Volcanic eruptions, Heat and cold waves, Climatic change: global warming, Sea level rise, ozone depletion

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Volcanic eruptions, Heat and cold waves, Climatic change: global warming, Sea level rise, ozone depletion

 

Volcanic eruptions

·               Direct harm of the volcano or the fall of rock during eruption.

·               Lava be produced during the eruption of a volcano destroys many buildings and plants it encounters.

·                Volcanic ash (cooled ash) may form a cloud, and settle thickly in nearby locations and forms a concrete-like material when mixed with water. In sufficient quantity ash may cause roofs to collapse under its weight but even small quantities will harm humans if inhaled. Since the ash has the consistency of ground glass it causes abrasion damage to moving parts such as engines. The main killer of humans in the immediate surroundings of a volcanic eruption is the pyroclastic flows, which consist of a cloud of hot volcanic ash which builds up in the air above the volcano and rushes down the slopes when the eruption no longer supports the lifting of the gases. It is believed that Pompeii was destroyed by a pyroclastic flow. A lahar is a volcanic mudflow or landslide. The 1953 Tangiwai disaster was caused by a lahar, as was the 1985 Armero tragedy in which the town of Armero was buried and an estimated 23,000 people were killed.

·         A specific type of volcano is the supervolcano. According to the Toba catastrophe theory 75,000 to 80,000 years ago a super volcanic event at Lake Toba reduced the human population to 10,000 or even 1,000 breeding pairs creating a bottleneck in human evolution. It also killed three quarters of all plant life in the northern hemisphere. The main danger from a super volcano is the immense cloud of ash which has a disastrous global effect on climate and temperature for many years.

Heat waves and cold waves

A cold wave is a weather phenomenon that is distinguished by a cooling of the air. Specifically, as used by the U.S. National Weather Service, a cold wave is a rapid fall in temperature within a 24 hour period requiring substantially increased protection to agriculture, industry, commerce, and social activities. The precise criterion for a cold wave is determined by the rate at which the temperature falls, and the minimum to which it falls. This minimum temperature is dependent on the geographical region and time of year.

Effects

A cold wave can cause death and injury to livestock and wildlife. Exposure to cold mandates greater caloric intake for all animals, including humans, and if a cold wave is accompanied by heavy and persistent snow, grazing animals may be unable to reach needed food and die of hypothermia or starvation. They often necessitate the purchase of foodstuffs at considerable cost to farmers to feed livestock.

The belief that more deaths are caused by cold weather in comparison to hot weather is true as a result of the after affects of these temperatures (i.e. cold, flu, pneumonia, etc.) all contributing factors to hypothermia. However statistics have shown that more deaths occur during a heat wave than in a cold snap in developed regions of the world. Studies have shown that these numbers are significantly higher in undeveloped regions.

Extreme winter cold often causes poorly insulated water pipelines and mains to freeze. Even some poorly protected indoor plumbing ruptures as water expands within them, causing much damage to property and costly insurance claims. Demand for electrical power and fuels rises dramatically during such times, even though the generation of electrical power may fail due to the freezing of water necessary for the generation of hydroelectricity. Some metals may become brittle at low temperatures. Motor vehicles may fail as antifreeze fails and motor oil gels, resulting even in the failure of the transportation system. To be sure, such is more likely in places like Siberia and much of Canada that customarily get very cold weather.

Fires become even more of a hazard during extreme cold. Water mains may break and water supplies may become unreliable, making fire fighting more difficult. The air during a cold wave is typically denser and any cold air that a fire draws in is likely to cause a more intense fire because the colder, denser air contains more oxygen.

Winter cold waves that aren't considered cold in some areas, but cause temperatures significantly below average for an area, are also destructive. Areas with subtropical climates may recognize unusual cold, perhaps barely freezing, temperatures, as a cold wave. In such places, plant and animal life is less tolerant of such cold as may appear rarely.

