The extinction risk of climate change is the risk of species becoming extinct due to the effects of climate change. This may be contributing to Earth's sixth major extinction, also called the Anthropocene or Holocene extinction.
While the past extinctions have been due to primarily volcanic
eruptions and meteorites, this sixth major extinction is attributed to
human behaviors.
Climate change is occurring at an alarming rate: Studies done by the
Intergovernmental Panel on Climate Change (IPCC) show that it is
estimated that the temperature will rise from about 1.4 to 5.5 degrees
Celsius (2.5 to 10 degrees Fahrenheit) within the next century.
These rising rates, to a certain degree, may benefit some regions while
harming others. However, after about 5.4 degrees Fahrenheit of rising
temperature, it will get into harmful climate change.
Efforts have been made such as the Paris Climate Agreement, in attempt
to stop or reduce the effects of a rising temperature, or at least
decrease the number in which the temperature rises. However, even if
this goal is accomplished, it is estimated that about 25% of their
particular animal species will be lost.
A large fraction of both
terrestrial and freshwater species faces increased extinction risk under
projected climate change during and beyond the 21st century, especially
as climate change interacts with other stressors, such as habitat
modification, over-exploitation, pollution, and invasive species.
Extinction risk is increased under all RCP
scenarios, with risk increasing with both magnitude and rate of climate
change. Many species will be unable to track suitable climates under
mid- and high-range rates of climate change during the 21st century.
Lower rates of climate change will pose fewer problems.
— IPCC, 2014
Some predictions of how life would be affected:
Mediterranean Monk Seal: These animals have lost about 60% of their population in the past sixty years.
Miombo Woodlands of South Africa: If the temperature were to rise by
at least 4.5 degrees Celsius, this area would lose about 90% of its
amphibians, 86% of birds, and 80% of mammals.
The Amazon could lose 69 percent of its plant species.
In southwest Australia 89 percent of amphibians could become locally extinct.
60 percent of all species are at risk of localised extinction in Madagascar.
The Fynbos in the Western Cape Region of South Africa, which is
experiencing a drought that has led to water shortages in Cape Town,
could face localized extinctions of a third of its species, many of
which are unique to that region." - WorldWildLife Fund
Temperature increase would affect the amount of rainfall and
therefore the amount of drinking water animals need to survive. It would
affect plant growth and desertification. This would further spread in
other issues including overgrazing and loss of biodiversity.
Extinction risks reported
2004
In one study published in Nature
in 2004 found that between 15 and 37% of 1103 endemic or near-endemic
known plant and animal species will be "committed to extinction" by
2050.
More properly, changes in habitat by 2050 will put them outside the
survival range for the inhabitants, thus committing the species to
extinction.
Other researchers, such as Thuiller et al., Araújo et al., Person et al., Buckley and Roughgarden, and Harte et al. have raised concern regarding uncertainty in Thomas et al.'s projections; some of these studies believe it is an overestimate, others believe the risk could be greater. Thomas et al. replied in Nature
addressing criticisms and concluding "Although further investigation is
needed into each of these areas, it is unlikely to result in
substantially reduced estimates of extinction. Anthropogenic climate change seems set to generate very large numbers of species-level extinctions." On the other hand, Daniel Botkin et al.
state "... global estimates of extinctions due to climate change
(Thomas et al. 2004) may have greatly overestimated the probability of
extinction..."
Mechanistic studies are documenting extinctions due to recent climate change: McLaughlin et al. documented two populations of Bay checkerspot butterfly being threatened by precipitation change. Parmesan states, "Few studies have been conducted at a scale that encompasses an entire species" and McLaughlin et al. agreed "few mechanistic studies have linked extinctions to recent climate change."
2008
In 2008, the white lemuroid possum was reported to be the first known mammal species to be driven extinct by climate change. However, these reports were based on a misunderstanding. One population of these possums in the mountain forests of North Queensland
is severely threatened by climate change as the animals cannot survive
extended temperatures over 30 °C. However, another population 100
kilometres south remains in good health.
2010
The risk of
extinction does need to lead to a demonstrable extinction process to
validate future extinctions attributable to climate change. In a study
led by Barry Sinervo,
a mathematical-biologist at the University of California Santa Cruz,
researchers analyzed observed contemporary extinctions (since dramatic
modern climate warming began in 1975). Results of the study indicate
that climate-forced extinctions of lizard families of the world have
already started. The model is premised on the ecophysiological limits of
an organism being exceeded. In the case of lizards, this occurs when
their preferred body temperature is exceeded in their local environment.
Lizards are ectotherms that regulate body temperature using heat
sources of their local environment (the sun, warm air temperatures, or
warm rocks). Surveys of 200 sites in Mexico showed 24 local extinctions
(= extirpations), of Sceloporus lizards. Using a model developed from
these observed extinctions the researchers surveyed other extinctions
around the world and found that the model predicted those observed
extirpations, thus attributing the extirpations around the world to
climate warming. These models predict that extinctions of the lizard
species around the world will reach 20% by 2080, but up to 40%
extinctions in tropical ecosystems where the lizards are closer to their
ecophysiological limits than lizards in the temperate zone.
2012
According to research published in the January 4, 2012 Proceedings of the Royal Society B
current climate models may be flawed because they overlook two
important factors: the differences in how quickly species relocate and
competition among species. According to the researchers, led by Mark C. Urban,
an ecologist at the University of Connecticut, diversity decreased when
they took these factors into account, and that new communities of
organisms, which do not exist today, emerged. As a result, the rate of
extinctions may be higher than previously projected.
2014
According to research published in the 30 May 2014 issue of Science,
most known species have small ranges, and the numbers of small-ranged
species are increasing quickly. They are geographically concentrated and
are disproportionately likely to be threatened or already extinct.
According to the research, current rates of extinction are three orders
of magnitude higher than the background extinction rate,
and future rates, which depend on many factors, are poised to increase.
Although there has been rapid progress in developing protected areas,
such efforts are not ecologically representative, nor do they optimally
protect biodiversity. In the researchers' view, human activity tends to
destroy critical habitats where species live, warms the planet, and
tends to move species around the planet to places where they don't
belong and where they can come into conflict with human needs (e.g.
causing species to become pests).
According to a long-term study of more than 60 bee species published in the journal Science said that climate change effect drastic declines in the population and diversity of bumblebees across North America and Europe.This
research show that bumblebees are disappearing at rates same as
"consistent with a mass extinction."North America's bumblebee
populations fell by 46% during the two time periods the study used which
is from 1901 to 1974 and from 2000 to 2014.North America's bumblebee
populations fell by 46% because bee populations were hardest hit in
warming southern regions such as Mexico.According to the study, more frequent extreme warm years, which exceeded the species’ historical temperature ranges.
