How Are Weather Extremes Linked to Climate Change?

Extreme event attribution: the climate versus weather blame game (Rebecca Lindsey, NOAA Climate, Dec. 15, 2016)

 Today we review a paper that describes the statistical process of attributing short term weather extreme events to the longer term changes underway as a result of climate change, whether that is due to natural or man-made burning of carbon fuels. It is important to understand the meaning of return periods. While the probability of a 100 year flood in a given year is 1%, the probability of the same flood over a period of 50 years is 40%. The blaming of an event on climate change depends on how good the observations of past events are, how well climate models can simulate the specific event and how well the physical processes are known and their association with climate change. Extended heat or cold events are more attributable than short term convective storms where the cross links are not as well understood.

   

Key Quotes:

“What is extreme event attribution?

• tells us how much of the credit or risk for an event (or type of events) should go to global warming and how much should go to natural weather patterns or random climate variability.”

“What can extreme event attribution tell us?

• whether global warming made (or will make) an event more likely than it would have been without the rise in greenhouse gases from burning fossil fuels.
• It can tell us if the average number of years between similar events is shorter or longer than it used to be.
• It can tell us what the risk is for a given extreme weather event and if and how much global warming has increased that risk”

“Sigmas are used to describe the range of natural variability in a given climate or weather characteristic. For most types of climate data, there are many more observations close to the average (within 1 or 2 sigmas) than there are far away. So, if a climate expert describes a heavy rain event as a “5-sigma” event, she is talking about rainfall so extreme that it was 5 standard deviations away from the average high tide water level—way out at the tail end of the range of all values that have been observed.”

“So what does a hundred-year event mean?

• The risk that a 100-year event will happen this year, or next year, or any single year is low: 1% chance that it will happen, 99% chance that it won’t. But the chance that it will happen within a given 20-year period is 18%. Within any 50-year period, 40%. Within any 100-year period, 63%. By the time 500 years have passed, there’s less than a 1% chance that such an event won’t have happened.”

“Why are some events more difficult than others to connect to global warming?

Attribution analysis depends on ‘three pillars’ of scientific knowledge:

• The quality of the observational record,
• The ability of models to simulate a given type of extreme event, and
• How well we understand the physical processes that create an event and how global warming may influence those processes.

For event types where all three of these pillars are strong, our confidence in the results is higher. If any of the three pillars is weak, it becomes harder to conduct an attribution study, and our confidence in the results is lower. In general, scientists have the highest confidence for heat events because all three of the pillars are strong”

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Do Trees in Cities Help or Harm Our Health?

Air pollution: outdoor air quality and health (National Institute for Health and Care Excellence, Dec.1, 2016)

Also discussed here: Trees could make urban pollution even worse (quartz, Dec.6, 2016)

And here: Neighborhood greenspace and health in a large urban center (Nature, Scientific Reports, Jul. 9, 2015)

Today we review a guide about urban air pollution that looks into the role that street trees play with respect to reducing air pollution. The overall conclusion was that trees are unlikely to reduce air pollution and could add to it, especially if the trees reduce ventilation of air currents. This is true also of the more recent use of green walls. It is also acknowledged [in a Toronto study]that urban trees can improve health – as much as a $10,000 raise or feeling 7 years younger. Pine trees are singled out as a particular contributer to urban pollution through their emissions of volatile organic compounds (VOC) which combine with the NO2 in car emissions to produce low level ozone, one of a handful of pollutants harmful to health.

   

Key Quotes:

“Street trees were unlikely to reduce air pollution in most street designs and could worsen it in some cases,” “Leaves and branches slow air currents, causing pollutants to settle out.”

“Urban trees and plants can improve mental and physical health - an average of 10 extra trees per block made people living there feel like they would be much healthier—as much as a $10,000 raise or being seven years younger would”

“not all trees are equal. The pungency of a cedar, eucalyptus, or pine woodland, to name a few examples, comes from a blend of volatile organic compounds (VOC) in these species. When these VOCs interact with the nitrogen oxide that is in car emissions, in the presence of sunlight, they produce ozone—at ground level, the pollutant can be harmful enough to cause heart disease.”

“having 10 more trees in a city block, on average, improves health perception in ways comparable to an increase in annual personal income of $10,000 and moving to a neighborhood with $10,000 higher median income or being 7 years younger. … having 11 more trees in a city block, on average, decreases cardio-metabolic conditions in ways comparable to an increase in annual personal income of $20,000 and moving to a neighborhood with $20,000 higher median income or being 1.4 years younger.”

