Global Warming
"Top climate scientist James Hansen tells the story of his involvement in the science of and debate over global climate change. In doing so he outlines the overwhelming evidence that change is happening and why that makes him deeply worried about the future."
What is Global Warming aka Climate Change?
Global warming is the increase of the average temperature in the atmosphere and oceans over time due primarily to human influences. Since the late 19th century, scientists have monitored the fluctuations in temperature and studied global warming theories and trends to determine the causes and to assess the extent to which they are due to human activity. The greenhouse effect is largely caused by human-generated carbon dioxide (CO2) and, to some extent, by increases in solar activity. The term "global warming" is used to imply a human influence while "climate change" is most often used in association with changes in climate with no easily identifiable cause, such as the processes that produced the Ice Ages.
Current climate models (simulations) based on estimates of increasing CO2 and, to a lesser extent, by decreasing sulfate aerosols, predict that temperatures will increase by 1.4-5.8°C (2.5-10.4°F) between 1990-2100. This is a somewhat wide range; however, it is difficult to predict CO2 emissions because of the number of variables involved. Some climate studies have shown that, even in the absence of the CO2 emission variable, global climate will increase by 0.5°C (0.9°F) over the next one hundred years due to warming caused just by the ocean. In addition, models predict that sea levels will rise by about 10 cm over the next century.
Evidence of global warming includes decreased snowfall, rising sea levels and changes to weather trends. Precipitation levels, precipitation patterns, cloud cover, severe weather, and other elements will be impacted by the increase in greenhouse gas concentrations in the atmosphere. "Greenhouse gases" are so named because they trap radiant energy from the sun that would otherwise be radiated back into space.
The Kyoto Protocol was developed by the United Nations Framework Convention on Climate Change (UNFCCC) as an international agreement to reduce greenhouse gas emissions worldwide. The Protocol was entered into force in February 2005, and signed by countries committed to reducing CO2 emissions and 5 other greenhouse gases. They may also engage in emissions trading, or the purchase of credits from other countries that remain under the limits of greenhouse gas emissions. In this way, countries that may exceed the limits can still comply with the protocol. To date, 141 countries have ratified the agreement. Unfortunately, neither the United States nor Australia have been participating, which has generated speculation as to whether the Kyoto Protocol will successfully reduce greenhouse gases, even if completely implemented by all signed countries.
Global climate change has been studied on a large scale based on analyses of global temperature fluctuations over thousands of years; for example, since the last Ice Age, which occurred approximately 12,000 years ago, global temperatures have been relatively stable. Studies on a smaller scale, however, show that temperatures in the lower troposphere have increased between 0.08 and 0.22°C per decade since 1979. Still, these modern day changes are not always linear, which has created a source of debate within the scientific community and the news media.
The study of paleoclimatology (ancient climates) is increasingly linked to modern day climate study. For example, the Earth was in an ice age for the last 160,000 years prior to the end of the last Ice Age. Earlier studies of this time period showed little variability in temperatures; however, more recent studies showed the variability to be about twice as great as previously published, indicating that temperature fluctuations are more frequent throughout time than first thought. However, this does not negate the impact of human activity on the current rate of global warming.
Climate change is caused by both natural and external forces, the latter including both human—greenhouse gases—and non-human causes such as changes in the Earth's orbit around the Sun, solar activity, and volcanic emissions. Science is increasingly pointing to human activities as the reason that global warming is accelerating.
The greenhouse gas theory started in the 19th century when the Swedish chemist and 1903 Nobel Laureate, Svante Arrhenius, determined that increases in greenhouse gas concentration would lead to higher global mean temperatures, while decreases would lead to colder global mean temperatures. His finding was a result of his research on ice ages, and was largely rejected by his peers at the time. A colleague of Arrhenius, Arvid Högbom, was one of the first scientists to study the carbon cycle. Arrhenius used his data to base his assessment that in 1890, emission and absorption of CO2 in the atmosphere were roughly in balance, and that burning fossil fuels would not cause problems. However, this was based solely on the use of coal, not on the use of fossil fuels in the automobile and other industries.
