Lethal Heating: 05/07/17

07/05/2017

Sea Level Rise Is On The Rise

Anthropocene - Sarah DeWeerdt

One prediction of where rising sea levels will end up at Cottesloe Beach, Perth Western Australia. Credit: go_greener_oz via Flickr

Global sea level is rising faster now than it was in the 1990s, according to a mammoth analysis of 26 different data sets, published last month in Geophysical Research Letters.
The study uses a ‘sea level budget’ approach, which places the mass of the oceans in the context of the entire hydrological cycle. The amount of water on Earth is constant, so the sum of changes in all forms of water—chiefly oceans, glaciers, the Greenland and Antarctic ice sheets, terrestrial liquid water such as lakes and rivers, atmospheric water vapor, and snowpack—should be zero.
To track those changes, the researchers drew on multiple sources of data for each element of the hydrological cycle, integrating the work of various research groups and government and international initiatives spanning multiple continents. This yields a more accurate picture than any single data set, they found, because random sources of error tend to average out.
They focused on the sea level budget from January 1993 to December 2015. This is because a major impetus of the study was to correct for inaccuracies in recordings of sea level during the early- to mid-1990s. Since late 1992, researchers have been measuring sea level by satellite altimetry, a method that involves timing how long it takes a radar pulse to travel between an orbiting satellite and a beacon on the ocean surface.
At first, that beacon was an altimeter known as TOPEX A. But it was old, and its measurements were known to be off by just a hair, so it was retired in early 1999. Two recent studies have attempted to quantify the impact of this instrument glitch, but with fairly divergent results. The sea level budget approach offers a more robust, reliable methodology to do this, the researchers say.
According to their calculations, correcting for the TOPEX A inaccuracies reveals that global mean sea level rose 3.0 millimeters per year between 1993 and 2015. That’s slightly lower than generally accepted estimates of about 3.3 millimeters per year.
But finer-grained analysis reveals a more complex picture, and a disheartening one. Sea level rose 2.7 millimeters per year from 1993 to 2004. And it accelerated to 3.5 millimeters per year during 2004 to 2015—an increase of about 25 percent.
Previous studies had suggested a slowdown of sea level rise during the 2000s due to shorter-term climate cycles known as La Niña events. “Here we show that in spite of the several temporary sea level drops caused by La Niña events, the [global mean sea level] rise has increased during the last decade,” the researchers write.
The accelerated sea level rise is primarily due to increased melting of the Greenland ice sheet, they found. (And that’s before taking into account the latest dire projections about Arctic sea ice melt.)
Even without the issue of correcting for past measurement errors, the new study would represent an impressively comprehensive analysis. Yet there’s something poignant about the story of TOPEX A, a lone beacon out there riding the waves. Is it a metaphor for humanity trying to understand our collective predicament with limited powers of perception?
Or maybe the lesson is a more straightforward and practical one, about the vulnerability of our understanding when we have limited sources of data to rely on. That, in turn, implies a need for multiple monitoring efforts using a diversity of approaches.
To paraphrase an old saying: Measure twice—six times, even. You only get to save the climate system once.

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The Impact Of Climate Change On The Great Barrier Reef

The Economist

The corals of the reef have been bleached white for a second year in a row

THE Great Barrier Reef stretches some 2,300 km down Australia's north-east coast, covering an area the size of Italy. It is home to about 600 types of coral and 1,625 species of fish. UNESCO calls it a "site of remarkable variety and beauty". That may not last. For the second consecutive year, expanses of coral have lost the vivid colours that draw thousands of annual sightseers. Instead, they have bleached a deathly white. Worse, this year the bleaching has extended further south than in 2016. Bleachings were also reported in 1998 and 2002. But for it to happen two years running is unprecedented. Why are the corals turning white?
In the 36 years since the reef was declared a World Heritage Area, mounting stresses from human activity have left it struggling. One factor is the nutrients and pesticides flowing into the ocean from coastal farms and cities in the north-eastern state of Queensland, which have polluted its waters. But experts agree that the biggest culprit is warmer ocean temperatures linked to climate change. Corals are marine animals that get their colour and most of their food from the algae that live within them. The higher temperatures stress algae, causing the rich hues to disappear. Some marine scientists liken this to the impact of a prolonged heatwave or drought on a forest. The Climate Council, an Australian research body, says the reef's surface sea temperatures in early 2016 were the hottest since records began in 1900.
Under prolonged stress corals can expel algae, causing them to starve and die. About a fifth of the reef's corals died from the 2016 bleaching. In the northern region, where bleaching was most intense, the coral mortality figure was alarming: about two-thirds. Depending on different coral species' capacity to resist stress, and the distribution of heat patterns through waters, reefs can revive over several years. The difference this time, say experts, is that back-to-back bleaching from two successive seasons of extreme heat have given the reef no time to recover, and have lowered its corals' stress tolerance. It is too early to measure coral deaths from the 2017 bleaching, but the Climate Council predicts "high mortality rates".
Two years ago UNESCO was concerned enough about the reef's health to consider adding it to the short list of world heritage sites in danger. The Australian and Queensland state governments responded with a plan aimed at improving the local marine environment. Yet both governments simultaneously support a plan by Adani, an Indian energy company, to open one of Australia's biggest coal mines in the Queensland outback, and to ship coal to India from Abbot Point, on the Queensland coast, through the reef's waters. Critics charge that burning this fossil fuel will only boost the global warming that seems to be killing parts of the reef. Russell Reichelt, head of the Great Barrier Reef Marine Park Authority, says there are signs that such happenings will become more frequent due to rising ocean temperatures: "If they do, it will change the whole character of the coral community." The reef looks set to become Australia's next environmental battleground.

