The Effects of Climate Change on Animal Species

 

Abstract

   The current global warming trend is causing physical and biological changes to occur throughout the entire planet and is impacting regional climates, ecosystems, and the organisms that inhabit them in a number of ways. Animal species can only survive within specific ranges of climatic and environmental factors, if conditions change beyond the tolerance of species, or to rapidly for evolutionary adaptations, then animals may exhibit ecological responses to these changes. The threat of extinction to species who are unable to adapt or have limited habitat is expected to increase with climatic changes, and the extinction of some species has already been directly linked to climate change. Changes is animals phenology, such as migration, breeding and spring appearance, has occurred throughout the world and is linked to seasonal variability. Changes in the spatial distribution of animals, particularly poleward and elevational shifts, is occurring as suitable habitat disappears or extends beyond its current range.  Arctic and marine ecosystems are  undergoing physical environmental changes that are effecting the species that inhabit them. Temperature change and melting sea ice in the arctic is adversely affecting the species of the region, and sea level rise, increased sea temperature and higher pH are among the issues changing the planets marine ecosystems. Spread of pests and disease are occurring as a  result of milder temperatures. All of these changes threaten the planets ecological biodiversity and changes projected for the environment will increasingly affect all life on Earth.

Climate Change

 Climate Change is occurring as a result of the greenhouse effect, which is the amount of solar radiation that is trapped in Earth's atmosphere, and which regulates the temperature of Earth. Anthropogenic greenhouse gases, primarily carbon dioxide and methane, are causing an increase in the amount of solar radiation that gets reflected back to Earth. The atmospheric concentrations of greenhouse gases have increased since the pre-industrial era due to human activities, primarily the combustion of fossil fuels and land use change (IPCC, 2002). In response, changes in the Earth's climate over the 20th century have accelerated beyond normal environmental conditions. Some of the changes include an increase in land and ocean temperatures (Figure 1, 2), changes in spatial and temporal precipitation patterns, sea level rise, reduction of sea ice, changes in vegetation, seasonal changes, and increases in the frequency and intensity of weather events (IPCC, 2002).

Figure1. Global Temperatures
(Wordpress.com, 2010)

Figure 2. Land and Ocean Temperatures
 (Wordpress.com, 2010)

Ecosystems and Biodiversity

Animal responses vary greatly between species, but climatic changes lead to disruption of biotic interactions, such as predator/prey interactions, and changes to ecosystem composition and functioning (IPCC, 2007c). Habitat fragmentation and loss, competition from invasive species, natural disturbances, pollution and other human induced issues have already been stressing animal populations and are expected to increase and compound with climate change factors (Kirby, 2004). The projected increase in temperatures over the next centuries is expected to lead to mass extinctions and have drastic, irreversible effects on biodiversity and ecosystems (IPCC, 2007a). Climate change can  affect individual organisms, populations, species distributions, and ecosystem function and composition both directly and indirectly (IPCC, 2002).While the long term impacts and existing trends still need more research, and may not always link directly to climate change, climatic changes are affecting all of the physical and biological systems on the planet (IPCC, 2007a).

Biodiversity is short for biological diversity, the term biodiversity describes the richness and complexity of life on Earth. Biodiversity refers to both the number of living species and the number of different genes in those species' gene pools (Sierra Club, 2008). The composition of most ecosystems is likely to change as species migrate at different rates and are affected differently by climatic changes, and by changes in vegetation and ground cover (Figure 3) (IPCC, 2002).

Figure 3. Changes in ground cover
(IPCC, 2007)

    Species are unlikely to shift together, creating imbalanced ecosystems and allowing new, invasive species to move in (IPCC, 2002). A loss of biodiversity has been, or is projected to occur as a result of climatic factors (IPCC, 2002). For every degree Celsius increase that the globe undergoes, the Intergovernmental Panel on Climate Change (IPCC) has two scenarios that project a variety of large scale changes to ecosystems over the next centuries (Figure 4), (IPCC, 2002).

Figure 4.  Projected risks due to temperature increase
over the next 300 years (IPCC, 2007)

Extinction

Animals are going extinct due to a variety of human caused disturbances, including climate change. At the current rate of extinction, Earth will have lost 25% of its present number of species by 2050 (Sierra Club, 2008). Species with limited climatic ranges and/or small populations are the most vulnerable to extinction (IPCC, 2002). Endemic mountain species, and animals restricted to islands, peninsulas, or coastal areas are at greatest risk (IPCC, 2002).

