We’re about to kill a massive, accidental experiment in reducing global warming

We’re about to kill a massive, accidental experiment in reducing global warming

SOURCE: MIT Technology Review DATE: January 22, 2018 SNIP: Studies have found that ships have a net cooling effect on the planet, despite belching out nearly a billion tons of carbon dioxide each year. That’s almost entirely because they also emit sulfur, which can scatter sunlight in the atmosphere and form or thicken clouds that reflect it away. In effect, the shipping industry has been carrying out an unintentional experiment in climate engineering for more than a century. Global mean temperatures could be as much as 0.25 ˚C lower than they would otherwise have been, based on the mean “forcing effect” calculated by a 2009 study that pulled together other findings. For a world struggling to keep temperatures from rising more than 2 ˚C, that’s a big helping hand. And we’re about to take it away. In 2016, the UN’s International Maritime Organization announced that by 2020, international shipping vessels will have to significantly cut sulfur pollution. There are very good reasons to cut sulfur: it contributes to both ozone depletion and acid rain, and it can cause or exacerbate respiratory problems. But as a 2009 paper in Environmental Science & Technology noted, limiting sulfur emissions is a double-edged sword. “Given these reductions, shipping will, relative to present-day impacts, impart a ‘double warming’ effect: one from [carbon dioxide], and one from the reduction of [sulfur dioxide],” wrote the authors. “Therefore, after some decades the net climate effect of shipping will shift from cooling to...
Scientists just presented a sweeping new estimate of how much humans have transformed the planet

Scientists just presented a sweeping new estimate of how much humans have transformed the planet

SOURCE: Washington Post DATE: December 20, 2017 SNIP: In this age of climate change, we naturally train our attention on all the fossil fuels being combusted for human use — but scientists have long known that what’s happening is also all about the land. Just as buried fossil fuels are filled with carbon from ancient plant and animal life, so too are living trees and vegetation on Earth’s surface today. Razing forests or plowing grasslands puts carbon in the atmosphere just like burning fossil fuels does. Now, new research provides a surprisingly large estimate of just how consequential our treatment of land surfaces and vegetation has been for the planet and its atmosphere. If true, it’s a finding that could shape not only our response to climate change, but our understanding of ourselves as agents of planetary transformation. Using a series of detailed maps derived from satellite information and other types of ecological measurements, Karl-Heinz Erb, the lead study author, and his colleagues estimated how much carbon is contained in Earth’s current vegetation. The number is massive: 450 billion tons of carbon, which, if it were to somehow arrive in the atmosphere as carbon dioxide, would amount to over a trillion tons of the gas. But the study also presented an even larger and perhaps more consequential number: 916 billion tons. That’s the amount of carbon, the research calculated, that could reside in the world’s vegetation — so not in the atmosphere — if humans somehow entirely ceased all uses of land and allowed it to return to its natural state. The inference is that current human use of...
Study discovers why global warming will accelerate CO2 rise

Study discovers why global warming will accelerate CO2 rise

SOURCE: University of Reading DATE: November 28, 2017 SNIP: Global warming is likely to speed up as the Earth becomes increasingly more sensitive to atmospheric CO₂ concentrations, scientists from the University of Reading have warned. In a new study, published this week in the prestigious journal PNAS, the scientists explain that the influence of increasing levels of atmospheric CO2 on global warming will become more severe over time because the patterns of warming of the Earth’s surface will lead to reduced cloud cover in some sensitive regions and less heat being able to escape into space. The findings are supported by observations, suggesting that forecasts made by climate models evaluated by the Intergovernmental Panel on Climate Change are...
Fossil fuel burning set to hit record high in 2017, scientists warn

Fossil fuel burning set to hit record high in 2017, scientists warn

SOURCE: The Global Carbon Project, The Guardian, Associated Press, Earth System Science Data (PDF) DATE: November 13, 2017 SNIP: The burning of fossil fuels around the world is set to hit a record high in 2017, climate scientists have warned, following three years of flat growth that raised hopes that a peak in global emissions had been reached. The expected jump in the carbon emissions that drive global warming is a “giant leap backwards for humankind”, according to some scientists. However, other experts said they were not alarmed, saying fluctuations in emissions are to be expected and that big polluters such as China are acting to cut emissions. Global emissions need to reach their peak by 2020 and then start falling quickly in order to have a realistic chance of keeping global warming below the 2C danger limit, according to leading scientists. Whether the anticipated increase in CO2 emissions in 2017 is just a blip that is followed by a falling trend, or is the start of a worrying upward trend, remains to be seen. Estimates for 2017 put it at about 40.8 billion tons (37 billion metric tons). Sixty years ago , the world spewed only 9.2 billion tons (8.3 billion metric tons). “It’s a bit staggering,” said co-author Ralph Keeling, a Scripps Institution of Oceanography scientist, noting in an email that levels have increased fourfold since he was born in the 1950s. “We race headlong into the unknown.” The ability to monitor emissions quickly and accurately is of growing importance. The Paris agreement is based on voluntary cuts by nations, and without verification that pledges have been...
Global atmospheric CO2 levels hit record high

Global atmospheric CO2 levels hit record high

SOURCE: The Guardian DATE: October 30, 2017 SNIP: The concentration of carbon dioxide in the atmosphere increased at record speed last year to hit a level not seen for more than three million years, the UN has warned. The new report has raised alarm among scientists and prompted calls for nations to consider more drastic emissions reductions at the upcoming climate negotiations in Bonn. This acceleration occurred despite a slowdown – and perhaps even a plateauing – of emissions because El Niño intensified droughts and weakened the ability of vegetation to absorb carbon dioxide. As the planet warms, El Niños are expected to become more frequent. The increase of 3.3 ppm is considerably higher than both the 2.3 ppm rise of the previous 12 months and the average annual increase over the past decade of 2.08ppm. It is also well above the previous big El Niño year of 1998, when the rise was 2.7 ppm. The study, which uses monitoring ships, aircraft and stations on the land to track emissions trends since 1750, said carbon dioxide in the atmosphere is now increasing 100 times faster than at the end of the last ice age due to population growth, intensive agriculture, deforestation and...