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Medical Scientists Report On The Impact Climate Change Is Having On Health

The Guardian - John Abraham

A new report breaks down climate impacts on health by US region

A Russian woman wears a face mask to protect herself from acrid smoke while walking in central Moscow on August 9, 2010. Air pollution from a heatwave-fueled forest fire smog caused hundreds of extra deaths each day compared to a normal period. Photograph: Natalia Kolesnikova/AFP/Getty Images

As a climate scientist, I spend time and energy studying how fast the Earth is warming and what is causing the warming. This knowledge helps us predict what the future will look like. But, what most people are interested in is, "how will it affect me?"
Some impacts we are pretty clear about, like the impacts related to sea level rise, increased storms and heavy precipitation, and increased drought and heat waves – particularly the impacts these events have on the economy. But climate change will affect us personally as well (by personally, I mean our physical person).
In fact, climate change is already affecting personal human health around the world. This subject was the focus of a summary report just published by the Medical Society Consortium. What I really liked about this report is that it breaks down some of the key impacts by region. Unfortunately, the report is limited in scope to the USA. However, the general conclusions and trends can be illuminating for people outside the USA as well.
What was also welcome is that this report was prepared by physicians (not climate scientists) of major medical societies and the conclusions are based on the best available and current information of both the climate and health fields.
So what did they find? Perhaps most importantly they find that climate change is already affecting our health. This isn't a future problem for the next generation. It is a problem that is present and growing. They also report that some populations are more susceptible to climate change effects. Among the most vulnerable groups are children, student athletes, pregnant women, elderly, people with chronic health conditions, and the impoverished. A third key takeaway is that the problems will get much worse as climate change continues.
The study reports that if you live on the West Coast, wildfires, extreme temperatures, poorer air quality, extreme weather events, and agricultural risks are occurring. On the East Coast, you can add vector-borne diseases as a risk area. The central USA region is also similarly being affected.
As you dig deeper into the report, you learn about how these various climate-related features are affecting health. Each factor is dealt with by three questions: 1) What is happening? 2) How does it harm our health? 3) Who is being harmed?
For instance, with respect to extreme weather, the report correctly notes that the frequency and severity of some weather events such as heavy downpours, floods, droughts, and major storms are increasing. This harms our health because these events can cause direct injury and death as well as displacement. Extreme weather can also harm vital infrastructure like communication systems, homes, and reduce the availability of clean water and food. Finally, extreme weather can lead to acute outbreaks of infectious disease while at the same time reducing access to health care.
Air pollution is another example area. Climate change is affecting air quality in many ways, including increasing chemical reactions in surface air (air we breathe), increasing pollen, and leading to more forest fires. Lower air quality obviously affects people with breathing problems (such as asthma and allergies). It can prolong the pollen seasons and worsen allergy symptoms. Less obvious effects like increased humidity and more heavy rainfalls can exacerbate air-quality problems indoors through mold growth for instance.
One issue I was not aware of was the threat of climate change to nutrition. Increases in carbon dioxide actually result in a lowered nutritional value of grown food such as wheat, rice, barley, and potatoes. This occurs because plants produce less protein and more sugars/starches in a carbon rich atmosphere. Plants also are less effective at taking in essential soil minerals. This is all in addition to the threats to our food system by droughts and extreme weather. We've certainly seen very severe droughts in the USA (2011 in Oklahoma and Texas, 2012 in Midwest USA, and 2012–2016 in California) that have caused severe problems in the agricultural industries.
This report was written in an easy-to-understand manner. It is accessible and authoritative. It also gets to the issue people are most concerned about – the impact of climate change in their lives. I encourage anyone who is interested to download and read this document at the link above.

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