 Amphibians

Amphibians are particularly affected by climate change and are going extinct as a result of climate change induced disease, warming temperatures and dryer air (Pounds et al., 2005). An estimated 67% of the 110 species of Atelopus, which are endemic to the American tropics, have gone extinct as a result of a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) (Pounds et al., 2005).  Warming temperatures are shifting the optimum growth conditions for the fungus into the amphibians habitat, and is responsible for the extinction of these species (Pounds et al., 2005). The Global Amphibian Assessment  lists 427 species as critically endangered.

             The golden toad (Bufo periglenes), (Figure 5) and the Monteverde harlequin frog (Atelopus various) disappeared as a result of decreased mist frequency during warmer years in the mountainous Monteverde cloud forest of Costa Rica. They were the first amphibians to have their disappearance linked to climate change (Pounds et al., 2005).

Figure 5.  Golden Toad
(global-greenhouse-warming.com, 2010)

 

Phenology

Phenology is the timing of biological events or seasonal activities in animals and plants. Changes in the timing of spring activities include earlier breeding or first singing of birds, earlier arrival of migrant birds, earlier appearance of butterflies, and earlier choruses and spawning in amphibians (Walther et al., 2002). Numerous studies and analysis' have documented a progressively earlier spring by about 2.3 to 5.2 days/decade over the past 30 years, in response to warming (IPCC, 2007c). Changes in the timing of spring events, particularly migration and breeding, has been observed in many plant and animal species around Earth.   

Migration

Many migratory bird species have altered their wintering (Figure 6) and stopover habitats. This affects when birds breed and lay their eggs (EPA, 2009). Changes in the return dates of migratory birds is associated with changes in temperature in bird wintering or breeding grounds, or along migration routes (IPCC, 2007c), and has been studied around the world:

Birds are further affected by climate change; of the bird species listed by the Convention on the Conservation of Migratory Species of Wild Animals, 42%  of them are threatened because of changes in water regime (Amodeo, 2005).

 

Figure 6. Winter migration
(Pentland, 2009)

Breeding

    Breeding is instinctual in animals, and correlates with the seasons, changes in breeding has been researched in a variety of animals in recent years:

Spatial Distribution

 Many animal species have responded to regional warming and changes in vegetation by increasing their normal range, and exhibiting poleward and elevational shifts as their current habitat becomes unsuitable (IPCC, 2007b). Poleward and elevational shifts associated with regional warming have been documented in the ranges of North American, British, and European butterfly, birds and insect species (IPPC, 2007b).  Examples of spatial distribution include:

 the arctic ecosystem

In the arctic, climate change impacts are being seen earlier and more dramatically then anywhere else in the world (WWF(a), n/d). The arctic has warmed at about twice the rate as the rest of the planet (WWF(a), n/d). Decreasing sea ice extent has been documented over the past 30-40 years (Figure 7), and coincides with warming temperatures (Tynan and DeMaster, 1997).

Figure 7. Sea Ice Extent
(NSIDC, 2010)

 Since the 1950s, Arctic sea-ice extent has declined by about 10-15%; in recent decades, there has been about a 40% decline in Arctic sea-ice thickness during late summer to early autumn, which is projected to continue at increasing rates over the next century (Figure 8), (IPCC, 2007b).

Figure 8. Projected Arctic Conditions
 (IPCC, 2007a)

Arctic Species at Risk

    The effects of climate change near the poles can be observed in a variety of ways and affects both marine and terrestrial animals. Changes in the extent and concentration of sea ice may alter the seasonal distributions, geographic ranges, patterns of migration, nutritional status, reproductive success, and ultimately the abundance and stock structure of some arctic species (Tynan and DeMaster, 1997). Entire Arctic and Antarctic ecosystems depend on sea ice to survive. These physical processes, which affect arctic ecosystems result in shifts in range and abundance, physical fitness, and survival of many species (Ferguson, 2005). Reductions in winter sea-ice will affect the reproduction, growth and development of fish, krill, and their predators, including seals and seal-dependent polar bears, and leading to further changes in abundance and distribution of marine species (IPCC, 2007 a). As these changes  rapidly occur, it is more difficult for many species to survive (WWF(a), n/d). Examples of arctic species at risk:

Polar Bear (Ursus maritimus):
The status of Polar Bear subpopulations are declining in some areas as sea ice around the arctic melts (Figure 9). Polar bears rely on sea ice to access their food, primarily seals, and to move from hunting grounds to their denning or summer resting areas (WWF(b), n/d). Less food is available as seal populations decline or migrate. Polar bear subpopulations found at the southern range of their habitat are particularly threatened. The Hudson Bay and James Bay of Canada, and the Southern Beaufort subpopulations have declined in recent years (WWF(b), n/d).   There has  been an observed drop in body condition and an increase in cub mortality, as polar bears have less time on the ice to store the energy they need to survive through the summer (WWF(b), n/d). The main cause of death for cubs in the Hudson Bay is either lack of food, or lack of fat on nursing mothers (WWF(b), n/d). The US recently added the Polar bear to the endangered species list, and it is listed as threatened on the IUCN red list. If current warming trends continue unabated, scientists believe that polar bears will be vulnerable to extinction within the next century (WWF(b), n/d).