Cold waves that bring unexpected freezes and frosts during the growing season in mid-latitude zones can kill plants during the early and most vulnerable stages of growth, resulting in crop failure as plants are killed before they can be harvested economically. Such cold waves have caused famines. At times as deadly to plants as drought, cold waves can leave a land in danger of later brush and forest fires that consume dead biomass. One extreme was the so-called Year Without a Summer of 1816, one of several years during the 1810s in which numerous crops failed during freakish summer cold snaps after volcanic eruptions that reduced incoming sunlight.

A heat wave is a prolonged period of excessively hot weather, which may be accompanied by high humidity. While definitions vary, a heat wave is measured relative to the usual weather in the area and relative to normal temperatures for the season. Temperatures that people from a hotter climate consider normal can be termed a heat wave in a cooler area if they are outside the normal climate pattern for that area. The term is applied both to routine weather variations and to extraordinary spells of heat which may occur only once a century. Severe heat waves have caused catastrophic crop failures, thousands of deaths from hyperthermia, and widespread power outages due to increased use of air conditioning.

The definition recommended by the World Meteorological Organization is when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 °C (9 °F), the normal period being 1961–1990.

Heat waves form when high pressure aloft (from 10,000–25,000 feet (3,000–7,600 metres)) strengthens and remains over a region for several days up to several weeks. This is common in summer (in both Northern and Southern Hemispheres) as the jet stream 'follows the sun'. On the equator side of the jet stream, in the middle layers of the atmosphere, is the high pressure area.

Summertime weather patterns are generally slower to change than in winter. As a result, this mid-level high pressure also moves slowly. Under high pressure, the air subsides (sinks) toward the surface. This sinking air acts as a dome capping the atmosphere.

This cap helps to trap heat instead of allowing it to lift. Without the lift there is little or no convection and therefore little or no convective clouds (cumulus clouds) with minimal chances for rain. The end result is a continual build-up of heat at the surface that we experience as a heat wave.

Effects

·                     Health hazards like heat edema (presents as a transient swelling of the hands, feet, and ankles and is generally secondary to increased aldosterone secretion, which enhances water retention), heat rash, (prickly heat), heat cramps (painful, often severe), heat syncope (heat exposure that produces orthostatic hypotension), heat exhaustion (forerunner of heat stroke, hyperthermia).

·                     Mortality occurs due to exposure to heat waves are the most lethal type of weather phenomenon, overall.

·                     Heat build-up causes air conditioners to turn on earlier and to stay on later in the day. As a result, available electricity supplies are challenged during a higher, wider, peak electricity consumption period. Heat waves often lead to electricity spikes due to increased air conditioning use, which can create power outages, exacerbating the problem.

·                     If a heat wave occurs during a drought, which dries out vegetation, it can contribute to bushfires and wildfires.

·                     Heat waves can and do cause roads and highways to buckle, water lines to burst, power transformers to detonate, causing fires.

Climate change

India exhibits great diversity in climate, topography, flora, fauna and land use and as the seventh largest country in the world, it is distinct in its snow capped mountains of the Himalayas in the north, long sea coast in the south, east and west (surrounded by three Seas), plateaus, forests, desert regions and numerous river systems spread all over the country. However with such topographical miscellany come certain climate induced natural hazards such as floods, droughts, landslides and cyclones that expose India’s vulnerability time and again. Not only do these have an environmental fall out but also adverse socio-economic and physical infrastructure impacts.

Various studies conclude that surface temperatures in India show warming with considerable regional variations i.e. 0.5 to 0.6°C during 1901-2005 with 1971-2003 having seen a relatively accelerated warming of 0.22°C/decade. Warming is projected to increase by 2-5°C by 2100s. While no clear trend has emerged for rainfall increase or decrease however it is projected that rainfall intensity will increase and rainy days will decrease by 2100. Having said this however it has been noted that rainfall variability from one extreme to the other i.e. droughts and floods seems to have become a regular occurrence thus adversely affecting agricultural output and in turn the economy. According to Intergovernmental Panel on Climate Change (IPCC), India’s Initial National Communication on climate change 2004 (NATCOM) to the United Nations Framework Convention on Climate Change (UNFCCC), and recent projections by different studies in India, anticipated climate change will alter rainfall and temperature patterns, thus posing a range of threats to development in India such as change in agricultural production (implications on food security), reduction in fresh water availability, boundary shifts in forests (affecting dependent communities), adverse impacts on natural ecosystems (e.g. Himalayan mountain ecosystem), sea level rise along coastal zones, changes in disease patterns, increased energy demands and impact on climate sensitive infrastructure.