2016
In 2016, the Bramble Cay melomys, which lived on a Great Barrier Reef
island, was reported to probably be the first mammal to become extinct
because of sea level rises due to human-made climate change.
Extinction risks of the Adelie penguin are being reported because of climate change. The Adelie penguin (Pygoscelis adeliae)
species is declining and data analysis done on the breeding colonies is
used to estimate and project future habitat and population
sustainability in relation to warming sea temperatures. By 2060,
one-third of the observed Adelie penguin colony along the West Antarctic
Peninsula (WAP) will be in decline. The Adelie penguins are a
circumpolar species, used to the ranges of Antarctic climate, and
experiencing population decline. Climate model projections predict
sanctuary for the species past 2099. The observed population is
similarly proportional to the species-wide population (one-third of the
observed population is equal to 20% of the species-wide population).
Sex ratios for sea turtles in the Caribbean
are being affected because of climate change. Environmental data were
collected from the annual rainfall and tide temperatures over the course
of 200 years and showed an increase in air temperature (mean of 31.0
degree Celsius). These data were used to relate the decline of the sex
ratios of sea turtles in the North East Caribbean and climate change.
The species of sea turtles include Dermochelys coriacea, Chelonia myads, and Eretmochelys imbricata.
Extinction is a risk for these species as the sex ratio is being
afflicted causing a higher female to male ratio. Projections estimate
the declining rate of male Chelonia myads as 2.4% hatchlings being male by 2030 and 0.4% by 2090.
2019
According to the World Wildlife Fund, the jaguar is already "near threatened" and the loss of food supplies and habitat due to the fires make the situation more critical.
The fires affect water chemistry (such as decreasing the amount
of dissolved oxygen in the water), temperature, and erosion rates, which
in turn affects fish and mammals that depend on fish, such as the giant otter (Pteronura brasiliensis).
2020
The unprecedented fires of the 2019–20 Australian bushfire season
that have swept through 18 million acres (7 million hectares) have
claimed 29 human lives and have stressed Australia's wildlife. Before the fires, only 500 tiny Kangaroo Island dunnarts (Sminthopsis aitkeni) lived on one island; after half the island was burned, it is possible only one has survived. Bramble Cay melomys (Melomys rubicola)
became the first known casualty of human-caused climate change in 2015
due to rising sea levels and repeated storm surges; the greater stick-nest rat (Leporillus conditor) may be next.
Emus (Dromaius novaehollandiae)
are not in danger of total extinction, although they might suffer local
extinctions as a result of bushfires; in northern New South Wales,
coastal emus could be wiped out by fire. The loss of 8,000 koalas (Phascolarctos cinereus) in NSW alone was significant, but the animals are endangered but not functionally extinct.
A February 2020 study found that one-third of all plant and animal species could be extinct by 2070 as a result of climate change.
Climate change has adversely affected both terrestrial and marine ecosystems, and is expected to further affect many ecosystems, including tundra, mangroves, coral reefs, and caves.
Increasing global temperature, more frequent occurrence of extreme
weather, and rising sea level are among some of the effects of climate
change that will have the most significant impact. Some of the possible
consequences of these effects include species decline and extinction,
behavior change within ecosystems, increased prevalence of invasive
species, a shift from forests being carbon sinks to carbon sources,
ocean acidification, disruption of the water cycle, and increased
occurrence of natural disasters, among others.
General
Global warming is likely to affect terrestrial ecoregions. Increasing global temperature means that ecosystems will change; some species are being forced out of their habitats (possibly to extinction) because of changing conditions, while others are flourishing.
Other effects of global warming include lessened snow cover, rising sea
levels, and weather changes, may influence human activities and the ecosystem.
Within the IPCC Fourth Assessment Report, experts assessed the literature on the impacts of climate change on ecosystems. Rosenzweig et al.
(2007) concluded that over the last three decades, human-induced
warming had likely had a discernible influence on many physical and
biological systems (p. 81). Schneider et al. (2007) concluded, with very high confidence, that regional temperature trends had already affected species and ecosystems around the world (p. 792).
They also concluded that climate change would result in the extinction
of many species and a reduction in the diversity of ecosystems (p. 792).
Terrestrial ecosystems and biodiversity: With a warming
of 3 °C, relative to 1990 levels, it is likely that global terrestrial
vegetation would become a net source of carbon (Schneider et al., 2007:792). With high confidence, Schneider et al.
(2007:788) concluded that a global mean temperature increase of around
4 °C (above the 1990-2000 level) by 2100 would lead to major extinctions
around the globe.
Marine ecosystems and biodiversity: With very high confidence, Schneider et al.
(2007:792) concluded that a warming of 2 °C above 1990 levels would
result in mass mortality of coral reefs globally. In addition, several
studies dealing with planktonic organisms and modelling have shown that
temperature plays a transcendental role in marine microbial food webs,
which may have a deep influence on the biological carbon pump of marine
planktonic pelagic and mesopelagic ecosystems.
Freshwater ecosystems: Above about a 4 °C increase in global mean temperature by 2100 (relative to 1990-2000), Schneider et al. (2007:789) concluded, with high confidence, that many freshwater species would become extinct.
Biodiversity
Extinction
Studying the association between Earth climate and extinctions over the past 520 million years, scientists from the University of York
write, "The global temperatures predicted for the coming centuries may
trigger a new ‘mass extinction event’, where over 50 percent of animal
and plant species would be wiped out."
Many of the species at risk are Arctic and Antarctic fauna such as polar bears and emperor penguins. In the Arctic, the waters of Hudson Bay are ice-free for three weeks longer than they were thirty years ago, affecting polar bears, which prefer to hunt on sea ice. Species that rely on cold weather conditions such as gyrfalcons, and snowy owls that prey on lemmings that use the cold winter to their advantage may be negatively affected. Marine invertebrates achieve peak growth at the temperatures they have adapted to, and cold-blooded animals found at high latitudes and altitudes generally grow faster to compensate for the short growing season. Warmer-than-ideal conditions result in higher metabolism and consequent reductions in body size despite increased foraging, which in turn elevates the risk of predation. Indeed, even a slight increase in temperature during development impairs growth efficiency and survival rate in rainbow trout.
Mechanistic studies have documented extinctions due to recent climate change: McLaughlin et al. documented two populations of Bay checkerspot butterfly being threatened by precipitation change.
Parmesan states, "Few studies have been conducted at a scale that encompasses an entire species" and McLaughlin et al. agreed "few mechanistic studies have linked extinctions to recent climate change." Daniel Botkin and other authors in one study believe that projected rates of extinction are overestimated.
