Everything is connected, and everything is changing
By Kate Marvel on December 30, 2019
A state of emergency was declared on November 11, 2019 and residents in the Sydney area were warned of “catastrophic” fire danger as Australia prepared for a fresh wave of deadly bushfires that have ravaged the drought-stricken east of the country.
It rains in the Amazon because the trees want it to. There is plenty of moisture in the oceans that surround the continent, but there is also a hidden reservoir on the land feeding an invisible river that flows upward to the sky. The water held in the soil is lifted up by the bodies of the trees and lost through the surfaces of their leaves to the atmosphere. The local sky plumps with moisture, primed for the arrival of the seasonal rains driven by the annual back-and-forth march of the sun’s rays. As climate scientist Alex Hall puts it, the trees are co-conspiring with the sky to attract an earlier monsoon.
This is the decade we knew we were right. It began with the warmest year on record; it then broke that record at least five times. Carbon dioxide in the atmosphere reached levels unprecedented since humans were hominins. There were droughts and floods and brutal heat waves. Coral reefs turned white and gave up. Australia is in drought. The Amazon is on fire.
Nothing is eternal and nothing is infinite. There were once forests in the Sahara—if not quite the Amazon, still lush and tropical, clustered around the largest freshwater lake on the planet. In geologic time, this was practically yesterday: less than ten thousand years ago. The lake is mostly gone now, vanished in the span of a few hundred years. In its place there is nothing but dust.
The changes now are different. We expected most of them, and they are occurring with a terrifying rapidity that is no more reassuring because it is easily understood. We have known that carbon dioxide traps heat for over a hundred years. We have known that we are changing the planet for decades now. There is no consolation in being right.
The climate always changes. It is dry in the Sahara because the planet wobbled slightly in its orbit, weakening the monsoon rains in the west of Africa. The plants sucked the moisture from the soil; it was not replaced. They died, and no more moisture entered the atmosphere: a vicious cycle of dying and drying that led to the dusty, depopulated desert we know today. This was climate change; it was likely not the fault of humans. But the existence of past climate change does not mean we are not responsible for it this time. There have always been gentle and natural deaths. This does not make murder impossible.
The decade began with lies and ended with evasions. Hackers, probably Russian, stole the emails of a few scientists and offered single sentences, taken wildly out of context, to an eager and credulous media. We heard both sides: the truth, and the not-truth, and were encouraged to draw our own conclusions. The temperature rose; physics was not watching the debate. We learned nothing from the experience.
The winds over the Sahara come from the East, dense, sinking forced sideways as the Earth rotates away underneath it. The dust is carried across the Atlantic, enlarging the beaches of the Caribbean, scattering low-angle sunlight into brilliant purple-orange sunsets, and landing gently on the forests of the Amazon. But the air over the Sahara has arrived from the tropics, rising and shedding its moisture on a journey toward the poles. When it can go no further, it cools and sinks. There are no deserts without the tropics.
Everything is connected. Children were murdered in their schools, and were angry about it. Children saw their futures bargained away for short-term profit, and were angry about it. Children saw the changing world, and were angry about it. The streets swelled with angry children and heartbroken parents, a chorus of hurt that would have echoed through the halls of power had they been able to hear. Nothing was done, and the anger grew louder. This was the decade we saw that history was renewable. We promised to make more of it.
If you want to see the future of the Amazon, you must use physics and assumptions and know that you are almost certainly wrong. All models are wrong, but all climate models strive to be useful, to show a plausible future that may still be avoidable. If the future atmosphere is larded with even more carbon dioxide, the plants of the Amazon will not need to open the pores on their leaves quite so much to take in the gases they need. They will expel less water from these shrunken pores into the atmosphere. The trees will lose their ability to summon the monsoon. There will be fire and drought. Where there was once forest will be only dust.
Here is one thing worth remembering in the dark days of the northern mid-latitude winter. The rainforest is so lush that it cannot fertilize itself. Every nutrient is seized by the greedy vegetation, locked up in the bodies of plants before it can leach into the soil. But the forest is fertilized, given life by the dead lake in the Sahara. There is phosphorus in the lakebed, turned into dust and swept across the Atlantic by the prevailing winds.
From the old comes the new, a fragile phoenix borne upward from the tropics on the rising updrafts of thick convective cloud. The Amazon exists because the Sahara does, the desert is there because the tropics are here. None of this was ever going to stand alone.Scientific American Blog Network @ https://blogs.scientificamerican.com/hot-planet/this-was-the-decade-we-knew-we-were-right/
LONDON, 6 January, 2016 – There is fresh concern among scientists over the rises they are detecting in one of the chief greenhouse gases, methane. A team of researchers from universities in Sweden and the US says methane is increasing in the atmosphere fast enough for emissions of the gas possibly to rise by between 20% and 50% before the end of the century. Over a century, methane is 25 times more powerful as a greenhouse gas than carbon dioxide, the main gas contributing to global warming. But over a 20-year period, methane is 84 times more potent than CO2. Many methane sources are poorly understood, including lakes at high northern latitudes. But the researchers hope this may change. Water bodies A study in Nature Geoscience describes how compiling previously reported measurements made at 733 northern water bodies − from small ponds formed by beavers to large lakes formed by permafrost thaw or ice-sheets – has enabled researchers to estimate emissions over large scales more accurately. “The release of methane from northern lakes and ponds needs to be taken seriously,” says study leader Martin Wik, a PhD student at the Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University. “These waters are significant, contemporary sources because they cover large parts of the landscape. They are also likely to emit even more methane in the future.” “Efforts to reduce human-induced warming are even more urgent in order to minimise this type of feedback of natural greenhouse gas emissions” Average temperatures in the Arctic are rising twice as fast as they are anywhere else in the world. At high northern latitudes, this warming means longer ice-free seasons. Together with permafrost thaw, this is likely to fuel methane release from lakes, potentially causing emissions to increase by between a fifth and a half by 2100. Change on this scale would probably generate a positive feedback in future warming, causing emissions to increase still further. “This means that efforts to reduce human-induced warming are even more urgent in order to minimise this type of feedback of natural greenhouse gas emissions,” says a co-author of the study, David Bastviken, senior lecturer in environmental change at Linköping University. Sweden. “In a sense, every reduction in emissions from fossil fuels is a double victory.”