Figure 9. Status of Polar Bear, (WWF, 2010)

 

Caribou (Rangifer tarandus):
Caribou numbers in northern Canada have dropped significantly in recent years. Experts suspect climate change contributes to the decline because increased warm spells during the winter thaw the snow cover, which refreezes to create an ice cover over vegetation (WWF, n/d). Tundra vegetation zones are moving north due to warming conditions, making it harder for caribou to find food and raise young (EPA, 2009).

 

Ringed Seal (Phoca hispida):
 Seals are affected by the absence of summer sea ice because they give birth and nurse there young on sea ice (EPA, 2009). The Saimaa ringed seal population found in Lake Saimaa in Finland, is the most endangered seal species in the world with only 250 individuals left (WWF(a), n/d). These seals build their dens out of snow, and decreasing snowfall has made it more difficult for them to build dens(WWF(a), n/d). Variable winter weather can also lead to melting and collapsing dens, which can kill the young and make them vulnerable to predators if they survive (WWF(a), n/d).

 

Marine Ecosystems

 Sea level rise, higher sea surface temperatures, lower salinities, contraction of seasonal sea ice extent, lower pH, and ocean freshening are impacting  marine species (Ferguson, 2005).  Sea level rise (Figure 10) has been documented over the last 100 years, and is projected to rise over the next century (IPCC, 2007).

Figure 10. Projected Sea level rise,
 (IPCC, 2007)

      Sea surface warming has led to phenological, biogeographical, physiological, and species abundance changes in marine ecosystems (IPCC, 2007a). Shifts of marine organisms due to oceanic warming have been observed in the intertidal communities of the Pacific and British Isles, fish communities in southern California, and a major ecosystem shift in the Bering sea (IPCC, 2007a). Warming in the southern ocean has caused a decline in Krill, which has led to a reduction in population size of many seals, seabirds and other animals whose food source it is (IPCC, 2007a). Changes in the geographical range or extended ranges have been observed in  fish on the European continental shelf, as a result of warmer temperatures (IPCC, 2007a).Ocean chlorophyll records show that the global ocean annual primary production has decreased by more than 6% since the 1980's (IPCC, 2007a).

    Ocean freshening occurs as a result of melting glaciers, and has been observed in the North Atlantic and the Ross Sea. Ocean freshening has caused some fish species to move south, because of a shift in plankton (IPCC, 2007a). Ocean uptake of carbon dioxide, due to increased atmospheric levels, reduces surface ocean pH (Figure 11) and carbonate ion concentrations. This causes aragonite, which is used by many organisms to make their shells or skeletons to decline or become under-saturated (IPCC, 2007a).

Figure 11. Change in ocean pH between
1700’s and 1990’s (Astrobio, 2010)

 

Coral Reefs: Corals are affected by the warming of surface waters, which causes bleaching to occur. Coral bleaching is whitening caused by the death or expulsion of symbiotic, algae-like protozoa, zooxanthellae from the coral, which is a result of stress to the coral (IPCC, 2007a). There are key temperature thresholds for mass bleaching to occur. It is projected that annual or bi-annual exceedance of bleaching thresholds will occur at the majority of reefs worldwide by 2030 to 2050 (IPCC, 2007a). In 1998 the largest bleaching event to date occurred, killing 16% of the worlds corals, and leading to shifts in reef fish species composition (IPCC, 2007c).

      Corals are also affected  by increased atmospheric CO² concentrations, which results in declining calcification (IPCC, 2007a). Corals are also physically damaged through wave action and light attenuation by storms, such as hurricanes, tropical storms, and tsunamis (IPCC, 2007c). Climate change is increasing the intensity and frequency of storm, posing further threat to reefs (IPCC, 2007c). Corals could become rare on tropical and subtropical reefs by 2050 due to the combined effects of increasing CO2 and increasing frequency of bleaching events (IPCC, 2007a). Coral reefs are habitat for about a quarter of marine species and are the most diverse marine ecosystems (IPCC, 2007a).