Many species of freshwater and saltwater plants and animals are
dependent on glacier-fed waters to ensure a cold water habitat that they
have adapted to. Some species of freshwater fish need cold water to
survive and to reproduce, and this is especially true with salmon and cutthroat trout. Reduced glacier runoff can lead to insufficient stream flow to allow these species to thrive. Ocean krill, a cornerstone species, prefer cold water and are the primary food source for aquatic mammals such as the blue whale. Alterations to the ocean currents, due to increased freshwater inputs from glacier melt, and the potential alterations to thermohaline circulation of the worlds oceans, may affect existing fisheries upon which humans depend as well.
The white lemuroid possum, only found in the Daintree
mountain forests of northern Queensland, may be the first mammal species
to be driven extinct by global warming in Australia. In 2008, the white
possum has not been seen in over three years. The possums cannot
survive extended temperatures over 30 °C (86 °F), which occurred in
2005.
A 27-year study of the largest colony of Magellanic penguins
in the world, published in 2014, found that extreme weather caused by
climate change is responsible for killing 7% of penguin chicks per year
on average, and in some years studied climate change accounted for up to
50% of all chick deaths. Since 1987, the number of breeding pairs in the colony has reduced by 24%.
Furthermore, climate change may disrupt ecological partnerships
among interacting species, via changes on behaviour and phenology, or
via climate niche mismatch The disruption of species-species associations is a potential
consequence of climate-driven movements of each individual species
towards opposite directions
Climate change may, thus, lead to another extinction, more silent and
mostly overlooked: the extinction of species' interactions. As a
consequence of the spatial decoupling of species-species associations, ecosystem services derived from biotic interactions are also at risk from climate niche mismatch.
Behaviour change
Rising temperatures are beginning to have a noticeable impact on birds, and butterflies
have shifted their ranges northward by 200 km in Europe and North
America. The migration range of larger animals may be constrained by
human development. In Britain, spring butterflies are appearing an average of 6 days earlier than two decades ago.
A 2002 article in Nature
surveyed the scientific literature to find recent changes in range or
seasonal behaviour by plant and animal species. Of species showing
recent change, 4 out of 5 shifted their ranges towards the poles or
higher altitudes, creating "refugee species". Frogs were breeding,
flowers blossoming and birds migrating an average 2.3 days earlier each
decade; butterflies, birds and plants moving towards the poles by 6.1 km
per decade. A 2005 study concludes human activity is the cause of the
temperature rise and resultant changing species behaviour, and links
these effects with the predictions of climate models to provide validation for them. Scientists have observed that Antarctic hair grass is colonizing areas of Antarctica where previously their survival range was limited.
Climate change is leading to a mismatch between the snow camouflage of arctic animals such as snowshoe hares with the increasingly snow-free landscape.
Invasive species
Buffelgrass (Cenchrus ciliaris) is an invasive species throughout the world that is pushing out native species.
As the northern forests are a carbon sink,
while dead forests are a major carbon source, the loss of such large
areas of forest has a positive feedback on global warming. In the worst
years, the carbon emission due to beetle infestation of forests in
British Columbia alone approaches that of an average year of forest
fires in all of Canada or five years worth of emissions from that country's transportation sources.
Research suggests that slow-growing trees only are stimulated in growth for a short period under higher CO2 levels, while faster growing plants like liana benefit in the long term. In general, but especially in rainforests,
this means that liana become the prevalent species; and because they
decompose much faster than trees their carbon content is more quickly
returned to the atmosphere. Slow growing trees incorporate atmospheric
carbon for decades.
Wildfires
Healthy and unhealthy forests appear to face an increased risk of forest fires because of the warming climate. The 10-year average of boreal forest burned in North America, after several decades of around 10,000 km2 (2.5 million acres), has increased steadily since 1970 to more than 28,000 km2 (7 million acres) annually.
Though this change may be due in part to changes in forest management
practices, in the western U.S., since 1986, longer, warmer summers have
resulted in a fourfold increase of major wildfires and a sixfold
increase in the area of forest burned, compared to the period from 1970
to 1986. A similar increase in wildfire activity has been reported in
Canada from 1920 to 1999.
Forest fires in Indonesia
have dramatically increased since 1997 as well. These fires are often
actively started to clear forest for agriculture. They can set fire to
the large peat bogs in the region and the CO₂released by these peat bog
fires has been estimated, in an average year, to be 15% of the quantity
of CO₂produced by fossil fuel combustion.
A 2018 study found that trees grow faster due to increased carbon
dioxide levels, however, the trees are also eight to twelve percent
lighter and denser since 1900. The authors note, "Even though a greater
volume of wood is being produced today, it now contains less material
than just a few decades ago."
In 2019 unusually hot and dry weather in parts of the northern
hemisphere caused massive wildfires, from the Mediterranean to – in
particular – the Arctic. Climate change, by rising temperatures and
shifts in precipitation patterns, is amplifying the risk of wildfires
and prolonging their season. The northern part of the world is warming
faster than the planet on average. The average June temperature in the
parts of Siberia, where wildfires are raging, was almost ten degrees
higher than the 1981–2010 average. Temperatures in Alaska reach record
highs of up to 90 °F (32 °C) on 4 July, fuelling fires in the state,
including along the Arctic Circle.
In addition to the direct threat from burning, wildfires cause
air pollution, that can be carried over long distances, affecting air
quality in far away regions. Wildfires also release carbon dioxide
into the atmosphere, contributing to global warming. For example, the
2014 megafires in Canada burned more than 7 million acres of forest,
releasing more than 103 million tonnes of carbon – half as much as all
the plants in Canada typically absorb in an entire year.
Wildfires are common in the northern hemisphere between May and
October, but the latitude, intensity, and the length of the fires, were
particularly unusual. In June 2019, the Copernicus Atmosphere Monitoring
Service (CAMS) has tracked over 100 intense and long-lived wildfires in
the Arctic. In June alone, they emitted 50 megatones of carbon dioxide -
equivalent to Sweden's annual GHG emissions. This is more than was
released by Arctic fires in the same month in the years 2010 - 2018
combined. The fires have been most severe in Alaska and Siberia, where
some cover territory equal to almost 100 000 football pitches. In
Alberta, one fire was bigger than 300 000 pitches. In Alaska alone, CAMS
has registered almost 400 wildfires this year, with new ones igniting
every day. In Canada, smoke from massive wildfires near Ontario are
producing large amounts of air pollution. The heat wave in Europe also
caused wildfires in a number of countries, including Germany, Greece and
Spain. The heat is drying forests and making them more susceptible to
wildfires. Boreal forests are now burning at a rate unseen in at least 10,000 years.