Opponents to the global warming theory postulate that water vapor and clouds will cancel out warming effect of CO2 emissions. However, the warming trends over the past few decades are increasingly negating the cancellation hypothesis. Furthermore, sophisticated computer models of the climate, validated by the scientific community in demonstrating accurate simulations of known climate variations such as El Niño events, have predicted that adding CO2 to the atmosphere will create a warmer climate in the future. The degree to which this warming will occur varies by model, however, and opponents of the global warming theory point out variables that models are not equipped to factor, such as changes in vegetation and cloud cover.
In spite of the dying debate, it is known that coal-burning power plants, automobile exhausts, factory smokestacks, and other waste vents contribute about 22 billion tons of CO2 (6 billion tons of pure carbon) and other greenhouse gases into the earth's atmosphere each year. CO2 levels have increased by about 31% since 1750, about 75% of which can be attributed to fossil fuel burning. The remaining 25% is largely due to land-use change, particularly deforestation.
In their 2006 report, the IPCC stated that the atmospheric concentration of CO2 has exceeded levels over the natural range for the last 650,000 years. The consensus is that human activity is, in almost all aspects of global warming, the most likely cause. This is a change from the previous report that stated human activity was merely a likely cause.
Take Action Against Global Warming
Share your thoughts
Feedback & Citation
Global Warming News :: ScienceDaily1,000 years of climate data confirms Australia's warming
In the first study of its kind in Australasia, scientists have used 27 natural climate records to create the first large-scale temperature reconstruction for the region over the last 1,000 years.
Humanmade pollutants may be driving Earth's tropical belt expansion: May impact large-scale atmospheric circulation
Black carbon aerosols and tropospheric ozone, both humanmade pollutants emitted predominantly in the Northern Hemisphere's low- to mid-latitudes, are most likely pushing the boundary of the tropics further poleward in that hemisphere, new research shows. While stratospheric ozone depletion has already been shown to be the primary driver of the expansion of the tropics in the Southern Hemisphere, the researchers are the first to report that black carbon and tropospheric ozone are the most likely primary drivers of the tropical expansion observed in the Northern Hemisphere.
Ancient tree-ring records from southwest U.S. suggest today's megafires are truly unusual
Today's mega forest fires of the southwestern U.S. are truly unusual and exceptional in the long-term record, suggests an unprecedented study that examined 1,500 years of ancient tree ring and fire data from two distinct climate periods. Researchers constructed and analyzed a statistical model and found that today's dry, hot climate combined with the past century of human fire suppression is causing megafires.
Statistical analysis projects future temperatures in North America
For the first time, researchers have been able to combine different climate models using spatial statistics -- to project future seasonal temperature changes in regions across North America.
Arctic seabirds adapt to climate change
The planet is warming up, especially at the poles. How do organisms react to this rise in temperatures? Biologists have now shown that little auks, the most common seabirds in the Arctic, are adapting their fishing behavior to warming surface waters in the Greenland Sea. So far, their reproductive and survival rates have not been affected. However, further warming could threaten the species.
Measuring CO<sub>2</sub> to fight global warming, enforce future treaty
If the world's nations ever sign a treaty to limit emissions of climate-warming carbon dioxide gas, there may be a way to help verify compliance. Using measurements from only three carbon-dioxide (monitoring stations in the Salt Lake Valley, the method could reliably detect changes in CO2 emissions of 15 percent or more, researchers report.
Time, place and how wood is used are factors in carbon emissions from deforestation
A new study holds implications for the impact of biofuels production on deforestation and greenhouse gas emissions. The volume of greenhouse gas released when a forest is cleared depends on how the trees will be used and in which part of the world the trees are grown.
Wasted milk is a real drain on our resources, study shows
Milk poured down Britain's kitchen sinks each year creates a carbon footprint equivalent to thousands of car exhaust emissions, research shows.