“In 2010 the total mortality burden of human-produced PM2.5 in London was 9 52,630 life-years lost and of long-term exposure to NO2 was up to 88,113 life-years 10 lost …The health impact of PM2.5 pollution from human activities in the UK is estimated to 15 cost between £8.5 billion and £18.6 billion a year “

“Where solid barriers are planned alongside major roads (sometimes 10 used to protect local people from noise) consider whether action is 11 needed to mitigate any adverse effects on air quality…Take into account the effect that trees can have on street ventilation, based on where they are planted and how they are maintained, to avoid creating areas of poorer air quality.”

 “Evidence showed that street trees and green walls or roofs have a mixed effect on 20 street air quality – in some cases they restrict street ventilation causing poorer air 21 quality, in others they improve it “

“Leaves and branches slow air currents, causing pollutants to settle out. They may also act as 'sinks' for particulates and chemicals that may have direct or indirect effects on air quality (in particular, volatile organic compounds [VOCs]). The extent to which this is the case depends on factors such as species, time of year and growing conditions.”

 “air quality might deteriorate at street level near vehicle sources if ventilation were restricted, while improving near first floor windows above the canopy. Although it is important to avoid the possible negative”

The Impact of Traffic-Related Air Pollution on Cloud Formation

Effect of vehicular traffic, remote sources and new particle formation on the activation properties of cloud condensation nuclei in the megacity of São Paulo, Brazil (22 page pdf, Carlos Eduardo Souto-Oliveira, Maria de Fátima Andrade, Prashant Kumar, Fábio Juliano da Silva Lopes, Marly Babinski, and Eduardo Landulfo^, Atmos. Chem. Phys., Nov. 24, 2016)

 Today we review research on the impact vehicle emissions have on cloud formation in the largest city in South America with a 20M population and 7 M vehicles. Such a concentration of emissions may have global impacts on precipitation. Cloud condensation nuclei in this city originate from three sources: vehicle emissions, biomass burning in the vast tropical forests and from sea-salt. Careful direct and indirect (lidart) measurements over a four month period revealed that vehicles were predominant in producing these nuclei with two diurnal maxima during rush hours.

   

Key Quotes:

“Atmospheric aerosol is the primary source of cloud condensation nuclei (CCN). The microphysics and chemical composition of aerosols can affect cloud development and the precipitation process.”

 “The high concentrations of CCN in the air favor the formation of clouds with small droplets, which can lead to suppression of precipitation in shallow and short-lived clouds”

 “Primary aerosols are emitted into the atmosphere directly by anthropogenic and natural sources. In contrast, secondary aerosols are formed in the atmosphere through the nucleation of no- or low-volatile gases containing inorganic and organic compounds, followed by growth to larger particles”

 “With over 20 million inhabitants, the MASP [Metropolitan Area of São Paulo] is the biggest megacity in South America. Therefore, the MASP represents an important city for global-scale atmospheric studies. The MASP fleet comprises more than 7 million vehicles, which constitute one of the main sources of particles, together with a variety of industries and construction activities “

 “The PNCs [particle number concentration]were highest between 07:00 and 19:00 LT, whereas they were lowest between 19:00 and 07:00 LT (Fig. 2b), hereafter referred to as the daytime and nighttime periods, respectively. During the daytime period, PNCs were elevated, especially during the rush hours, which are primarily associated with vehicular emissions. However, CCN peaks showed the opposite behavior, CCN concentrations being higher during the afternoon and the nighttime period. “

 “in the MASP, the morning rush occurs between 07:00 and 10:00 LT, whereas the afternoon rush occurs between 17:00 to 20:00 LT. The decrease began, and the lower values of AR [Mean activation ratio] occurred, during the morning rush and formation of a secondary aerosol. Vehicular traffic and secondary aerosol formation constitute the main sources of particles in megacities such as the MASP”

 “The regional atmosphere is highly affected by vehicular traffic emissions, and lower by remote sources such as biomass burning and sea-salt transport.”

“Our results show the influence that vehicular traffic, long-range transport of sea salt, biomass-burning plumes and NPF events have on CCN properties”

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Are Regional (not Global) Interventions Needed to Reduce Impacts and Mitigate Climate Change?

The Rationale for Accelerating Regionally Focused Climate Intervention Research (17 page pdf, Michael C. MacCracken, Earth's Future, Nov. 14, 2016)

Today we review a proposal to focus on particular regions where effort to reduce climate impacts would be more effective and likely have fewer unintended negative consequences than efforts aimed at the globe as a whole. Included in the potential approaches are modifying arctic warming by injecting sulfate aerosols directly into the Arctic atmosphere, moderate the intensity of tropical cyclones by brightening cloud albedoes, slowing the melting of Greenland and Antarctic ice sheets by blocking ice streams, and compensate for the reduced cooling from SO2 emissions in Asia by brightening the Pacific Ocean.