The Arctic region, is particularly sensitive and warming faster
than most other regions. Particles of smoke can land on snow and ice,
causing them to absorb sunlight that it would otherwise reflect,
accelerating the warming. Fires in the Arctic also increase the risk of
permafrost thawing that releases methane - strong greenhouse gas.
Improving forecasting systems is important to solve the problem. In view
of the risks, WMO
has created a Vegetation Fire and Smoke Pollution Warning and Advisory
System for forecasting fires and related impacts and hazards across the
globe. WMO's Global Atmosphere Watch Programme has released a short
video about the issue.
Invasive species
An invasive species is any kind of living organism that is not native to an ecosystem that adversely affects it.
These negative effects can include the extinction of native plants or
animals, biodiversity destruction, and permanent habitat alteration.
Pine forests in British Columbia have been devastated by a pine beetle
infestation, which has expanded unhindered since 1998 at least in part
due to the lack of severe winters since that time; a few days of extreme
cold kill most mountain pine beetles and have kept outbreaks in the
past naturally contained. The infestation, which (by November 2008) has
killed about half of the province's lodgepole pines (33 million acres or
135,000 km2) is an order of magnitude larger than any previously recorded outbreak.
One reason for unprecedented host tree mortality may be due to that the
mountain pine beetles have higher reproductive success in lodgepole
pine trees growing in areas where the trees have not experienced
frequent beetle epidemics, which includes much of the current outbreak
area. In 2007 the outbreak spread, via unusually strong winds, over the continental divide to Alberta. An epidemic also started, be it at a lower rate, in 1999 in Colorado, Wyoming, and Montana. The United States forest service predicts that between 2011 and 2013 virtually all 5 million acres (20,000 km2) of Colorado's lodgepole pine trees over five inches (127 mm) in diameter will be lost.
Taiga
Climate change is having a disproportionate impact on boreal forests, which are warming at a faster rate than the global average. leading to drier conditions in the Taiga, which leads to a whole host of subsequent issues. Climate change has a direct impact on the productivity of the boreal forest, as well as health and regeneration.
As a result of the rapidly changing climate, trees are migrating to
higher latitudes and altitudes (northward), but some species may not be
migrating fast enough to follow their climatic habitat. Moreover, trees within the southern limit of their range may begin to show declines in growth. Drier conditions are also leading to a shift from conifers to aspen in more fire and drought-prone areas.
Assisted migration
Assisted migration, the act of moving plants or animals to a different habitat,
has been proposed as a solution to the above problem. For species that
may not be able to disperse easily, have long generation times or have
small populations, this form of adaptative management and human
intervention may help them survive in this rapidly changing climate.
The assisted migration of North American forests has been discussed and debated by the science community for decades. In the late 2000s and early 2010s, the Canadian provinces of Alberta and British Columbia finally acted and modified their tree reseeding guidelines to account for the northward movement of forest's optimal ranges. British Columbia even gave the green light for the relocation of a single species, the western larch, 1000 km northward.
Mountains
Mountains
cover approximately 25 percent of earth's surface and provide a home to
more than one-tenth of global human population. Changes in global
climate pose a number of potential risks to mountain habitats. Researchers expect that over time, climate change will affect mountain and lowland ecosystems, the frequency and intensity of forest fires, the diversity of wildlife, and the distribution of fresh water.
Studies suggest a warmer climate in the United States would cause
lower-elevation habitats to expand into the higher alpine zone.
Such a shift would encroach on the rare alpine meadows and other
high-altitude habitats. High-elevation plants and animals have limited
space available for new habitat as they move higher on the mountains in
order to adapt to long-term changes in regional climate.
Changes in climate will also affect the depth of the mountains
snowpacks and glaciers. Any changes in their seasonal melting can have
powerful impacts on areas that rely on freshwater runoff
from mountains. Rising temperature may cause snow to melt earlier and
faster in the spring and shift the timing and distribution of runoff.
These changes could affect the availability of freshwater for natural
systems and human uses.
Oceans
Ocean acidification
Estimated
annual mean sea surface anthropogenic dissolved inorganic carbon
concentration for the present day (normalised to year 2002) from the
Global Ocean Data Analysis Project v2 (GLODAPv2) climatology.
Ocean acidification poses a severe threat to the earth's natural process of regulating atmospheric C02 levels, causing a decrease in water's ability to dissolve oxygen and created oxygen-vacant bodies of water called "dead zones." The ocean absorbs up to 55% of atmospheric carbon dioxide, lessoning the effects of climate change. This diffusion of carbon dioxide into seawater results in three acidic molecules: bicarbonate ion (HCO3-), aqueous carbon dioxide (CO2aq), and carbonic acid (H2CO3).
These three compounds increase the ocean's acidity, decreasing its ph
by up to 0.1 per 100ppm (part per million) of atmospheric CO2.
The increase of ocean acidity also decelerates the rate of
calcification in salt water, leading to slower growing reefs which
support a whopping 25% of marine life.
As seen with the great barrier reef, the increase in ocean acidity in
not only killing the coral, but also the wildly diverse population of
marine inhabitants which coral reefs support.
Dissolved oxygen
Another
issue faced by increasing global temperatures is the decrease of the
ocean's ability to dissolve oxygen, one with potentially more severe
consequences than other repercussions of global warming.
Ocean depths between 100 meters and 1,000 meters are known as "oceanic
mid zones" and host a plethora of biologically diverse species, one of
which being zooplankton. Zooplankton feed on smaller organisms such as phytoplankton, which are an integral part of the marine food web.
Phytoplankton perform photosynthesis, receiving energy from light, and
provide sustenance and energy for the larger zooplankton, which provide
sustenance and energy for the even larger fish, and so on up the food
chain.
The increase in oceanic temperatures lowers the ocean's ability to
retain oxygen generated from phytoplankton, and therefore reduces the
amount of bioavailable oxygen that fish and other various marine
wildlife rely on for their survival.
This creates marine dead zones, and the phenomenon has already
generated multiple marine dead zones around the world, as marine
currents effectively "trap" the deoxygenated water.
Algal bloom
Climate change can increase the frequency and the magnitude of algal bloom. In 2019 the biggest Sargassum bloom ever seen created a crisis in the Tourism industry in North America. The event was probably caused by Climate Change and Fertilizers.
Several Caribbean countries, even considered declaring a state of
emergency due to the impact on tourism. The bloom can benefit the marine
life, but, can also block the sunlight necessary for it.
Impact on phytoplankton
Satellite measurement and chlorophyll observations show decline in the number of phytoplankton,
microorganisms that produce half of the earth's oxygen, absorb half of
the world carbon dioxide and serve foundation of the entire marine food
chain. The decline is probably linked to climate change. However, there are some measurements that show increases in the number of phytoplankton.