A major part of India’s population of over one billion with decadal growth of 21.34% from 1991-2001 is rural and agriculturally oriented for whom the rivers and groundwater are the source of their prosperity. It is investigated that if the National Population Policy (NPP) if fully implemented, the population of India should be 1,107 million by 2010. However, country’s population is expected to reach a level of around 1,390 million by 2025 and 1,700 million by 2050. According to World Bank’s development data 2008 put India’s population at 1,123.3 million for the year 2007 with an estimated growth rate of 1.4% during 2001-07. In its poverty estimations for the same period it positioned infant mortality rate at 57 per 1000 live births, child malnutrition (children under 5) at 44%, literacy age 15+) at 61% and access to an improved water source at 89% of the total population. Furthermore, in an another report by Departm=ent for International Development (DFID) highlighted that in India 300 million people live in extreme poverty and earn less than US$1 per day, while 500 million earn less than US$2 a day. It is these groups according to them who are most adversely affected by the above mentioned climate variability as they rely heavily on climate sensitive sectors (rainfed agriculture, fisheries) for livelihood and sustenance, tend to be geographically located in exposed or marginal areas such as flood plains and are less able to respond due to limited human, institutional and financial capacity.

It is keeping this countrywide context in mind that there has been growing awareness and mobilization over recent years regarding the problem of extreme weather events/ natural disasters that cause widespread damage and disruption in India are droughts, floods, cyclones, storms/storm surges/ coastal flooding, extreme temperature, landslides, and avalanches etc., on the part of many of the actors concerned: scientists, policy makers, NGOs, and states. These hydro meteorological disasters are on the rise and threaten the development gains and poverty alleviations efforts of many developing countries. At the same time, climate change is modifying the hazards triggering these disasters, leading to more severe impacts. These changes should be factored into development practices and especially disaster risk management in order to reduce the rising human, economic and financial losses from extreme weather events and climate variability. Since disasters are human phenomena, we can change our ways to reduce our risks. There is need to bring a paradigm shift in disaster management approach especially under the changing climate.

Global statistics highlight the increasing number of the people affected by hydro meteorological disasters that account for 90 % of those killed. In assessing the sensitivity and vulnerability of communities to weather and climate hazards, long- term climate records and related sectoral information are of vital importance. Such records are also essential for preparedness, planning and response strategies that build resilience for coping with extreme events. Otherwise each extreme event will cause distractions and set back development, in some cases, for many years.

Myth and realty of the climate change: planet is getting warmer, the sea level is rising, concentration of greenhouse gases in the atmosphere is increasing at an unprecedented rate and glacial is retreating. Yet, there continues to be skepticism, and in some sections of society outright hostility, towards the concept of global warming and its human origins.

Global warming is real and will explain the scientific basis for the validity of the proposition that global warming is a clear and present danger. The projected trends implicate human activity and that no natural causes can possibly be responsible for the unprecedented changes.  Adaptation and mitigation strategies, and possible roles of individuals, institutions and governments in responding to the consequences of projected climate change.

“The recent projections of climate change over India” There is now world-wide concern about anthropogenic climate change and recent occurrences of extreme weather events in India and their unusual intensities and duration are a matter of concern for scientists and society. One of the anticipated effects of climate change is the possible increase in both frequency and intensity of extreme weather events leads to hydro-meteorological disasters.

“Adapting Indian agriculture to global climate change”. The global climatic changes and increasing climatic variability are likely to exert pressure on agricultural systems and may constrain attainment of future food production targets.