Faster than expected Two reports published last month raised concerns that methane emissions could be increasing faster than expected.
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Global warming will progress faster than what was previously believed. The reason is that greenhouse gas emissions that arise naturally are also affected by increased temperatures. This has been confirmed in a new study that measures natural methane emissions. Share: 2188 0 61 45 Total shares: 4588 FULL STORY Greenhouse gas emissions from the burning of fossil fuels lead to higher temperatures, which in turn lead to increased natural emissions and further warming. – Linköping University
SETH BORENSTEIN, THE ASSOCIATED PRESS 11.24.2015.
UN weather agency says 2015 already the hottest year on record, smashing the record set last year. Temperatures have reached their highest point since records began in 1880.
Call it a contradiction of glacial proportions—an Arctic paradox. The world pushes for stronger protective measures to curb climate change scientists say is accelerating the destruction of the Arctic—melting ice sheets, thawing frozen soil and threatening the iconic polar bear. Call it plan A. There is a contingency plan, however, that takes advantage of new Arctic opportunities—in shipping, mining, drilling and national security—if the big melt continues apace. Call it plan B.
Carbon pledges from 147 nations to Paris climate summit ‘are not enough to stop temperature rise’, experts conclude
In the Andes of South America and across the mountains of Central Asia, the glaciers are receding. As temperatures continue to warm, their melting will bring more water to farms and cities earlier in the growing season, raising the risk of damaging floods. Within a few decades, however, the risk of flood in these areas will become risk of drought. Without action to stop the drivers of climate change, most of the Andean glaciers and two-thirds of Central Asia’s glaciers could be gone by the end of the century.These changes are already underway, with global temperatures 0.8 degrees Celsius above pre-industrial times, and the impact on food security, water supplies and livelihoods is just beginning.A new report explores the impact of climate change in Latin America and the Caribbean, the Middle East and North Africa, and Eastern Europe and Central Asia and finds that warming of close to 1.5°C above pre-industrial times is already locked into Earth’s atmospheric system by past and predicted greenhouse gas emissions. Without concerted action to reduce emissions, the planet is on pace for 2°C warming by mid-century and 4°C or more by the time today’s teenagers are in their 80s.The report warns that as temperatures rise, heat extremes on par with the heat waves in the United States in 2012 and Russia in 2010 will become more common. Melting permafrost will release methane, a powerful greenhouse gas that will drive more warming in a dangerous feedback loop. Forests, including the Amazon, are also at risk. A world even 1.5°C will mean more severe droughts and global sea level rise, increasing the risk of damage from storm surges and crop loss and raising the cost of adaptation for millions of people.
The Antarctic Ice Sheet stores water equivalent to 58 m in global sea-level rise. We show in simulations using the Parallel Ice Sheet Model that burning the currently attainable fossil fuel resources is sufficient to eliminate the ice sheet. With cumulative fossil fuel emissions of 10,000 gigatonnes of carbon (GtC), Antarctica is projected to become almost ice-free with an average contribution to sea-level rise exceeding 3 m per century during the first millennium. Consistent with recent observations and simulations, the West Antarctic Ice Sheet becomes unstable with 600 to 800 GtC of additional carbon emissions. Beyond this additional carbon release, the destabilization of ice basins in both West and East Antarctica results in a threshold increase in global sea level. Unabated carbon emissions thus threaten the Antarctic Ice Sheet in its entirety with associated sea-level rise that far exceeds that of all other possible sources.
We are trapped in a vicious cycle: we will need to grow 50% more food by 2050 to feed 9 billion people but agriculture, which is paradoxically vulnerable to climate change, generates 25% of heat-trapping greenhouse gas emissions that lead to climate change. The more we grow using conventional methods, the more we exacerbate the problem. It’s time for a climate-smart agriculture but first we must address a few man-made problems.
First, there is a frustrating lack of attention paid to agriculture in the current global climate talks leading up to the Paris conference later this year. By definition, food production affects all countries, rich and poor, and it is hard to imagine any effective post-Kyoto climate change agreement that ignores 25% of the problem. So, we need a climate change agreement where agriculture is a big part of the solution, and delivers a triple win: higher agricultural productivity to feed more people and raise the incomes of poor farmers – especially women, greater climate resilience, and reduced greenhouse gas emissions.
Pope Francis’ much anticipated encyclical “Laudato Si” on inequality and the environment mirrors not only religious insights but also the findings of climate science. “Not the poor but the wealthy are putting our planet, and ultimately humanity, at risk,” said Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research (PIK), at the presentation of the encyclical in the Vatican today. “Those who profited least from the exploitation of fossil fuels and contributed least to greenhouse-gas emissions are hit hardest by global warming impacts, unless we strongly reduce emissions.” Schellnhuber is the only scientist who has been invited to speak, alongside Cardinal Peter Turkson.