Coral bleaching
The warming of water lead to bleaching of the corals what can cause serious damage to them. In the Great Barrier Reef,
before 1998 there were not such events. The first event happened in
1998 and after it they begun to occur more and more frequently so in the
years 2016 - 2020 there were 3 of them.
Combined impact
Eventually
the planet will warm to such a degree that the ocean's ability to
dissolve oxygen will no longer exist, resulting in a worldwide dead
zone.
Dead zones, in combination with ocean acidification, will usher in an
era where marine life in most forms will cease to exist, causing a sharp
decline in the amount of oxygen generated through bio carbon
sequestration, perpetuating the cycle.
This disruption to the food chain will cascade upward, thinning out
populations of primary consumers, secondary consumers, tertiary
consumers, etc., as primary consumers being the initial victims of these
phenomenon.
Marine wildlife
The effect of climate change on marine life and mammals is a growing concern. Many of the effects of global warming
are currently unknown due to unpredictability, but many are becoming
increasingly evident today. Some effects are very direct such as loss of habitat,
temperature stress, and exposure to severe weather. Other effects are
more indirect, such as changes in host pathogen associations, changes in
body condition because of predator–prey interaction, changes in
exposure to toxins and CO 2 emissions, and increased human interactions.
Despite the large potential impacts of ocean warming on marine
mammals, the global vulnerability of marine mammals to global warming is
still poorly understood.
It has been generally assumed that the Arctic marine mammals were the
most vulnerable in the face of climate change given the substantial
observed and projected decline in Arctic sea ice cover. However, the
implementation of a trait-based approach on assessment of the
vulnerability of all marine mammals under future global warming has
suggested that the North Pacific Ocean, the Greenland Sea and the
Barents Sea host the species that are most vulnerable to global warming. The North Pacific has already been identified as a hotspot for human threats for marine mammals
and now is also a hotspot of vulnerability to global warming. This
emphasizes that marine mammals in this region will face double jeopardy
from both human activities (e.g., marine traffic, pollution and offshore
oil and gas development) and global warming, with potential additive or
synergetic effect and as a result, these ecosystems face irreversible
consequences for marine ecosystem functioning. Consequently the future conservation plans should therefore focus on these regions.
Fresh water
Disruption to water cycle
The water cycle
Fresh water covers only 0.8% of the Earth's surface, but contains up to 6% of all life on the planet.
However, the impacts climate change deal to its ecosystems are often
overlooked. Very few studies showcase the potential results of climate
change on large-scale ecosystems which are reliant on freshwater, such
as river ecosystems, lake ecosystems, desert ecosystems, etc. However, a
comprehensive study published in 2009 delves into the effects to be
felt by lotic (flowing) and lentic (still) freshwater ecosystems in the
American Northeast. According to the study, persistent rainfall,
typically felt year round, will begin to diminish and rates of
evaporation will increase, resulting in drier summers and more sporadic
periods of precipitation throughout the year.
Additionally, a decrease in snowfall is expected, which leads to less
runoff in the spring when snow thaws and enters the watershed, resulting
in lower-flowing fresh water rivers.
This decrease in snowfall also leads to increased runoff during winter
months, as rainfall cannot permeate the frozen ground usually covered by
water-absorbing snow. These effects on the water cycle will wreak havoc for indigenous species residing in fresh water lakes and streams.
Salt water contamination and cool water species
Eagle River in central Alaska, home to various indigenous freshwater species.
Species of fish living in cold or cool water can see a reduction in
population of up to 50% in the majority of U.S. fresh water streams,
according to most climate change models.
The increase in metabolic demands due to higher water temperatures, in
combination with decreasing amounts of food will be the main
contributors to their decline.
Additionally, many fish species (such as salmon) utilize seasonal water
levels of streams as a means of reproducing, typically breeding when
water flow is high and migrating to the ocean after spawning.
Because snowfall is expected to be reduced due to climate change, water
runoff is expected to decrease which leads to lower flowing streams,
effecting the spawning of millions of salmon.
To add to this, rising seas will begin to flood coastal river systems,
converting them from fresh water habitats to saline environments where
indigenous species will likely perish. In southeast Alaska, the sea
rises by 3.96 cm/year, redepositing sediment in various river channels
and bringing salt water inland.
This rise in sea level not only contaminates streams and rivers with
saline water, but also the reservoirs they are connected to, where
species such as Sockeye Salmon live. Although this species of Salmon can
survive in both salt and fresh water, the loss of a body of fresh water
stops them from reproducing in the spring, as the spawning process
requires fresh water.
Undoubtedly, the loss of fresh water systems of lakes and rivers in
Alaska will result in the imminent demise of the state's once-abundant
population of salmon.
Droughts
Droughts
have been occurring more frequently because of global warming and they
are expected to become more frequent and intense in Africa, southern
Europe, the Middle East, most of the Americas, Australia, and Southeast
Asia.
Their impacts are aggravated because of increased water demand,
population growth, urban expansion, and environmental protection efforts
in many areas. Droughts result in crop failures and the loss of pasture grazing land for livestock.
Droughts are becoming more frequent and intense in arid and
semiarid western North America as temperatures have been rising,
advancing the timing and magnitude of spring snow melt floods and
reducing river flow volume in summer. Direct effects of climate change
include increased heat and water stress, altered crop phenology,
and disrupted symbiotic interactions. These effects may be exacerbated
by climate changes in river flow, and the combined effects are likely to
reduce the abundance of native trees in favor of non-native herbaceous
and drought-tolerant competitors, reduce the habitat quality for many
native animals, and slow litter decomposition and nutrient cycling.
Climate change effects on human water demand and irrigation may
intensify these effects.
Combined impact
In
general, as the planet warms, the amount of fresh water bodies across
the planet decreases, as evaporation rates increase, rain patterns
become more sporadic, and watershed patterns become fragmented,
resulting in less cyclical water flow in river and stream systems. This
disruption to fresh water cycles disrupts the feeding, mating, and
migration patterns of organisms reliant on fresh water ecosystems.
Additionally, the encroachment of saline water into fresh water river
systems endangers indigenous species which can only survive in fresh
water.
Species migration
In 2010, a gray whale
was found in the Mediterranean Sea, even though the species had not
been seen in the North Atlantic Ocean since the 18th century. The whale
is thought to have migrated from the Pacific Ocean via the Arctic.
Climate Change & European Marine Ecosystem Research (CLAMER) has also reported that the Neodenticula seminae
alga has been found in the North Atlantic, where it had gone extinct
nearly 800,000 years ago. The alga has drifted from the Pacific Ocean
through the Arctic, following the reduction in polar ice.