Increase in CO₂ to 550 ppm increases yields of rice, wheat, legumes and oilseeds by 10-20%, a 1 ^oC increase in temperature may reduce yields of wheat, soybean, mustard, groundnut, and potato by 3-7%, productivity of most crops to decrease marginally by 2020 but by 10- 40% by 2100 and length of growing period in rainfed areas is likely to reduce, especially in peninsular regions and southern India. Increased droughts, floods and heat waves will increase production variability and available adaptation strategies can help reduce negative impacts in short-term but to a limited extent. We, therefore, need to urgently take steps to increase our adaptive capacity. This would require increased adaptation research, capacity building, development activities, and changes in policies. Most of these are actions that are required even today for sustainable development and are related to judicious applications of current scientific knowledge, pricing policies, institutions, and good environmental behaviour at all scales. Although the costs of adaptation and mitigation are not clearly known but these are expected to be high.

“Climate change and its impacts on the water resources with a special emphasis on floods and droughts disasters”. Climate change is likely to affect the temporal and spatial variability of the available water.  NIH has initiated a few studies to investigate the impact of climate change on water resources and in this regard, some of the Himalayan and Peninsular rivers sub-basins are selected for carrying out these studies. Various studies need to be carried out for addressing the important issues involved in flood and drought management under changed climatic conditions.

“Global warming characteristics of water under changing climatic conditions” in the case of developing economies, the global warming crisis due to changing climate and its economic consequences presume vital importance in the process of realizing sustainable development. In the Natural Resources Defense Council report it has been concluded that, the global warming may increase the risk of floods, so an efficient and conservative water use will be of paramount importance for future water supply. The broad area of water management issues such as the major river system of India, condition of ground water resources, the current water utilization, water losses, water under stress, water pollution and increased population & its impact on the problem of scarcity of water etc.,.

An interdisciplinary approach combining knowledge from environmental sciences with social sciences is necessary.

“CC adaptation to water induced hazards: a study in the flood plains of the Brahmaputra river basin in eastern Assam” and results of a study on coping and adaptation strategies- both traditional and contemporary that are in practice among the indigenous communities in two remote and socio-economically, under-developed but highly flood prone areas of the Lakhimpur and Dhemaji districts of eastern Assam.

The study carried out in five villages in the two chosen sites attempts to understand how ethnic communities living in remote and isolated pockets of very high flood risk zones have lived with and adapted (housing & livelihood) to floods and associated water-induced hazards. To crease awareness, sensitivity, and capacity of communities to adapt to their changing environment and to develop alternative livelihood, train farmers in innovative agricultural techniques suitable for degraded lands, and promulgate suitable policies pertaining to embankments, flood insurance, resettlement and rehabilitation, and implement these programmes effectively.

“Glacier lake monitoring using remote sensing and GIS in the baralalacha la region, Himachal Himalaya”. A study of glacier lake monitoring is being carried out based on the Satellite imagery and GIS as well as field observation in the Baralacha La region at about 16,500 ft high. The glacial area has increased about 54% during last 8 years. To make downstream people aware about GLOF and other flash floods like, cloud bursts which is very common in the mountains; to update about Glacial Lakes under changing Climate; develop GLOF hazard zonation map; warning system in the downstream well before GLOF can happen; Strategies to cope with GLOF hazard; learning lessons from previous disaster; and Knowledge and support for adaptation etc.,

“A comprehensive glacial lake outburst flood risk assessment in the hindukush–Himalayas”. Climate change has resulted in the retreat of glaciers in the Hindu Kush – Himalayas (HKH) region. One of the most visible and tangible impacts is the formation of glacial lakes. Some of these lakes can burst out causing large flash flood with potentials to cause significant damages to property, lives and livelihoods. The awareness among scientists, decision makers and media on the glacial lake formation and outburst process has increased in recent years and this prompted several initiatives related to glacial lakes, and there is need for a concerted and coordinated assessment of the risk for glacial lake outburst floods (GLOF) in the HKH, and their socio-economic implications. He stresses that at the moment, knowledge of the current GLOF risk in the HKH is incomplete, and a proper risk assessment is often circumvented. There is urgent need for a comprehensive GLOF risk assessment in order to support proper planning of mitigation and adaptation strategies in this context. ICIMOD has developed a methodological approach for the GLOF risk assessment