  

Sea turtles: Sea turtles are affected by climate change in two ways. Sea turtles physical nests are affected by rising sea levels. They lay their eggs on beaches, such as Brazilian beaches which are threatened by rising sea levels. A third of turtle nesting sites in the Caribbean are threatened by rising sea levels. (Amodeo, 2005). Another issue is the reproductive success of sea turtles. According to a report from the Climate Change and Migratory Species study, sea turtles are under threat because the temperature at which there eggs are incubated determines their sex, with warmer sites producing female offspring (Amodeo, 2005). A nest-warming trend is reducing the number of male offspring, which threatens turtle populations (WWF (c), n/d).

 

Penguins:
 Penguins are at risk as the Antarctic Peninsula is warming faster than anywhere else in the Southern Hemisphere. The loss of sea ice in harming Emperor Penguins who rear their chicks on land locked sea ice. When the sea ice breaks up before the chicks have matured and grown their waterproof feathers, chicks are likely to be swept into the ocean and drown. Loss of sea ice also leads to lower food availability, which raises mortality rates (WWF (c), n/d). The Emperor penguin colony at Terra Adelie in Antarctica could decline by 95% before the end of the century, if sea-ice continues to decline at the current rate. This would place the population at serious risk of extinction (WWF (c), n/d).

 

North Atlantic Right Whale (Eubalaena glacialis): The right whale is one of the most endangered whales, and is further threatened by warming sea temperatures. The availability of food is a problem because warmer waters contain less plankton which is the whale’s main food source. Only 300-350 individuals still exist (WWF (c), n/d).

 

 

Insects and Disease

Pest and diseases have spread to higher altitudes and latitudes due to warmer temperatures and milder winters (IPPC, 2007b). Many diseases are expected to become more lethal or spread more rapidly as the climate warms (Pounds et al., 2005).

Get Involved

There is overwhelming evidence that humans are responsible for the climatic changes that have been observed in Earth's environment and are projected to increase with the continued output of greenhouse gas emissions. It is our responsibility to take action against climate change in order to protect and preserve the animals with which we inhabit this planet, and, ourselves. Reducing our consumption and fossil fuel use is critical if we hope to make a difference before it is too late. Here are a few ways to get involved:

President Obama's Policy

"So we have a choice to make.  We can remain one of the world's leading importers of foreign oil, or we can make the investments that would allow us to become the world's leading exporter of renewable energy.  We can let climate change continue to go unchecked, or we can help stop it.  We can let the jobs of tomorrow be created abroad, or we can create those jobs right here in America and lay the foundation for lasting prosperity."

President Obama, March 19, 2009

The progress that the Obama Administration has made toward climate change include:

  • The American Recovery and Reinvestment Act included more than $80 billion in clean energy investments that will jump-start our economy and build the clean energy jobs of tomorrow.

  • Increasing the fuel economy standards for model year 2011 cars and trucks so they will get better mileage, saving drivers money and spurring companies to develop more innovative products

  • The President issued a memorandum to the Department of Energy to implement more aggressive efficiency standards for common household appliances, like dishwashers and refrigerators.

  • On Earth Day 2009, the President unveiled a program to develop the renewable energy projects on the waters of our Outer Continental Shelf that produce electricity from wind, wave, and ocean currents.

  •  Closing the carbon loophole: by stemming carbon pollution through a market-based cap, we can address in a systematic way all the energy challenges that we face: curbing our dependence on foreign oil, reducing our use of fossil fuels, and promoting new industries right here in America (White House, 2010).

    The Obama administration has created an Interagency Climate Change Adaptation Task Force, which is working on the issue. The key components to a national strategy on climate change adaptation include: integration of science into adaptation decisions and policy; communications and capacity building; coordination and collaboration; prioritization; a flexible framework for Agencies; and evaluation. There is a progress report of the task force released on March 16, 2010 (White House, 2010).

     

    Conclusion

        The issues facing the animal kingdom are broad and complex. The link between climate change and observed impacts on species can be difficult to substantiate given all the contributing factors that can possibly affect changes in animal behavior, distribution, and health. While more evidence is needed, there is a strong correlation between the observed physical changes to the environment and responses from animals. The countless studies and observations of animal species across the globe show us how animals are being affected, and expert predictions for the future are grim without a halt to the current climatic trends.

     

    Useful Links

    Intergovernmental Panel on Climate Change (IPCC) www.ipcc.ch
    World Wildlife Fund (WWF)     http://wwf.panda.org/

 

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