In the Siberian subarctic,
species migration is contributing to another warming albedo-feedback,
as needle-shedding larch trees are being replaced with dark-foliage
evergreen conifers which can absorb some of the solar radiation that
previously reflected off the snowpack beneath the forest canopy. It has been projected many fish species will migrate towards the North
and South poles as a result of climate change, and that many species of
fish near the Equator will go extinct as a result of global warming.
Migratory birds are especially at risk for endangerment due to
the extreme dependability on temperature and air pressure for migration,
foraging, growth, and reproduction. Much research has been done on the
effects of climate change on birds, both for future predictions and for
conservation. The species said to be most at risk for endangerment or
extinction are populations that are not of conservation concern.
It is predicted that a 3.5 degree increase in surface temperature will
occur by year 2100, which could result in between 600 and 900
extinctions, which mainly will occur in the tropical environments.
Species adaptation
In November 2019 it was revealed that a 45-year study indicated that climate change had affected the gene pool of the red deer population on Rùm, one of the Inner Hebrides islands, Scotland.
Warmer temperatures resulted in deer giving birth on average three days
earlier for each decade of the study. The gene which selects for
earlier birth has increased in the population because does with the gene
have more calves over their lifetime. Dr Timothée Bonnet, of the Australian National University, leader of the study, said they had "documented evolution in action".
In December 2019 the results of a joint study by Chicago's Field Museum and the University of Michigan into changes in the morphology of birds was published in Ecology Letters.
The study uses bodies of birds which died as a result of colliding with
buildings in Chicago, Illinois, since 1978. The sample is made up of
over 70,000 specimens from 52 species and span the period from 1978 to
2016. The study shows that the length of birds' lower leg bones (an
indicator of body sizes) shortened by an average of 2.4% and their wings
lengthened by 1.3%. The findings of the study suggest the morphological
changes are the result of climate change, and demonstrate an example of
evolutionary change following Bergmann's rule.
Impacts of species degradation due to climate change on livelihoods
The livelihoods of nature dependent communities depend on abundance and availability of certain species.
Climate change conditions such as increase in atmospheric temperature
and carbon dioxide concentration directly affect availability of biomass
energy, food, fiber and other ecosystem services. Degradation of species supplying such products directly affect the livelihoods of people relying on them more so in Africa. The situation is likely to be exacerbated by changes in rainfall variability which is likely to give dominance to invasive species especially those that are spread across large latitudinal gradients.
The effects that climate change has on both plant and animal species
within certain ecosystems has the ability to directly affect the human
inhabitants who rely on natural resources. Frequently, the extinction of
plant and animal species create a cyclic relationship of species
endangerment in ecosystems which are directly affected by climate
change.
Cloud feedback is the coupling between cloudiness and surface air temperature
where a surface air temperature change leads to a change in clouds,
which could then amplify or diminish the initial temperature
perturbation. Cloud feedbacks can affect the magnitude of internally
generated climate variability or they can affect the magnitude of climate change resulting from external radiative forcings.
Global warming is expected to change the distribution and type of clouds. Seen from below, clouds emit infrared radiation
back to the surface, and so exert a warming effect; seen from above,
clouds reflect sunlight and emit infrared radiation to space, and so
exert a cooling effect. Cloud representations vary among global climate models, and small changes in cloud cover have a large impact on the climate.Differences in planetary boundary layer cloud modeling schemes can lead to large differences in derived values of climate sensitivity.
A model that decreases boundary layer clouds in response to global
warming has a climate sensitivity twice that of a model that does not
include this feedback. However, satellite data show that cloud optical thickness actually increases with increasing temperature.
Whether the net effect is warming or cooling depends on details such as
the type and altitude of the cloud; details that are difficult to
represent in climate models.
Other effects of cloud feedback
In
addition to how clouds themselves will respond to increased
temperatures, other feedbacks affect clouds properties and formation.
The amount and vertical distribution of water vapor is closely linked to the formation of clouds. Ice crystals have been shown to largely influence the amount of water vapor.
Water vapor in the subtropical upper troposphere has been linked to the
convection of water vapor and ice. Changes in subtropical humidity
could provide a negative feedback that decreases the amount of water
vapor which in turn would act to mediate global climate transitions.
Changes in cloud cover are closely coupled with other feedback, including the water vapor feedback and ice-albedo feedback. Changing climate is expected to alter the relationship between cloud ice and supercooled cloud water, which in turn would influence the microphysics
of the cloud which would result in changes in the radiative properties
of the cloud. Climate models suggest that a warming will increase
fractional cloudiness. The albedo of increased cloudiness cools the
climate, resulting in a negative feedback; while the reflection of
infrared radiation by clouds warms the climate, resulting in a positive
feedback. Increasing temperatures in the polar regions
is expected in increase the amount of low-level clouds, whose
stratification prevents the convection of moisture to upper levels. This
feedback would partially cancel the increased surface warming due to
the cloudiness. This negative feedback has less effect than the positive
feedback. The upper atmosphere more than cancels negative feedback that
causes cooling, and therefore the increase of CO2 is actually exacerbating the positive feedback as more CO2 enters the system.
A 2019 simulation predicts that if greenhouse gases reach three
times the current level of atmospheric carbon dioxide that stratocumulus
clouds could abruptly disperse, contributing to additional global
warming.
By reflecting solar radiation back to space (the albedo
effect of clouds) and by trapping infrared radiation emitted by the
surface and the lower troposphere (the greenhouse effect
of clouds), clouds exert two competing effects on the Earth’s radiation
budget. These two effects are usually referred to as the SW (shortwave)
and LW (longwave) components of the cloud radiative forcing (CRF). The
balance between these two components depends on many factors, including
macrophysical and microphysical cloud properties. In the current
climate, clouds exert a cooling effect on climate (the global mean CRF
is negative). In response to global warming, the cooling effect of
clouds on climate might be enhanced or weakened, thereby producing a
radiative feedback to climate warming (Randall et al., 2006; NRC, 2003; Zhang, 2004; Stephens, 2005; Bony et al., 2006).
In the most recent, the IPCC Fifth Assessment Report (2013), cloud feedback effects are discussed in the Working Group 1 report, in Chapter 7, "Clouds and Aerosols", with some additional discussion on uncertainties in Chapter 9, "Evaluation of Climate Models".