“Performance of DRR strategies in changing climate: a case study of Eastern U.P.”. Historically we have been dealing with the phenomenon of floods through various structural and non-structural strategies. These strategies adopted by the state as well as communities have given both benefits and dis-benefits in the past. He discussed the results of a cost-benefit analysis exercise carried out of all possible Disaster Risk Reduction (DRR) strategies under the changing climate. Due to projected increase in rainfall (intensity and amount) during middle of 21st century flood event will increase; projected climate change may negatively impact on embankment performance; therefore a proper planning is needed. He opined talk with opinion that while hard structural solutions (e.g., embankments) to deal with floods will not give very good economic results therefore, more decentralized, community based soft options will be beneficial.

“Empowering communities to understand climate change” Climate Change issue in the Indonesian Context which is extremely prone to various forms of hazards. In the Indonesian context temperature is increasing and rainfall is decreasing since 1940, resulting in drop in catch of fish near the coast areas. According to the Centre for Research on the Epidemiology of Disasters (CRED), in the last century, there have been over 100 major floods, 85 earthquakes and 46 volcanic eruptions and sea level rise is likely to lead to the submergence of about 40000sq. Km of land mass by 2080. S

Some of the world’s poorest people live in regions which are disaster prone and highly subject to the changing course of climate. While policy frameworks have been developed, the community engagement on the ground is yet to find a voice in these legislations. In this situation, civil society organizations working with disaster vulnerable populations are looking beyond conventional means of disaster preparedness and risk reduction.

“Climate change adaptation: is it all about ‘good’ development?” Adaptation ‘solutions’ cannot be exported to a vulnerable area or community but need to be premised on sustainable development approach that empowers vulnerable communities with adequate capacity and resources to build their resilience to adapt to the changing climate. He observed that though the issue is global but impact will be local and therefore community need to be aware and their capacity need to be improved. From a policy perspective, adaptation should be seen as an integral and urgent part of overall poverty and risk reduction strategies that will reduce the levels of relative or total risk vulnerability as a determinant of risk. Adaptation cannot be seen as an outcome but as the process to build resilience of communities to climate variability and change.

“Climate change: to learn to adapt is the best policy” In South and Southeast Asia, the most affected countries include India, Pakistan, Bangladesh, southern and eastern China, Myanmar, Vietnam, Philippines and Indonesia and the only way to reduce the present human impact is through adaptation. In last decade the climate scientists and disaster managers were working in different direction. The need of the hour is that scientist, policy makers and disaster managers should come together under one umbrella

As mitigation is long term solution, despite the lack of funding, some cases of successful adaptation do provide a glimmer of hope and integrating strategies between adaptation, mitigation, development and disaster risk reduction is the need of the hour. Mechanisms and sanctions, including a globally accepted solution on taxing CO₂, should also be pursued in right earnest. But such a pricing system must not add to burden of the poor. He emphasized that it is urgent need of the day to address sustainable alternate livelihoods to enhance resilience in changing climate.

Recommendations

·         Setting up of high density observational networks suitable for detection and monitoring ™ of hydro-meteorological disasters on priority Deployment of high resolution global and regional climate models which to be run on ™ petaflop computing systems Improving the accuracy of weather forecasting and short-term climate prediction for ™ high impact weather events.

·         Development and implementation of Early Warning Systems for all hydro-meteorological disasters

·         Up-gradation of communication systems for improving dissemination of warnings™

·         Establishment of a State-of-the-art Regional Centre for Climate Change Research ™ through multi-lateral cooperation

·         Urgent need to train young scientists in the best available Institutes or acquire trained ™ manpower available across the world in the field of climate science A national policy for sharing and access of meteorological, hydrological, geological and ™ environmental data and products within the government and among the communities.

·         Launch of massive Public awareness programmes to address people at grass-root levels ™ (Farmers, Workers, NGOs, community level organizations, local administrators/ disaster managers, etc) using mass media and other media.

·         Efforts should also be made to launch TV /Radio Channels on weather and climate information. 

·         Launch of programmes to enhance coping capacity of community (including alternative ™ livelihoods) to reduce risk from disasters under climate change scenarios.