Key Quotes:

“Global-scale climate intervention is seen as a potential emergency backstop, even though the impacts from initiating melting of the polar ice sheets and biodiversity loss may well be irreversible and even undertaking testing steps in the intervention process outside the laboratory are controversial, at best”

 “model-based simulations ..… project global average temperature to increase to 3-4ºC above its preindustrial level by 2100 “

“surface-based approaches to altering energy flows as a means for moderating adverse regional impacts might well pose less difficult governance challenges and more regionally constrained evaluations of intended outcomes and unintended consequences. “ “near-term reductions in positive radiative forcing could most rapidly be achieved by reducing the atmospheric loadings of short-lived species (particularly methane, black carbon, and tropospheric ozone). “

 “The potential for moderating amplified Arctic warming:

• high-latitude injection of sulfate aerosols into the stratosphere not only cooled the Arctic, but also, due to their roughly one-year half-life, spread to sub-Arctic latitudes and depressed the summer monsoon.
• Potential approaches ....include brightening land, ocean, and clear and/or cloudy skies during the sunlit season .. reversing the warming influence caused by reducing air pollutant emissions flowing into the region … and, during the fall and winter seasons, cirrus thinning … bypassing the thermal barrier created by the sea ice ..and ice thickening by pumping sea water up onto existing sea ice.”

“The potential for moderating ocean warming in the tropical cyclone intensification zones:
* moderate the intensification effect of warmer ocean waters in only a few specific regions, so the amount of sea salt and/or sulfate aerosols needed to brighten clouds in only a few regions might well remain within reasonable bounds”

“The potential for slowing mass loss from the Greenland and Antarctic Ice Sheets:
*In addition to approaches involving physically blocking the exits of ice streams that may well be unworkable, approaches to consider might include cloud brightening, injection of reflective bubbles, and vertical mixing to lower the temperature of the waters that are observed to be inducing melting at the faces of ice streams. “

“The potential for a regional replacement for the loss of global sulfate cooling:

• the centroid of the 0.5-1.0ºC cooling influence resulting from SO2 emissions has moved from the North Atlantic basin to southern and eastern Asia, a region where the per-ton-of-emission influence of SO2 emissions is likely larger due to the higher amounts of incoming solar radiation
• inducing modest clear and cloudy sky brightening in the troposphere over the vast Pacific Ocean that would cause changes in the global energy balance comparable to those induced by the present highly concentrated, health-damaging sulfate loading presently centered over China, India, and downwind would seem to be possible as an alternative global-scale climate intervention”

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How Do Air Pollution Alerts Affect Public Health Use?

Effects of an air pollution personal alert system on health service usage in a high-risk general population: a quasi-experimental study using linked data (7 page pdf, R A Lyons, S E Rodgers, S Thomas, R Bailey, H Brunt, D Thayer, J Bidmead, B A Evans, P Harold, M Hooper, H Snooks, J Epidemiol Community Health, May 23, 2016)

Today we review an analysis of the reaction of an “intervention” group of patients with air pollution- related illnesses (cardio-respiratory and COPD) to alerts produced by the UK’s airAware alert system over a two year period, as measured by visits to hospital emergency departments, compared to a control group which were not similarly afflicted. Results indicate a doubling of emergency admissions and four times the number of respiratory conditions for the intervention group compared to the control group. The authors conclude that some health interventions or alerts beyond a certain distribution level are harmful in terms of health service utilisation.

 .  

Key Quotes:

“The airAware system was a novel development because it integrated near real-time data rather than forecasting. Its design facilitated early identification of local air pollution problems and issued timely warnings of air pollution episodes reflecting levels of particulate matter (measured as particulate matter 10 μm or less in diameter”

“The number of messages per day was limited to three; on any single day no more than three alerts could be issued. Only one alert was issued for the day unless a higher pollution trigger level was met during the daily alerting period.”

“The intervention group experienced a doubling of emergency admissions for all relevant conditions and a fourfold admissions increase for respiratory conditions”

 “Our findings raise questions about the trade off between harms and benefits of air pollution alerting services. .. There is a growing evidence base demonstrating some public health interventions are harmful. Wider roll-out of such systems does not appear to be warranted given the current evidence base.“

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How Does Air Pollution Accelerate Aging?

Telomere (Photo credit: Wikipedia)

Long-term exposure to air pollution is associated with biological aging (16 page pdf, Cavin K. Ward-Caviness, Jamaji C. Nwanaji-Enwerem, Kathrin Wolf, Simone Wahl, Elena Colicino, Letizia Trevisi, Itai Kloog, Allan C. Just, Pantel Vokonas, Josef Cyrys, Christian Gieger, Joel Schwartz, Andrea A. Baccarelli, Alexandra Schneider and Annette Peters, Oncotarget, Oct. 25, 2016)

Also discussed here: Telomere (Wikipedia)

Today we review research conducted with older men and women (median age 74) where several measures of aging and old age illnesses, such as cardiovascular disease, cancer and cognitive abilities, were studied including chromosome characteristics (telomere length) and immune cell counts. Results indicate that air pollution exposure over a long time can damage the DNA, alter immune cell counts and add to oxidative stress with greater impact on men than women.  