The report states "Cloud feedback studies point to five aspects of the
cloud response to climate change which are distinguished here: changes
in high-level cloud altitude, effects of hydrological cycle and storm
track changes on cloud systems,
changes in low-level cloud amount, microphysically induced opacity
(optical depth) changes and changes in high-latitude clouds." The net
radiative feedback is the sum of the warming and cooling feedbacks; the
executive summary states "The sign of the net radiative feedback due to
all cloud types is less certain but likely positive. Uncertainty in the
sign and magnitude of the cloud feedback is due primarily to continuing
uncertainty in the impact of warming on low clouds." They estimate the
cloud feedback from all cloud types to be +0.6 W/m2°C (with
an uncertainty band of −0.2 to +2.0), and continue, "All global models
continue to produce a near-zero to moderately strong positive net cloud
feedback."
The closely related effective climate sensitivity has increased
substantially in the latest generation of global climate models.
Differences in the physical representation of clouds in models drive
this enhanced sensitivity relative to the previous generation of models.
Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula (CH3)2SO. This colorless liquid is an important polaraprotic solvent that dissolves both polar and nonpolar compounds and is miscible
in a wide range of organic solvents as well as water. It has a
relatively high boiling point. DMSO has the unusual property that many
individuals perceive a garlic-like taste in the mouth after contact with the skin.
It was first synthesized in 1866 by the Russian scientist Alexander Zaytsev, who reported his findings in 1867. Dimethyl sulfoxide is produced industrially from dimethyl sulfide, a by-product of the Kraft process, by oxidation with oxygen or nitrogen dioxide.
The methyl groups of DMSO are only weakly acidic, with a pKa = 35. For this reason, the basicities of many weakly basic organic compounds have been examined in this solvent.
Related to its ability to dissolve many salts, DMSO is a common ligand in coordination chemistry. Illustrative is the complex dichlorotetrakis(dimethyl sulfoxide)ruthenium(II) (RuCl2(dmso)4). In this complex, three DMSO ligands are bonded to ruthenium through sulfur. The fourth DMSO is bonded through oxygen. In general, the oxygen-bonded mode is more common.
In carbon tetrachloride solutions DMSO functions as a Lewis base with a variety Lewis acids such as I2, phenols, trimethyltin chloride, metalloporphyrins, and the dimer Rh2Cl2(CO)4. The donor properties are discussed in the ECW model. The relative donor strength of DMSO toward a series of acids, versus other Lewis bases, can be illustrated by C-B plots.
Applications
Solvent
Distillation of DMSO requires a partial vacuum to achieve a lower boiling point.
DMSO is a polar aprotic solvent and is less toxic than other members of this class, such as dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, and HMPA. DMSO is frequently used as a solvent for chemical reactions involving salts, most notably Finkelstein reactions and other nucleophilic substitutions. It is also extensively used as an extractant in biochemistry and cell biology. Because DMSO is only weakly acidic, it tolerates relatively strong bases and as such has been extensively used in the study of carbanions. A set of non-aqueous pKa values (C-H, O-H, S-H and N-H acidities) for thousands of organic compounds have been determined in DMSO solution.
Because of its high boiling point, 189 °C (372 °F), DMSO
evaporates slowly at normal atmospheric pressure. Samples dissolved in
DMSO cannot be as easily recovered compared to other solvents, as it is
very difficult to remove all traces of DMSO by conventional rotary evaporation.
One technique to fully recover samples is removal of the organic
solvent by evaporation followed by addition of water (to dissolve DMSO)
and cryodesiccation
to remove both DMSO and water. Reactions conducted in DMSO are often
diluted with water to precipitate or phase-separate products. The
relatively high freezing point of DMSO, 18.5 °C (65.3 °F), means that
at, or just below, room temperature it is a solid, which can limit its
utility in some chemical processes (e.g. crystallization with cooling).
In its deuterated form (DMSO-d6), it is a useful solvent for NMR
spectroscopy, again due to its ability to dissolve a wide range of
analytes, the simplicity of its own spectrum, and its suitability for
high-temperature NMR spectroscopic studies. Disadvantages to the use of
DMSO-d6 are its high viscosity, which broadens signals, and its hygroscopicity, which leads to an overwhelming H2O resonance in the 1H-NMR spectrum. It is often mixed with CDCl3 or CD2Cl2 for lower viscosity and melting points.
DMSO is used as a solvent in in vitro and in vivo drug testing.
DMSO is also used to dissolve test compounds in in vitrodrug discovery and drug designscreening programs (including high-throughput screening programs). This is because it able to dissolve both polar and nonpolar compounds, can be used to maintain stock solutions of test compounds (important when working with a large chemical library), is readily miscible with water and cell culture media,
and has a high boiling point (this improves the accuracy of test
compound concentrations by reducing room temperature evaporation). One limitation with DMSO is that it can affect cell line
growth and viability (with low DMSO concentrations sometimes
stimulating cell growth, and high DMSO concentrations sometimes
inhibiting or killing cells).
DMSO is used as a vehicle in in vivo studies of test compounds too. It has, for example, been employed as a co-solvent to assist absorption of the flavonol glycosideIcariin in the nematode worm Caenorhabditis elegans. As with its use in in vitro studies, DMSO has some limitations in animal models. Pleiotropic
effects can occur and, if DMSO control groups are not carefully
planned, then solvent effects can falsely be attributed to the
prospective drug. For example, even a very low dose of DMSO has a powerful protective effect against paracetamol (acetaminophen)-induced liver injury in mice.
In addition to the above, DMSO is finding increased use in manufacturing processes to produce microelectronic devices.
It is widely used to strip photoresist in TFT-LCD 'flat panel' displays
and advanced packaging applications (such as wafer-level packaging /
solder bump patterning). DMSO is an effective paint stripper too, being safer than many of the others such as nitromethane and dichloromethane.
DMSO in a PCR reaction is applicable for supercoiled plasmids (to relax before amplification) or DNA templates with high GC-content (to decrease thermostability).
For example, 10% final concentration of DMSO in the PCR mixture with
Phusion decreases primer annealing temperature (i.e. primer melting
temperature) by 5.5–6.0 °C (9.9–10.8 °F).
It is well known as a reversible cell cycle arrester at phase G1 of human lymphoid cells.
DMSO may also be used as a cryoprotectant, added to cell media to reduce ice formation and thereby prevent cell death during the freezing process. Approximately 10% may be used with a slow-freeze method, and the cells may be frozen at −80 °C (−112 °F) or stored in liquid nitrogen safely.
In cell culture, DMSO is used to induce differentiation of P19
embryonic carcinoma cells into cardiomyocytes and skeletal muscle cells.
Medicine
Use of DMSO in medicine dates from around 1963, when an Oregon Health & Science University Medical School team, headed by Stanley Jacob,
discovered it could penetrate the skin and other membranes without
damaging them and could carry other compounds into a biological system.