·         Launch of programmes for assessing sectoral vulnerability of climate change impacts ™ based on future scenarios

·          Involvement of state/district level communities in the areas of water resources.™ Involvement of civil societies, educational institutions, and religious organizations in ™ the climate change related adaptation and mitigation actions.

Ozone depletion

Ozone depletion describes two distinct but related phenomena observed since the late 1970s: a steady decline of about 4% per decade in the total volume of ozone in Earth's stratosphere (the ozone layer), and a much larger springtime decrease in stratospheric ozone over Earth's polar regions. The latter phenomenon is referred to as the ozone hole. In addition to these well-known stratospheric phenomena, there are also springtime polartropospheric ozone depletion events.

The details of polar ozone hole formation differ from that of mid-latitude thinning, but the most important process in both is catalytic destruction of ozone by atomic halogens. The main source of these halogen atoms in the stratosphere is photodissociation of man-made halocarbon refrigerants (CFCs,freons, halons). These compounds are transported into the stratosphere after being emitted at the surface. Both types of ozone depletion were observed to increase as emissions of halo-carbons increased.

CFCs and other contributory substances are referred to as ozone-depleting substances (ODS). Since the ozone layer prevents most harmful UVB wavelengths (280–315 nm) of ultraviolet light (UV light) from passing through the Earth's atmosphere, observed and projected decreases in ozone have generated worldwide concern leading to adoption of the Montreal Protocol that bans the production of CFCs, halons, and other ozone-depleting chemicals such as carbon tetrachloride and trichloroethane. It is suspected that a variety of biological consequences such as increases in skin cancer,cataracts, damage to plants, and reduction of plankton populations in the ocean's photic zone may result from the increased UV exposure due to ozone depletion.

Consequences of ozone layer depletion

Since the ozone layer absorbs UVB ultraviolet light from the sun, ozone layer depletion is expected to increase surface UVB levels, which could lead to damage, including increase in skin cancer. This was the reason for the Montreal Protocol. Although decreases in stratospheric ozone are well-tied to CFCs and there are good theoretical reasons to believe that decreases in ozone will lead to increases in surface UVB, there is no direct observational evidence linking ozone depletion to higher incidence of skin cancer and eye damage in human beings. This is partly because UVA, which has also been implicated in some forms of skin cancer, is not absorbed by ozone, and it is nearly impossible to control statistics for lifestyle changes in the populace.

Increased UV

Ozone, while a minority constituent in Earth's atmosphere, is responsible for most of the absorption of UVB radiation. The amount of UVB radiation that penetrates through the ozone layer decreases exponentially with the slant-path thickness and density of the layer. Correspondingly, a decrease in atmospheric ozone is expected to give rise to significantly increased levels of UVB near the surface. Ozone-driven phenolic formation in tree rings has dated the start of ozone depletion in northern latitudes to the late 1700s.

Increases in surface UVB due to the ozone hole can be partially inferred by radiative transfer model calculations, but cannot be calculated from direct measurements because of the lack of reliable historical (pre-ozone-hole) surface UV data, although more recent surface UV observation measurement programmes exist (e.g. at Lauder, New Zealand).

UV-215 and more energetic radiation is responsible for creation ozone in the ozone layer from O₂ (regular oxygen). UV-215 through UV-280 increases as a result of reduction in stratospheric ozone, but this is insufficient to do more than dissociate the single oxygen bond of ozone, and of course disrupt DNA bonding.

 

Biological effects

The main public concern regarding the ozone hole has been the effects of increased surface UV radiation on human health. So far, ozone depletion in most locations has been typically a few percent and, as noted above, no direct evidence of health damage is available in most latitudes. Were the high levels of depletion seen in the ozone hole ever to be common across the globe, the effects could be substantially more dramatic. As the ozone hole over Antarctica has in some instances grown so large as to reach southern parts of Australia, New Zealand, Chile, Argentina, and South Africa, environmentalists have been concerned that the increase in surface UV could be significant.

Ozone depletion would change all of the effects of UVB on human health, both positive and negative.