NASA's new carbon-counting instrument leaves the nest
Its construction now complete, the science instrument that is the heart of NASA's Orbiting Carbon Observatory-2 (OCO-2) spacecraft -- NASA's first mission dedicated to studying atmospheric carbon dioxide -- has left its nest at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and has arrived at its integration and test site in Gilbert, Ariz.
Population pressure impacts world wetlands
The area of the globe covered by wetlands (swamps, marshes, lakes, etc.) has dropped by 6% in fifteen years. This decline is particularly severe in tropical and subtropical regions, and in areas that have experienced the largest increases in population in recent decades.
First forecast calls for mild Amazon fire season in 2012
Forests in the Amazon Basin are expected to be less vulnerable to wildfires this year, according to the first forecast from a new fire severity model.
Potential instability in West Antarctic Ice Sheet from newly discovered basin size of New Jersey
Scientists have uncovered a previously unknown sub-glacial basin nearly the size of New Jersey beneath the West Antarctic Ice Sheet near the Weddell Sea. The location, shape and texture of the mile-deep basin suggest that this region of the ice sheet is at a much greater risk of collapse than previously thought.
New weak point discovered in the Antarctic ice sheet
The Filchner-Ronne Ice Shelf fringing the Weddell Sea, Antarctica, may start to melt rapidly in this century and no longer act as a barrier for ice streams draining the Antarctic Ice Sheet, new research shows.
Antarctic octopus study shows West Antarctic Ice Sheet may have collapsed 200,000 years ago
Scientists have found that genetic information on the Antarctic octopus supports studies indicating that the West Antarctic Ice Sheet could have collapsed during its history, possibly as recently as 200,000 years ago.
Effect of groundwater use: Using water from wells leads to sea level rise, cancels out effect of dams
As people pump groundwater for irrigation, drinking water, and industrial uses, the water doesn't just seep back into the ground -- it also evaporates into the atmosphere, or runs off into rivers and canals, eventually emptying into the world's oceans. This water adds up, and a new study calculates that by 2050, groundwater pumping will cause a global sea level rise of about 0.8 millimeters per year.
Support for climate change action drops, poll finds
Americans' support for government action on global warming remains high but has dropped during the past two years, according to a new survey.
Not always safety in numbers when it comes to extinction risk
A basic tenet underpinning scientists' understanding of extinction is that more abundant species persist longer than their less abundant counterparts. A new study reveals a much more complex relationship. A team of scientists analyzed more than 46,000 fossils from 52 sites and found that greater numbers did indeed help clam-like brachiopods survive the Ordovician extinction. Surprisingly, abundance did not help brachiopod species persist for extended periods outside of the extinction event.
Adirondack lakes in North Eastern US lose ice cover as climate warms: Most pristine lake marks biggest change
Researchers have found lakes in the undeveloped High Peaks area of the Adirondack Park are covered with ice for significantly shorter periods than they were 32 years ago, providing evidence that climate change is occurring rapidly. Not even the most pristine wilderness areas are immune.
New research brings satellite measurements and global climate models closer
One popular climate record that shows a slower atmospheric warming trend than other studies contains a data calibration problem, and when the problem is corrected the results fall in line with other records and climate models, according to a new study.
European mountain plant population shows delayed response to climate change
A modeling study from the European Alps suggests that population declines to be observed during the upcoming decades will probably underestimate the long-term effects of recent climate warming on mountain plants. A European team of ecologists has presented a new modeling tool to predict migration of mountain plants which explicitly takes population dynamic processes into account.
Help us continue to share the wonders of the ocean with the world, raise awareness of marine conservation issues and their solutions, and support marine conservation scientists and students involved in the marine life sciences. Join the MarineBio Conservation Society or make a donation today. We would like to sincerely thank all of our members, donors, and sponsors, we simply could not have achieved what we have without you and we look forward to doing even more.