In medicine, DMSO is predominantly used as a topical analgesic, a vehicle for topical application of pharmaceuticals, as an anti-inflammatory, and an antioxidant. Because DMSO increases the rate of absorption of some compounds through biological tissues, including skin, it is used in some transdermaldrug delivery systems. Its effect may be enhanced with the addition of EDTA.
It is frequently compounded with antifungal medications, enabling them
to penetrate not just skin but also toenails and fingernails.
DMSO has been examined for the treatment of numerous conditions and ailments, but the U.S. Food and Drug Administration (FDA) has approved its use only for the symptomatic relief of patients with interstitial cystitis. A 1978 study concluded that DMSO brought significant relief to the majority of the 213 patients with inflammatory genitourinary disorders that were studied.
The authors recommended DMSO for genitourinary inflammatory conditions
not caused by infection or tumor in which symptoms were severe or
patients failed to respond to conventional therapy.
A gel containing DMSO, dexpanthenol, and heparin, is sold in Germany and eastern Europe (commercialized under the Dolobene brand) for topical use in sprains, tendinitis, and local inflammation.
In cryobiology DMSO has been used as a cryoprotectant and is still an important constituent of cryoprotectant vitrification
mixtures used to preserve organs, tissues, and cell suspensions.
Without it, up to 90% of frozen cells will become inactive. It is
particularly important in the freezing and long-term storage of embryonic stem cells and hematopoietic stem cells, which are often frozen in a mixture of 10% DMSO, a freezing medium, and 30% fetal bovine serum. In the cryogenic freezing of heteroploid cell lines (MDCK, VERO, etc.) a mixture of 10% DMSO with 90% EMEM (70% EMEM + 30% fetal bovine serum + antibiotic mixture) is used. As part of an autologousbone marrow transplant the DMSO is re-infused along with the patient's own hematopoietic stem cells.
DMSO is metabolized by disproportionation to dimethyl sulfide and dimethyl sulfone.
It is subject to renal and pulmonary excretion. A possible side effect
of DMSO is therefore elevated blood dimethyl sulfide, which may cause a
blood borne halitosis symptom.
Alternative medicine
DMSO is marketed as an alternative medicine. Its popularity as an alternative cure is stated to stem from a 60 Minutes documentary featuring an early proponent. However, DMSO is an ingredient in some products listed by the U.S. FDA as fake cancer cures and the FDA has had a running battle with distributors. One such distributor is Mildred Miller, who promoted DMSO for a variety of disorders and was consequently convicted of Medicare fraud.
The use of DMSO as an alternative treatment for cancer is of
particular concern, as it has been shown to interfere with a variety of chemotherapy drugs, including cisplatin, carboplatin, and oxaliplatin. There is insufficient evidence to support the hypothesis that DMSO has any effect,
and most sources agree that its history of side effects when tested
warrants caution when using it as a dietary supplement, for which it is
marketed heavily with the usual disclaimer.
Veterinary medicine
DMSO is commonly used in veterinary medicine as a liniment for horses,
alone or in combination with other ingredients. In the latter case,
often, the intended function of the DMSO is as a solvent, to carry the
other ingredients across the skin. Also in horses, DMSO is used
intravenously, again alone or in combination with other drugs. It is
used alone for the treatment of increased intracranial pressure and/or
cerebral edema in horses.
Taste
The perceived garlic taste upon skin contact with DMSO may be due to nonolfactory activation of TRPA1 receptors in trigeminal ganglia. Unlike dimethyl and diallyl disulfide (also with odors resembling garlic), the mono- and tri- sulfides (typically with foul odors), and other similar structures, the pure chemical DMSO is odorless.
Safety
Toxicity
DMSO is a non-toxic solvent with a median lethal dose higher than ethanol (DMSO: LD50, oral, rat, 14,500 mg/kg; ethanol: LD50, oral, rat, 7,060 mg/kg).
Early clinical trials with DMSO were stopped because of questions
about its safety, especially its ability to harm the eye. The most
commonly reported side effects include headaches and burning and itching
on contact with the skin. Strong allergic reactions have been reported.
DMSO can cause contaminants, toxins, and medicines to be absorbed
through the skin, which may cause unexpected effects. DMSO is thought to
increase the effects of blood thinners, steroids, heart medicines,
sedatives, and other drugs. In some cases this could be harmful or
dangerous.
In Australia, it is listed as a Schedule 4 (S4) Drug, and a company has been prosecuted for adding it to products as a preservative.
Because DMSO easily penetrates the skin, substances dissolved in DMSO may be quickly absorbed. Glove selection is important when working with DMSO. Butyl rubber, fluoroelastomer, neoprene, or thick (15mil / 0.4mm) latex gloves are recommended. Nitrile
gloves, which are very commonly used in chemical laboratories, may
protect from brief contact but have been found to degrade rapidly with
exposure to DMSO.
On September 9, 1965, The Wall Street Journal
reported that a manufacturer of the chemical warned that the death of
an Irish woman after undergoing DMSO treatment for a sprained wrist may
have been due to the treatment, although no autopsy was done, nor was a
causal relationship established. Clinical research using DMSO was halted and did not begin again until the National Academy of Sciences (NAS) published findings in favor of DMSO in 1972. In 1978, the US FDA approved DMSO for treating interstitial cystitis.
In 1980, the US Congress held hearings on claims that the FDA was slow
in approving DMSO for other medical uses. In 2007, the US FDA granted
"fast track" designation on clinical studies of DMSO's use in reducing
brain tissue swelling following traumatic brain injury. DMSO exposure to developing mouse brains can produce brain degeneration. This neurotoxicity could be detected at doses as low as 0.3mL/kg, a level exceeded in children exposed to DMSO during bone marrow transplant.
DMSO disposed into sewers can also cause odor problems in municipal effluents: waste water bacteria transform DMSO under hypoxic (anoxic) conditions into dimethyl sulfide (DMS) that has a strong disagreeable odor, similar to rotten cabbage. However, chemically pure DMSO is odorless because of the lack of C-S-C (sulfide) and C-S-H (mercaptan) linkages. Deodorization of DMSO is achieved by removing the odorous impurities it contains.
Explosion hazard
Dimethyl sulfoxide can produce an explosive reaction when exposed to acyl chlorides; at a low temperature, this reaction produces the oxidant for Swern oxidation.
DMSO can decompose at the boiling temperature of 189 °C at normal
pressure, possibly leading to an explosion. The decomposition is
catalyzed by acids and bases and therefore can be relevant at even lower
temperatures. A strong to explosive reaction also takes place in
combination with halogen compounds, metal nitrides, metal perchlorates,
sodium hydride, periodic acid and fluorinating agents.
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