UVB (the higher energy UV radiation absorbed by ozone) is generally accepted to be a contributory factor to skin cancer and to produce Vitamin D. In addition, increased surface UV leads to increased tropospheric ozone, which is a health risk to humans.

Basal and squamous cell carcinomas

The most common forms of skin cancer in humans, basal and squamous cell carcinomas, have been strongly linked to UVB exposure. The mechanism by which UVB induces these cancers is well understood—absorption of UVB radiation causes the pyrimidine bases in the DNA molecule to form dimers, resulting in transcription errors when the DNA replicates. These cancers are relatively mild and rarely fatal, although the treatment of squamous cell carcinoma sometimes requires extensive reconstructive surgery. By combining epidemiological data with results of animal studies, scientists have estimated that a one percent decrease in stratospheric ozone would increase the incidence of these cancers by 2%.

Malignant melanoma

Another form of skin cancer, malignant melanoma, is much less common but far more dangerous, being lethal in about 15–20% of the cases diagnosed. The relationship between malignant melanoma and ultraviolet exposure is not yet well understood, but it appears that both UVB and UVA are involved. Experiments on fish suggest that 90 to 95% of malignant melanomas may be due to UVA and visible radiation whereas experiments on opossums suggest a larger role for UVB. Because of this uncertainty, it is difficult to estimate the impact of ozone depletion on melanoma incidence. One study showed that a 10% increase in UVB radiation was associated with a 19% increase in melanomas for men and 16% for women. A study of people in Punta Arenas, at the southern tip of Chile, showed a 56% increase in melanoma and a 46% increase in nonmelanoma skin cancer over a period of seven years, along with decreased ozone and increased UVB levels.

Cortical cataracts

Studies are suggestive of an association between ocular cortical cataracts and UV-B exposure, using crude approximations of exposure and various cataract assessment techniques. A detailed assessment of ocular exposure to UV-B was carried out in a study on Chesapeake Bay Watermen, where increases in average annual ocular exposure were associated with increasing risk of cortical opacity. In this highly exposed group of predominantly white males, the evidence linking cortical opacities to sunlight exposure was the strongest to date. However, subsequent data from a population-based study in Beaver Dam, WI suggested the risk may be confined to men. In the Beaver Dam study, the exposures among women were lower than exposures among men, and no association was seen. Moreover, there were no data linking sunlight exposure to risk of cataract in African Americans, although other eye diseases have different prevalences among the different racial groups, and cortical opacity appears to be higher in African Americans compared with whites.

Increased tropospheric ozone

Increased surface UV leads to increased tropospheric ozone. Ground-level ozone is generally recognized to be a health risk, as ozone is toxic due to its strong oxidant properties. At this time, ozone at ground level is produced mainly by the action of UV radiation on combustion gases from vehicle exhausts.

Increased production of vitamin D

Vitamin D is produced in the skin by ultraviolet light. Thus, higher UV-B exposure raises human vitamin D in those deficient in it. Recent research (primarily since the Montreal protocol), shows that many humans have less than optimal vitamin D levels. In particular, the lowest quartile of vitamin D (<17.8 ng/ml), in the US population were found using information from the National Health and Nutrition Examination Survey to be associated with an increase in all cause mortality in the general population. While higher level of Vitamin D are associated with higher mortality, the body has mechanisms that prevent sunlight from producing too much Vitamin D.

Effects on non-human animals

Scientists at the Institute of Zoology in London found that whales off the coast of California have shown a sharp rise in sun damage, and these scientists "fear that the thinning ozone layer is to blame".

The study photographed and took skin biopsies from over 150 whales in the Gulf of California and found "widespread evidence of epidermal damage commonly associated with acute and severe sunburn", having cells that form when the DNA is damaged by UV radiation. The findings suggest "rising UV levels as a result of ozone depletion are to blame for the observed skin damage, in the same way that human skin cancer rates have been on the increase in recent decades."

Effects on crops

An increase of UV radiation would be expected to affect crops. A number of economically important species of plants, such as rice, depend on cyanobacteria residing on their roots for the retention of nitrogen. Cyanobacteria are sensitive to UV radiation and would be affected by its increase.