Key Quotes:

“Accelerated biological aging was assessed using telomere length (TeloAA) and three epigenetic measures: DNA methylation age acceleration (DNAmAA), extrinsic epigenetic age acceleration (correlated with immune cell counts, EEAA), and intrinsic epigenetic age acceleration (independent of immune cell counts, IEAA).

“A telomere is a region of repetitive nucleotide sequences at each end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes… In humans, average telomere length declines from about 11 kilobases at birt to less than four kilobases in old age, with average rate of decline being greater in men than in women

 “Air pollution exposure is associated with cardiovascular disease, impaired cognitive function , cancer, metabolic outcomes, and mortality. All of the aforementioned air pollution associated outcomes are also associated with aging …have linked air pollution exposure with DNA damage, epigenetic alterations, inflammation, and oxidative stress ”

“Both accelerated and decelerated biological aging have been linked with negative health outcomes with accelerated aging linked to mortality and metabolic dysfunction, and decelerated biological aging associated with the development of psychosocial stress”

“A 2015 study of 211 twins indicated that decreased residential traffic exposure of mothers was associated with longer placental telomere lengths indicating that long-term traffic exposure during pregnancy may be passed down and affect biological aging in utero.”

“Telomere-based and epigenetic measures of biological aging are associated with long-term exposure to air pollution and have distinct patterns of sex-specific associations.”

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The Threat to Children’s Health from Air Pollution

Clear the air for children - The impact of air pollution on children (100 page pdf, Editor-In-Chief, David Anthony, UNICEF, Oct. 2016)

Also discussed here: A Staggering Number of the World's Children Are Breathing Toxic Air (Mother Jones, Oct. 31, 2016)

Today we review a report that documents the impact of indoor and outdoor pollution on the children of the world who are particularly vulnerable because, for their size, they breathe more air than adults into lungs that are only beginning to develop. 300 million children live in areas with toxic air pollution and 2 billion live in areas where the air pollution exceeds minimum quality standards as set by the World Health Organization. Steps are recommended (that apply to highly developed countries and cities as well as developing countries) to reduce this toll including less pollution indoors by using ventilation, better insulation to reduce fuel burning and cleaner stoves. Outdoors, situate schools and day cares away from traffic related pollution, replace private vehicle transportation with public transit, walking and cycling and monitor air pollution more carefully especially as it impacts child health.


 
Key Quotes:

“Air Pollution:

• causes miscarriages, early delivery, and low birth weight.
• contributes to diseases that account for almost 1 in 10 of all deaths of children under the age of five.. making air pollution one of the leading dangers to children’s health.
• can harm the healthy development of children’s brains.
• is a drag on economies and societies, already costing as much as 0.3 per cent of global GDP – and rising.”

“around the world today, 300 million children live in areas with extremely toxic levels of air pollution. Approximately 2 billion children live in areas where pollution levels exceed the minimum air quality standards set by the World Health Organization.”

 “Every year, nearly 600,000 children under the age of five die from diseases caused or exacerbated by the effects of indoor and outdoor air pollution. Millions more suffer from respiratory diseases that diminish their resilience and affect their physical and cognitive development.”

“how to protect their children

• improved indoor ventilation, so smoke does not linger …
• better insulation, so less heating fuel is burned …
• cleaner cook stoves…More than 60 per cent of the population in India continue to use solid fuels in household cooking – contributing to over 100,000 child deaths associated with indoor air pollution in 2012.
• Outside the home, it means improving urban planning so schools and playgrounds are not located in close proximity to sources of toxic pollution.
• improving waste disposal systems …More than 40 per cent of the world’s municipal garbage is openly burned in over 160 countries. In these countries, the most deprived communities without reliable waste collection services are affected the most.
• increasing public transportation options to reduce automobile traffic and the harmful fossil fuel emissions it produces.. In the three countries with the highest child populations (India, China and Nigeria), the number of cars is likely to grow considerably in the coming decades, which will be particularly marked in Africa, and substantial too in South Asia.
• investing in sustainable energy solutions to reduce reliance on pollution-causing sources of energy.
• monitoring air pollution levels more carefully and including this critical data in our approach to other issues, like child health.,,, will help minimize exposure and will educate the public and policymakers on key health risks. Better monitoring can also inspire greater action by a range of public and private stakeholders.

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