh Edelson/AFP/Getty Images)
The year 2018 is likely to have been the fourth warmest year on record, a scientific group pronounced Thursday -- and joins three other extra-hot years since 2015 that suggest a leap upward in warmth that the Earth may never return from in our lifetimes.
The warmest year on record for the Earth’s land and oceans was 2016 -- by a long shot, thanks to a very strong El Nino event. That’s followed by 2017, 2015, and now 2018, said Zeke Hausfather, a research scientist with Berkeley Earth, which released the findings.
“2018 is consistent with the long term warming trend,” Hausfather said. “It’s significantly warmer than any of the years before 2015. There’s still this big bump up after 2014, and 2015, 2016, 2017, and 2018 are all in a class of their own.”
Berkeley Earth. (n/a)
While expert groups have sometimes divided on such annual temperature rankings -- and not all assessments are yet in -- Berkeley Earth’s findings appear unlikely to be disputed.
The Copernicus Climate Change Service, a European Union body, has also proclaimed 2018 the fourth warmest year on record earlier this month.
And Kevin Cowtan, a researcher at the University of York who also keeps an influential temperature dataset, agreed with the ranking, though he noted by email that he is only able to track data through November of last year due to the U.S. government shutdown, leaving his assessment one month short at present.
“Our results to November clearly put 2018 in 4th place, significantly warmer than 2010 in 5th,” said Cowtan. “The 11 hottest years on record have all occurred since 2005.”
Amid the government shutdown the U.S.'s two top keepers of temperature records -- NASA and NOAA -- have not yet released their findings. Last year, both agencies released their assessments for 2017′s temperatures, which NASA called the second warmest and NOAA the third, on January 18.
Hausfather said a coordinated release had been planned for January 17 with his organization and the U.S. government agencies -- before the shutdown, that is. Once that happened, he said, Berkeley Earth decided to go ahead and release its own numbers.
In response to a request for comment, NOAA said that it would look into the state of the 2018 temperature release. Meanwhile, on Thursday NASA’s Gavin Schmidt, who heads the agency office that keeps the temperature record, tweeted that their release has been “indefinitely postponed” due to the shutdown.
But Hausfather said that based on where the other temperature datasets currently stand, with data through November and thus only one month remaining to add, it’s likely there will be no disagreement about the rankings this year by any party.
Indeed, NASA’s Schmidt had tweeted back in October that 2018 would surely be the 4th warmest year.
IMAGE
“At this point, it would be almost impossible for 2018 not to be the fourth warmest in all the records,” Hausfather said.
2018 was yet another year of suspiciously extreme weather events -- such as the devastating California wildfires -- and also extra hot summer temperatures in Europe.
29 countries had their hottest years on record, Berkeley Earth found, including European countries like France and Germany but also Middle Eastern nations like Oman and the United Arab Emirates.
Notably, Antarctica also saw its warmest year on record, the group found.
Berkeley Earth (n/a)
The year yet again featured an odd cold anomaly in the seas to the southeast of Greenland, which some scientists think may represent a slowing down of the “overturning” ocean circulation in the Atlantic. Clearly, this region is bucking the overall warming trend.
From a political and policy perspective, the last several extra warm years are highly significant. That’s because, as the tweet from NASA’s Schmidt above notes, they appear to be at or above a 1 degree Celsius, or 1.8 degree Fahrenheit, increase above so-called “preindustrial” temperatures, or temperatures from the later part of the 19th century.
In Berkeley Earth’s dataset, the last 5 years are all above 1C; in two other datasets the last four years are expected to be above that threshold, according to data provided by Hausfather. In the National Oceanic and Atmospheric Administration dataset, 2018 is trending slightly under it.
Either way, this matters because scientists have outlined increasingly dire consequences as soon as the Earth reaches 1.5 C or 2C, temperature targets that are both flagged in the 2015 Paris climate agreement.
The arrival of 1.5 degrees C -- 2.7 degrees F -- could happen in under 2 decades. In fact, it has in effect already happened for many land areas, since land surfaces are warming quicker than the ocean at this point. But the oceans are warming too -- they may have been the warmest on record in 2018.
Berkeley Earth projects that 2019 may well be warmer than every year so far except for 2016 -- and thus will once again be above 1 C.
“It’s unlikely at this point that we’ll have a situation where temperatures dip back below that, at least for the globally complete datasets,” said Hausfather. He termed the current temperature range -- which has seen more extreme heat events, major coral bleaching and death around the world, and alarming wildfires, among other climate-linked occurrences -- a “new normal.”
Hausfather himself, living in the Bay Area, said he has been personally affected.
“We have a 1 and a half year old baby,” he said. “Earlier this fall after the Camp Fire, when the air quality was worse in San Francisco than it was in Beijing, we had to stay inside, bought an air purifier, had to wear masks outside.”
“We’ve also seen some crazy extreme heat events," he continued. "It reached 100 degrees in San Francisco two weeks after the baby was born….and obviously none of us have air conditioning, it’s San Francisco. So in general we’ve certainly noticed that these extremes appear to have become more common.”

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