The Effect of Global Warming on Animals and Plants: The Findings of Fourth Assesssment Report
Over the last 100 years, the average global surface temperature has warmed ~0.75°C (~1.4°F) and is projected to rise at an escalating rate over the next century. This rate of warming is significantly larger than the rate of sustained warming over the 6,000 years it took for the globe to warm about 6°C from the last ice age to our current warm interglacial period. Extrapolating the more recent warming trend, we see that a 7°C/1000 years rise in temperature is some seven times faster than in the last 18,000 years. As the planet warms, the rate will continue to escalate.
Not only are wild species and their ecosystems having to adapt to rapidly warming temperatures but they also have to cope with other human-caused problems, such as pollution, land-use change, and invasive species. The synergistic effects of these stresses are greatly affecting the resilience of many species and ecosystems. Noticeable changes have been measured in species over the last 30 to 40 years while the global temperature increased around 0.5°C. As the Summary for Policymakers of Working Group I of the Fourth Assessment Report of the IPCC explained, the global temperature could rise over the next 90 years as much as 6.4°C if we stay on our current energy path—allowing few species to adapt without severe disruptions. Hundreds of studies have found that wild animals and plants on all continents are already exhibiting discernible changes in response to regional climatic changes.
CHANGES IN RANGES
As the globe warms, species in North America are extending their ranges north and up in elevation, as habitats in these areas have warmed sufficiently to allow colonization. The movements of species forced by rapidly rising temperatures, however, are frequently slowed or blocked by other human-made stresses, such as land-use changes. Consequently, moving populations have to navigate around, over, or across freeways, agricultural areas, industrial parks, and cities.
Species near the poleward side of continents (e. g., South Africa’s fynbos) and near mountaintops will have no habitats into which they can disperse as their habitat warms. Species living in these areas will be further stressed by species from farther inland or farther down the mountain moving into their habitats. Indeed, many species currently on islands, on the poleward side of continents, and near the tops of mountains could easily go extinct unless humans move them to another location and make sure they survive there.
From pre-historic to more recent times, species have been found to move independently from other species in their ecosystem, depending on their unique metabolic, physiological, and other requirements. Such independent movement could tear apart communities and disrupt biotic interactions such as predator-prey relationships.
Progressive acidification of oceans due to increasing atmospheric carbon dioxide is also expected to have negative impacts on marine shell-forming organisms (e.g., corals) and their dependent species. Indeed, by 2100 ocean pH is very likely to be lower than during the last 20 million years.
CHANGES IN TIMING
Species on every continent are shifting their timing, such as frogs breeding earlier, cherry blossoms blooming earlier, and leaves turning color later. Over the last 30 years, around 115 species that have exhibited significant changes (plants and animals) in locations around the globe were found to be changing the timing of a spring event earlier by around five days per decade.Only six out of the 115 species (~5%) showed a later timing change.
EXTIRPATION AND EXTINCTION
The escalating rise in average global temperatures over the past century has put numerous species in danger of extinction. “Functionally extinct” species, or species highly likely to go extinct, include those that cannot move to a different location as the temperature increases due to either lack of available habitat or the inability to access it. Without human assistance the probability of these species going extinct is quite high.
Money, land, personnel, or political will are not available for such adaptive endeavors to occur. Also absent is the long-term commitment to translocate even half of the functionally extinct species we know of today. Consequently, many scientists predict that we are standing at the brink of a mass extinction that would be caused by one very careless species.
Roughly 20 to 30 percent of known species are likely to be at increasingly high risk of extinction if global mean temperatures exceed 2–3°C above pre-industrial temperatures (1.3–2.3°C above current). Somewhere between 340,000 and 570,000 of 1.7 million identified species could be committed to extinction primarily due to our negligence.
If we do not change our present trajectory of carbonemitting energy, the global average temperature could warm by 4°C, committing more than 40 percent of the known species to eventual extinction. That is an unethically high price to pay.
What can we do? LOTS! Just as each vote counts, what each of us does adds up to help the Earth win. Some suggestions: drive fuel-efficient cars; stop using incandescent light bulbs in your home or office; when replacing your roof install an insulating one; use highly energy-efficient windows, heaters, air conditioners, and appliances when remodeling. Use material that does not need to be shipped long distances and make sure those materials are harvested sustainably. Buy as much locally produced food as possible, and, last but by no means least, support government officials who are not afraid to take the lead in solving this problem.
FINDINGS OF THE FOURTH ASSESSMENT REPORT OF THE INTERGOVERNMENTAL PANEL CLIMATE CHANGE
This time around, the Intergovernmental Panel on Climate Change (IPCC) reports have bluntly stated Findings of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change that humans are indeed causing the globe to warm and the warming is more rapid than it has ever been in the last 18,000 years. In unusually direct language, Working Group I stated that recent warming is “unequivocal” and that humans are very likely to be a major cause in the past several decades at least. Increased heat waves and more intense hurricanes were also said to be associated with this warming trend.
